Reserved memory regions defined in the devicetree can be broken up into
two groups:
i) Statically-placed reserved memory regions
i.e. regions defined with a static start address and size using the
"reg" property.
ii) Dynamically-placed reserved memory regions.
i.e. regions defined by specifying an address range where they can be
placed in memory using the "alloc_ranges" and "size" properties.
These regions are processed and set aside at boot time.
This is done in two stages as seen below:
Stage 1:
At this stage, fdt_scan_reserved_mem() scans through the child nodes of
the reserved_memory node using the flattened devicetree and does the
following:
1) If the node represents a statically-placed reserved memory region,
i.e. if it is defined using the "reg" property:
- Call memblock_reserve() or memblock_mark_nomap() as needed.
- Add the information for that region into the reserved_mem array
using fdt_reserved_mem_save_node().
i.e. fdt_reserved_mem_save_node(node, name, base, size).
2) If the node represents a dynamically-placed reserved memory region,
i.e. if it is defined using "alloc-ranges" and "size" properties:
- Add the information for that region to the reserved_mem array with
the starting address and size set to 0.
i.e. fdt_reserved_mem_save_node(node, name, 0, 0).
Note: This region is saved to the array with a starting address of 0
because a starting address is not yet allocated for it.
Stage 2:
After iterating through all the reserved memory nodes and storing their
relevant information in the reserved_mem array,fdt_init_reserved_mem() is
called and does the following:
1) For statically-placed reserved memory regions:
- Call the region specific init function using
__reserved_mem_init_node().
2) For dynamically-placed reserved memory regions:
- Call __reserved_mem_alloc_size() which is used to allocate memory
for each of these regions, and mark them as nomap if they have the
nomap property specified in the DT.
- Call the region specific init function.
The current size of the resvered_mem array is 64 as is defined by
MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for
how many reserved memory regions can be specified on a system.
As systems continue to grow more and more complex, the number of
reserved memory regions needed are also growing and are starting to hit
this 64 count limit, hence the need to make the reserved_mem array
dynamically sized (i.e. dynamically allocating memory for the
reserved_mem array using membock_alloc_*).
On architectures such as arm64, memory allocated using memblock is
writable only after the page tables have been setup. This means that if
the reserved_mem array is going to be dynamically allocated, it needs to
happen after the page tables have been setup, not before.
Since the reserved memory regions are currently being processed and
added to the array before the page tables are setup, there is a need to
change the order in which some of the processing is done to allow for
the reserved_mem array to be dynamically sized.
It is possible to process the statically-placed reserved memory regions
without needing to store them in the reserved_mem array until after the
page tables have been setup because all the information stored in the
array is readily available in the devicetree and can be referenced at
any time.
Dynamically-placed reserved memory regions on the other hand get
assigned a start address only at runtime, and hence need a place to be
stored once they are allocated since there is no other referrence to the
start address for these regions.
Hence this patch changes the processing order of the reserved memory
regions in the following ways:
Step 1:
fdt_scan_reserved_mem() scans through the child nodes of
the reserved_memory node using the flattened devicetree and does the
following:
1) If the node represents a statically-placed reserved memory region,
i.e. if it is defined using the "reg" property:
- Call memblock_reserve() or memblock_mark_nomap() as needed.
2) If the node represents a dynamically-placed reserved memory region,
i.e. if it is defined using "alloc-ranges" and "size" properties:
- Call __reserved_mem_alloc_size() which will:
i) Allocate memory for the reserved region and call
memblock_mark_nomap() as needed.
ii) Call the region specific initialization function using
fdt_init_reserved_mem_node().
iii) Save the region information in the reserved_mem array using
fdt_reserved_mem_save_node().
Step 2:
1) This stage of the reserved memory processing is now only used to add
the statically-placed reserved memory regions into the reserved_mem
array using fdt_scan_reserved_mem_reg_nodes(), as well as call their
region specific initialization functions.
2) This step has also been moved to be after the page tables are
setup. Moving this will allow us to replace the reserved_mem
array with a dynamically sized array before storing the rest of
these regions.
Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
---
drivers/of/fdt.c | 5 +-
drivers/of/of_private.h | 3 +-
drivers/of/of_reserved_mem.c | 168 ++++++++++++++++++++++++-----------
3 files changed, 122 insertions(+), 54 deletions(-)
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 4d528c10df3a..d0dbc8183ac4 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -511,8 +511,6 @@ void __init early_init_fdt_scan_reserved_mem(void)
break;
memblock_reserve(base, size);
}
-
- fdt_init_reserved_mem();
}
/**
@@ -1212,6 +1210,9 @@ void __init unflatten_device_tree(void)
{
void *fdt = initial_boot_params;
+ /* Save the statically-placed regions in the reserved_mem array */
+ fdt_scan_reserved_mem_reg_nodes();
+
/* Don't use the bootloader provided DTB if ACPI is enabled */
if (!acpi_disabled)
fdt = NULL;
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index 04aa2a91f851..29525c0b9939 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -9,6 +9,7 @@
*/
#define FDT_ALIGN_SIZE 8
+#define MAX_RESERVED_REGIONS 64
/**
* struct alias_prop - Alias property in 'aliases' node
@@ -180,7 +181,7 @@ static inline struct device_node *__of_get_dma_parent(const struct device_node *
#endif
int fdt_scan_reserved_mem(void);
-void fdt_init_reserved_mem(void);
+void __init fdt_scan_reserved_mem_reg_nodes(void);
bool of_fdt_device_is_available(const void *blob, unsigned long node);
diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 46e1c3fbc769..2011174211f9 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -27,7 +27,6 @@
#include "of_private.h"
-#define MAX_RESERVED_REGIONS 64
static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
static int reserved_mem_count;
@@ -56,6 +55,7 @@ static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
return err;
}
+static void __init fdt_init_reserved_mem_node(struct reserved_mem *rmem);
/*
* fdt_reserved_mem_save_node() - save fdt node for second pass initialization
*/
@@ -74,6 +74,9 @@ static void __init fdt_reserved_mem_save_node(unsigned long node, const char *un
rmem->base = base;
rmem->size = size;
+ /* Call the region specific initialization function */
+ fdt_init_reserved_mem_node(rmem);
+
reserved_mem_count++;
return;
}
@@ -106,7 +109,6 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
phys_addr_t base, size;
int len;
const __be32 *prop;
- int first = 1;
bool nomap;
prop = of_get_flat_dt_prop(node, "reg", &len);
@@ -134,10 +136,6 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
uname, &base, (unsigned long)(size / SZ_1M));
len -= t_len;
- if (first) {
- fdt_reserved_mem_save_node(node, uname, base, size);
- first = 0;
- }
}
return 0;
}
@@ -165,12 +163,77 @@ static int __init __reserved_mem_check_root(unsigned long node)
return 0;
}
+static void __init __rmem_check_for_overlap(void);
+
+/**
+ * fdt_scan_reserved_mem_reg_nodes() - Store info for the "reg" defined
+ * reserved memory regions.
+ *
+ * This function is used to scan through the DT and store the
+ * information for the reserved memory regions that are defined using
+ * the "reg" property. The region node number, name, base address, and
+ * size are all stored in the reserved_mem array by calling the
+ * fdt_reserved_mem_save_node() function.
+ */
+void __init fdt_scan_reserved_mem_reg_nodes(void)
+{
+ int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
+ const void *fdt = initial_boot_params;
+ phys_addr_t base, size;
+ const __be32 *prop;
+ int node, child;
+ int len;
+
+ if (!fdt)
+ return;
+
+ node = fdt_path_offset(fdt, "/reserved-memory");
+ if (node < 0) {
+ pr_info("Reserved memory: No reserved-memory node in the DT\n");
+ return;
+ }
+
+ if (__reserved_mem_check_root(node)) {
+ pr_err("Reserved memory: unsupported node format, ignoring\n");
+ return;
+ }
+
+ fdt_for_each_subnode(child, fdt, node) {
+ const char *uname;
+
+ prop = of_get_flat_dt_prop(child, "reg", &len);
+ if (!prop)
+ continue;
+ if (!of_fdt_device_is_available(fdt, child))
+ continue;
+
+ uname = fdt_get_name(fdt, child, NULL);
+ if (len && len % t_len != 0) {
+ pr_err("Reserved memory: invalid reg property in '%s', skipping node.\n",
+ uname);
+ continue;
+ }
+ base = dt_mem_next_cell(dt_root_addr_cells, &prop);
+ size = dt_mem_next_cell(dt_root_size_cells, &prop);
+
+ if (size)
+ fdt_reserved_mem_save_node(child, uname, base, size);
+ }
+
+ /* check for overlapping reserved regions */
+ __rmem_check_for_overlap();
+}
+
+static int __init __reserved_mem_alloc_size(unsigned long node, const char *uname);
+
/*
* fdt_scan_reserved_mem() - scan a single FDT node for reserved memory
*/
int __init fdt_scan_reserved_mem(void)
{
int node, child;
+ int dynamic_nodes_cnt = 0;
+ int dynamic_nodes[MAX_RESERVED_REGIONS];
const void *fdt = initial_boot_params;
node = fdt_path_offset(fdt, "/reserved-memory");
@@ -192,8 +255,24 @@ int __init fdt_scan_reserved_mem(void)
uname = fdt_get_name(fdt, child, NULL);
err = __reserved_mem_reserve_reg(child, uname);
- if (err == -ENOENT && of_get_flat_dt_prop(child, "size", NULL))
- fdt_reserved_mem_save_node(child, uname, 0, 0);
+ /*
+ * Save the nodes for the dynamically-placed regions
+ * into an array which will be used for allocation right
+ * after all the statically-placed regions are reserved
+ * or marked as no-map. This is done to avoid dynamically
+ * allocating from one of the statically-placed regions.
+ */
+ if (err == -ENOENT && of_get_flat_dt_prop(child, "size", NULL)) {
+ dynamic_nodes[dynamic_nodes_cnt] = child;
+ dynamic_nodes_cnt++;
+ }
+ }
+ for (int i = 0; i < dynamic_nodes_cnt; i++) {
+ const char *uname;
+
+ child = dynamic_nodes[i];
+ uname = fdt_get_name(fdt, child, NULL);
+ __reserved_mem_alloc_size(child, uname);
}
return 0;
}
@@ -253,8 +332,7 @@ static int __init __reserved_mem_alloc_in_range(phys_addr_t size,
* __reserved_mem_alloc_size() - allocate reserved memory described by
* 'size', 'alignment' and 'alloc-ranges' properties.
*/
-static int __init __reserved_mem_alloc_size(unsigned long node,
- const char *uname, phys_addr_t *res_base, phys_addr_t *res_size)
+static int __init __reserved_mem_alloc_size(unsigned long node, const char *uname)
{
int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
phys_addr_t start = 0, end = 0;
@@ -334,9 +412,8 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
return -ENOMEM;
}
- *res_base = base;
- *res_size = size;
-
+ /* Save region in the reserved_mem array */
+ fdt_reserved_mem_save_node(node, uname, base, size);
return 0;
}
@@ -425,48 +502,37 @@ static void __init __rmem_check_for_overlap(void)
}
/**
- * fdt_init_reserved_mem() - allocate and init all saved reserved memory regions
+ * fdt_init_reserved_mem_node() - Initialize a reserved memory region
+ * @rmem: reserved_mem struct of the memory region to be initialized.
+ *
+ * This function is used to call the region specific initialization
+ * function for a reserved memory region.
*/
-void __init fdt_init_reserved_mem(void)
+static void __init fdt_init_reserved_mem_node(struct reserved_mem *rmem)
{
- int i;
-
- /* check for overlapping reserved regions */
- __rmem_check_for_overlap();
-
- for (i = 0; i < reserved_mem_count; i++) {
- struct reserved_mem *rmem = &reserved_mem[i];
- unsigned long node = rmem->fdt_node;
- int err = 0;
- bool nomap;
+ unsigned long node = rmem->fdt_node;
+ int err = 0;
+ bool nomap;
- nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
+ nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
- if (rmem->size == 0)
- err = __reserved_mem_alloc_size(node, rmem->name,
- &rmem->base, &rmem->size);
- if (err == 0) {
- err = __reserved_mem_init_node(rmem);
- if (err != 0 && err != -ENOENT) {
- pr_info("node %s compatible matching fail\n",
- rmem->name);
- if (nomap)
- memblock_clear_nomap(rmem->base, rmem->size);
- else
- memblock_phys_free(rmem->base,
- rmem->size);
- } else {
- phys_addr_t end = rmem->base + rmem->size - 1;
- bool reusable =
- (of_get_flat_dt_prop(node, "reusable", NULL)) != NULL;
-
- pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
- &rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
- nomap ? "nomap" : "map",
- reusable ? "reusable" : "non-reusable",
- rmem->name ? rmem->name : "unknown");
- }
- }
+ err = __reserved_mem_init_node(rmem);
+ if (err != 0 && err != -ENOENT) {
+ pr_info("node %s compatible matching fail\n", rmem->name);
+ if (nomap)
+ memblock_clear_nomap(rmem->base, rmem->size);
+ else
+ memblock_phys_free(rmem->base, rmem->size);
+ } else {
+ phys_addr_t end = rmem->base + rmem->size - 1;
+ bool reusable =
+ (of_get_flat_dt_prop(node, "reusable", NULL)) != NULL;
+
+ pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
+ &rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
+ nomap ? "nomap" : "map",
+ reusable ? "reusable" : "non-reusable",
+ rmem->name ? rmem->name : "unknown");
}
}
--
2.34.1Hi Oreoluwa,
On 10/8/2024 3:06 PM, Oreoluwa Babatunde wrote:
> Reserved memory regions defined in the devicetree can be broken up into
> two groups:
> i) Statically-placed reserved memory regions
> i.e. regions defined with a static start address and size using the
> "reg" property.
> ii) Dynamically-placed reserved memory regions.
> i.e. regions defined by specifying an address range where they can be
> placed in memory using the "alloc_ranges" and "size" properties.
>
> These regions are processed and set aside at boot time.
> This is done in two stages as seen below:
>
> Stage 1:
> At this stage, fdt_scan_reserved_mem() scans through the child nodes of
> the reserved_memory node using the flattened devicetree and does the
> following:
>
> 1) If the node represents a statically-placed reserved memory region,
> i.e. if it is defined using the "reg" property:
> - Call memblock_reserve() or memblock_mark_nomap() as needed.
> - Add the information for that region into the reserved_mem array
> using fdt_reserved_mem_save_node().
> i.e. fdt_reserved_mem_save_node(node, name, base, size).
>
> 2) If the node represents a dynamically-placed reserved memory region,
> i.e. if it is defined using "alloc-ranges" and "size" properties:
> - Add the information for that region to the reserved_mem array with
> the starting address and size set to 0.
> i.e. fdt_reserved_mem_save_node(node, name, 0, 0).
> Note: This region is saved to the array with a starting address of 0
> because a starting address is not yet allocated for it.
>
> Stage 2:
> After iterating through all the reserved memory nodes and storing their
> relevant information in the reserved_mem array,fdt_init_reserved_mem() is
> called and does the following:
>
> 1) For statically-placed reserved memory regions:
> - Call the region specific init function using
> __reserved_mem_init_node().
> 2) For dynamically-placed reserved memory regions:
> - Call __reserved_mem_alloc_size() which is used to allocate memory
> for each of these regions, and mark them as nomap if they have the
> nomap property specified in the DT.
> - Call the region specific init function.
>
> The current size of the resvered_mem array is 64 as is defined by
> MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for
> how many reserved memory regions can be specified on a system.
> As systems continue to grow more and more complex, the number of
> reserved memory regions needed are also growing and are starting to hit
> this 64 count limit, hence the need to make the reserved_mem array
> dynamically sized (i.e. dynamically allocating memory for the
> reserved_mem array using membock_alloc_*).
>
> On architectures such as arm64, memory allocated using memblock is
> writable only after the page tables have been setup. This means that if
> the reserved_mem array is going to be dynamically allocated, it needs to
> happen after the page tables have been setup, not before.
>
> Since the reserved memory regions are currently being processed and
> added to the array before the page tables are setup, there is a need to
> change the order in which some of the processing is done to allow for
> the reserved_mem array to be dynamically sized.
>
> It is possible to process the statically-placed reserved memory regions
> without needing to store them in the reserved_mem array until after the
> page tables have been setup because all the information stored in the
> array is readily available in the devicetree and can be referenced at
> any time.
> Dynamically-placed reserved memory regions on the other hand get
> assigned a start address only at runtime, and hence need a place to be
> stored once they are allocated since there is no other referrence to the
> start address for these regions.
>
> Hence this patch changes the processing order of the reserved memory
> regions in the following ways:
>
> Step 1:
> fdt_scan_reserved_mem() scans through the child nodes of
> the reserved_memory node using the flattened devicetree and does the
> following:
>
> 1) If the node represents a statically-placed reserved memory region,
> i.e. if it is defined using the "reg" property:
> - Call memblock_reserve() or memblock_mark_nomap() as needed.
>
> 2) If the node represents a dynamically-placed reserved memory region,
> i.e. if it is defined using "alloc-ranges" and "size" properties:
> - Call __reserved_mem_alloc_size() which will:
> i) Allocate memory for the reserved region and call
> memblock_mark_nomap() as needed.
> ii) Call the region specific initialization function using
> fdt_init_reserved_mem_node().
> iii) Save the region information in the reserved_mem array using
> fdt_reserved_mem_save_node().
>
> Step 2:
> 1) This stage of the reserved memory processing is now only used to add
> the statically-placed reserved memory regions into the reserved_mem
> array using fdt_scan_reserved_mem_reg_nodes(), as well as call their
> region specific initialization functions.
>
> 2) This step has also been moved to be after the page tables are
> setup. Moving this will allow us to replace the reserved_mem
> array with a dynamically sized array before storing the rest of
> these regions.
I am running into a call trace with this order change on armv7 chip when
I tried to allocate dma coherent memory from the device reserved memory.
The issue does not happen on armv8 chips.
[ 0.000000] Reserved memory: created CMA memory pool at 0x1e000000,
size 32 MiB
[ 0.000000] OF: reserved mem: initialized node dt_reserved_cma,
compatible id shared-dma-pool
[ 0.000000] OF: reserved mem: 0x1e000000..0x1fffffff (32768 KiB) map
reusable dt_reserved_cma
....
[ 0.445322] ------------[ cut here ]------------
[ 0.445353] WARNING: CPU: 0 PID: 1 at mm/memory.c:3069
__apply_to_page_range+0x380/0x388
[ 0.488911] Modules linked in:
[ 0.492027] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted
6.16.0-rc1-g27605c8c0f69-dirty #3 NONE
[ 0.501174] Hardware name: Generic DT based system
[ 0.505965] Call trace:
[ 0.505985] unwind_backtrace from show_stack+0x10/0x14
[ 0.513764] show_stack from dump_stack_lvl+0x54/0x68
[ 0.518834] dump_stack_lvl from __warn+0x7c/0x128
[ 0.523639] __warn from warn_slowpath_fmt+0x184/0x18c
[ 0.527676] Freeing initrd memory: 65536K
[ 0.532788] warn_slowpath_fmt from __apply_to_page_range+0x380/0x388
[ 0.539242] __apply_to_page_range from apply_to_page_range+0x1c/0x24
[ 0.545689] apply_to_page_range from __alloc_from_contiguous+0xc0/0x14c
[ 0.552398] __alloc_from_contiguous from cma_allocator_alloc+0x34/0x3c
[ 0.559016] cma_allocator_alloc from arch_dma_alloc+0x11c/0x2ac
[ 0.565025] arch_dma_alloc from dma_alloc_attrs+0x90/0x2e8
[ 0.570603] dma_alloc_attrs from dmydev_probe+0x8c/0xe8
[ 0.575919] dmydev_probe from platform_probe+0x5c/0xb0
[ 0.581152] platform_probe from really_probe+0xc8/0x2c8
[ 0.586467] really_probe from __driver_probe_device+0x88/0x19c
[ 0.592387] __driver_probe_device from driver_probe_device+0x30/0x104
[ 0.598915] driver_probe_device from __driver_attach+0x90/0x178
[ 0.604921] __driver_attach from bus_for_each_dev+0x7c/0xcc
[ 0.610582] bus_for_each_dev from bus_add_driver+0xcc/0x1ec
[ 0.616241] bus_add_driver from driver_register+0x7c/0x114
[ 0.621814] driver_register from dmydev_init+0x20/0x28
[ 0.627045] dmydev_init from do_one_initcall+0x58/0x200
[ 0.632363] do_one_initcall from kernel_init_freeable+0x1cc/0x228
[ 0.638550] kernel_init_freeable from kernel_init+0x1c/0x12c
[ 0.644299] kernel_init from ret_from_fork+0x14/0x28
[ 0.649351] Exception stack(0xe0819fb0 to 0xe0819ff8)
[ 0.654401] 9fa0: 00000000
00000000 00000000 00000000
[ 0.662575] 9fc0: 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000
[ 0.670747] 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000
[ 0.677403] ---[ end trace 0000000000000000 ]---
[ 0.682083] dmydev dmy_device: Allocate dma memory at 0xde000000 dma
addr 0x1e000000
The reason is that now reserved memory's fixup function
dma_contiguous_early_fixup is called after the page table is
initialized. This fixup function increases the dma_mmu_remap count for
each reserved memory. And the dma_contiguous_remap function depends on
it to properly set up the reserved memory mmu table entry. Before this
change, the paging_init function calls dma_contiguous_remap and it
founds the reserved memory and set it up properly. After the change,
this function found there is no reserved memory so skip any
initialization hence causes the crash later on when my driver tries to
allocate dma memory from the reserved memory.
My workaround below is to move the dma_contiguous_remap out from the
paging_init function to the place right after unflatten_device_tree
where the dma_mmu_remap count is correctly set. But this is not ideal
solution and would like to see if you have any better way to solve the
issue.
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index a41c93988d2c..535d1bf44529 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -1079,6 +1079,7 @@ void __init hyp_mode_check(void)
#endif
}
+void __init dma_contiguous_remap(void);
static void (*__arm_pm_restart)(enum reboot_mode reboot_mode, const
char *cmd);
static int arm_restart(struct notifier_block *nb, unsigned long action,
@@ -1164,6 +1165,7 @@ void __init setup_arch(char **cmdline_p)
}
unflatten_device_tree();
+ dma_contiguous_remap();
arm_dt_init_cpu_maps();
psci_dt_init();
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index edb7f56b7c91..1828c8737d70 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -1773,7 +1773,6 @@ void __init paging_init(const struct machine_desc
*mdesc)
* be used
*/
map_kernel();
- dma_contiguous_remap();
early_fixmap_shutdown();
devicemaps_init(mdesc);
kmap_init();
You can reproduce the issue on any v7 devices by adding these nodes to
the device tree
+ reserved-memory {
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges;
+
+ dt_reserved_cma: dt_reserved_cma {
+ compatible = "shared-dma-pool";
+ reusable;
+
+ reg = <0x1e000000 0x2000000>;
+ };
+ };
+
+ dmy_device {
+ compatible = "xyz,dmydev";
+ memory-region = <&dt_reserved_cma>;
+ };
And use this test driver to trigger the call stack:
diff --git a/drivers/char/dmydev.c b/drivers/char/dmydev.c
new file mode 100644
index 000000000000..1dd52ec492eb
--- /dev/null
+++ b/drivers/char/dmydev.c
@@ -0,0 +1,67 @@
+#include<linux/module.h>
+#include<linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/of_reserved_mem.h>
+#include <linux/dma-mapping.h>
+
+static int dmydev_probe(struct platform_device *pdev)
+{
+ void* virt_addr;
+ dma_addr_t dma_addr;
+ int ret;
+
+ printk(KERN_ALERT "dmydev_probe called\n");
+
+ ret = of_reserved_mem_device_init(&pdev->dev);
+ if (ret && ret != -ENODEV) {
+ dev_err(&pdev->dev, "Couldn't assign reserve memory to
device ret = %d\n", ret);
+ return ret;
+ }
+
+ virt_addr = dma_alloc_coherent(&pdev->dev, 0x800000, &dma_addr,
GFP_KERNEL);
+ if (virt_addr == NULL) {
+ dev_err(&pdev->dev,"Failed to allocated cma memory\n");
+ ret = -ENOMEM;
+ }
+ else
+ dev_err(&pdev->dev,"Allocate dma memory at 0x%px dma
addr %pad\n", virt_addr, &dma_addr);
+
+ return ret;
+}
+
+static void dmydev_remove(struct platform_device *pdev)
+{
+}
+
+static const struct of_device_id dmydev_of_match[] = {
+ {.compatible = "xyz,dmydev"},
+ {}
+};
+MODULE_DEVICE_TABLE(of, dmydev_of_match);
Let me know if you need more info.
>
> Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
> ---
> drivers/of/fdt.c | 5 +-
> drivers/of/of_private.h | 3 +-
> drivers/of/of_reserved_mem.c | 168 ++++++++++++++++++++++++-----------
> 3 files changed, 122 insertions(+), 54 deletions(-)
>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 4d528c10df3a..d0dbc8183ac4 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -511,8 +511,6 @@ void __init early_init_fdt_scan_reserved_mem(void)
> break;
> memblock_reserve(base, size);
> }
> -
> - fdt_init_reserved_mem();
> }
>
> /**
> @@ -1212,6 +1210,9 @@ void __init unflatten_device_tree(void)
> {
> void *fdt = initial_boot_params;
>
> + /* Save the statically-placed regions in the reserved_mem array */
> + fdt_scan_reserved_mem_reg_nodes();
> +
> /* Don't use the bootloader provided DTB if ACPI is enabled */
> if (!acpi_disabled)
> fdt = NULL;
> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
> index 04aa2a91f851..29525c0b9939 100644
> --- a/drivers/of/of_private.h
> +++ b/drivers/of/of_private.h
> @@ -9,6 +9,7 @@
> */
>
> #define FDT_ALIGN_SIZE 8
> +#define MAX_RESERVED_REGIONS 64
>
> /**
> * struct alias_prop - Alias property in 'aliases' node
> @@ -180,7 +181,7 @@ static inline struct device_node *__of_get_dma_parent(const struct device_node *
> #endif
>
> int fdt_scan_reserved_mem(void);
> -void fdt_init_reserved_mem(void);
> +void __init fdt_scan_reserved_mem_reg_nodes(void);
>
> bool of_fdt_device_is_available(const void *blob, unsigned long node);
>
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> index 46e1c3fbc769..2011174211f9 100644
> --- a/drivers/of/of_reserved_mem.c
> +++ b/drivers/of/of_reserved_mem.c
> @@ -27,7 +27,6 @@
>
> #include "of_private.h"
>
> -#define MAX_RESERVED_REGIONS 64
> static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
> static int reserved_mem_count;
>
> @@ -56,6 +55,7 @@ static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
> return err;
> }
>
> +static void __init fdt_init_reserved_mem_node(struct reserved_mem *rmem);
> /*
> * fdt_reserved_mem_save_node() - save fdt node for second pass initialization
> */
> @@ -74,6 +74,9 @@ static void __init fdt_reserved_mem_save_node(unsigned long node, const char *un
> rmem->base = base;
> rmem->size = size;
>
> + /* Call the region specific initialization function */
> + fdt_init_reserved_mem_node(rmem);
> +
> reserved_mem_count++;
> return;
> }
> @@ -106,7 +109,6 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
> phys_addr_t base, size;
> int len;
> const __be32 *prop;
> - int first = 1;
> bool nomap;
>
> prop = of_get_flat_dt_prop(node, "reg", &len);
> @@ -134,10 +136,6 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
> uname, &base, (unsigned long)(size / SZ_1M));
>
> len -= t_len;
> - if (first) {
> - fdt_reserved_mem_save_node(node, uname, base, size);
> - first = 0;
> - }
> }
> return 0;
> }
> @@ -165,12 +163,77 @@ static int __init __reserved_mem_check_root(unsigned long node)
> return 0;
> }
>
> +static void __init __rmem_check_for_overlap(void);
> +
> +/**
> + * fdt_scan_reserved_mem_reg_nodes() - Store info for the "reg" defined
> + * reserved memory regions.
> + *
> + * This function is used to scan through the DT and store the
> + * information for the reserved memory regions that are defined using
> + * the "reg" property. The region node number, name, base address, and
> + * size are all stored in the reserved_mem array by calling the
> + * fdt_reserved_mem_save_node() function.
> + */
> +void __init fdt_scan_reserved_mem_reg_nodes(void)
> +{
> + int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
> + const void *fdt = initial_boot_params;
> + phys_addr_t base, size;
> + const __be32 *prop;
> + int node, child;
> + int len;
> +
> + if (!fdt)
> + return;
> +
> + node = fdt_path_offset(fdt, "/reserved-memory");
> + if (node < 0) {
> + pr_info("Reserved memory: No reserved-memory node in the DT\n");
> + return;
> + }
> +
> + if (__reserved_mem_check_root(node)) {
> + pr_err("Reserved memory: unsupported node format, ignoring\n");
> + return;
> + }
> +
> + fdt_for_each_subnode(child, fdt, node) {
> + const char *uname;
> +
> + prop = of_get_flat_dt_prop(child, "reg", &len);
> + if (!prop)
> + continue;
> + if (!of_fdt_device_is_available(fdt, child))
> + continue;
> +
> + uname = fdt_get_name(fdt, child, NULL);
> + if (len && len % t_len != 0) {
> + pr_err("Reserved memory: invalid reg property in '%s', skipping node.\n",
> + uname);
> + continue;
> + }
> + base = dt_mem_next_cell(dt_root_addr_cells, &prop);
> + size = dt_mem_next_cell(dt_root_size_cells, &prop);
> +
> + if (size)
> + fdt_reserved_mem_save_node(child, uname, base, size);
> + }
> +
> + /* check for overlapping reserved regions */
> + __rmem_check_for_overlap();
> +}
> +
> +static int __init __reserved_mem_alloc_size(unsigned long node, const char *uname);
> +
> /*
> * fdt_scan_reserved_mem() - scan a single FDT node for reserved memory
> */
> int __init fdt_scan_reserved_mem(void)
> {
> int node, child;
> + int dynamic_nodes_cnt = 0;
> + int dynamic_nodes[MAX_RESERVED_REGIONS];
> const void *fdt = initial_boot_params;
>
> node = fdt_path_offset(fdt, "/reserved-memory");
> @@ -192,8 +255,24 @@ int __init fdt_scan_reserved_mem(void)
> uname = fdt_get_name(fdt, child, NULL);
>
> err = __reserved_mem_reserve_reg(child, uname);
> - if (err == -ENOENT && of_get_flat_dt_prop(child, "size", NULL))
> - fdt_reserved_mem_save_node(child, uname, 0, 0);
> + /*
> + * Save the nodes for the dynamically-placed regions
> + * into an array which will be used for allocation right
> + * after all the statically-placed regions are reserved
> + * or marked as no-map. This is done to avoid dynamically
> + * allocating from one of the statically-placed regions.
> + */
> + if (err == -ENOENT && of_get_flat_dt_prop(child, "size", NULL)) {
> + dynamic_nodes[dynamic_nodes_cnt] = child;
> + dynamic_nodes_cnt++;
> + }
> + }
> + for (int i = 0; i < dynamic_nodes_cnt; i++) {
> + const char *uname;
> +
> + child = dynamic_nodes[i];
> + uname = fdt_get_name(fdt, child, NULL);
> + __reserved_mem_alloc_size(child, uname);
> }
> return 0;
> }
> @@ -253,8 +332,7 @@ static int __init __reserved_mem_alloc_in_range(phys_addr_t size,
> * __reserved_mem_alloc_size() - allocate reserved memory described by
> * 'size', 'alignment' and 'alloc-ranges' properties.
> */
> -static int __init __reserved_mem_alloc_size(unsigned long node,
> - const char *uname, phys_addr_t *res_base, phys_addr_t *res_size)
> +static int __init __reserved_mem_alloc_size(unsigned long node, const char *uname)
> {
> int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
> phys_addr_t start = 0, end = 0;
> @@ -334,9 +412,8 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
> return -ENOMEM;
> }
>
> - *res_base = base;
> - *res_size = size;
> -
> + /* Save region in the reserved_mem array */
> + fdt_reserved_mem_save_node(node, uname, base, size);
> return 0;
> }
>
> @@ -425,48 +502,37 @@ static void __init __rmem_check_for_overlap(void)
> }
>
> /**
> - * fdt_init_reserved_mem() - allocate and init all saved reserved memory regions
> + * fdt_init_reserved_mem_node() - Initialize a reserved memory region
> + * @rmem: reserved_mem struct of the memory region to be initialized.
> + *
> + * This function is used to call the region specific initialization
> + * function for a reserved memory region.
> */
> -void __init fdt_init_reserved_mem(void)
> +static void __init fdt_init_reserved_mem_node(struct reserved_mem *rmem)
> {
> - int i;
> -
> - /* check for overlapping reserved regions */
> - __rmem_check_for_overlap();
> -
> - for (i = 0; i < reserved_mem_count; i++) {
> - struct reserved_mem *rmem = &reserved_mem[i];
> - unsigned long node = rmem->fdt_node;
> - int err = 0;
> - bool nomap;
> + unsigned long node = rmem->fdt_node;
> + int err = 0;
> + bool nomap;
>
> - nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
> + nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
>
> - if (rmem->size == 0)
> - err = __reserved_mem_alloc_size(node, rmem->name,
> - &rmem->base, &rmem->size);
> - if (err == 0) {
> - err = __reserved_mem_init_node(rmem);
> - if (err != 0 && err != -ENOENT) {
> - pr_info("node %s compatible matching fail\n",
> - rmem->name);
> - if (nomap)
> - memblock_clear_nomap(rmem->base, rmem->size);
> - else
> - memblock_phys_free(rmem->base,
> - rmem->size);
> - } else {
> - phys_addr_t end = rmem->base + rmem->size - 1;
> - bool reusable =
> - (of_get_flat_dt_prop(node, "reusable", NULL)) != NULL;
> -
> - pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
> - &rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
> - nomap ? "nomap" : "map",
> - reusable ? "reusable" : "non-reusable",
> - rmem->name ? rmem->name : "unknown");
> - }
> - }
> + err = __reserved_mem_init_node(rmem);
> + if (err != 0 && err != -ENOENT) {
> + pr_info("node %s compatible matching fail\n", rmem->name);
> + if (nomap)
> + memblock_clear_nomap(rmem->base, rmem->size);
> + else
> + memblock_phys_free(rmem->base, rmem->size);
> + } else {
> + phys_addr_t end = rmem->base + rmem->size - 1;
> + bool reusable =
> + (of_get_flat_dt_prop(node, "reusable", NULL)) != NULL;
> +
> + pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
> + &rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
> + nomap ? "nomap" : "map",
> + reusable ? "reusable" : "non-reusable",
> + rmem->name ? rmem->name : "unknown");
> }
> }
>
On Tue, Jun 17, 2025 at 10:15 AM William Zhang
<william.zhang@broadcom.com> wrote:
>
> Hi Oreoluwa,
>
> On 10/8/2024 3:06 PM, Oreoluwa Babatunde wrote:
> > Reserved memory regions defined in the devicetree can be broken up into
> > two groups:
> > i) Statically-placed reserved memory regions
> > i.e. regions defined with a static start address and size using the
> > "reg" property.
> > ii) Dynamically-placed reserved memory regions.
> > i.e. regions defined by specifying an address range where they can be
> > placed in memory using the "alloc_ranges" and "size" properties.
> >
> > These regions are processed and set aside at boot time.
> > This is done in two stages as seen below:
> >
> > Stage 1:
> > At this stage, fdt_scan_reserved_mem() scans through the child nodes of
> > the reserved_memory node using the flattened devicetree and does the
> > following:
> >
> > 1) If the node represents a statically-placed reserved memory region,
> > i.e. if it is defined using the "reg" property:
> > - Call memblock_reserve() or memblock_mark_nomap() as needed.
> > - Add the information for that region into the reserved_mem array
> > using fdt_reserved_mem_save_node().
> > i.e. fdt_reserved_mem_save_node(node, name, base, size).
> >
> > 2) If the node represents a dynamically-placed reserved memory region,
> > i.e. if it is defined using "alloc-ranges" and "size" properties:
> > - Add the information for that region to the reserved_mem array with
> > the starting address and size set to 0.
> > i.e. fdt_reserved_mem_save_node(node, name, 0, 0).
> > Note: This region is saved to the array with a starting address of 0
> > because a starting address is not yet allocated for it.
> >
> > Stage 2:
> > After iterating through all the reserved memory nodes and storing their
> > relevant information in the reserved_mem array,fdt_init_reserved_mem() is
> > called and does the following:
> >
> > 1) For statically-placed reserved memory regions:
> > - Call the region specific init function using
> > __reserved_mem_init_node().
> > 2) For dynamically-placed reserved memory regions:
> > - Call __reserved_mem_alloc_size() which is used to allocate memory
> > for each of these regions, and mark them as nomap if they have the
> > nomap property specified in the DT.
> > - Call the region specific init function.
> >
> > The current size of the resvered_mem array is 64 as is defined by
> > MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for
> > how many reserved memory regions can be specified on a system.
> > As systems continue to grow more and more complex, the number of
> > reserved memory regions needed are also growing and are starting to hit
> > this 64 count limit, hence the need to make the reserved_mem array
> > dynamically sized (i.e. dynamically allocating memory for the
> > reserved_mem array using membock_alloc_*).
> >
> > On architectures such as arm64, memory allocated using memblock is
> > writable only after the page tables have been setup. This means that if
> > the reserved_mem array is going to be dynamically allocated, it needs to
> > happen after the page tables have been setup, not before.
> >
> > Since the reserved memory regions are currently being processed and
> > added to the array before the page tables are setup, there is a need to
> > change the order in which some of the processing is done to allow for
> > the reserved_mem array to be dynamically sized.
> >
> > It is possible to process the statically-placed reserved memory regions
> > without needing to store them in the reserved_mem array until after the
> > page tables have been setup because all the information stored in the
> > array is readily available in the devicetree and can be referenced at
> > any time.
> > Dynamically-placed reserved memory regions on the other hand get
> > assigned a start address only at runtime, and hence need a place to be
> > stored once they are allocated since there is no other referrence to the
> > start address for these regions.
> >
> > Hence this patch changes the processing order of the reserved memory
> > regions in the following ways:
> >
> > Step 1:
> > fdt_scan_reserved_mem() scans through the child nodes of
> > the reserved_memory node using the flattened devicetree and does the
> > following:
> >
> > 1) If the node represents a statically-placed reserved memory region,
> > i.e. if it is defined using the "reg" property:
> > - Call memblock_reserve() or memblock_mark_nomap() as needed.
> >
> > 2) If the node represents a dynamically-placed reserved memory region,
> > i.e. if it is defined using "alloc-ranges" and "size" properties:
> > - Call __reserved_mem_alloc_size() which will:
> > i) Allocate memory for the reserved region and call
> > memblock_mark_nomap() as needed.
> > ii) Call the region specific initialization function using
> > fdt_init_reserved_mem_node().
> > iii) Save the region information in the reserved_mem array using
> > fdt_reserved_mem_save_node().
> >
> > Step 2:
> > 1) This stage of the reserved memory processing is now only used to add
> > the statically-placed reserved memory regions into the reserved_mem
> > array using fdt_scan_reserved_mem_reg_nodes(), as well as call their
> > region specific initialization functions.
> >
> > 2) This step has also been moved to be after the page tables are
> > setup. Moving this will allow us to replace the reserved_mem
> > array with a dynamically sized array before storing the rest of
> > these regions.
> I am running into a call trace with this order change on armv7 chip when
> I tried to allocate dma coherent memory from the device reserved memory.
> The issue does not happen on armv8 chips.
>
> [ 0.000000] Reserved memory: created CMA memory pool at 0x1e000000,
> size 32 MiB
> [ 0.000000] OF: reserved mem: initialized node dt_reserved_cma,
> compatible id shared-dma-pool
> [ 0.000000] OF: reserved mem: 0x1e000000..0x1fffffff (32768 KiB) map
> reusable dt_reserved_cma
> ....
>
> [ 0.445322] ------------[ cut here ]------------
> [ 0.445353] WARNING: CPU: 0 PID: 1 at mm/memory.c:3069
> __apply_to_page_range+0x380/0x388
> [ 0.488911] Modules linked in:
> [ 0.492027] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted
> 6.16.0-rc1-g27605c8c0f69-dirty #3 NONE
> [ 0.501174] Hardware name: Generic DT based system
> [ 0.505965] Call trace:
> [ 0.505985] unwind_backtrace from show_stack+0x10/0x14
> [ 0.513764] show_stack from dump_stack_lvl+0x54/0x68
> [ 0.518834] dump_stack_lvl from __warn+0x7c/0x128
> [ 0.523639] __warn from warn_slowpath_fmt+0x184/0x18c
> [ 0.527676] Freeing initrd memory: 65536K
> [ 0.532788] warn_slowpath_fmt from __apply_to_page_range+0x380/0x388
> [ 0.539242] __apply_to_page_range from apply_to_page_range+0x1c/0x24
> [ 0.545689] apply_to_page_range from __alloc_from_contiguous+0xc0/0x14c
> [ 0.552398] __alloc_from_contiguous from cma_allocator_alloc+0x34/0x3c
> [ 0.559016] cma_allocator_alloc from arch_dma_alloc+0x11c/0x2ac
> [ 0.565025] arch_dma_alloc from dma_alloc_attrs+0x90/0x2e8
> [ 0.570603] dma_alloc_attrs from dmydev_probe+0x8c/0xe8
> [ 0.575919] dmydev_probe from platform_probe+0x5c/0xb0
> [ 0.581152] platform_probe from really_probe+0xc8/0x2c8
> [ 0.586467] really_probe from __driver_probe_device+0x88/0x19c
> [ 0.592387] __driver_probe_device from driver_probe_device+0x30/0x104
> [ 0.598915] driver_probe_device from __driver_attach+0x90/0x178
> [ 0.604921] __driver_attach from bus_for_each_dev+0x7c/0xcc
> [ 0.610582] bus_for_each_dev from bus_add_driver+0xcc/0x1ec
> [ 0.616241] bus_add_driver from driver_register+0x7c/0x114
> [ 0.621814] driver_register from dmydev_init+0x20/0x28
> [ 0.627045] dmydev_init from do_one_initcall+0x58/0x200
> [ 0.632363] do_one_initcall from kernel_init_freeable+0x1cc/0x228
> [ 0.638550] kernel_init_freeable from kernel_init+0x1c/0x12c
> [ 0.644299] kernel_init from ret_from_fork+0x14/0x28
> [ 0.649351] Exception stack(0xe0819fb0 to 0xe0819ff8)
> [ 0.654401] 9fa0: 00000000
> 00000000 00000000 00000000
> [ 0.662575] 9fc0: 00000000 00000000 00000000 00000000 00000000
> 00000000 00000000 00000000
> [ 0.670747] 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000
> [ 0.677403] ---[ end trace 0000000000000000 ]---
> [ 0.682083] dmydev dmy_device: Allocate dma memory at 0xde000000 dma
> addr 0x1e000000
>
> The reason is that now reserved memory's fixup function
> dma_contiguous_early_fixup is called after the page table is
> initialized. This fixup function increases the dma_mmu_remap count for
> each reserved memory. And the dma_contiguous_remap function depends on
> it to properly set up the reserved memory mmu table entry. Before this
> change, the paging_init function calls dma_contiguous_remap and it
> founds the reserved memory and set it up properly. After the change,
> this function found there is no reserved memory so skip any
> initialization hence causes the crash later on when my driver tries to
> allocate dma memory from the reserved memory.
>
> My workaround below is to move the dma_contiguous_remap out from the
> paging_init function to the place right after unflatten_device_tree
> where the dma_mmu_remap count is correctly set. But this is not ideal
> solution and would like to see if you have any better way to solve the
> issue.
>
> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> index a41c93988d2c..535d1bf44529 100644
> --- a/arch/arm/kernel/setup.c
> +++ b/arch/arm/kernel/setup.c
> @@ -1079,6 +1079,7 @@ void __init hyp_mode_check(void)
> #endif
> }
>
> +void __init dma_contiguous_remap(void);
> static void (*__arm_pm_restart)(enum reboot_mode reboot_mode, const
> char *cmd);
>
> static int arm_restart(struct notifier_block *nb, unsigned long action,
> @@ -1164,6 +1165,7 @@ void __init setup_arch(char **cmdline_p)
> }
>
> unflatten_device_tree();
> + dma_contiguous_remap();
>
> arm_dt_init_cpu_maps();
> psci_dt_init();
> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> index edb7f56b7c91..1828c8737d70 100644
> --- a/arch/arm/mm/mmu.c
> +++ b/arch/arm/mm/mmu.c
> @@ -1773,7 +1773,6 @@ void __init paging_init(const struct machine_desc
> *mdesc)
> * be used
> */
> map_kernel();
> - dma_contiguous_remap();
> early_fixmap_shutdown();
> devicemaps_init(mdesc);
> kmap_init();
>
> You can reproduce the issue on any v7 devices by adding these nodes to
> the device tree
> + reserved-memory {
> + #address-cells = <1>;
> + #size-cells = <1>;
> + ranges;
> +
> + dt_reserved_cma: dt_reserved_cma {
> + compatible = "shared-dma-pool";
> + reusable;
> +
> + reg = <0x1e000000 0x2000000>;
> + };
> + };
> +
> + dmy_device {
> + compatible = "xyz,dmydev";
> + memory-region = <&dt_reserved_cma>;
> + };
>
> And use this test driver to trigger the call stack:
> diff --git a/drivers/char/dmydev.c b/drivers/char/dmydev.c
> new file mode 100644
> index 000000000000..1dd52ec492eb
> --- /dev/null
> +++ b/drivers/char/dmydev.c
> @@ -0,0 +1,67 @@
> +#include<linux/module.h>
> +#include<linux/kernel.h>
> +#include <linux/platform_device.h>
> +#include <linux/of.h>
> +#include <linux/of_reserved_mem.h>
> +#include <linux/dma-mapping.h>
> +
> +static int dmydev_probe(struct platform_device *pdev)
> +{
> + void* virt_addr;
> + dma_addr_t dma_addr;
> + int ret;
> +
> + printk(KERN_ALERT "dmydev_probe called\n");
> +
> + ret = of_reserved_mem_device_init(&pdev->dev);
> + if (ret && ret != -ENODEV) {
> + dev_err(&pdev->dev, "Couldn't assign reserve memory to
> device ret = %d\n", ret);
> + return ret;
> + }
> +
> + virt_addr = dma_alloc_coherent(&pdev->dev, 0x800000, &dma_addr,
> GFP_KERNEL);
> + if (virt_addr == NULL) {
> + dev_err(&pdev->dev,"Failed to allocated cma memory\n");
> + ret = -ENOMEM;
> + }
> + else
> + dev_err(&pdev->dev,"Allocate dma memory at 0x%px dma
> addr %pad\n", virt_addr, &dma_addr);
> +
> + return ret;
> +}
> +
> +static void dmydev_remove(struct platform_device *pdev)
> +{
> +}
> +
> +static const struct of_device_id dmydev_of_match[] = {
> + {.compatible = "xyz,dmydev"},
> + {}
> +};
> +MODULE_DEVICE_TABLE(of, dmydev_of_match);
>
> Let me know if you need more info.
>
> >
> > Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
> > ---
> > drivers/of/fdt.c | 5 +-
> > drivers/of/of_private.h | 3 +-
> > drivers/of/of_reserved_mem.c | 168 ++++++++++++++++++++++++-----------
> > 3 files changed, 122 insertions(+), 54 deletions(-)
> >
> > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> > index 4d528c10df3a..d0dbc8183ac4 100644
> > --- a/drivers/of/fdt.c
> > +++ b/drivers/of/fdt.c
> > @@ -511,8 +511,6 @@ void __init early_init_fdt_scan_reserved_mem(void)
> > break;
> > memblock_reserve(base, size);
> > }
> > -
> > - fdt_init_reserved_mem();
> > }
> >
> > /**
> > @@ -1212,6 +1210,9 @@ void __init unflatten_device_tree(void)
> > {
> > void *fdt = initial_boot_params;
> >
> > + /* Save the statically-placed regions in the reserved_mem array */
> > + fdt_scan_reserved_mem_reg_nodes();
> > +
> > /* Don't use the bootloader provided DTB if ACPI is enabled */
> > if (!acpi_disabled)
> > fdt = NULL;
> > diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
> > index 04aa2a91f851..29525c0b9939 100644
> > --- a/drivers/of/of_private.h
> > +++ b/drivers/of/of_private.h
> > @@ -9,6 +9,7 @@
> > */
> >
> > #define FDT_ALIGN_SIZE 8
> > +#define MAX_RESERVED_REGIONS 64
> >
> > /**
> > * struct alias_prop - Alias property in 'aliases' node
> > @@ -180,7 +181,7 @@ static inline struct device_node *__of_get_dma_parent(const struct device_node *
> > #endif
> >
> > int fdt_scan_reserved_mem(void);
> > -void fdt_init_reserved_mem(void);
> > +void __init fdt_scan_reserved_mem_reg_nodes(void);
> >
> > bool of_fdt_device_is_available(const void *blob, unsigned long node);
> >
> > diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> > index 46e1c3fbc769..2011174211f9 100644
> > --- a/drivers/of/of_reserved_mem.c
> > +++ b/drivers/of/of_reserved_mem.c
> > @@ -27,7 +27,6 @@
> >
> > #include "of_private.h"
> >
> > -#define MAX_RESERVED_REGIONS 64
> > static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
> > static int reserved_mem_count;
> >
> > @@ -56,6 +55,7 @@ static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
> > return err;
> > }
> >
> > +static void __init fdt_init_reserved_mem_node(struct reserved_mem *rmem);
> > /*
> > * fdt_reserved_mem_save_node() - save fdt node for second pass initialization
> > */
> > @@ -74,6 +74,9 @@ static void __init fdt_reserved_mem_save_node(unsigned long node, const char *un
> > rmem->base = base;
> > rmem->size = size;
> >
> > + /* Call the region specific initialization function */
> > + fdt_init_reserved_mem_node(rmem);
> > +
> > reserved_mem_count++;
> > return;
> > }
> > @@ -106,7 +109,6 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
> > phys_addr_t base, size;
> > int len;
> > const __be32 *prop;
> > - int first = 1;
> > bool nomap;
> >
> > prop = of_get_flat_dt_prop(node, "reg", &len);
> > @@ -134,10 +136,6 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
> > uname, &base, (unsigned long)(size / SZ_1M));
> >
> > len -= t_len;
> > - if (first) {
> > - fdt_reserved_mem_save_node(node, uname, base, size);
> > - first = 0;
> > - }
> > }
> > return 0;
> > }
> > @@ -165,12 +163,77 @@ static int __init __reserved_mem_check_root(unsigned long node)
> > return 0;
> > }
> >
> > +static void __init __rmem_check_for_overlap(void);
> > +
> > +/**
> > + * fdt_scan_reserved_mem_reg_nodes() - Store info for the "reg" defined
> > + * reserved memory regions.
> > + *
> > + * This function is used to scan through the DT and store the
> > + * information for the reserved memory regions that are defined using
> > + * the "reg" property. The region node number, name, base address, and
> > + * size are all stored in the reserved_mem array by calling the
> > + * fdt_reserved_mem_save_node() function.
> > + */
> > +void __init fdt_scan_reserved_mem_reg_nodes(void)
> > +{
> > + int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
> > + const void *fdt = initial_boot_params;
> > + phys_addr_t base, size;
> > + const __be32 *prop;
> > + int node, child;
> > + int len;
> > +
> > + if (!fdt)
> > + return;
> > +
> > + node = fdt_path_offset(fdt, "/reserved-memory");
> > + if (node < 0) {
> > + pr_info("Reserved memory: No reserved-memory node in the DT\n");
> > + return;
> > + }
> > +
> > + if (__reserved_mem_check_root(node)) {
> > + pr_err("Reserved memory: unsupported node format, ignoring\n");
> > + return;
> > + }
> > +
> > + fdt_for_each_subnode(child, fdt, node) {
> > + const char *uname;
> > +
> > + prop = of_get_flat_dt_prop(child, "reg", &len);
> > + if (!prop)
> > + continue;
> > + if (!of_fdt_device_is_available(fdt, child))
> > + continue;
> > +
> > + uname = fdt_get_name(fdt, child, NULL);
> > + if (len && len % t_len != 0) {
> > + pr_err("Reserved memory: invalid reg property in '%s', skipping node.\n",
> > + uname);
> > + continue;
> > + }
> > + base = dt_mem_next_cell(dt_root_addr_cells, &prop);
> > + size = dt_mem_next_cell(dt_root_size_cells, &prop);
> > +
> > + if (size)
> > + fdt_reserved_mem_save_node(child, uname, base, size);
> > + }
> > +
> > + /* check for overlapping reserved regions */
> > + __rmem_check_for_overlap();
> > +}
> > +
> > +static int __init __reserved_mem_alloc_size(unsigned long node, const char *uname);
> > +
> > /*
> > * fdt_scan_reserved_mem() - scan a single FDT node for reserved memory
> > */
> > int __init fdt_scan_reserved_mem(void)
> > {
> > int node, child;
> > + int dynamic_nodes_cnt = 0;
> > + int dynamic_nodes[MAX_RESERVED_REGIONS];
> > const void *fdt = initial_boot_params;
> >
> > node = fdt_path_offset(fdt, "/reserved-memory");
> > @@ -192,8 +255,24 @@ int __init fdt_scan_reserved_mem(void)
> > uname = fdt_get_name(fdt, child, NULL);
> >
> > err = __reserved_mem_reserve_reg(child, uname);
> > - if (err == -ENOENT && of_get_flat_dt_prop(child, "size", NULL))
> > - fdt_reserved_mem_save_node(child, uname, 0, 0);
> > + /*
> > + * Save the nodes for the dynamically-placed regions
> > + * into an array which will be used for allocation right
> > + * after all the statically-placed regions are reserved
> > + * or marked as no-map. This is done to avoid dynamically
> > + * allocating from one of the statically-placed regions.
> > + */
> > + if (err == -ENOENT && of_get_flat_dt_prop(child, "size", NULL)) {
> > + dynamic_nodes[dynamic_nodes_cnt] = child;
> > + dynamic_nodes_cnt++;
> > + }
> > + }
> > + for (int i = 0; i < dynamic_nodes_cnt; i++) {
> > + const char *uname;
> > +
> > + child = dynamic_nodes[i];
> > + uname = fdt_get_name(fdt, child, NULL);
> > + __reserved_mem_alloc_size(child, uname);
> > }
> > return 0;
> > }
> > @@ -253,8 +332,7 @@ static int __init __reserved_mem_alloc_in_range(phys_addr_t size,
> > * __reserved_mem_alloc_size() - allocate reserved memory described by
> > * 'size', 'alignment' and 'alloc-ranges' properties.
> > */
> > -static int __init __reserved_mem_alloc_size(unsigned long node,
> > - const char *uname, phys_addr_t *res_base, phys_addr_t *res_size)
> > +static int __init __reserved_mem_alloc_size(unsigned long node, const char *uname)
> > {
> > int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
> > phys_addr_t start = 0, end = 0;
> > @@ -334,9 +412,8 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
> > return -ENOMEM;
> > }
> >
> > - *res_base = base;
> > - *res_size = size;
> > -
> > + /* Save region in the reserved_mem array */
> > + fdt_reserved_mem_save_node(node, uname, base, size);
> > return 0;
> > }
> >
> > @@ -425,48 +502,37 @@ static void __init __rmem_check_for_overlap(void)
> > }
> >
> > /**
> > - * fdt_init_reserved_mem() - allocate and init all saved reserved memory regions
> > + * fdt_init_reserved_mem_node() - Initialize a reserved memory region
> > + * @rmem: reserved_mem struct of the memory region to be initialized.
> > + *
> > + * This function is used to call the region specific initialization
> > + * function for a reserved memory region.
> > */
> > -void __init fdt_init_reserved_mem(void)
> > +static void __init fdt_init_reserved_mem_node(struct reserved_mem *rmem)
> > {
> > - int i;
> > -
> > - /* check for overlapping reserved regions */
> > - __rmem_check_for_overlap();
> > -
> > - for (i = 0; i < reserved_mem_count; i++) {
> > - struct reserved_mem *rmem = &reserved_mem[i];
> > - unsigned long node = rmem->fdt_node;
> > - int err = 0;
> > - bool nomap;
> > + unsigned long node = rmem->fdt_node;
> > + int err = 0;
> > + bool nomap;
> >
> > - nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
> > + nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
> >
> > - if (rmem->size == 0)
> > - err = __reserved_mem_alloc_size(node, rmem->name,
> > - &rmem->base, &rmem->size);
> > - if (err == 0) {
> > - err = __reserved_mem_init_node(rmem);
> > - if (err != 0 && err != -ENOENT) {
> > - pr_info("node %s compatible matching fail\n",
> > - rmem->name);
> > - if (nomap)
> > - memblock_clear_nomap(rmem->base, rmem->size);
> > - else
> > - memblock_phys_free(rmem->base,
> > - rmem->size);
> > - } else {
> > - phys_addr_t end = rmem->base + rmem->size - 1;
> > - bool reusable =
> > - (of_get_flat_dt_prop(node, "reusable", NULL)) != NULL;
> > -
> > - pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
> > - &rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
> > - nomap ? "nomap" : "map",
> > - reusable ? "reusable" : "non-reusable",
> > - rmem->name ? rmem->name : "unknown");
> > - }
> > - }
> > + err = __reserved_mem_init_node(rmem);
> > + if (err != 0 && err != -ENOENT) {
> > + pr_info("node %s compatible matching fail\n", rmem->name);
> > + if (nomap)
> > + memblock_clear_nomap(rmem->base, rmem->size);
> > + else
> > + memblock_phys_free(rmem->base, rmem->size);
> > + } else {
> > + phys_addr_t end = rmem->base + rmem->size - 1;
> > + bool reusable =
> > + (of_get_flat_dt_prop(node, "reusable", NULL)) != NULL;
> > +
> > + pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
> > + &rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
> > + nomap ? "nomap" : "map",
> > + reusable ? "reusable" : "non-reusable",
> > + rmem->name ? rmem->name : "unknown");
> > }
> > }
> >
>
Just want to follow up on this issue. Do you need any further detail
or clarification?
Any ARM memory manage guru on this thread can comment?
Or is my workaround acceptable as a patch?
On 6/22/2025 6:24 PM, William Zhang wrote:
> On Tue, Jun 17, 2025 at 10:15 AM William Zhang
> <william.zhang@broadcom.com> wrote:
>>
>> Hi Oreoluwa,
>>
>> On 10/8/2024 3:06 PM, Oreoluwa Babatunde wrote:
>>> Reserved memory regions defined in the devicetree can be broken up into
>>> two groups:
>>> i) Statically-placed reserved memory regions
>>> i.e. regions defined with a static start address and size using the
>>> "reg" property.
>>> ii) Dynamically-placed reserved memory regions.
>>> i.e. regions defined by specifying an address range where they can be
>>> placed in memory using the "alloc_ranges" and "size" properties.
>>>
>>> These regions are processed and set aside at boot time.
>>> This is done in two stages as seen below:
>>>
>>> Stage 1:
>>> At this stage, fdt_scan_reserved_mem() scans through the child nodes of
>>> the reserved_memory node using the flattened devicetree and does the
>>> following:
>>>
>>> 1) If the node represents a statically-placed reserved memory region,
>>> i.e. if it is defined using the "reg" property:
>>> - Call memblock_reserve() or memblock_mark_nomap() as needed.
>>> - Add the information for that region into the reserved_mem array
>>> using fdt_reserved_mem_save_node().
>>> i.e. fdt_reserved_mem_save_node(node, name, base, size).
>>>
>>> 2) If the node represents a dynamically-placed reserved memory region,
>>> i.e. if it is defined using "alloc-ranges" and "size" properties:
>>> - Add the information for that region to the reserved_mem array with
>>> the starting address and size set to 0.
>>> i.e. fdt_reserved_mem_save_node(node, name, 0, 0).
>>> Note: This region is saved to the array with a starting address of 0
>>> because a starting address is not yet allocated for it.
>>>
>>> Stage 2:
>>> After iterating through all the reserved memory nodes and storing their
>>> relevant information in the reserved_mem array,fdt_init_reserved_mem() is
>>> called and does the following:
>>>
>>> 1) For statically-placed reserved memory regions:
>>> - Call the region specific init function using
>>> __reserved_mem_init_node().
>>> 2) For dynamically-placed reserved memory regions:
>>> - Call __reserved_mem_alloc_size() which is used to allocate memory
>>> for each of these regions, and mark them as nomap if they have the
>>> nomap property specified in the DT.
>>> - Call the region specific init function.
>>>
>>> The current size of the resvered_mem array is 64 as is defined by
>>> MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for
>>> how many reserved memory regions can be specified on a system.
>>> As systems continue to grow more and more complex, the number of
>>> reserved memory regions needed are also growing and are starting to hit
>>> this 64 count limit, hence the need to make the reserved_mem array
>>> dynamically sized (i.e. dynamically allocating memory for the
>>> reserved_mem array using membock_alloc_*).
>>>
>>> On architectures such as arm64, memory allocated using memblock is
>>> writable only after the page tables have been setup. This means that if
>>> the reserved_mem array is going to be dynamically allocated, it needs to
>>> happen after the page tables have been setup, not before.
>>>
>>> Since the reserved memory regions are currently being processed and
>>> added to the array before the page tables are setup, there is a need to
>>> change the order in which some of the processing is done to allow for
>>> the reserved_mem array to be dynamically sized.
>>>
>>> It is possible to process the statically-placed reserved memory regions
>>> without needing to store them in the reserved_mem array until after the
>>> page tables have been setup because all the information stored in the
>>> array is readily available in the devicetree and can be referenced at
>>> any time.
>>> Dynamically-placed reserved memory regions on the other hand get
>>> assigned a start address only at runtime, and hence need a place to be
>>> stored once they are allocated since there is no other referrence to the
>>> start address for these regions.
>>>
>>> Hence this patch changes the processing order of the reserved memory
>>> regions in the following ways:
>>>
>>> Step 1:
>>> fdt_scan_reserved_mem() scans through the child nodes of
>>> the reserved_memory node using the flattened devicetree and does the
>>> following:
>>>
>>> 1) If the node represents a statically-placed reserved memory region,
>>> i.e. if it is defined using the "reg" property:
>>> - Call memblock_reserve() or memblock_mark_nomap() as needed.
>>>
>>> 2) If the node represents a dynamically-placed reserved memory region,
>>> i.e. if it is defined using "alloc-ranges" and "size" properties:
>>> - Call __reserved_mem_alloc_size() which will:
>>> i) Allocate memory for the reserved region and call
>>> memblock_mark_nomap() as needed.
>>> ii) Call the region specific initialization function using
>>> fdt_init_reserved_mem_node().
>>> iii) Save the region information in the reserved_mem array using
>>> fdt_reserved_mem_save_node().
>>>
>>> Step 2:
>>> 1) This stage of the reserved memory processing is now only used to add
>>> the statically-placed reserved memory regions into the reserved_mem
>>> array using fdt_scan_reserved_mem_reg_nodes(), as well as call their
>>> region specific initialization functions.
>>>
>>> 2) This step has also been moved to be after the page tables are
>>> setup. Moving this will allow us to replace the reserved_mem
>>> array with a dynamically sized array before storing the rest of
>>> these regions.
>> I am running into a call trace with this order change on armv7 chip when
>> I tried to allocate dma coherent memory from the device reserved memory.
>> The issue does not happen on armv8 chips.
>>
>> [ 0.000000] Reserved memory: created CMA memory pool at 0x1e000000,
>> size 32 MiB
>> [ 0.000000] OF: reserved mem: initialized node dt_reserved_cma,
>> compatible id shared-dma-pool
>> [ 0.000000] OF: reserved mem: 0x1e000000..0x1fffffff (32768 KiB) map
>> reusable dt_reserved_cma
>> ....
>>
>> [ 0.445322] ------------[ cut here ]------------
>> [ 0.445353] WARNING: CPU: 0 PID: 1 at mm/memory.c:3069
>> __apply_to_page_range+0x380/0x388
>> [ 0.488911] Modules linked in:
>> [ 0.492027] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted
>> 6.16.0-rc1-g27605c8c0f69-dirty #3 NONE
>> [ 0.501174] Hardware name: Generic DT based system
>> [ 0.505965] Call trace:
>> [ 0.505985] unwind_backtrace from show_stack+0x10/0x14
>> [ 0.513764] show_stack from dump_stack_lvl+0x54/0x68
>> [ 0.518834] dump_stack_lvl from __warn+0x7c/0x128
>> [ 0.523639] __warn from warn_slowpath_fmt+0x184/0x18c
>> [ 0.527676] Freeing initrd memory: 65536K
>> [ 0.532788] warn_slowpath_fmt from __apply_to_page_range+0x380/0x388
>> [ 0.539242] __apply_to_page_range from apply_to_page_range+0x1c/0x24
>> [ 0.545689] apply_to_page_range from __alloc_from_contiguous+0xc0/0x14c
>> [ 0.552398] __alloc_from_contiguous from cma_allocator_alloc+0x34/0x3c
>> [ 0.559016] cma_allocator_alloc from arch_dma_alloc+0x11c/0x2ac
>> [ 0.565025] arch_dma_alloc from dma_alloc_attrs+0x90/0x2e8
>> [ 0.570603] dma_alloc_attrs from dmydev_probe+0x8c/0xe8
>> [ 0.575919] dmydev_probe from platform_probe+0x5c/0xb0
>> [ 0.581152] platform_probe from really_probe+0xc8/0x2c8
>> [ 0.586467] really_probe from __driver_probe_device+0x88/0x19c
>> [ 0.592387] __driver_probe_device from driver_probe_device+0x30/0x104
>> [ 0.598915] driver_probe_device from __driver_attach+0x90/0x178
>> [ 0.604921] __driver_attach from bus_for_each_dev+0x7c/0xcc
>> [ 0.610582] bus_for_each_dev from bus_add_driver+0xcc/0x1ec
>> [ 0.616241] bus_add_driver from driver_register+0x7c/0x114
>> [ 0.621814] driver_register from dmydev_init+0x20/0x28
>> [ 0.627045] dmydev_init from do_one_initcall+0x58/0x200
>> [ 0.632363] do_one_initcall from kernel_init_freeable+0x1cc/0x228
>> [ 0.638550] kernel_init_freeable from kernel_init+0x1c/0x12c
>> [ 0.644299] kernel_init from ret_from_fork+0x14/0x28
>> [ 0.649351] Exception stack(0xe0819fb0 to 0xe0819ff8)
>> [ 0.654401] 9fa0: 00000000
>> 00000000 00000000 00000000
>> [ 0.662575] 9fc0: 00000000 00000000 00000000 00000000 00000000
>> 00000000 00000000 00000000
>> [ 0.670747] 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000
>> [ 0.677403] ---[ end trace 0000000000000000 ]---
>> [ 0.682083] dmydev dmy_device: Allocate dma memory at 0xde000000 dma
>> addr 0x1e000000
>>
>> The reason is that now reserved memory's fixup function
>> dma_contiguous_early_fixup is called after the page table is
>> initialized. This fixup function increases the dma_mmu_remap count for
>> each reserved memory. And the dma_contiguous_remap function depends on
>> it to properly set up the reserved memory mmu table entry. Before this
>> change, the paging_init function calls dma_contiguous_remap and it
>> founds the reserved memory and set it up properly. After the change,
>> this function found there is no reserved memory so skip any
>> initialization hence causes the crash later on when my driver tries to
>> allocate dma memory from the reserved memory.
>>
>> My workaround below is to move the dma_contiguous_remap out from the
>> paging_init function to the place right after unflatten_device_tree
>> where the dma_mmu_remap count is correctly set. But this is not ideal
>> solution and would like to see if you have any better way to solve the
>> issue.
>>
>> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
>> index a41c93988d2c..535d1bf44529 100644
>> --- a/arch/arm/kernel/setup.c
>> +++ b/arch/arm/kernel/setup.c
>> @@ -1079,6 +1079,7 @@ void __init hyp_mode_check(void)
>> #endif
>> }
>>
>> +void __init dma_contiguous_remap(void);
>> static void (*__arm_pm_restart)(enum reboot_mode reboot_mode, const
>> char *cmd);
>>
>> static int arm_restart(struct notifier_block *nb, unsigned long action,
>> @@ -1164,6 +1165,7 @@ void __init setup_arch(char **cmdline_p)
>> }
>>
>> unflatten_device_tree();
>> + dma_contiguous_remap();
>>
>> arm_dt_init_cpu_maps();
>> psci_dt_init();
>> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
>> index edb7f56b7c91..1828c8737d70 100644
>> --- a/arch/arm/mm/mmu.c
>> +++ b/arch/arm/mm/mmu.c
>> @@ -1773,7 +1773,6 @@ void __init paging_init(const struct machine_desc
>> *mdesc)
>> * be used
>> */
>> map_kernel();
>> - dma_contiguous_remap();
>> early_fixmap_shutdown();
>> devicemaps_init(mdesc);
>> kmap_init();
>>
>> You can reproduce the issue on any v7 devices by adding these nodes to
>> the device tree
>> + reserved-memory {
>> + #address-cells = <1>;
>> + #size-cells = <1>;
>> + ranges;
>> +
>> + dt_reserved_cma: dt_reserved_cma {
>> + compatible = "shared-dma-pool";
>> + reusable;
>> +
>> + reg = <0x1e000000 0x2000000>;
>> + };
>> + };
>> +
>> + dmy_device {
>> + compatible = "xyz,dmydev";
>> + memory-region = <&dt_reserved_cma>;
>> + };
>>
>> And use this test driver to trigger the call stack:
>> diff --git a/drivers/char/dmydev.c b/drivers/char/dmydev.c
>> new file mode 100644
>> index 000000000000..1dd52ec492eb
>> --- /dev/null
>> +++ b/drivers/char/dmydev.c
>> @@ -0,0 +1,67 @@
>> +#include<linux/module.h>
>> +#include<linux/kernel.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/of.h>
>> +#include <linux/of_reserved_mem.h>
>> +#include <linux/dma-mapping.h>
>> +
>> +static int dmydev_probe(struct platform_device *pdev)
>> +{
>> + void* virt_addr;
>> + dma_addr_t dma_addr;
>> + int ret;
>> +
>> + printk(KERN_ALERT "dmydev_probe called\n");
>> +
>> + ret = of_reserved_mem_device_init(&pdev->dev);
>> + if (ret && ret != -ENODEV) {
>> + dev_err(&pdev->dev, "Couldn't assign reserve memory to
>> device ret = %d\n", ret);
>> + return ret;
>> + }
>> +
>> + virt_addr = dma_alloc_coherent(&pdev->dev, 0x800000, &dma_addr,
>> GFP_KERNEL);
>> + if (virt_addr == NULL) {
>> + dev_err(&pdev->dev,"Failed to allocated cma memory\n");
>> + ret = -ENOMEM;
>> + }
>> + else
>> + dev_err(&pdev->dev,"Allocate dma memory at 0x%px dma
>> addr %pad\n", virt_addr, &dma_addr);
>> +
>> + return ret;
>> +}
>> +
>> +static void dmydev_remove(struct platform_device *pdev)
>> +{
>> +}
>> +
>> +static const struct of_device_id dmydev_of_match[] = {
>> + {.compatible = "xyz,dmydev"},
>> + {}
>> +};
>> +MODULE_DEVICE_TABLE(of, dmydev_of_match);
>>
>> Let me know if you need more info.
>>
>>>
>>> Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
>>> ---
>>> drivers/of/fdt.c | 5 +-
>>> drivers/of/of_private.h | 3 +-
>>> drivers/of/of_reserved_mem.c | 168 ++++++++++++++++++++++++-----------
>>> 3 files changed, 122 insertions(+), 54 deletions(-)
>>>
>>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
>>> index 4d528c10df3a..d0dbc8183ac4 100644
>>> --- a/drivers/of/fdt.c
>>> +++ b/drivers/of/fdt.c
>>> @@ -511,8 +511,6 @@ void __init early_init_fdt_scan_reserved_mem(void)
>>> break;
>>> memblock_reserve(base, size);
>>> }
>>> -
>>> - fdt_init_reserved_mem();
>>> }
>>>
>>> /**
>>> @@ -1212,6 +1210,9 @@ void __init unflatten_device_tree(void)
>>> {
>>> void *fdt = initial_boot_params;
>>>
>>> + /* Save the statically-placed regions in the reserved_mem array */
>>> + fdt_scan_reserved_mem_reg_nodes();
>>> +
>>> /* Don't use the bootloader provided DTB if ACPI is enabled */
>>> if (!acpi_disabled)
>>> fdt = NULL;
>>> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
>>> index 04aa2a91f851..29525c0b9939 100644
>>> --- a/drivers/of/of_private.h
>>> +++ b/drivers/of/of_private.h
>>> @@ -9,6 +9,7 @@
>>> */
>>>
>>> #define FDT_ALIGN_SIZE 8
>>> +#define MAX_RESERVED_REGIONS 64
>>>
>>> /**
>>> * struct alias_prop - Alias property in 'aliases' node
>>> @@ -180,7 +181,7 @@ static inline struct device_node *__of_get_dma_parent(const struct device_node *
>>> #endif
>>>
>>> int fdt_scan_reserved_mem(void);
>>> -void fdt_init_reserved_mem(void);
>>> +void __init fdt_scan_reserved_mem_reg_nodes(void);
>>>
>>> bool of_fdt_device_is_available(const void *blob, unsigned long node);
>>>
>>> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
>>> index 46e1c3fbc769..2011174211f9 100644
>>> --- a/drivers/of/of_reserved_mem.c
>>> +++ b/drivers/of/of_reserved_mem.c
>>> @@ -27,7 +27,6 @@
>>>
>>> #include "of_private.h"
>>>
>>> -#define MAX_RESERVED_REGIONS 64
>>> static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
>>> static int reserved_mem_count;
>>>
>>> @@ -56,6 +55,7 @@ static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
>>> return err;
>>> }
>>>
>>> +static void __init fdt_init_reserved_mem_node(struct reserved_mem *rmem);
>>> /*
>>> * fdt_reserved_mem_save_node() - save fdt node for second pass initialization
>>> */
>>> @@ -74,6 +74,9 @@ static void __init fdt_reserved_mem_save_node(unsigned long node, const char *un
>>> rmem->base = base;
>>> rmem->size = size;
>>>
>>> + /* Call the region specific initialization function */
>>> + fdt_init_reserved_mem_node(rmem);
>>> +
>>> reserved_mem_count++;
>>> return;
>>> }
>>> @@ -106,7 +109,6 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
>>> phys_addr_t base, size;
>>> int len;
>>> const __be32 *prop;
>>> - int first = 1;
>>> bool nomap;
>>>
>>> prop = of_get_flat_dt_prop(node, "reg", &len);
>>> @@ -134,10 +136,6 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
>>> uname, &base, (unsigned long)(size / SZ_1M));
>>>
>>> len -= t_len;
>>> - if (first) {
>>> - fdt_reserved_mem_save_node(node, uname, base, size);
>>> - first = 0;
>>> - }
>>> }
>>> return 0;
>>> }
>>> @@ -165,12 +163,77 @@ static int __init __reserved_mem_check_root(unsigned long node)
>>> return 0;
>>> }
>>>
>>> +static void __init __rmem_check_for_overlap(void);
>>> +
>>> +/**
>>> + * fdt_scan_reserved_mem_reg_nodes() - Store info for the "reg" defined
>>> + * reserved memory regions.
>>> + *
>>> + * This function is used to scan through the DT and store the
>>> + * information for the reserved memory regions that are defined using
>>> + * the "reg" property. The region node number, name, base address, and
>>> + * size are all stored in the reserved_mem array by calling the
>>> + * fdt_reserved_mem_save_node() function.
>>> + */
>>> +void __init fdt_scan_reserved_mem_reg_nodes(void)
>>> +{
>>> + int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
>>> + const void *fdt = initial_boot_params;
>>> + phys_addr_t base, size;
>>> + const __be32 *prop;
>>> + int node, child;
>>> + int len;
>>> +
>>> + if (!fdt)
>>> + return;
>>> +
>>> + node = fdt_path_offset(fdt, "/reserved-memory");
>>> + if (node < 0) {
>>> + pr_info("Reserved memory: No reserved-memory node in the DT\n");
>>> + return;
>>> + }
>>> +
>>> + if (__reserved_mem_check_root(node)) {
>>> + pr_err("Reserved memory: unsupported node format, ignoring\n");
>>> + return;
>>> + }
>>> +
>>> + fdt_for_each_subnode(child, fdt, node) {
>>> + const char *uname;
>>> +
>>> + prop = of_get_flat_dt_prop(child, "reg", &len);
>>> + if (!prop)
>>> + continue;
>>> + if (!of_fdt_device_is_available(fdt, child))
>>> + continue;
>>> +
>>> + uname = fdt_get_name(fdt, child, NULL);
>>> + if (len && len % t_len != 0) {
>>> + pr_err("Reserved memory: invalid reg property in '%s', skipping node.\n",
>>> + uname);
>>> + continue;
>>> + }
>>> + base = dt_mem_next_cell(dt_root_addr_cells, &prop);
>>> + size = dt_mem_next_cell(dt_root_size_cells, &prop);
>>> +
>>> + if (size)
>>> + fdt_reserved_mem_save_node(child, uname, base, size);
>>> + }
>>> +
>>> + /* check for overlapping reserved regions */
>>> + __rmem_check_for_overlap();
>>> +}
>>> +
>>> +static int __init __reserved_mem_alloc_size(unsigned long node, const char *uname);
>>> +
>>> /*
>>> * fdt_scan_reserved_mem() - scan a single FDT node for reserved memory
>>> */
>>> int __init fdt_scan_reserved_mem(void)
>>> {
>>> int node, child;
>>> + int dynamic_nodes_cnt = 0;
>>> + int dynamic_nodes[MAX_RESERVED_REGIONS];
>>> const void *fdt = initial_boot_params;
>>>
>>> node = fdt_path_offset(fdt, "/reserved-memory");
>>> @@ -192,8 +255,24 @@ int __init fdt_scan_reserved_mem(void)
>>> uname = fdt_get_name(fdt, child, NULL);
>>>
>>> err = __reserved_mem_reserve_reg(child, uname);
>>> - if (err == -ENOENT && of_get_flat_dt_prop(child, "size", NULL))
>>> - fdt_reserved_mem_save_node(child, uname, 0, 0);
>>> + /*
>>> + * Save the nodes for the dynamically-placed regions
>>> + * into an array which will be used for allocation right
>>> + * after all the statically-placed regions are reserved
>>> + * or marked as no-map. This is done to avoid dynamically
>>> + * allocating from one of the statically-placed regions.
>>> + */
>>> + if (err == -ENOENT && of_get_flat_dt_prop(child, "size", NULL)) {
>>> + dynamic_nodes[dynamic_nodes_cnt] = child;
>>> + dynamic_nodes_cnt++;
>>> + }
>>> + }
>>> + for (int i = 0; i < dynamic_nodes_cnt; i++) {
>>> + const char *uname;
>>> +
>>> + child = dynamic_nodes[i];
>>> + uname = fdt_get_name(fdt, child, NULL);
>>> + __reserved_mem_alloc_size(child, uname);
>>> }
>>> return 0;
>>> }
>>> @@ -253,8 +332,7 @@ static int __init __reserved_mem_alloc_in_range(phys_addr_t size,
>>> * __reserved_mem_alloc_size() - allocate reserved memory described by
>>> * 'size', 'alignment' and 'alloc-ranges' properties.
>>> */
>>> -static int __init __reserved_mem_alloc_size(unsigned long node,
>>> - const char *uname, phys_addr_t *res_base, phys_addr_t *res_size)
>>> +static int __init __reserved_mem_alloc_size(unsigned long node, const char *uname)
>>> {
>>> int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
>>> phys_addr_t start = 0, end = 0;
>>> @@ -334,9 +412,8 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
>>> return -ENOMEM;
>>> }
>>>
>>> - *res_base = base;
>>> - *res_size = size;
>>> -
>>> + /* Save region in the reserved_mem array */
>>> + fdt_reserved_mem_save_node(node, uname, base, size);
>>> return 0;
>>> }
>>>
>>> @@ -425,48 +502,37 @@ static void __init __rmem_check_for_overlap(void)
>>> }
>>>
>>> /**
>>> - * fdt_init_reserved_mem() - allocate and init all saved reserved memory regions
>>> + * fdt_init_reserved_mem_node() - Initialize a reserved memory region
>>> + * @rmem: reserved_mem struct of the memory region to be initialized.
>>> + *
>>> + * This function is used to call the region specific initialization
>>> + * function for a reserved memory region.
>>> */
>>> -void __init fdt_init_reserved_mem(void)
>>> +static void __init fdt_init_reserved_mem_node(struct reserved_mem *rmem)
>>> {
>>> - int i;
>>> -
>>> - /* check for overlapping reserved regions */
>>> - __rmem_check_for_overlap();
>>> -
>>> - for (i = 0; i < reserved_mem_count; i++) {
>>> - struct reserved_mem *rmem = &reserved_mem[i];
>>> - unsigned long node = rmem->fdt_node;
>>> - int err = 0;
>>> - bool nomap;
>>> + unsigned long node = rmem->fdt_node;
>>> + int err = 0;
>>> + bool nomap;
>>>
>>> - nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
>>> + nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
>>>
>>> - if (rmem->size == 0)
>>> - err = __reserved_mem_alloc_size(node, rmem->name,
>>> - &rmem->base, &rmem->size);
>>> - if (err == 0) {
>>> - err = __reserved_mem_init_node(rmem);
>>> - if (err != 0 && err != -ENOENT) {
>>> - pr_info("node %s compatible matching fail\n",
>>> - rmem->name);
>>> - if (nomap)
>>> - memblock_clear_nomap(rmem->base, rmem->size);
>>> - else
>>> - memblock_phys_free(rmem->base,
>>> - rmem->size);
>>> - } else {
>>> - phys_addr_t end = rmem->base + rmem->size - 1;
>>> - bool reusable =
>>> - (of_get_flat_dt_prop(node, "reusable", NULL)) != NULL;
>>> -
>>> - pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
>>> - &rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
>>> - nomap ? "nomap" : "map",
>>> - reusable ? "reusable" : "non-reusable",
>>> - rmem->name ? rmem->name : "unknown");
>>> - }
>>> - }
>>> + err = __reserved_mem_init_node(rmem);
>>> + if (err != 0 && err != -ENOENT) {
>>> + pr_info("node %s compatible matching fail\n", rmem->name);
>>> + if (nomap)
>>> + memblock_clear_nomap(rmem->base, rmem->size);
>>> + else
>>> + memblock_phys_free(rmem->base, rmem->size);
>>> + } else {
>>> + phys_addr_t end = rmem->base + rmem->size - 1;
>>> + bool reusable =
>>> + (of_get_flat_dt_prop(node, "reusable", NULL)) != NULL;
>>> +
>>> + pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
>>> + &rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
>>> + nomap ? "nomap" : "map",
>>> + reusable ? "reusable" : "non-reusable",
>>> + rmem->name ? rmem->name : "unknown");
>>> }
>>> }
>>>
>>
> Just want to follow up on this issue. Do you need any further detail
> or clarification?
> Any ARM memory manage guru on this thread can comment?
> Or is my workaround acceptable as a patch?
Hi William,
Sorry about the delay in getting back to you.
Instead of moving dma_contiguous_remap(), I suggest moving dma_contiguous_early_fixup()
to the function that parses the reserved regions so that it is done before paging_init.
Here is what that could look like. Can you please give this a try?
diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 77016c0cc296..132d2c66cafc 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -25,6 +25,7 @@
#include <linux/memblock.h>
#include <linux/kmemleak.h>
#include <linux/cma.h>
+#include <linux/dma-map-ops.h>
#include "of_private.h"
@@ -175,13 +176,17 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
base = dt_mem_next_cell(dt_root_addr_cells, &prop);
size = dt_mem_next_cell(dt_root_size_cells, &prop);
- if (size &&
- early_init_dt_reserve_memory(base, size, nomap) == 0)
+ if (size && early_init_dt_reserve_memory(base, size, nomap) == 0) {
+ /* Architecture specific contiguous memory fixup. */
+ if (of_flat_dt_is_compatible(node, "shared-dma-pool"))
+ dma_contiguous_early_fixup(base, size);
+
pr_debug("Reserved memory: reserved region for node '%s': base %pa, size %lu MiB\n",
uname, &base, (unsigned long)(size / SZ_1M));
- else
+ } else {
pr_err("Reserved memory: failed to reserve memory for node '%s': base %pa, size %lu MiB\n",
uname, &base, (unsigned long)(size / SZ_1M));
+ }
len -= t_len;
}
@@ -472,6 +477,9 @@ static int __init __reserved_mem_alloc_size(unsigned long node, const char *unam
uname, (unsigned long)(size / SZ_1M));
return -ENOMEM;
}
+ /* Architecture specific contiguous memory fixup. */
+ if (of_flat_dt_is_compatible(node, "shared-dma-pool"))
+ dma_contiguous_early_fixup(base, size);
/* Save region in the reserved_mem array */
fdt_reserved_mem_save_node(node, uname, base, size);
diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
index 8df0dfaaca18..9e5d63efe7c5 100644
--- a/kernel/dma/contiguous.c
+++ b/kernel/dma/contiguous.c
@@ -480,8 +480,6 @@ static int __init rmem_cma_setup(struct reserved_mem *rmem)
pr_err("Reserved memory: unable to setup CMA region\n");
return err;
}
- /* Architecture specific contiguous memory fixup. */
- dma_contiguous_early_fixup(rmem->base, rmem->size);
if (default_cma)
dma_contiguous_default_area = cma;
Regards,
Oreoluwa
> -----Original Message-----
> From: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
> Sent: Friday, June 27, 2025 11:02 AM
> To: William Zhang <william.zhang@broadcom.com>; robh@kernel.org
> Cc: aisheng.dong@nxp.com; andy@black.fi.intel.com;
> catalin.marinas@arm.com; devicetree@vger.kernel.org; hch@lst.de;
> iommu@lists.linux.dev; kernel@quicinc.com; klarasmodin@gmail.com; linux-
> kernel@vger.kernel.org; m.szyprowski@samsung.com;
> quic_ninanaik@quicinc.com; robin.murphy@arm.com; saravanak@google.com;
> will@kernel.org; oreoluwa.babatunde@oss.qualcomm.com
> Subject: Re: [PATCH v10 1/2] of: reserved_mem: Restruture how the reserved
> memory regions are processed
>
>
>
> On 6/22/2025 6:24 PM, William Zhang wrote:
> > On Tue, Jun 17, 2025 at 10:15 AM William Zhang
> > <william.zhang@broadcom.com> wrote:
> >>
> >> Hi Oreoluwa,
> >>
> >> On 10/8/2024 3:06 PM, Oreoluwa Babatunde wrote:
> >>> Reserved memory regions defined in the devicetree can be broken up
> >>> into
> >>> two groups:
> >>> i) Statically-placed reserved memory regions
> >>> i.e. regions defined with a static start address and size using the
> >>> "reg" property.
> >>> ii) Dynamically-placed reserved memory regions.
> >>> i.e. regions defined by specifying an address range where they can be
> >>> placed in memory using the "alloc_ranges" and "size" properties.
> >>>
> >>> These regions are processed and set aside at boot time.
> >>> This is done in two stages as seen below:
> >>>
> >>> Stage 1:
> >>> At this stage, fdt_scan_reserved_mem() scans through the child nodes
> >>> of
> >>> the reserved_memory node using the flattened devicetree and does the
> >>> following:
> >>>
> >>> 1) If the node represents a statically-placed reserved memory region,
> >>> i.e. if it is defined using the "reg" property:
> >>> - Call memblock_reserve() or memblock_mark_nomap() as needed.
> >>> - Add the information for that region into the reserved_mem array
> >>> using fdt_reserved_mem_save_node().
> >>> i.e. fdt_reserved_mem_save_node(node, name, base, size).
> >>>
> >>> 2) If the node represents a dynamically-placed reserved memory region,
> >>> i.e. if it is defined using "alloc-ranges" and "size" properties:
> >>> - Add the information for that region to the reserved_mem array
> >>> with
> >>> the starting address and size set to 0.
> >>> i.e. fdt_reserved_mem_save_node(node, name, 0, 0).
> >>> Note: This region is saved to the array with a starting address of
> >>> 0
> >>> because a starting address is not yet allocated for it.
> >>>
> >>> Stage 2:
> >>> After iterating through all the reserved memory nodes and storing
> >>> their
> >>> relevant information in the reserved_mem array,fdt_init_reserved_mem()
> >>> is
> >>> called and does the following:
> >>>
> >>> 1) For statically-placed reserved memory regions:
> >>> - Call the region specific init function using
> >>> __reserved_mem_init_node().
> >>> 2) For dynamically-placed reserved memory regions:
> >>> - Call __reserved_mem_alloc_size() which is used to allocate
> >>> memory
> >>> for each of these regions, and mark them as nomap if they have
> >>> the
> >>> nomap property specified in the DT.
> >>> - Call the region specific init function.
> >>>
> >>> The current size of the resvered_mem array is 64 as is defined by
> >>> MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for
> >>> how many reserved memory regions can be specified on a system.
> >>> As systems continue to grow more and more complex, the number of
> >>> reserved memory regions needed are also growing and are starting to
> >>> hit
> >>> this 64 count limit, hence the need to make the reserved_mem array
> >>> dynamically sized (i.e. dynamically allocating memory for the
> >>> reserved_mem array using membock_alloc_*).
> >>>
> >>> On architectures such as arm64, memory allocated using memblock is
> >>> writable only after the page tables have been setup. This means that
> >>> if
> >>> the reserved_mem array is going to be dynamically allocated, it needs
> >>> to
> >>> happen after the page tables have been setup, not before.
> >>>
> >>> Since the reserved memory regions are currently being processed and
> >>> added to the array before the page tables are setup, there is a need
> >>> to
> >>> change the order in which some of the processing is done to allow for
> >>> the reserved_mem array to be dynamically sized.
> >>>
> >>> It is possible to process the statically-placed reserved memory
> >>> regions
> >>> without needing to store them in the reserved_mem array until after
> >>> the
> >>> page tables have been setup because all the information stored in the
> >>> array is readily available in the devicetree and can be referenced at
> >>> any time.
> >>> Dynamically-placed reserved memory regions on the other hand get
> >>> assigned a start address only at runtime, and hence need a place to be
> >>> stored once they are allocated since there is no other referrence to
> >>> the
> >>> start address for these regions.
> >>>
> >>> Hence this patch changes the processing order of the reserved memory
> >>> regions in the following ways:
> >>>
> >>> Step 1:
> >>> fdt_scan_reserved_mem() scans through the child nodes of
> >>> the reserved_memory node using the flattened devicetree and does the
> >>> following:
> >>>
> >>> 1) If the node represents a statically-placed reserved memory region,
> >>> i.e. if it is defined using the "reg" property:
> >>> - Call memblock_reserve() or memblock_mark_nomap() as needed.
> >>>
> >>> 2) If the node represents a dynamically-placed reserved memory region,
> >>> i.e. if it is defined using "alloc-ranges" and "size" properties:
> >>> - Call __reserved_mem_alloc_size() which will:
> >>> i) Allocate memory for the reserved region and call
> >>> memblock_mark_nomap() as needed.
> >>> ii) Call the region specific initialization function using
> >>> fdt_init_reserved_mem_node().
> >>> iii) Save the region information in the reserved_mem array using
> >>> fdt_reserved_mem_save_node().
> >>>
> >>> Step 2:
> >>> 1) This stage of the reserved memory processing is now only used to
> >>> add
> >>> the statically-placed reserved memory regions into the
> >>> reserved_mem
> >>> array using fdt_scan_reserved_mem_reg_nodes(), as well as call
> >>> their
> >>> region specific initialization functions.
> >>>
> >>> 2) This step has also been moved to be after the page tables are
> >>> setup. Moving this will allow us to replace the reserved_mem
> >>> array with a dynamically sized array before storing the rest of
> >>> these regions.
> >> I am running into a call trace with this order change on armv7 chip
> >> when
> >> I tried to allocate dma coherent memory from the device reserved
> >> memory.
> >> The issue does not happen on armv8 chips.
> >>
> >> [ 0.000000] Reserved memory: created CMA memory pool at 0x1e000000,
> >> size 32 MiB
> >> [ 0.000000] OF: reserved mem: initialized node dt_reserved_cma,
> >> compatible id shared-dma-pool
> >> [ 0.000000] OF: reserved mem: 0x1e000000..0x1fffffff (32768 KiB) map
> >> reusable dt_reserved_cma
> >> ....
> >>
> >> [ 0.445322] ------------[ cut here ]------------
> >> [ 0.445353] WARNING: CPU: 0 PID: 1 at mm/memory.c:3069
> >> __apply_to_page_range+0x380/0x388
> >> [ 0.488911] Modules linked in:
> >> [ 0.492027] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted
> >> 6.16.0-rc1-g27605c8c0f69-dirty #3 NONE
> >> [ 0.501174] Hardware name: Generic DT based system
> >> [ 0.505965] Call trace:
> >> [ 0.505985] unwind_backtrace from show_stack+0x10/0x14
> >> [ 0.513764] show_stack from dump_stack_lvl+0x54/0x68
> >> [ 0.518834] dump_stack_lvl from __warn+0x7c/0x128
> >> [ 0.523639] __warn from warn_slowpath_fmt+0x184/0x18c
> >> [ 0.527676] Freeing initrd memory: 65536K
> >> [ 0.532788] warn_slowpath_fmt from
> __apply_to_page_range+0x380/0x388
> >> [ 0.539242] __apply_to_page_range from
> apply_to_page_range+0x1c/0x24
> >> [ 0.545689] apply_to_page_range from
> __alloc_from_contiguous+0xc0/0x14c
> >> [ 0.552398] __alloc_from_contiguous from
> cma_allocator_alloc+0x34/0x3c
> >> [ 0.559016] cma_allocator_alloc from arch_dma_alloc+0x11c/0x2ac
> >> [ 0.565025] arch_dma_alloc from dma_alloc_attrs+0x90/0x2e8
> >> [ 0.570603] dma_alloc_attrs from dmydev_probe+0x8c/0xe8
> >> [ 0.575919] dmydev_probe from platform_probe+0x5c/0xb0
> >> [ 0.581152] platform_probe from really_probe+0xc8/0x2c8
> >> [ 0.586467] really_probe from __driver_probe_device+0x88/0x19c
> >> [ 0.592387] __driver_probe_device from
> >> driver_probe_device+0x30/0x104
> >> [ 0.598915] driver_probe_device from __driver_attach+0x90/0x178
> >> [ 0.604921] __driver_attach from bus_for_each_dev+0x7c/0xcc
> >> [ 0.610582] bus_for_each_dev from bus_add_driver+0xcc/0x1ec
> >> [ 0.616241] bus_add_driver from driver_register+0x7c/0x114
> >> [ 0.621814] driver_register from dmydev_init+0x20/0x28
> >> [ 0.627045] dmydev_init from do_one_initcall+0x58/0x200
> >> [ 0.632363] do_one_initcall from kernel_init_freeable+0x1cc/0x228
> >> [ 0.638550] kernel_init_freeable from kernel_init+0x1c/0x12c
> >> [ 0.644299] kernel_init from ret_from_fork+0x14/0x28
> >> [ 0.649351] Exception stack(0xe0819fb0 to 0xe0819ff8)
> >> [ 0.654401] 9fa0: 00000000
> >> 00000000 00000000 00000000
> >> [ 0.662575] 9fc0: 00000000 00000000 00000000 00000000 00000000
> >> 00000000 00000000 00000000
> >> [ 0.670747] 9fe0: 00000000 00000000 00000000 00000000 00000013
> 00000000
> >> [ 0.677403] ---[ end trace 0000000000000000 ]---
> >> [ 0.682083] dmydev dmy_device: Allocate dma memory at 0xde000000 dma
> >> addr 0x1e000000
> >>
> >> The reason is that now reserved memory's fixup function
> >> dma_contiguous_early_fixup is called after the page table is
> >> initialized. This fixup function increases the dma_mmu_remap count for
> >> each reserved memory. And the dma_contiguous_remap function depends
> on
> >> it to properly set up the reserved memory mmu table entry. Before this
> >> change, the paging_init function calls dma_contiguous_remap and it
> >> founds the reserved memory and set it up properly. After the change,
> >> this function found there is no reserved memory so skip any
> >> initialization hence causes the crash later on when my driver tries to
> >> allocate dma memory from the reserved memory.
> >>
> >> My workaround below is to move the dma_contiguous_remap out from the
> >> paging_init function to the place right after unflatten_device_tree
> >> where the dma_mmu_remap count is correctly set. But this is not ideal
> >> solution and would like to see if you have any better way to solve the
> >> issue.
> >>
> >> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> >> index a41c93988d2c..535d1bf44529 100644
> >> --- a/arch/arm/kernel/setup.c
> >> +++ b/arch/arm/kernel/setup.c
> >> @@ -1079,6 +1079,7 @@ void __init hyp_mode_check(void)
> >> #endif
> >> }
> >>
> >> +void __init dma_contiguous_remap(void);
> >> static void (*__arm_pm_restart)(enum reboot_mode reboot_mode, const
> >> char *cmd);
> >>
> >> static int arm_restart(struct notifier_block *nb, unsigned long
> >> action,
> >> @@ -1164,6 +1165,7 @@ void __init setup_arch(char **cmdline_p)
> >> }
> >>
> >> unflatten_device_tree();
> >> + dma_contiguous_remap();
> >>
> >> arm_dt_init_cpu_maps();
> >> psci_dt_init();
> >> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> >> index edb7f56b7c91..1828c8737d70 100644
> >> --- a/arch/arm/mm/mmu.c
> >> +++ b/arch/arm/mm/mmu.c
> >> @@ -1773,7 +1773,6 @@ void __init paging_init(const struct machine_desc
> >> *mdesc)
> >> * be used
> >> */
> >> map_kernel();
> >> - dma_contiguous_remap();
> >> early_fixmap_shutdown();
> >> devicemaps_init(mdesc);
> >> kmap_init();
> >>
> >> You can reproduce the issue on any v7 devices by adding these nodes to
> >> the device tree
> >> + reserved-memory {
> >> + #address-cells = <1>;
> >> + #size-cells = <1>;
> >> + ranges;
> >> +
> >> + dt_reserved_cma: dt_reserved_cma {
> >> + compatible = "shared-dma-pool";
> >> + reusable;
> >> +
> >> + reg = <0x1e000000 0x2000000>;
> >> + };
> >> + };
> >> +
> >> + dmy_device {
> >> + compatible = "xyz,dmydev";
> >> + memory-region = <&dt_reserved_cma>;
> >> + };
> >>
> >> And use this test driver to trigger the call stack:
> >> diff --git a/drivers/char/dmydev.c b/drivers/char/dmydev.c
> >> new file mode 100644
> >> index 000000000000..1dd52ec492eb
> >> --- /dev/null
> >> +++ b/drivers/char/dmydev.c
> >> @@ -0,0 +1,67 @@
> >> +#include<linux/module.h>
> >> +#include<linux/kernel.h>
> >> +#include <linux/platform_device.h>
> >> +#include <linux/of.h>
> >> +#include <linux/of_reserved_mem.h>
> >> +#include <linux/dma-mapping.h>
> >> +
> >> +static int dmydev_probe(struct platform_device *pdev)
> >> +{
> >> + void* virt_addr;
> >> + dma_addr_t dma_addr;
> >> + int ret;
> >> +
> >> + printk(KERN_ALERT "dmydev_probe called\n");
> >> +
> >> + ret = of_reserved_mem_device_init(&pdev->dev);
> >> + if (ret && ret != -ENODEV) {
> >> + dev_err(&pdev->dev, "Couldn't assign reserve memory to
> >> device ret = %d\n", ret);
> >> + return ret;
> >> + }
> >> +
> >> + virt_addr = dma_alloc_coherent(&pdev->dev, 0x800000, &dma_addr,
> >> GFP_KERNEL);
> >> + if (virt_addr == NULL) {
> >> + dev_err(&pdev->dev,"Failed to allocated cma memory\n");
> >> + ret = -ENOMEM;
> >> + }
> >> + else
> >> + dev_err(&pdev->dev,"Allocate dma memory at 0x%px dma
> >> addr %pad\n", virt_addr, &dma_addr);
> >> +
> >> + return ret;
> >> +}
> >> +
> >> +static void dmydev_remove(struct platform_device *pdev)
> >> +{
> >> +}
> >> +
> >> +static const struct of_device_id dmydev_of_match[] = {
> >> + {.compatible = "xyz,dmydev"},
> >> + {}
> >> +};
> >> +MODULE_DEVICE_TABLE(of, dmydev_of_match);
> >>
> >> Let me know if you need more info.
> >>
> >>>
> >>> Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
> >>> ---
> >>> drivers/of/fdt.c | 5 +-
> >>> drivers/of/of_private.h | 3 +-
> >>> drivers/of/of_reserved_mem.c | 168
> >>> ++++++++++++++++++++++++----------
> -
> >>> 3 files changed, 122 insertions(+), 54 deletions(-)
> >>>
> >>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> >>> index 4d528c10df3a..d0dbc8183ac4 100644
> >>> --- a/drivers/of/fdt.c
> >>> +++ b/drivers/of/fdt.c
> >>> @@ -511,8 +511,6 @@ void __init early_init_fdt_scan_reserved_mem(void)
> >>> break;
> >>> memblock_reserve(base, size);
> >>> }
> >>> -
> >>> - fdt_init_reserved_mem();
> >>> }
> >>>
> >>> /**
> >>> @@ -1212,6 +1210,9 @@ void __init unflatten_device_tree(void)
> >>> {
> >>> void *fdt = initial_boot_params;
> >>>
> >>> + /* Save the statically-placed regions in the reserved_mem array
> >>> */
> >>> + fdt_scan_reserved_mem_reg_nodes();
> >>> +
> >>> /* Don't use the bootloader provided DTB if ACPI is enabled */
> >>> if (!acpi_disabled)
> >>> fdt = NULL;
> >>> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
> >>> index 04aa2a91f851..29525c0b9939 100644
> >>> --- a/drivers/of/of_private.h
> >>> +++ b/drivers/of/of_private.h
> >>> @@ -9,6 +9,7 @@
> >>> */
> >>>
> >>> #define FDT_ALIGN_SIZE 8
> >>> +#define MAX_RESERVED_REGIONS 64
> >>>
> >>> /**
> >>> * struct alias_prop - Alias property in 'aliases' node
> >>> @@ -180,7 +181,7 @@ static inline struct device_node
> *__of_get_dma_parent(const struct device_node *
> >>> #endif
> >>>
> >>> int fdt_scan_reserved_mem(void);
> >>> -void fdt_init_reserved_mem(void);
> >>> +void __init fdt_scan_reserved_mem_reg_nodes(void);
> >>>
> >>> bool of_fdt_device_is_available(const void *blob, unsigned long
> >>> node);
> >>>
> >>> diff --git a/drivers/of/of_reserved_mem.c
> >>> b/drivers/of/of_reserved_mem.c
> >>> index 46e1c3fbc769..2011174211f9 100644
> >>> --- a/drivers/of/of_reserved_mem.c
> >>> +++ b/drivers/of/of_reserved_mem.c
> >>> @@ -27,7 +27,6 @@
> >>>
> >>> #include "of_private.h"
> >>>
> >>> -#define MAX_RESERVED_REGIONS 64
> >>> static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
> >>> static int reserved_mem_count;
> >>>
> >>> @@ -56,6 +55,7 @@ static int __init
> early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
> >>> return err;
> >>> }
> >>>
> >>> +static void __init fdt_init_reserved_mem_node(struct reserved_mem
> *rmem);
> >>> /*
> >>> * fdt_reserved_mem_save_node() - save fdt node for second pass
> initialization
> >>> */
> >>> @@ -74,6 +74,9 @@ static void __init
> fdt_reserved_mem_save_node(unsigned long node, const char *un
> >>> rmem->base = base;
> >>> rmem->size = size;
> >>>
> >>> + /* Call the region specific initialization function */
> >>> + fdt_init_reserved_mem_node(rmem);
> >>> +
> >>> reserved_mem_count++;
> >>> return;
> >>> }
> >>> @@ -106,7 +109,6 @@ static int __init
> __reserved_mem_reserve_reg(unsigned long node,
> >>> phys_addr_t base, size;
> >>> int len;
> >>> const __be32 *prop;
> >>> - int first = 1;
> >>> bool nomap;
> >>>
> >>> prop = of_get_flat_dt_prop(node, "reg", &len);
> >>> @@ -134,10 +136,6 @@ static int __init
> __reserved_mem_reserve_reg(unsigned long node,
> >>> uname, &base, (unsigned long)(size /
> >>> SZ_1M));
> >>>
> >>> len -= t_len;
> >>> - if (first) {
> >>> - fdt_reserved_mem_save_node(node, uname, base,
> >>> size);
> >>> - first = 0;
> >>> - }
> >>> }
> >>> return 0;
> >>> }
> >>> @@ -165,12 +163,77 @@ static int __init
> __reserved_mem_check_root(unsigned long node)
> >>> return 0;
> >>> }
> >>>
> >>> +static void __init __rmem_check_for_overlap(void);
> >>> +
> >>> +/**
> >>> + * fdt_scan_reserved_mem_reg_nodes() - Store info for the "reg"
> >>> defined
> >>> + * reserved memory regions.
> >>> + *
> >>> + * This function is used to scan through the DT and store the
> >>> + * information for the reserved memory regions that are defined using
> >>> + * the "reg" property. The region node number, name, base address,
> >>> and
> >>> + * size are all stored in the reserved_mem array by calling the
> >>> + * fdt_reserved_mem_save_node() function.
> >>> + */
> >>> +void __init fdt_scan_reserved_mem_reg_nodes(void)
> >>> +{
> >>> + int t_len = (dt_root_addr_cells + dt_root_size_cells) *
> >>> sizeof(__be32);
> >>> + const void *fdt = initial_boot_params;
> >>> + phys_addr_t base, size;
> >>> + const __be32 *prop;
> >>> + int node, child;
> >>> + int len;
> >>> +
> >>> + if (!fdt)
> >>> + return;
> >>> +
> >>> + node = fdt_path_offset(fdt, "/reserved-memory");
> >>> + if (node < 0) {
> >>> + pr_info("Reserved memory: No reserved-memory node in the
> DT\n");
> >>> + return;
> >>> + }
> >>> +
> >>> + if (__reserved_mem_check_root(node)) {
> >>> + pr_err("Reserved memory: unsupported node format,
> >>> ignoring\n");
> >>> + return;
> >>> + }
> >>> +
> >>> + fdt_for_each_subnode(child, fdt, node) {
> >>> + const char *uname;
> >>> +
> >>> + prop = of_get_flat_dt_prop(child, "reg", &len);
> >>> + if (!prop)
> >>> + continue;
> >>> + if (!of_fdt_device_is_available(fdt, child))
> >>> + continue;
> >>> +
> >>> + uname = fdt_get_name(fdt, child, NULL);
> >>> + if (len && len % t_len != 0) {
> >>> + pr_err("Reserved memory: invalid reg property in
> >>> '%s', skipping
> node.\n",
> >>> + uname);
> >>> + continue;
> >>> + }
> >>> + base = dt_mem_next_cell(dt_root_addr_cells, &prop);
> >>> + size = dt_mem_next_cell(dt_root_size_cells, &prop);
> >>> +
> >>> + if (size)
> >>> + fdt_reserved_mem_save_node(child, uname, base,
> >>> size);
> >>> + }
> >>> +
> >>> + /* check for overlapping reserved regions */
> >>> + __rmem_check_for_overlap();
> >>> +}
> >>> +
> >>> +static int __init __reserved_mem_alloc_size(unsigned long node, const
> char *uname);
> >>> +
> >>> /*
> >>> * fdt_scan_reserved_mem() - scan a single FDT node for reserved
> >>> memory
> >>> */
> >>> int __init fdt_scan_reserved_mem(void)
> >>> {
> >>> int node, child;
> >>> + int dynamic_nodes_cnt = 0;
> >>> + int dynamic_nodes[MAX_RESERVED_REGIONS];
> >>> const void *fdt = initial_boot_params;
> >>>
> >>> node = fdt_path_offset(fdt, "/reserved-memory");
> >>> @@ -192,8 +255,24 @@ int __init fdt_scan_reserved_mem(void)
> >>> uname = fdt_get_name(fdt, child, NULL);
> >>>
> >>> err = __reserved_mem_reserve_reg(child, uname);
> >>> - if (err == -ENOENT && of_get_flat_dt_prop(child, "size",
> >>> NULL))
> >>> - fdt_reserved_mem_save_node(child, uname, 0, 0);
> >>> + /*
> >>> + * Save the nodes for the dynamically-placed regions
> >>> + * into an array which will be used for allocation right
> >>> + * after all the statically-placed regions are reserved
> >>> + * or marked as no-map. This is done to avoid
> >>> dynamically
> >>> + * allocating from one of the statically-placed regions.
> >>> + */
> >>> + if (err == -ENOENT && of_get_flat_dt_prop(child, "size",
> >>> NULL)) {
> >>> + dynamic_nodes[dynamic_nodes_cnt] = child;
> >>> + dynamic_nodes_cnt++;
> >>> + }
> >>> + }
> >>> + for (int i = 0; i < dynamic_nodes_cnt; i++) {
> >>> + const char *uname;
> >>> +
> >>> + child = dynamic_nodes[i];
> >>> + uname = fdt_get_name(fdt, child, NULL);
> >>> + __reserved_mem_alloc_size(child, uname);
> >>> }
> >>> return 0;
> >>> }
> >>> @@ -253,8 +332,7 @@ static int __init
> __reserved_mem_alloc_in_range(phys_addr_t size,
> >>> * __reserved_mem_alloc_size() - allocate reserved memory described
> >>> by
> >>> * 'size', 'alignment' and 'alloc-ranges' properties.
> >>> */
> >>> -static int __init __reserved_mem_alloc_size(unsigned long node,
> >>> - const char *uname, phys_addr_t *res_base, phys_addr_t *res_size)
> >>> +static int __init __reserved_mem_alloc_size(unsigned long node, const
> char *uname)
> >>> {
> >>> int t_len = (dt_root_addr_cells + dt_root_size_cells) *
> >>> sizeof(__be32);
> >>> phys_addr_t start = 0, end = 0;
> >>> @@ -334,9 +412,8 @@ static int __init
> __reserved_mem_alloc_size(unsigned long node,
> >>> return -ENOMEM;
> >>> }
> >>>
> >>> - *res_base = base;
> >>> - *res_size = size;
> >>> -
> >>> + /* Save region in the reserved_mem array */
> >>> + fdt_reserved_mem_save_node(node, uname, base, size);
> >>> return 0;
> >>> }
> >>>
> >>> @@ -425,48 +502,37 @@ static void __init
> __rmem_check_for_overlap(void)
> >>> }
> >>>
> >>> /**
> >>> - * fdt_init_reserved_mem() - allocate and init all saved reserved
> >>> memory
> regions
> >>> + * fdt_init_reserved_mem_node() - Initialize a reserved memory region
> >>> + * @rmem: reserved_mem struct of the memory region to be initialized.
> >>> + *
> >>> + * This function is used to call the region specific initialization
> >>> + * function for a reserved memory region.
> >>> */
> >>> -void __init fdt_init_reserved_mem(void)
> >>> +static void __init fdt_init_reserved_mem_node(struct reserved_mem
> *rmem)
> >>> {
> >>> - int i;
> >>> -
> >>> - /* check for overlapping reserved regions */
> >>> - __rmem_check_for_overlap();
> >>> -
> >>> - for (i = 0; i < reserved_mem_count; i++) {
> >>> - struct reserved_mem *rmem = &reserved_mem[i];
> >>> - unsigned long node = rmem->fdt_node;
> >>> - int err = 0;
> >>> - bool nomap;
> >>> + unsigned long node = rmem->fdt_node;
> >>> + int err = 0;
> >>> + bool nomap;
> >>>
> >>> - nomap = of_get_flat_dt_prop(node, "no-map", NULL) !=
> >>> NULL;
> >>> + nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
> >>>
> >>> - if (rmem->size == 0)
> >>> - err = __reserved_mem_alloc_size(node,
> >>> rmem->name,
> >>> - &rmem->base,
> >>> &rmem->size);
> >>> - if (err == 0) {
> >>> - err = __reserved_mem_init_node(rmem);
> >>> - if (err != 0 && err != -ENOENT) {
> >>> - pr_info("node %s compatible matching
> >>> fail\n",
> >>> - rmem->name);
> >>> - if (nomap)
> >>> - memblock_clear_nomap(rmem->base,
> >>> rmem->size);
> >>> - else
> >>> - memblock_phys_free(rmem->base,
> >>> - rmem->size);
> >>> - } else {
> >>> - phys_addr_t end = rmem->base +
> >>> rmem->size - 1;
> >>> - bool reusable =
> >>> - (of_get_flat_dt_prop(node,
> >>> "reusable", NULL)) !=
> NULL;
> >>> -
> >>> - pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
> >>> - &rmem->base, &end, (unsigned
> >>> long)(rmem->size /
> SZ_1K),
> >>> - nomap ? "nomap" : "map",
> >>> - reusable ? "reusable" :
> >>> "non-reusable",
> >>> - rmem->name ? rmem->name :
> >>> "unknown");
> >>> - }
> >>> - }
> >>> + err = __reserved_mem_init_node(rmem);
> >>> + if (err != 0 && err != -ENOENT) {
> >>> + pr_info("node %s compatible matching fail\n",
> >>> rmem->name);
> >>> + if (nomap)
> >>> + memblock_clear_nomap(rmem->base, rmem->size);
> >>> + else
> >>> + memblock_phys_free(rmem->base, rmem->size);
> >>> + } else {
> >>> + phys_addr_t end = rmem->base + rmem->size - 1;
> >>> + bool reusable =
> >>> + (of_get_flat_dt_prop(node, "reusable", NULL)) !=
> >>> NULL;
> >>> +
> >>> + pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
> >>> + &rmem->base, &end, (unsigned long)(rmem->size /
> >>> SZ_1K),
> >>> + nomap ? "nomap" : "map",
> >>> + reusable ? "reusable" : "non-reusable",
> >>> + rmem->name ? rmem->name : "unknown");
> >>> }
> >>> }
> >>>
> >>
> > Just want to follow up on this issue. Do you need any further detail
> > or clarification?
> > Any ARM memory manage guru on this thread can comment?
> > Or is my workaround acceptable as a patch?
>
>
> Hi William,
>
> Sorry about the delay in getting back to you.
>
> Instead of moving dma_contiguous_remap(), I suggest moving
> dma_contiguous_early_fixup()
> to the function that parses the reserved regions so that it is done before
> paging_init.
>
> Here is what that could look like. Can you please give this a try?
>
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> index 77016c0cc296..132d2c66cafc 100644
> --- a/drivers/of/of_reserved_mem.c
> +++ b/drivers/of/of_reserved_mem.c
> @@ -25,6 +25,7 @@
> #include <linux/memblock.h>
> #include <linux/kmemleak.h>
> #include <linux/cma.h>
> +#include <linux/dma-map-ops.h>
>
> #include "of_private.h"
>
> @@ -175,13 +176,17 @@ static int __init
> __reserved_mem_reserve_reg(unsigned long node,
> base = dt_mem_next_cell(dt_root_addr_cells, &prop);
> size = dt_mem_next_cell(dt_root_size_cells, &prop);
>
> - if (size &&
> - early_init_dt_reserve_memory(base, size, nomap) == 0)
> + if (size && early_init_dt_reserve_memory(base, size,
> nomap) == 0) {
> + /* Architecture specific contiguous memory fixup.
> */
> + if (of_flat_dt_is_compatible(node,
> "shared-dma-pool"))
> + dma_contiguous_early_fixup(base, size);
> +
> pr_debug("Reserved memory: reserved region for
> node '%s':
> base %pa, size %lu MiB\n",
> uname, &base, (unsigned long)(size /
> SZ_1M));
> - else
> + } else {
> pr_err("Reserved memory: failed to reserve memory
> for node '%s':
> base %pa, size %lu MiB\n",
> uname, &base, (unsigned long)(size /
> SZ_1M));
> + }
>
> len -= t_len;
> }
> @@ -472,6 +477,9 @@ static int __init __reserved_mem_alloc_size(unsigned
> long node, const char *unam
> uname, (unsigned long)(size / SZ_1M));
> return -ENOMEM;
> }
> + /* Architecture specific contiguous memory fixup. */
> + if (of_flat_dt_is_compatible(node, "shared-dma-pool"))
> + dma_contiguous_early_fixup(base, size);
> /* Save region in the reserved_mem array */
> fdt_reserved_mem_save_node(node, uname, base, size);
> diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
> index 8df0dfaaca18..9e5d63efe7c5 100644
> --- a/kernel/dma/contiguous.c
> +++ b/kernel/dma/contiguous.c
> @@ -480,8 +480,6 @@ static int __init rmem_cma_setup(struct reserved_mem
> *rmem)
> pr_err("Reserved memory: unable to setup CMA region\n");
> return err;
> }
> - /* Architecture specific contiguous memory fixup. */
> - dma_contiguous_early_fixup(rmem->base, rmem->size);
>
> if (default_cma)
> dma_contiguous_default_area = cma;
>
> Regards,
> Oreoluwa
Thank you Oreoluwa! Your patch fixed the issue too and it looks a more
localized and better fix!
On 6/28/2025 2:04 PM, William Zhang wrote:
>> -----Original Message-----
>> From: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
>> Sent: Friday, June 27, 2025 11:02 AM
>> To: William Zhang <william.zhang@broadcom.com>; robh@kernel.org
>> Cc: aisheng.dong@nxp.com; andy@black.fi.intel.com;
>> catalin.marinas@arm.com; devicetree@vger.kernel.org; hch@lst.de;
>> iommu@lists.linux.dev; kernel@quicinc.com; klarasmodin@gmail.com; linux-
>> kernel@vger.kernel.org; m.szyprowski@samsung.com;
>> quic_ninanaik@quicinc.com; robin.murphy@arm.com; saravanak@google.com;
>> will@kernel.org; oreoluwa.babatunde@oss.qualcomm.com
>> Subject: Re: [PATCH v10 1/2] of: reserved_mem: Restruture how the reserved
>> memory regions are processed
>>
>>
>>
>> On 6/22/2025 6:24 PM, William Zhang wrote:
>>> On Tue, Jun 17, 2025 at 10:15 AM William Zhang
>>> <william.zhang@broadcom.com> wrote:
>>>>
>>>> Hi Oreoluwa,
>>>>
>>>> On 10/8/2024 3:06 PM, Oreoluwa Babatunde wrote:
>>>>> Reserved memory regions defined in the devicetree can be broken up
>>>>> into
>>>>> two groups:
>>>>> i) Statically-placed reserved memory regions
>>>>> i.e. regions defined with a static start address and size using the
>>>>> "reg" property.
>>>>> ii) Dynamically-placed reserved memory regions.
>>>>> i.e. regions defined by specifying an address range where they can be
>>>>> placed in memory using the "alloc_ranges" and "size" properties.
>>>>>
>>>>> These regions are processed and set aside at boot time.
>>>>> This is done in two stages as seen below:
>>>>>
>>>>> Stage 1:
>>>>> At this stage, fdt_scan_reserved_mem() scans through the child nodes
>>>>> of
>>>>> the reserved_memory node using the flattened devicetree and does the
>>>>> following:
>>>>>
>>>>> 1) If the node represents a statically-placed reserved memory region,
>>>>> i.e. if it is defined using the "reg" property:
>>>>> - Call memblock_reserve() or memblock_mark_nomap() as needed.
>>>>> - Add the information for that region into the reserved_mem array
>>>>> using fdt_reserved_mem_save_node().
>>>>> i.e. fdt_reserved_mem_save_node(node, name, base, size).
>>>>>
>>>>> 2) If the node represents a dynamically-placed reserved memory region,
>>>>> i.e. if it is defined using "alloc-ranges" and "size" properties:
>>>>> - Add the information for that region to the reserved_mem array
>>>>> with
>>>>> the starting address and size set to 0.
>>>>> i.e. fdt_reserved_mem_save_node(node, name, 0, 0).
>>>>> Note: This region is saved to the array with a starting address of
>>>>> 0
>>>>> because a starting address is not yet allocated for it.
>>>>>
>>>>> Stage 2:
>>>>> After iterating through all the reserved memory nodes and storing
>>>>> their
>>>>> relevant information in the reserved_mem array,fdt_init_reserved_mem()
>>>>> is
>>>>> called and does the following:
>>>>>
>>>>> 1) For statically-placed reserved memory regions:
>>>>> - Call the region specific init function using
>>>>> __reserved_mem_init_node().
>>>>> 2) For dynamically-placed reserved memory regions:
>>>>> - Call __reserved_mem_alloc_size() which is used to allocate
>>>>> memory
>>>>> for each of these regions, and mark them as nomap if they have
>>>>> the
>>>>> nomap property specified in the DT.
>>>>> - Call the region specific init function.
>>>>>
>>>>> The current size of the resvered_mem array is 64 as is defined by
>>>>> MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for
>>>>> how many reserved memory regions can be specified on a system.
>>>>> As systems continue to grow more and more complex, the number of
>>>>> reserved memory regions needed are also growing and are starting to
>>>>> hit
>>>>> this 64 count limit, hence the need to make the reserved_mem array
>>>>> dynamically sized (i.e. dynamically allocating memory for the
>>>>> reserved_mem array using membock_alloc_*).
>>>>>
>>>>> On architectures such as arm64, memory allocated using memblock is
>>>>> writable only after the page tables have been setup. This means that
>>>>> if
>>>>> the reserved_mem array is going to be dynamically allocated, it needs
>>>>> to
>>>>> happen after the page tables have been setup, not before.
>>>>>
>>>>> Since the reserved memory regions are currently being processed and
>>>>> added to the array before the page tables are setup, there is a need
>>>>> to
>>>>> change the order in which some of the processing is done to allow for
>>>>> the reserved_mem array to be dynamically sized.
>>>>>
>>>>> It is possible to process the statically-placed reserved memory
>>>>> regions
>>>>> without needing to store them in the reserved_mem array until after
>>>>> the
>>>>> page tables have been setup because all the information stored in the
>>>>> array is readily available in the devicetree and can be referenced at
>>>>> any time.
>>>>> Dynamically-placed reserved memory regions on the other hand get
>>>>> assigned a start address only at runtime, and hence need a place to be
>>>>> stored once they are allocated since there is no other referrence to
>>>>> the
>>>>> start address for these regions.
>>>>>
>>>>> Hence this patch changes the processing order of the reserved memory
>>>>> regions in the following ways:
>>>>>
>>>>> Step 1:
>>>>> fdt_scan_reserved_mem() scans through the child nodes of
>>>>> the reserved_memory node using the flattened devicetree and does the
>>>>> following:
>>>>>
>>>>> 1) If the node represents a statically-placed reserved memory region,
>>>>> i.e. if it is defined using the "reg" property:
>>>>> - Call memblock_reserve() or memblock_mark_nomap() as needed.
>>>>>
>>>>> 2) If the node represents a dynamically-placed reserved memory region,
>>>>> i.e. if it is defined using "alloc-ranges" and "size" properties:
>>>>> - Call __reserved_mem_alloc_size() which will:
>>>>> i) Allocate memory for the reserved region and call
>>>>> memblock_mark_nomap() as needed.
>>>>> ii) Call the region specific initialization function using
>>>>> fdt_init_reserved_mem_node().
>>>>> iii) Save the region information in the reserved_mem array using
>>>>> fdt_reserved_mem_save_node().
>>>>>
>>>>> Step 2:
>>>>> 1) This stage of the reserved memory processing is now only used to
>>>>> add
>>>>> the statically-placed reserved memory regions into the
>>>>> reserved_mem
>>>>> array using fdt_scan_reserved_mem_reg_nodes(), as well as call
>>>>> their
>>>>> region specific initialization functions.
>>>>>
>>>>> 2) This step has also been moved to be after the page tables are
>>>>> setup. Moving this will allow us to replace the reserved_mem
>>>>> array with a dynamically sized array before storing the rest of
>>>>> these regions.
>>>> I am running into a call trace with this order change on armv7 chip
>>>> when
>>>> I tried to allocate dma coherent memory from the device reserved
>>>> memory.
>>>> The issue does not happen on armv8 chips.
>>>>
>>>> [ 0.000000] Reserved memory: created CMA memory pool at 0x1e000000,
>>>> size 32 MiB
>>>> [ 0.000000] OF: reserved mem: initialized node dt_reserved_cma,
>>>> compatible id shared-dma-pool
>>>> [ 0.000000] OF: reserved mem: 0x1e000000..0x1fffffff (32768 KiB) map
>>>> reusable dt_reserved_cma
>>>> ....
>>>>
>>>> [ 0.445322] ------------[ cut here ]------------
>>>> [ 0.445353] WARNING: CPU: 0 PID: 1 at mm/memory.c:3069
>>>> __apply_to_page_range+0x380/0x388
>>>> [ 0.488911] Modules linked in:
>>>> [ 0.492027] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted
>>>> 6.16.0-rc1-g27605c8c0f69-dirty #3 NONE
>>>> [ 0.501174] Hardware name: Generic DT based system
>>>> [ 0.505965] Call trace:
>>>> [ 0.505985] unwind_backtrace from show_stack+0x10/0x14
>>>> [ 0.513764] show_stack from dump_stack_lvl+0x54/0x68
>>>> [ 0.518834] dump_stack_lvl from __warn+0x7c/0x128
>>>> [ 0.523639] __warn from warn_slowpath_fmt+0x184/0x18c
>>>> [ 0.527676] Freeing initrd memory: 65536K
>>>> [ 0.532788] warn_slowpath_fmt from
>> __apply_to_page_range+0x380/0x388
>>>> [ 0.539242] __apply_to_page_range from
>> apply_to_page_range+0x1c/0x24
>>>> [ 0.545689] apply_to_page_range from
>> __alloc_from_contiguous+0xc0/0x14c
>>>> [ 0.552398] __alloc_from_contiguous from
>> cma_allocator_alloc+0x34/0x3c
>>>> [ 0.559016] cma_allocator_alloc from arch_dma_alloc+0x11c/0x2ac
>>>> [ 0.565025] arch_dma_alloc from dma_alloc_attrs+0x90/0x2e8
>>>> [ 0.570603] dma_alloc_attrs from dmydev_probe+0x8c/0xe8
>>>> [ 0.575919] dmydev_probe from platform_probe+0x5c/0xb0
>>>> [ 0.581152] platform_probe from really_probe+0xc8/0x2c8
>>>> [ 0.586467] really_probe from __driver_probe_device+0x88/0x19c
>>>> [ 0.592387] __driver_probe_device from
>>>> driver_probe_device+0x30/0x104
>>>> [ 0.598915] driver_probe_device from __driver_attach+0x90/0x178
>>>> [ 0.604921] __driver_attach from bus_for_each_dev+0x7c/0xcc
>>>> [ 0.610582] bus_for_each_dev from bus_add_driver+0xcc/0x1ec
>>>> [ 0.616241] bus_add_driver from driver_register+0x7c/0x114
>>>> [ 0.621814] driver_register from dmydev_init+0x20/0x28
>>>> [ 0.627045] dmydev_init from do_one_initcall+0x58/0x200
>>>> [ 0.632363] do_one_initcall from kernel_init_freeable+0x1cc/0x228
>>>> [ 0.638550] kernel_init_freeable from kernel_init+0x1c/0x12c
>>>> [ 0.644299] kernel_init from ret_from_fork+0x14/0x28
>>>> [ 0.649351] Exception stack(0xe0819fb0 to 0xe0819ff8)
>>>> [ 0.654401] 9fa0: 00000000
>>>> 00000000 00000000 00000000
>>>> [ 0.662575] 9fc0: 00000000 00000000 00000000 00000000 00000000
>>>> 00000000 00000000 00000000
>>>> [ 0.670747] 9fe0: 00000000 00000000 00000000 00000000 00000013
>> 00000000
>>>> [ 0.677403] ---[ end trace 0000000000000000 ]---
>>>> [ 0.682083] dmydev dmy_device: Allocate dma memory at 0xde000000 dma
>>>> addr 0x1e000000
>>>>
>>>> The reason is that now reserved memory's fixup function
>>>> dma_contiguous_early_fixup is called after the page table is
>>>> initialized. This fixup function increases the dma_mmu_remap count for
>>>> each reserved memory. And the dma_contiguous_remap function depends
>> on
>>>> it to properly set up the reserved memory mmu table entry. Before this
>>>> change, the paging_init function calls dma_contiguous_remap and it
>>>> founds the reserved memory and set it up properly. After the change,
>>>> this function found there is no reserved memory so skip any
>>>> initialization hence causes the crash later on when my driver tries to
>>>> allocate dma memory from the reserved memory.
>>>>
>>>> My workaround below is to move the dma_contiguous_remap out from the
>>>> paging_init function to the place right after unflatten_device_tree
>>>> where the dma_mmu_remap count is correctly set. But this is not ideal
>>>> solution and would like to see if you have any better way to solve the
>>>> issue.
>>>>
>>>> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
>>>> index a41c93988d2c..535d1bf44529 100644
>>>> --- a/arch/arm/kernel/setup.c
>>>> +++ b/arch/arm/kernel/setup.c
>>>> @@ -1079,6 +1079,7 @@ void __init hyp_mode_check(void)
>>>> #endif
>>>> }
>>>>
>>>> +void __init dma_contiguous_remap(void);
>>>> static void (*__arm_pm_restart)(enum reboot_mode reboot_mode, const
>>>> char *cmd);
>>>>
>>>> static int arm_restart(struct notifier_block *nb, unsigned long
>>>> action,
>>>> @@ -1164,6 +1165,7 @@ void __init setup_arch(char **cmdline_p)
>>>> }
>>>>
>>>> unflatten_device_tree();
>>>> + dma_contiguous_remap();
>>>>
>>>> arm_dt_init_cpu_maps();
>>>> psci_dt_init();
>>>> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
>>>> index edb7f56b7c91..1828c8737d70 100644
>>>> --- a/arch/arm/mm/mmu.c
>>>> +++ b/arch/arm/mm/mmu.c
>>>> @@ -1773,7 +1773,6 @@ void __init paging_init(const struct machine_desc
>>>> *mdesc)
>>>> * be used
>>>> */
>>>> map_kernel();
>>>> - dma_contiguous_remap();
>>>> early_fixmap_shutdown();
>>>> devicemaps_init(mdesc);
>>>> kmap_init();
>>>>
>>>> You can reproduce the issue on any v7 devices by adding these nodes to
>>>> the device tree
>>>> + reserved-memory {
>>>> + #address-cells = <1>;
>>>> + #size-cells = <1>;
>>>> + ranges;
>>>> +
>>>> + dt_reserved_cma: dt_reserved_cma {
>>>> + compatible = "shared-dma-pool";
>>>> + reusable;
>>>> +
>>>> + reg = <0x1e000000 0x2000000>;
>>>> + };
>>>> + };
>>>> +
>>>> + dmy_device {
>>>> + compatible = "xyz,dmydev";
>>>> + memory-region = <&dt_reserved_cma>;
>>>> + };
>>>>
>>>> And use this test driver to trigger the call stack:
>>>> diff --git a/drivers/char/dmydev.c b/drivers/char/dmydev.c
>>>> new file mode 100644
>>>> index 000000000000..1dd52ec492eb
>>>> --- /dev/null
>>>> +++ b/drivers/char/dmydev.c
>>>> @@ -0,0 +1,67 @@
>>>> +#include<linux/module.h>
>>>> +#include<linux/kernel.h>
>>>> +#include <linux/platform_device.h>
>>>> +#include <linux/of.h>
>>>> +#include <linux/of_reserved_mem.h>
>>>> +#include <linux/dma-mapping.h>
>>>> +
>>>> +static int dmydev_probe(struct platform_device *pdev)
>>>> +{
>>>> + void* virt_addr;
>>>> + dma_addr_t dma_addr;
>>>> + int ret;
>>>> +
>>>> + printk(KERN_ALERT "dmydev_probe called\n");
>>>> +
>>>> + ret = of_reserved_mem_device_init(&pdev->dev);
>>>> + if (ret && ret != -ENODEV) {
>>>> + dev_err(&pdev->dev, "Couldn't assign reserve memory to
>>>> device ret = %d\n", ret);
>>>> + return ret;
>>>> + }
>>>> +
>>>> + virt_addr = dma_alloc_coherent(&pdev->dev, 0x800000, &dma_addr,
>>>> GFP_KERNEL);
>>>> + if (virt_addr == NULL) {
>>>> + dev_err(&pdev->dev,"Failed to allocated cma memory\n");
>>>> + ret = -ENOMEM;
>>>> + }
>>>> + else
>>>> + dev_err(&pdev->dev,"Allocate dma memory at 0x%px dma
>>>> addr %pad\n", virt_addr, &dma_addr);
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static void dmydev_remove(struct platform_device *pdev)
>>>> +{
>>>> +}
>>>> +
>>>> +static const struct of_device_id dmydev_of_match[] = {
>>>> + {.compatible = "xyz,dmydev"},
>>>> + {}
>>>> +};
>>>> +MODULE_DEVICE_TABLE(of, dmydev_of_match);
>>>>
>>>> Let me know if you need more info.
>>>>
>>>>>
>>>>> Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
>>>>> ---
>>>>> drivers/of/fdt.c | 5 +-
>>>>> drivers/of/of_private.h | 3 +-
>>>>> drivers/of/of_reserved_mem.c | 168
>>>>> ++++++++++++++++++++++++----------
>> -
>>>>> 3 files changed, 122 insertions(+), 54 deletions(-)
>>>>>
>>>>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
>>>>> index 4d528c10df3a..d0dbc8183ac4 100644
>>>>> --- a/drivers/of/fdt.c
>>>>> +++ b/drivers/of/fdt.c
>>>>> @@ -511,8 +511,6 @@ void __init early_init_fdt_scan_reserved_mem(void)
>>>>> break;
>>>>> memblock_reserve(base, size);
>>>>> }
>>>>> -
>>>>> - fdt_init_reserved_mem();
>>>>> }
>>>>>
>>>>> /**
>>>>> @@ -1212,6 +1210,9 @@ void __init unflatten_device_tree(void)
>>>>> {
>>>>> void *fdt = initial_boot_params;
>>>>>
>>>>> + /* Save the statically-placed regions in the reserved_mem array
>>>>> */
>>>>> + fdt_scan_reserved_mem_reg_nodes();
>>>>> +
>>>>> /* Don't use the bootloader provided DTB if ACPI is enabled */
>>>>> if (!acpi_disabled)
>>>>> fdt = NULL;
>>>>> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
>>>>> index 04aa2a91f851..29525c0b9939 100644
>>>>> --- a/drivers/of/of_private.h
>>>>> +++ b/drivers/of/of_private.h
>>>>> @@ -9,6 +9,7 @@
>>>>> */
>>>>>
>>>>> #define FDT_ALIGN_SIZE 8
>>>>> +#define MAX_RESERVED_REGIONS 64
>>>>>
>>>>> /**
>>>>> * struct alias_prop - Alias property in 'aliases' node
>>>>> @@ -180,7 +181,7 @@ static inline struct device_node
>> *__of_get_dma_parent(const struct device_node *
>>>>> #endif
>>>>>
>>>>> int fdt_scan_reserved_mem(void);
>>>>> -void fdt_init_reserved_mem(void);
>>>>> +void __init fdt_scan_reserved_mem_reg_nodes(void);
>>>>>
>>>>> bool of_fdt_device_is_available(const void *blob, unsigned long
>>>>> node);
>>>>>
>>>>> diff --git a/drivers/of/of_reserved_mem.c
>>>>> b/drivers/of/of_reserved_mem.c
>>>>> index 46e1c3fbc769..2011174211f9 100644
>>>>> --- a/drivers/of/of_reserved_mem.c
>>>>> +++ b/drivers/of/of_reserved_mem.c
>>>>> @@ -27,7 +27,6 @@
>>>>>
>>>>> #include "of_private.h"
>>>>>
>>>>> -#define MAX_RESERVED_REGIONS 64
>>>>> static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
>>>>> static int reserved_mem_count;
>>>>>
>>>>> @@ -56,6 +55,7 @@ static int __init
>> early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
>>>>> return err;
>>>>> }
>>>>>
>>>>> +static void __init fdt_init_reserved_mem_node(struct reserved_mem
>> *rmem);
>>>>> /*
>>>>> * fdt_reserved_mem_save_node() - save fdt node for second pass
>> initialization
>>>>> */
>>>>> @@ -74,6 +74,9 @@ static void __init
>> fdt_reserved_mem_save_node(unsigned long node, const char *un
>>>>> rmem->base = base;
>>>>> rmem->size = size;
>>>>>
>>>>> + /* Call the region specific initialization function */
>>>>> + fdt_init_reserved_mem_node(rmem);
>>>>> +
>>>>> reserved_mem_count++;
>>>>> return;
>>>>> }
>>>>> @@ -106,7 +109,6 @@ static int __init
>> __reserved_mem_reserve_reg(unsigned long node,
>>>>> phys_addr_t base, size;
>>>>> int len;
>>>>> const __be32 *prop;
>>>>> - int first = 1;
>>>>> bool nomap;
>>>>>
>>>>> prop = of_get_flat_dt_prop(node, "reg", &len);
>>>>> @@ -134,10 +136,6 @@ static int __init
>> __reserved_mem_reserve_reg(unsigned long node,
>>>>> uname, &base, (unsigned long)(size /
>>>>> SZ_1M));
>>>>>
>>>>> len -= t_len;
>>>>> - if (first) {
>>>>> - fdt_reserved_mem_save_node(node, uname, base,
>>>>> size);
>>>>> - first = 0;
>>>>> - }
>>>>> }
>>>>> return 0;
>>>>> }
>>>>> @@ -165,12 +163,77 @@ static int __init
>> __reserved_mem_check_root(unsigned long node)
>>>>> return 0;
>>>>> }
>>>>>
>>>>> +static void __init __rmem_check_for_overlap(void);
>>>>> +
>>>>> +/**
>>>>> + * fdt_scan_reserved_mem_reg_nodes() - Store info for the "reg"
>>>>> defined
>>>>> + * reserved memory regions.
>>>>> + *
>>>>> + * This function is used to scan through the DT and store the
>>>>> + * information for the reserved memory regions that are defined using
>>>>> + * the "reg" property. The region node number, name, base address,
>>>>> and
>>>>> + * size are all stored in the reserved_mem array by calling the
>>>>> + * fdt_reserved_mem_save_node() function.
>>>>> + */
>>>>> +void __init fdt_scan_reserved_mem_reg_nodes(void)
>>>>> +{
>>>>> + int t_len = (dt_root_addr_cells + dt_root_size_cells) *
>>>>> sizeof(__be32);
>>>>> + const void *fdt = initial_boot_params;
>>>>> + phys_addr_t base, size;
>>>>> + const __be32 *prop;
>>>>> + int node, child;
>>>>> + int len;
>>>>> +
>>>>> + if (!fdt)
>>>>> + return;
>>>>> +
>>>>> + node = fdt_path_offset(fdt, "/reserved-memory");
>>>>> + if (node < 0) {
>>>>> + pr_info("Reserved memory: No reserved-memory node in the
>> DT\n");
>>>>> + return;
>>>>> + }
>>>>> +
>>>>> + if (__reserved_mem_check_root(node)) {
>>>>> + pr_err("Reserved memory: unsupported node format,
>>>>> ignoring\n");
>>>>> + return;
>>>>> + }
>>>>> +
>>>>> + fdt_for_each_subnode(child, fdt, node) {
>>>>> + const char *uname;
>>>>> +
>>>>> + prop = of_get_flat_dt_prop(child, "reg", &len);
>>>>> + if (!prop)
>>>>> + continue;
>>>>> + if (!of_fdt_device_is_available(fdt, child))
>>>>> + continue;
>>>>> +
>>>>> + uname = fdt_get_name(fdt, child, NULL);
>>>>> + if (len && len % t_len != 0) {
>>>>> + pr_err("Reserved memory: invalid reg property in
>>>>> '%s', skipping
>> node.\n",
>>>>> + uname);
>>>>> + continue;
>>>>> + }
>>>>> + base = dt_mem_next_cell(dt_root_addr_cells, &prop);
>>>>> + size = dt_mem_next_cell(dt_root_size_cells, &prop);
>>>>> +
>>>>> + if (size)
>>>>> + fdt_reserved_mem_save_node(child, uname, base,
>>>>> size);
>>>>> + }
>>>>> +
>>>>> + /* check for overlapping reserved regions */
>>>>> + __rmem_check_for_overlap();
>>>>> +}
>>>>> +
>>>>> +static int __init __reserved_mem_alloc_size(unsigned long node, const
>> char *uname);
>>>>> +
>>>>> /*
>>>>> * fdt_scan_reserved_mem() - scan a single FDT node for reserved
>>>>> memory
>>>>> */
>>>>> int __init fdt_scan_reserved_mem(void)
>>>>> {
>>>>> int node, child;
>>>>> + int dynamic_nodes_cnt = 0;
>>>>> + int dynamic_nodes[MAX_RESERVED_REGIONS];
>>>>> const void *fdt = initial_boot_params;
>>>>>
>>>>> node = fdt_path_offset(fdt, "/reserved-memory");
>>>>> @@ -192,8 +255,24 @@ int __init fdt_scan_reserved_mem(void)
>>>>> uname = fdt_get_name(fdt, child, NULL);
>>>>>
>>>>> err = __reserved_mem_reserve_reg(child, uname);
>>>>> - if (err == -ENOENT && of_get_flat_dt_prop(child, "size",
>>>>> NULL))
>>>>> - fdt_reserved_mem_save_node(child, uname, 0, 0);
>>>>> + /*
>>>>> + * Save the nodes for the dynamically-placed regions
>>>>> + * into an array which will be used for allocation right
>>>>> + * after all the statically-placed regions are reserved
>>>>> + * or marked as no-map. This is done to avoid
>>>>> dynamically
>>>>> + * allocating from one of the statically-placed regions.
>>>>> + */
>>>>> + if (err == -ENOENT && of_get_flat_dt_prop(child, "size",
>>>>> NULL)) {
>>>>> + dynamic_nodes[dynamic_nodes_cnt] = child;
>>>>> + dynamic_nodes_cnt++;
>>>>> + }
>>>>> + }
>>>>> + for (int i = 0; i < dynamic_nodes_cnt; i++) {
>>>>> + const char *uname;
>>>>> +
>>>>> + child = dynamic_nodes[i];
>>>>> + uname = fdt_get_name(fdt, child, NULL);
>>>>> + __reserved_mem_alloc_size(child, uname);
>>>>> }
>>>>> return 0;
>>>>> }
>>>>> @@ -253,8 +332,7 @@ static int __init
>> __reserved_mem_alloc_in_range(phys_addr_t size,
>>>>> * __reserved_mem_alloc_size() - allocate reserved memory described
>>>>> by
>>>>> * 'size', 'alignment' and 'alloc-ranges' properties.
>>>>> */
>>>>> -static int __init __reserved_mem_alloc_size(unsigned long node,
>>>>> - const char *uname, phys_addr_t *res_base, phys_addr_t *res_size)
>>>>> +static int __init __reserved_mem_alloc_size(unsigned long node, const
>> char *uname)
>>>>> {
>>>>> int t_len = (dt_root_addr_cells + dt_root_size_cells) *
>>>>> sizeof(__be32);
>>>>> phys_addr_t start = 0, end = 0;
>>>>> @@ -334,9 +412,8 @@ static int __init
>> __reserved_mem_alloc_size(unsigned long node,
>>>>> return -ENOMEM;
>>>>> }
>>>>>
>>>>> - *res_base = base;
>>>>> - *res_size = size;
>>>>> -
>>>>> + /* Save region in the reserved_mem array */
>>>>> + fdt_reserved_mem_save_node(node, uname, base, size);
>>>>> return 0;
>>>>> }
>>>>>
>>>>> @@ -425,48 +502,37 @@ static void __init
>> __rmem_check_for_overlap(void)
>>>>> }
>>>>>
>>>>> /**
>>>>> - * fdt_init_reserved_mem() - allocate and init all saved reserved
>>>>> memory
>> regions
>>>>> + * fdt_init_reserved_mem_node() - Initialize a reserved memory region
>>>>> + * @rmem: reserved_mem struct of the memory region to be initialized.
>>>>> + *
>>>>> + * This function is used to call the region specific initialization
>>>>> + * function for a reserved memory region.
>>>>> */
>>>>> -void __init fdt_init_reserved_mem(void)
>>>>> +static void __init fdt_init_reserved_mem_node(struct reserved_mem
>> *rmem)
>>>>> {
>>>>> - int i;
>>>>> -
>>>>> - /* check for overlapping reserved regions */
>>>>> - __rmem_check_for_overlap();
>>>>> -
>>>>> - for (i = 0; i < reserved_mem_count; i++) {
>>>>> - struct reserved_mem *rmem = &reserved_mem[i];
>>>>> - unsigned long node = rmem->fdt_node;
>>>>> - int err = 0;
>>>>> - bool nomap;
>>>>> + unsigned long node = rmem->fdt_node;
>>>>> + int err = 0;
>>>>> + bool nomap;
>>>>>
>>>>> - nomap = of_get_flat_dt_prop(node, "no-map", NULL) !=
>>>>> NULL;
>>>>> + nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
>>>>>
>>>>> - if (rmem->size == 0)
>>>>> - err = __reserved_mem_alloc_size(node,
>>>>> rmem->name,
>>>>> - &rmem->base,
>>>>> &rmem->size);
>>>>> - if (err == 0) {
>>>>> - err = __reserved_mem_init_node(rmem);
>>>>> - if (err != 0 && err != -ENOENT) {
>>>>> - pr_info("node %s compatible matching
>>>>> fail\n",
>>>>> - rmem->name);
>>>>> - if (nomap)
>>>>> - memblock_clear_nomap(rmem->base,
>>>>> rmem->size);
>>>>> - else
>>>>> - memblock_phys_free(rmem->base,
>>>>> - rmem->size);
>>>>> - } else {
>>>>> - phys_addr_t end = rmem->base +
>>>>> rmem->size - 1;
>>>>> - bool reusable =
>>>>> - (of_get_flat_dt_prop(node,
>>>>> "reusable", NULL)) !=
>> NULL;
>>>>> -
>>>>> - pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
>>>>> - &rmem->base, &end, (unsigned
>>>>> long)(rmem->size /
>> SZ_1K),
>>>>> - nomap ? "nomap" : "map",
>>>>> - reusable ? "reusable" :
>>>>> "non-reusable",
>>>>> - rmem->name ? rmem->name :
>>>>> "unknown");
>>>>> - }
>>>>> - }
>>>>> + err = __reserved_mem_init_node(rmem);
>>>>> + if (err != 0 && err != -ENOENT) {
>>>>> + pr_info("node %s compatible matching fail\n",
>>>>> rmem->name);
>>>>> + if (nomap)
>>>>> + memblock_clear_nomap(rmem->base, rmem->size);
>>>>> + else
>>>>> + memblock_phys_free(rmem->base, rmem->size);
>>>>> + } else {
>>>>> + phys_addr_t end = rmem->base + rmem->size - 1;
>>>>> + bool reusable =
>>>>> + (of_get_flat_dt_prop(node, "reusable", NULL)) !=
>>>>> NULL;
>>>>> +
>>>>> + pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
>>>>> + &rmem->base, &end, (unsigned long)(rmem->size /
>>>>> SZ_1K),
>>>>> + nomap ? "nomap" : "map",
>>>>> + reusable ? "reusable" : "non-reusable",
>>>>> + rmem->name ? rmem->name : "unknown");
>>>>> }
>>>>> }
>>>>>
>>>>
>>> Just want to follow up on this issue. Do you need any further detail
>>> or clarification?
>>> Any ARM memory manage guru on this thread can comment?
>>> Or is my workaround acceptable as a patch?
>>
>>
>> Hi William,
>>
>> Sorry about the delay in getting back to you.
>>
>> Instead of moving dma_contiguous_remap(), I suggest moving
>> dma_contiguous_early_fixup()
>> to the function that parses the reserved regions so that it is done before
>> paging_init.
>>
>> Here is what that could look like. Can you please give this a try?
>>
>> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
>> index 77016c0cc296..132d2c66cafc 100644
>> --- a/drivers/of/of_reserved_mem.c
>> +++ b/drivers/of/of_reserved_mem.c
>> @@ -25,6 +25,7 @@
>> #include <linux/memblock.h>
>> #include <linux/kmemleak.h>
>> #include <linux/cma.h>
>> +#include <linux/dma-map-ops.h>
>>
>> #include "of_private.h"
>>
>> @@ -175,13 +176,17 @@ static int __init
>> __reserved_mem_reserve_reg(unsigned long node,
>> base = dt_mem_next_cell(dt_root_addr_cells, &prop);
>> size = dt_mem_next_cell(dt_root_size_cells, &prop);
>>
>> - if (size &&
>> - early_init_dt_reserve_memory(base, size, nomap) == 0)
>> + if (size && early_init_dt_reserve_memory(base, size,
>> nomap) == 0) {
>> + /* Architecture specific contiguous memory fixup.
>> */
>> + if (of_flat_dt_is_compatible(node,
>> "shared-dma-pool"))
>> + dma_contiguous_early_fixup(base, size);
>> +
>> pr_debug("Reserved memory: reserved region for
>> node '%s':
>> base %pa, size %lu MiB\n",
>> uname, &base, (unsigned long)(size /
>> SZ_1M));
>> - else
>> + } else {
>> pr_err("Reserved memory: failed to reserve memory
>> for node '%s':
>> base %pa, size %lu MiB\n",
>> uname, &base, (unsigned long)(size /
>> SZ_1M));
>> + }
>>
>> len -= t_len;
>> }
>> @@ -472,6 +477,9 @@ static int __init __reserved_mem_alloc_size(unsigned
>> long node, const char *unam
>> uname, (unsigned long)(size / SZ_1M));
>> return -ENOMEM;
>> }
>> + /* Architecture specific contiguous memory fixup. */
>> + if (of_flat_dt_is_compatible(node, "shared-dma-pool"))
>> + dma_contiguous_early_fixup(base, size);
>> /* Save region in the reserved_mem array */
>> fdt_reserved_mem_save_node(node, uname, base, size);
>> diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
>> index 8df0dfaaca18..9e5d63efe7c5 100644
>> --- a/kernel/dma/contiguous.c
>> +++ b/kernel/dma/contiguous.c
>> @@ -480,8 +480,6 @@ static int __init rmem_cma_setup(struct reserved_mem
>> *rmem)
>> pr_err("Reserved memory: unable to setup CMA region\n");
>> return err;
>> }
>> - /* Architecture specific contiguous memory fixup. */
>> - dma_contiguous_early_fixup(rmem->base, rmem->size);
>>
>> if (default_cma)
>> dma_contiguous_default_area = cma;
>>
>> Regards,
>> Oreoluwa
>
> Thank you Oreoluwa! Your patch fixed the issue too and it looks a more
> localized and better fix!
Thank you for testing it out! I'm glad it worked for you.
I can work on an offical patch for this and submit it in
the next few days.
Regards,
Oreoluwa
On 03.07.2025 19:27, Oreoluwa Babatunde wrote:
> On 6/28/2025 2:04 PM, William Zhang wrote:
>>> -----Original Message-----
>>> From: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
>>> Sent: Friday, June 27, 2025 11:02 AM
>>> To: William Zhang <william.zhang@broadcom.com>; robh@kernel.org
>>> Cc: aisheng.dong@nxp.com; andy@black.fi.intel.com;
>>> catalin.marinas@arm.com; devicetree@vger.kernel.org; hch@lst.de;
>>> iommu@lists.linux.dev; kernel@quicinc.com; klarasmodin@gmail.com; linux-
>>> kernel@vger.kernel.org; m.szyprowski@samsung.com;
>>> quic_ninanaik@quicinc.com; robin.murphy@arm.com; saravanak@google.com;
>>> will@kernel.org; oreoluwa.babatunde@oss.qualcomm.com
>>> Subject: Re: [PATCH v10 1/2] of: reserved_mem: Restruture how the reserved
>>> memory regions are processed
>>>
>>>
>>>
>>> On 6/22/2025 6:24 PM, William Zhang wrote:
>>>> On Tue, Jun 17, 2025 at 10:15 AM William Zhang
>>>> <william.zhang@broadcom.com> wrote:
>>>>> Hi Oreoluwa,
>>>>>
>>>>> On 10/8/2024 3:06 PM, Oreoluwa Babatunde wrote:
>>>>>> Reserved memory regions defined in the devicetree can be broken up
>>>>>> into
>>>>>> two groups:
>>>>>> i) Statically-placed reserved memory regions
>>>>>> i.e. regions defined with a static start address and size using the
>>>>>> "reg" property.
>>>>>> ii) Dynamically-placed reserved memory regions.
>>>>>> i.e. regions defined by specifying an address range where they can be
>>>>>> placed in memory using the "alloc_ranges" and "size" properties.
>>>>>>
>>>>>> These regions are processed and set aside at boot time.
>>>>>> This is done in two stages as seen below:
>>>>>>
>>>>>> Stage 1:
>>>>>> At this stage, fdt_scan_reserved_mem() scans through the child nodes
>>>>>> of
>>>>>> the reserved_memory node using the flattened devicetree and does the
>>>>>> following:
>>>>>>
>>>>>> 1) If the node represents a statically-placed reserved memory region,
>>>>>> i.e. if it is defined using the "reg" property:
>>>>>> - Call memblock_reserve() or memblock_mark_nomap() as needed.
>>>>>> - Add the information for that region into the reserved_mem array
>>>>>> using fdt_reserved_mem_save_node().
>>>>>> i.e. fdt_reserved_mem_save_node(node, name, base, size).
>>>>>>
>>>>>> 2) If the node represents a dynamically-placed reserved memory region,
>>>>>> i.e. if it is defined using "alloc-ranges" and "size" properties:
>>>>>> - Add the information for that region to the reserved_mem array
>>>>>> with
>>>>>> the starting address and size set to 0.
>>>>>> i.e. fdt_reserved_mem_save_node(node, name, 0, 0).
>>>>>> Note: This region is saved to the array with a starting address of
>>>>>> 0
>>>>>> because a starting address is not yet allocated for it.
>>>>>>
>>>>>> Stage 2:
>>>>>> After iterating through all the reserved memory nodes and storing
>>>>>> their
>>>>>> relevant information in the reserved_mem array,fdt_init_reserved_mem()
>>>>>> is
>>>>>> called and does the following:
>>>>>>
>>>>>> 1) For statically-placed reserved memory regions:
>>>>>> - Call the region specific init function using
>>>>>> __reserved_mem_init_node().
>>>>>> 2) For dynamically-placed reserved memory regions:
>>>>>> - Call __reserved_mem_alloc_size() which is used to allocate
>>>>>> memory
>>>>>> for each of these regions, and mark them as nomap if they have
>>>>>> the
>>>>>> nomap property specified in the DT.
>>>>>> - Call the region specific init function.
>>>>>>
>>>>>> The current size of the resvered_mem array is 64 as is defined by
>>>>>> MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for
>>>>>> how many reserved memory regions can be specified on a system.
>>>>>> As systems continue to grow more and more complex, the number of
>>>>>> reserved memory regions needed are also growing and are starting to
>>>>>> hit
>>>>>> this 64 count limit, hence the need to make the reserved_mem array
>>>>>> dynamically sized (i.e. dynamically allocating memory for the
>>>>>> reserved_mem array using membock_alloc_*).
>>>>>>
>>>>>> On architectures such as arm64, memory allocated using memblock is
>>>>>> writable only after the page tables have been setup. This means that
>>>>>> if
>>>>>> the reserved_mem array is going to be dynamically allocated, it needs
>>>>>> to
>>>>>> happen after the page tables have been setup, not before.
>>>>>>
>>>>>> Since the reserved memory regions are currently being processed and
>>>>>> added to the array before the page tables are setup, there is a need
>>>>>> to
>>>>>> change the order in which some of the processing is done to allow for
>>>>>> the reserved_mem array to be dynamically sized.
>>>>>>
>>>>>> It is possible to process the statically-placed reserved memory
>>>>>> regions
>>>>>> without needing to store them in the reserved_mem array until after
>>>>>> the
>>>>>> page tables have been setup because all the information stored in the
>>>>>> array is readily available in the devicetree and can be referenced at
>>>>>> any time.
>>>>>> Dynamically-placed reserved memory regions on the other hand get
>>>>>> assigned a start address only at runtime, and hence need a place to be
>>>>>> stored once they are allocated since there is no other referrence to
>>>>>> the
>>>>>> start address for these regions.
>>>>>>
>>>>>> Hence this patch changes the processing order of the reserved memory
>>>>>> regions in the following ways:
>>>>>>
>>>>>> Step 1:
>>>>>> fdt_scan_reserved_mem() scans through the child nodes of
>>>>>> the reserved_memory node using the flattened devicetree and does the
>>>>>> following:
>>>>>>
>>>>>> 1) If the node represents a statically-placed reserved memory region,
>>>>>> i.e. if it is defined using the "reg" property:
>>>>>> - Call memblock_reserve() or memblock_mark_nomap() as needed.
>>>>>>
>>>>>> 2) If the node represents a dynamically-placed reserved memory region,
>>>>>> i.e. if it is defined using "alloc-ranges" and "size" properties:
>>>>>> - Call __reserved_mem_alloc_size() which will:
>>>>>> i) Allocate memory for the reserved region and call
>>>>>> memblock_mark_nomap() as needed.
>>>>>> ii) Call the region specific initialization function using
>>>>>> fdt_init_reserved_mem_node().
>>>>>> iii) Save the region information in the reserved_mem array using
>>>>>> fdt_reserved_mem_save_node().
>>>>>>
>>>>>> Step 2:
>>>>>> 1) This stage of the reserved memory processing is now only used to
>>>>>> add
>>>>>> the statically-placed reserved memory regions into the
>>>>>> reserved_mem
>>>>>> array using fdt_scan_reserved_mem_reg_nodes(), as well as call
>>>>>> their
>>>>>> region specific initialization functions.
>>>>>>
>>>>>> 2) This step has also been moved to be after the page tables are
>>>>>> setup. Moving this will allow us to replace the reserved_mem
>>>>>> array with a dynamically sized array before storing the rest of
>>>>>> these regions.
>>>>> I am running into a call trace with this order change on armv7 chip
>>>>> when
>>>>> I tried to allocate dma coherent memory from the device reserved
>>>>> memory.
>>>>> The issue does not happen on armv8 chips.
>>>>>
>>>>> [ 0.000000] Reserved memory: created CMA memory pool at 0x1e000000,
>>>>> size 32 MiB
>>>>> [ 0.000000] OF: reserved mem: initialized node dt_reserved_cma,
>>>>> compatible id shared-dma-pool
>>>>> [ 0.000000] OF: reserved mem: 0x1e000000..0x1fffffff (32768 KiB) map
>>>>> reusable dt_reserved_cma
>>>>> ....
>>>>>
>>>>> [ 0.445322] ------------[ cut here ]------------
>>>>> [ 0.445353] WARNING: CPU: 0 PID: 1 at mm/memory.c:3069
>>>>> __apply_to_page_range+0x380/0x388
>>>>> [ 0.488911] Modules linked in:
>>>>> [ 0.492027] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted
>>>>> 6.16.0-rc1-g27605c8c0f69-dirty #3 NONE
>>>>> [ 0.501174] Hardware name: Generic DT based system
>>>>> [ 0.505965] Call trace:
>>>>> [ 0.505985] unwind_backtrace from show_stack+0x10/0x14
>>>>> [ 0.513764] show_stack from dump_stack_lvl+0x54/0x68
>>>>> [ 0.518834] dump_stack_lvl from __warn+0x7c/0x128
>>>>> [ 0.523639] __warn from warn_slowpath_fmt+0x184/0x18c
>>>>> [ 0.527676] Freeing initrd memory: 65536K
>>>>> [ 0.532788] warn_slowpath_fmt from
>>> __apply_to_page_range+0x380/0x388
>>>>> [ 0.539242] __apply_to_page_range from
>>> apply_to_page_range+0x1c/0x24
>>>>> [ 0.545689] apply_to_page_range from
>>> __alloc_from_contiguous+0xc0/0x14c
>>>>> [ 0.552398] __alloc_from_contiguous from
>>> cma_allocator_alloc+0x34/0x3c
>>>>> [ 0.559016] cma_allocator_alloc from arch_dma_alloc+0x11c/0x2ac
>>>>> [ 0.565025] arch_dma_alloc from dma_alloc_attrs+0x90/0x2e8
>>>>> [ 0.570603] dma_alloc_attrs from dmydev_probe+0x8c/0xe8
>>>>> [ 0.575919] dmydev_probe from platform_probe+0x5c/0xb0
>>>>> [ 0.581152] platform_probe from really_probe+0xc8/0x2c8
>>>>> [ 0.586467] really_probe from __driver_probe_device+0x88/0x19c
>>>>> [ 0.592387] __driver_probe_device from
>>>>> driver_probe_device+0x30/0x104
>>>>> [ 0.598915] driver_probe_device from __driver_attach+0x90/0x178
>>>>> [ 0.604921] __driver_attach from bus_for_each_dev+0x7c/0xcc
>>>>> [ 0.610582] bus_for_each_dev from bus_add_driver+0xcc/0x1ec
>>>>> [ 0.616241] bus_add_driver from driver_register+0x7c/0x114
>>>>> [ 0.621814] driver_register from dmydev_init+0x20/0x28
>>>>> [ 0.627045] dmydev_init from do_one_initcall+0x58/0x200
>>>>> [ 0.632363] do_one_initcall from kernel_init_freeable+0x1cc/0x228
>>>>> [ 0.638550] kernel_init_freeable from kernel_init+0x1c/0x12c
>>>>> [ 0.644299] kernel_init from ret_from_fork+0x14/0x28
>>>>> [ 0.649351] Exception stack(0xe0819fb0 to 0xe0819ff8)
>>>>> [ 0.654401] 9fa0: 00000000
>>>>> 00000000 00000000 00000000
>>>>> [ 0.662575] 9fc0: 00000000 00000000 00000000 00000000 00000000
>>>>> 00000000 00000000 00000000
>>>>> [ 0.670747] 9fe0: 00000000 00000000 00000000 00000000 00000013
>>> 00000000
>>>>> [ 0.677403] ---[ end trace 0000000000000000 ]---
>>>>> [ 0.682083] dmydev dmy_device: Allocate dma memory at 0xde000000 dma
>>>>> addr 0x1e000000
>>>>>
>>>>> The reason is that now reserved memory's fixup function
>>>>> dma_contiguous_early_fixup is called after the page table is
>>>>> initialized. This fixup function increases the dma_mmu_remap count for
>>>>> each reserved memory. And the dma_contiguous_remap function depends
>>> on
>>>>> it to properly set up the reserved memory mmu table entry. Before this
>>>>> change, the paging_init function calls dma_contiguous_remap and it
>>>>> founds the reserved memory and set it up properly. After the change,
>>>>> this function found there is no reserved memory so skip any
>>>>> initialization hence causes the crash later on when my driver tries to
>>>>> allocate dma memory from the reserved memory.
>>>>>
>>>>> My workaround below is to move the dma_contiguous_remap out from the
>>>>> paging_init function to the place right after unflatten_device_tree
>>>>> where the dma_mmu_remap count is correctly set. But this is not ideal
>>>>> solution and would like to see if you have any better way to solve the
>>>>> issue.
>>>>>
>>>>> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
>>>>> index a41c93988d2c..535d1bf44529 100644
>>>>> --- a/arch/arm/kernel/setup.c
>>>>> +++ b/arch/arm/kernel/setup.c
>>>>> @@ -1079,6 +1079,7 @@ void __init hyp_mode_check(void)
>>>>> #endif
>>>>> }
>>>>>
>>>>> +void __init dma_contiguous_remap(void);
>>>>> static void (*__arm_pm_restart)(enum reboot_mode reboot_mode, const
>>>>> char *cmd);
>>>>>
>>>>> static int arm_restart(struct notifier_block *nb, unsigned long
>>>>> action,
>>>>> @@ -1164,6 +1165,7 @@ void __init setup_arch(char **cmdline_p)
>>>>> }
>>>>>
>>>>> unflatten_device_tree();
>>>>> + dma_contiguous_remap();
>>>>>
>>>>> arm_dt_init_cpu_maps();
>>>>> psci_dt_init();
>>>>> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
>>>>> index edb7f56b7c91..1828c8737d70 100644
>>>>> --- a/arch/arm/mm/mmu.c
>>>>> +++ b/arch/arm/mm/mmu.c
>>>>> @@ -1773,7 +1773,6 @@ void __init paging_init(const struct machine_desc
>>>>> *mdesc)
>>>>> * be used
>>>>> */
>>>>> map_kernel();
>>>>> - dma_contiguous_remap();
>>>>> early_fixmap_shutdown();
>>>>> devicemaps_init(mdesc);
>>>>> kmap_init();
>>>>>
>>>>> You can reproduce the issue on any v7 devices by adding these nodes to
>>>>> the device tree
>>>>> + reserved-memory {
>>>>> + #address-cells = <1>;
>>>>> + #size-cells = <1>;
>>>>> + ranges;
>>>>> +
>>>>> + dt_reserved_cma: dt_reserved_cma {
>>>>> + compatible = "shared-dma-pool";
>>>>> + reusable;
>>>>> +
>>>>> + reg = <0x1e000000 0x2000000>;
>>>>> + };
>>>>> + };
>>>>> +
>>>>> + dmy_device {
>>>>> + compatible = "xyz,dmydev";
>>>>> + memory-region = <&dt_reserved_cma>;
>>>>> + };
>>>>>
>>>>> And use this test driver to trigger the call stack:
>>>>> diff --git a/drivers/char/dmydev.c b/drivers/char/dmydev.c
>>>>> new file mode 100644
>>>>> index 000000000000..1dd52ec492eb
>>>>> --- /dev/null
>>>>> +++ b/drivers/char/dmydev.c
>>>>> @@ -0,0 +1,67 @@
>>>>> +#include<linux/module.h>
>>>>> +#include<linux/kernel.h>
>>>>> +#include <linux/platform_device.h>
>>>>> +#include <linux/of.h>
>>>>> +#include <linux/of_reserved_mem.h>
>>>>> +#include <linux/dma-mapping.h>
>>>>> +
>>>>> +static int dmydev_probe(struct platform_device *pdev)
>>>>> +{
>>>>> + void* virt_addr;
>>>>> + dma_addr_t dma_addr;
>>>>> + int ret;
>>>>> +
>>>>> + printk(KERN_ALERT "dmydev_probe called\n");
>>>>> +
>>>>> + ret = of_reserved_mem_device_init(&pdev->dev);
>>>>> + if (ret && ret != -ENODEV) {
>>>>> + dev_err(&pdev->dev, "Couldn't assign reserve memory to
>>>>> device ret = %d\n", ret);
>>>>> + return ret;
>>>>> + }
>>>>> +
>>>>> + virt_addr = dma_alloc_coherent(&pdev->dev, 0x800000, &dma_addr,
>>>>> GFP_KERNEL);
>>>>> + if (virt_addr == NULL) {
>>>>> + dev_err(&pdev->dev,"Failed to allocated cma memory\n");
>>>>> + ret = -ENOMEM;
>>>>> + }
>>>>> + else
>>>>> + dev_err(&pdev->dev,"Allocate dma memory at 0x%px dma
>>>>> addr %pad\n", virt_addr, &dma_addr);
>>>>> +
>>>>> + return ret;
>>>>> +}
>>>>> +
>>>>> +static void dmydev_remove(struct platform_device *pdev)
>>>>> +{
>>>>> +}
>>>>> +
>>>>> +static const struct of_device_id dmydev_of_match[] = {
>>>>> + {.compatible = "xyz,dmydev"},
>>>>> + {}
>>>>> +};
>>>>> +MODULE_DEVICE_TABLE(of, dmydev_of_match);
>>>>>
>>>>> Let me know if you need more info.
>>>>>
>>>>>> Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
>>>>>> ---
>>>>>> drivers/of/fdt.c | 5 +-
>>>>>> drivers/of/of_private.h | 3 +-
>>>>>> drivers/of/of_reserved_mem.c | 168
>>>>>> ++++++++++++++++++++++++----------
>>> -
>>>>>> 3 files changed, 122 insertions(+), 54 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
>>>>>> index 4d528c10df3a..d0dbc8183ac4 100644
>>>>>> --- a/drivers/of/fdt.c
>>>>>> +++ b/drivers/of/fdt.c
>>>>>> @@ -511,8 +511,6 @@ void __init early_init_fdt_scan_reserved_mem(void)
>>>>>> break;
>>>>>> memblock_reserve(base, size);
>>>>>> }
>>>>>> -
>>>>>> - fdt_init_reserved_mem();
>>>>>> }
>>>>>>
>>>>>> /**
>>>>>> @@ -1212,6 +1210,9 @@ void __init unflatten_device_tree(void)
>>>>>> {
>>>>>> void *fdt = initial_boot_params;
>>>>>>
>>>>>> + /* Save the statically-placed regions in the reserved_mem array
>>>>>> */
>>>>>> + fdt_scan_reserved_mem_reg_nodes();
>>>>>> +
>>>>>> /* Don't use the bootloader provided DTB if ACPI is enabled */
>>>>>> if (!acpi_disabled)
>>>>>> fdt = NULL;
>>>>>> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
>>>>>> index 04aa2a91f851..29525c0b9939 100644
>>>>>> --- a/drivers/of/of_private.h
>>>>>> +++ b/drivers/of/of_private.h
>>>>>> @@ -9,6 +9,7 @@
>>>>>> */
>>>>>>
>>>>>> #define FDT_ALIGN_SIZE 8
>>>>>> +#define MAX_RESERVED_REGIONS 64
>>>>>>
>>>>>> /**
>>>>>> * struct alias_prop - Alias property in 'aliases' node
>>>>>> @@ -180,7 +181,7 @@ static inline struct device_node
>>> *__of_get_dma_parent(const struct device_node *
>>>>>> #endif
>>>>>>
>>>>>> int fdt_scan_reserved_mem(void);
>>>>>> -void fdt_init_reserved_mem(void);
>>>>>> +void __init fdt_scan_reserved_mem_reg_nodes(void);
>>>>>>
>>>>>> bool of_fdt_device_is_available(const void *blob, unsigned long
>>>>>> node);
>>>>>>
>>>>>> diff --git a/drivers/of/of_reserved_mem.c
>>>>>> b/drivers/of/of_reserved_mem.c
>>>>>> index 46e1c3fbc769..2011174211f9 100644
>>>>>> --- a/drivers/of/of_reserved_mem.c
>>>>>> +++ b/drivers/of/of_reserved_mem.c
>>>>>> @@ -27,7 +27,6 @@
>>>>>>
>>>>>> #include "of_private.h"
>>>>>>
>>>>>> -#define MAX_RESERVED_REGIONS 64
>>>>>> static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
>>>>>> static int reserved_mem_count;
>>>>>>
>>>>>> @@ -56,6 +55,7 @@ static int __init
>>> early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
>>>>>> return err;
>>>>>> }
>>>>>>
>>>>>> +static void __init fdt_init_reserved_mem_node(struct reserved_mem
>>> *rmem);
>>>>>> /*
>>>>>> * fdt_reserved_mem_save_node() - save fdt node for second pass
>>> initialization
>>>>>> */
>>>>>> @@ -74,6 +74,9 @@ static void __init
>>> fdt_reserved_mem_save_node(unsigned long node, const char *un
>>>>>> rmem->base = base;
>>>>>> rmem->size = size;
>>>>>>
>>>>>> + /* Call the region specific initialization function */
>>>>>> + fdt_init_reserved_mem_node(rmem);
>>>>>> +
>>>>>> reserved_mem_count++;
>>>>>> return;
>>>>>> }
>>>>>> @@ -106,7 +109,6 @@ static int __init
>>> __reserved_mem_reserve_reg(unsigned long node,
>>>>>> phys_addr_t base, size;
>>>>>> int len;
>>>>>> const __be32 *prop;
>>>>>> - int first = 1;
>>>>>> bool nomap;
>>>>>>
>>>>>> prop = of_get_flat_dt_prop(node, "reg", &len);
>>>>>> @@ -134,10 +136,6 @@ static int __init
>>> __reserved_mem_reserve_reg(unsigned long node,
>>>>>> uname, &base, (unsigned long)(size /
>>>>>> SZ_1M));
>>>>>>
>>>>>> len -= t_len;
>>>>>> - if (first) {
>>>>>> - fdt_reserved_mem_save_node(node, uname, base,
>>>>>> size);
>>>>>> - first = 0;
>>>>>> - }
>>>>>> }
>>>>>> return 0;
>>>>>> }
>>>>>> @@ -165,12 +163,77 @@ static int __init
>>> __reserved_mem_check_root(unsigned long node)
>>>>>> return 0;
>>>>>> }
>>>>>>
>>>>>> +static void __init __rmem_check_for_overlap(void);
>>>>>> +
>>>>>> +/**
>>>>>> + * fdt_scan_reserved_mem_reg_nodes() - Store info for the "reg"
>>>>>> defined
>>>>>> + * reserved memory regions.
>>>>>> + *
>>>>>> + * This function is used to scan through the DT and store the
>>>>>> + * information for the reserved memory regions that are defined using
>>>>>> + * the "reg" property. The region node number, name, base address,
>>>>>> and
>>>>>> + * size are all stored in the reserved_mem array by calling the
>>>>>> + * fdt_reserved_mem_save_node() function.
>>>>>> + */
>>>>>> +void __init fdt_scan_reserved_mem_reg_nodes(void)
>>>>>> +{
>>>>>> + int t_len = (dt_root_addr_cells + dt_root_size_cells) *
>>>>>> sizeof(__be32);
>>>>>> + const void *fdt = initial_boot_params;
>>>>>> + phys_addr_t base, size;
>>>>>> + const __be32 *prop;
>>>>>> + int node, child;
>>>>>> + int len;
>>>>>> +
>>>>>> + if (!fdt)
>>>>>> + return;
>>>>>> +
>>>>>> + node = fdt_path_offset(fdt, "/reserved-memory");
>>>>>> + if (node < 0) {
>>>>>> + pr_info("Reserved memory: No reserved-memory node in the
>>> DT\n");
>>>>>> + return;
>>>>>> + }
>>>>>> +
>>>>>> + if (__reserved_mem_check_root(node)) {
>>>>>> + pr_err("Reserved memory: unsupported node format,
>>>>>> ignoring\n");
>>>>>> + return;
>>>>>> + }
>>>>>> +
>>>>>> + fdt_for_each_subnode(child, fdt, node) {
>>>>>> + const char *uname;
>>>>>> +
>>>>>> + prop = of_get_flat_dt_prop(child, "reg", &len);
>>>>>> + if (!prop)
>>>>>> + continue;
>>>>>> + if (!of_fdt_device_is_available(fdt, child))
>>>>>> + continue;
>>>>>> +
>>>>>> + uname = fdt_get_name(fdt, child, NULL);
>>>>>> + if (len && len % t_len != 0) {
>>>>>> + pr_err("Reserved memory: invalid reg property in
>>>>>> '%s', skipping
>>> node.\n",
>>>>>> + uname);
>>>>>> + continue;
>>>>>> + }
>>>>>> + base = dt_mem_next_cell(dt_root_addr_cells, &prop);
>>>>>> + size = dt_mem_next_cell(dt_root_size_cells, &prop);
>>>>>> +
>>>>>> + if (size)
>>>>>> + fdt_reserved_mem_save_node(child, uname, base,
>>>>>> size);
>>>>>> + }
>>>>>> +
>>>>>> + /* check for overlapping reserved regions */
>>>>>> + __rmem_check_for_overlap();
>>>>>> +}
>>>>>> +
>>>>>> +static int __init __reserved_mem_alloc_size(unsigned long node, const
>>> char *uname);
>>>>>> +
>>>>>> /*
>>>>>> * fdt_scan_reserved_mem() - scan a single FDT node for reserved
>>>>>> memory
>>>>>> */
>>>>>> int __init fdt_scan_reserved_mem(void)
>>>>>> {
>>>>>> int node, child;
>>>>>> + int dynamic_nodes_cnt = 0;
>>>>>> + int dynamic_nodes[MAX_RESERVED_REGIONS];
>>>>>> const void *fdt = initial_boot_params;
>>>>>>
>>>>>> node = fdt_path_offset(fdt, "/reserved-memory");
>>>>>> @@ -192,8 +255,24 @@ int __init fdt_scan_reserved_mem(void)
>>>>>> uname = fdt_get_name(fdt, child, NULL);
>>>>>>
>>>>>> err = __reserved_mem_reserve_reg(child, uname);
>>>>>> - if (err == -ENOENT && of_get_flat_dt_prop(child, "size",
>>>>>> NULL))
>>>>>> - fdt_reserved_mem_save_node(child, uname, 0, 0);
>>>>>> + /*
>>>>>> + * Save the nodes for the dynamically-placed regions
>>>>>> + * into an array which will be used for allocation right
>>>>>> + * after all the statically-placed regions are reserved
>>>>>> + * or marked as no-map. This is done to avoid
>>>>>> dynamically
>>>>>> + * allocating from one of the statically-placed regions.
>>>>>> + */
>>>>>> + if (err == -ENOENT && of_get_flat_dt_prop(child, "size",
>>>>>> NULL)) {
>>>>>> + dynamic_nodes[dynamic_nodes_cnt] = child;
>>>>>> + dynamic_nodes_cnt++;
>>>>>> + }
>>>>>> + }
>>>>>> + for (int i = 0; i < dynamic_nodes_cnt; i++) {
>>>>>> + const char *uname;
>>>>>> +
>>>>>> + child = dynamic_nodes[i];
>>>>>> + uname = fdt_get_name(fdt, child, NULL);
>>>>>> + __reserved_mem_alloc_size(child, uname);
>>>>>> }
>>>>>> return 0;
>>>>>> }
>>>>>> @@ -253,8 +332,7 @@ static int __init
>>> __reserved_mem_alloc_in_range(phys_addr_t size,
>>>>>> * __reserved_mem_alloc_size() - allocate reserved memory described
>>>>>> by
>>>>>> * 'size', 'alignment' and 'alloc-ranges' properties.
>>>>>> */
>>>>>> -static int __init __reserved_mem_alloc_size(unsigned long node,
>>>>>> - const char *uname, phys_addr_t *res_base, phys_addr_t *res_size)
>>>>>> +static int __init __reserved_mem_alloc_size(unsigned long node, const
>>> char *uname)
>>>>>> {
>>>>>> int t_len = (dt_root_addr_cells + dt_root_size_cells) *
>>>>>> sizeof(__be32);
>>>>>> phys_addr_t start = 0, end = 0;
>>>>>> @@ -334,9 +412,8 @@ static int __init
>>> __reserved_mem_alloc_size(unsigned long node,
>>>>>> return -ENOMEM;
>>>>>> }
>>>>>>
>>>>>> - *res_base = base;
>>>>>> - *res_size = size;
>>>>>> -
>>>>>> + /* Save region in the reserved_mem array */
>>>>>> + fdt_reserved_mem_save_node(node, uname, base, size);
>>>>>> return 0;
>>>>>> }
>>>>>>
>>>>>> @@ -425,48 +502,37 @@ static void __init
>>> __rmem_check_for_overlap(void)
>>>>>> }
>>>>>>
>>>>>> /**
>>>>>> - * fdt_init_reserved_mem() - allocate and init all saved reserved
>>>>>> memory
>>> regions
>>>>>> + * fdt_init_reserved_mem_node() - Initialize a reserved memory region
>>>>>> + * @rmem: reserved_mem struct of the memory region to be initialized.
>>>>>> + *
>>>>>> + * This function is used to call the region specific initialization
>>>>>> + * function for a reserved memory region.
>>>>>> */
>>>>>> -void __init fdt_init_reserved_mem(void)
>>>>>> +static void __init fdt_init_reserved_mem_node(struct reserved_mem
>>> *rmem)
>>>>>> {
>>>>>> - int i;
>>>>>> -
>>>>>> - /* check for overlapping reserved regions */
>>>>>> - __rmem_check_for_overlap();
>>>>>> -
>>>>>> - for (i = 0; i < reserved_mem_count; i++) {
>>>>>> - struct reserved_mem *rmem = &reserved_mem[i];
>>>>>> - unsigned long node = rmem->fdt_node;
>>>>>> - int err = 0;
>>>>>> - bool nomap;
>>>>>> + unsigned long node = rmem->fdt_node;
>>>>>> + int err = 0;
>>>>>> + bool nomap;
>>>>>>
>>>>>> - nomap = of_get_flat_dt_prop(node, "no-map", NULL) !=
>>>>>> NULL;
>>>>>> + nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
>>>>>>
>>>>>> - if (rmem->size == 0)
>>>>>> - err = __reserved_mem_alloc_size(node,
>>>>>> rmem->name,
>>>>>> - &rmem->base,
>>>>>> &rmem->size);
>>>>>> - if (err == 0) {
>>>>>> - err = __reserved_mem_init_node(rmem);
>>>>>> - if (err != 0 && err != -ENOENT) {
>>>>>> - pr_info("node %s compatible matching
>>>>>> fail\n",
>>>>>> - rmem->name);
>>>>>> - if (nomap)
>>>>>> - memblock_clear_nomap(rmem->base,
>>>>>> rmem->size);
>>>>>> - else
>>>>>> - memblock_phys_free(rmem->base,
>>>>>> - rmem->size);
>>>>>> - } else {
>>>>>> - phys_addr_t end = rmem->base +
>>>>>> rmem->size - 1;
>>>>>> - bool reusable =
>>>>>> - (of_get_flat_dt_prop(node,
>>>>>> "reusable", NULL)) !=
>>> NULL;
>>>>>> -
>>>>>> - pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
>>>>>> - &rmem->base, &end, (unsigned
>>>>>> long)(rmem->size /
>>> SZ_1K),
>>>>>> - nomap ? "nomap" : "map",
>>>>>> - reusable ? "reusable" :
>>>>>> "non-reusable",
>>>>>> - rmem->name ? rmem->name :
>>>>>> "unknown");
>>>>>> - }
>>>>>> - }
>>>>>> + err = __reserved_mem_init_node(rmem);
>>>>>> + if (err != 0 && err != -ENOENT) {
>>>>>> + pr_info("node %s compatible matching fail\n",
>>>>>> rmem->name);
>>>>>> + if (nomap)
>>>>>> + memblock_clear_nomap(rmem->base, rmem->size);
>>>>>> + else
>>>>>> + memblock_phys_free(rmem->base, rmem->size);
>>>>>> + } else {
>>>>>> + phys_addr_t end = rmem->base + rmem->size - 1;
>>>>>> + bool reusable =
>>>>>> + (of_get_flat_dt_prop(node, "reusable", NULL)) !=
>>>>>> NULL;
>>>>>> +
>>>>>> + pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
>>>>>> + &rmem->base, &end, (unsigned long)(rmem->size /
>>>>>> SZ_1K),
>>>>>> + nomap ? "nomap" : "map",
>>>>>> + reusable ? "reusable" : "non-reusable",
>>>>>> + rmem->name ? rmem->name : "unknown");
>>>>>> }
>>>>>> }
>>>>>>
>>>> Just want to follow up on this issue. Do you need any further detail
>>>> or clarification?
>>>> Any ARM memory manage guru on this thread can comment?
>>>> Or is my workaround acceptable as a patch?
>>>
>>> Hi William,
>>>
>>> Sorry about the delay in getting back to you.
>>>
>>> Instead of moving dma_contiguous_remap(), I suggest moving
>>> dma_contiguous_early_fixup()
>>> to the function that parses the reserved regions so that it is done before
>>> paging_init.
>>>
>>> Here is what that could look like. Can you please give this a try?
>>>
>>> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
>>> index 77016c0cc296..132d2c66cafc 100644
>>> --- a/drivers/of/of_reserved_mem.c
>>> +++ b/drivers/of/of_reserved_mem.c
>>> @@ -25,6 +25,7 @@
>>> #include <linux/memblock.h>
>>> #include <linux/kmemleak.h>
>>> #include <linux/cma.h>
>>> +#include <linux/dma-map-ops.h>
>>>
>>> #include "of_private.h"
>>>
>>> @@ -175,13 +176,17 @@ static int __init
>>> __reserved_mem_reserve_reg(unsigned long node,
>>> base = dt_mem_next_cell(dt_root_addr_cells, &prop);
>>> size = dt_mem_next_cell(dt_root_size_cells, &prop);
>>>
>>> - if (size &&
>>> - early_init_dt_reserve_memory(base, size, nomap) == 0)
>>> + if (size && early_init_dt_reserve_memory(base, size,
>>> nomap) == 0) {
>>> + /* Architecture specific contiguous memory fixup.
>>> */
>>> + if (of_flat_dt_is_compatible(node,
>>> "shared-dma-pool"))
>>> + dma_contiguous_early_fixup(base, size);
>>> +
>>> pr_debug("Reserved memory: reserved region for
>>> node '%s':
>>> base %pa, size %lu MiB\n",
>>> uname, &base, (unsigned long)(size /
>>> SZ_1M));
>>> - else
>>> + } else {
>>> pr_err("Reserved memory: failed to reserve memory
>>> for node '%s':
>>> base %pa, size %lu MiB\n",
>>> uname, &base, (unsigned long)(size /
>>> SZ_1M));
>>> + }
>>>
>>> len -= t_len;
>>> }
>>> @@ -472,6 +477,9 @@ static int __init __reserved_mem_alloc_size(unsigned
>>> long node, const char *unam
>>> uname, (unsigned long)(size / SZ_1M));
>>> return -ENOMEM;
>>> }
>>> + /* Architecture specific contiguous memory fixup. */
>>> + if (of_flat_dt_is_compatible(node, "shared-dma-pool"))
>>> + dma_contiguous_early_fixup(base, size);
>>> /* Save region in the reserved_mem array */
>>> fdt_reserved_mem_save_node(node, uname, base, size);
>>> diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
>>> index 8df0dfaaca18..9e5d63efe7c5 100644
>>> --- a/kernel/dma/contiguous.c
>>> +++ b/kernel/dma/contiguous.c
>>> @@ -480,8 +480,6 @@ static int __init rmem_cma_setup(struct reserved_mem
>>> *rmem)
>>> pr_err("Reserved memory: unable to setup CMA region\n");
>>> return err;
>>> }
>>> - /* Architecture specific contiguous memory fixup. */
>>> - dma_contiguous_early_fixup(rmem->base, rmem->size);
>>>
>>> if (default_cma)
>>> dma_contiguous_default_area = cma;
>>>
>>> Regards,
>>> Oreoluwa
>> Thank you Oreoluwa! Your patch fixed the issue too and it looks a more
>> localized and better fix!
> Thank you for testing it out! I'm glad it worked for you.
> I can work on an offical patch for this and submit it in
> the next few days.
I'm waiting for the final patch then.
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
On 7/8/2025 3:47 AM, Marek Szyprowski wrote:
> On 03.07.2025 19:27, Oreoluwa Babatunde wrote:
>> On 6/28/2025 2:04 PM, William Zhang wrote:
>>>> -----Original Message-----
>>>> From: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
>>>> Sent: Friday, June 27, 2025 11:02 AM
>>>> To: William Zhang <william.zhang@broadcom.com>; robh@kernel.org
>>>> Cc: aisheng.dong@nxp.com; andy@black.fi.intel.com;
>>>> catalin.marinas@arm.com; devicetree@vger.kernel.org; hch@lst.de;
>>>> iommu@lists.linux.dev; kernel@quicinc.com; klarasmodin@gmail.com; linux-
>>>> kernel@vger.kernel.org; m.szyprowski@samsung.com;
>>>> quic_ninanaik@quicinc.com; robin.murphy@arm.com; saravanak@google.com;
>>>> will@kernel.org; oreoluwa.babatunde@oss.qualcomm.com
>>>> Subject: Re: [PATCH v10 1/2] of: reserved_mem: Restruture how the reserved
>>>> memory regions are processed
>>>>
>>>>
>>>>
>>>> On 6/22/2025 6:24 PM, William Zhang wrote:
>>>>> On Tue, Jun 17, 2025 at 10:15 AM William Zhang
>>>>> <william.zhang@broadcom.com> wrote:
>>>>>> Hi Oreoluwa,
>>>>>>
>>>>>> On 10/8/2024 3:06 PM, Oreoluwa Babatunde wrote:
>>>>>>> Reserved memory regions defined in the devicetree can be broken up
>>>>>>> into
>>>>>>> two groups:
>>>>>>> i) Statically-placed reserved memory regions
>>>>>>> i.e. regions defined with a static start address and size using the
>>>>>>> "reg" property.
>>>>>>> ii) Dynamically-placed reserved memory regions.
>>>>>>> i.e. regions defined by specifying an address range where they can be
>>>>>>> placed in memory using the "alloc_ranges" and "size" properties.
>>>>>>>
>>>>>>> These regions are processed and set aside at boot time.
>>>>>>> This is done in two stages as seen below:
>>>>>>>
>>>>>>> Stage 1:
>>>>>>> At this stage, fdt_scan_reserved_mem() scans through the child nodes
>>>>>>> of
>>>>>>> the reserved_memory node using the flattened devicetree and does the
>>>>>>> following:
>>>>>>>
>>>>>>> 1) If the node represents a statically-placed reserved memory region,
>>>>>>> i.e. if it is defined using the "reg" property:
>>>>>>> - Call memblock_reserve() or memblock_mark_nomap() as needed.
>>>>>>> - Add the information for that region into the reserved_mem array
>>>>>>> using fdt_reserved_mem_save_node().
>>>>>>> i.e. fdt_reserved_mem_save_node(node, name, base, size).
>>>>>>>
>>>>>>> 2) If the node represents a dynamically-placed reserved memory region,
>>>>>>> i.e. if it is defined using "alloc-ranges" and "size" properties:
>>>>>>> - Add the information for that region to the reserved_mem array
>>>>>>> with
>>>>>>> the starting address and size set to 0.
>>>>>>> i.e. fdt_reserved_mem_save_node(node, name, 0, 0).
>>>>>>> Note: This region is saved to the array with a starting address of
>>>>>>> 0
>>>>>>> because a starting address is not yet allocated for it.
>>>>>>>
>>>>>>> Stage 2:
>>>>>>> After iterating through all the reserved memory nodes and storing
>>>>>>> their
>>>>>>> relevant information in the reserved_mem array,fdt_init_reserved_mem()
>>>>>>> is
>>>>>>> called and does the following:
>>>>>>>
>>>>>>> 1) For statically-placed reserved memory regions:
>>>>>>> - Call the region specific init function using
>>>>>>> __reserved_mem_init_node().
>>>>>>> 2) For dynamically-placed reserved memory regions:
>>>>>>> - Call __reserved_mem_alloc_size() which is used to allocate
>>>>>>> memory
>>>>>>> for each of these regions, and mark them as nomap if they have
>>>>>>> the
>>>>>>> nomap property specified in the DT.
>>>>>>> - Call the region specific init function.
>>>>>>>
>>>>>>> The current size of the resvered_mem array is 64 as is defined by
>>>>>>> MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for
>>>>>>> how many reserved memory regions can be specified on a system.
>>>>>>> As systems continue to grow more and more complex, the number of
>>>>>>> reserved memory regions needed are also growing and are starting to
>>>>>>> hit
>>>>>>> this 64 count limit, hence the need to make the reserved_mem array
>>>>>>> dynamically sized (i.e. dynamically allocating memory for the
>>>>>>> reserved_mem array using membock_alloc_*).
>>>>>>>
>>>>>>> On architectures such as arm64, memory allocated using memblock is
>>>>>>> writable only after the page tables have been setup. This means that
>>>>>>> if
>>>>>>> the reserved_mem array is going to be dynamically allocated, it needs
>>>>>>> to
>>>>>>> happen after the page tables have been setup, not before.
>>>>>>>
>>>>>>> Since the reserved memory regions are currently being processed and
>>>>>>> added to the array before the page tables are setup, there is a need
>>>>>>> to
>>>>>>> change the order in which some of the processing is done to allow for
>>>>>>> the reserved_mem array to be dynamically sized.
>>>>>>>
>>>>>>> It is possible to process the statically-placed reserved memory
>>>>>>> regions
>>>>>>> without needing to store them in the reserved_mem array until after
>>>>>>> the
>>>>>>> page tables have been setup because all the information stored in the
>>>>>>> array is readily available in the devicetree and can be referenced at
>>>>>>> any time.
>>>>>>> Dynamically-placed reserved memory regions on the other hand get
>>>>>>> assigned a start address only at runtime, and hence need a place to be
>>>>>>> stored once they are allocated since there is no other referrence to
>>>>>>> the
>>>>>>> start address for these regions.
>>>>>>>
>>>>>>> Hence this patch changes the processing order of the reserved memory
>>>>>>> regions in the following ways:
>>>>>>>
>>>>>>> Step 1:
>>>>>>> fdt_scan_reserved_mem() scans through the child nodes of
>>>>>>> the reserved_memory node using the flattened devicetree and does the
>>>>>>> following:
>>>>>>>
>>>>>>> 1) If the node represents a statically-placed reserved memory region,
>>>>>>> i.e. if it is defined using the "reg" property:
>>>>>>> - Call memblock_reserve() or memblock_mark_nomap() as needed.
>>>>>>>
>>>>>>> 2) If the node represents a dynamically-placed reserved memory region,
>>>>>>> i.e. if it is defined using "alloc-ranges" and "size" properties:
>>>>>>> - Call __reserved_mem_alloc_size() which will:
>>>>>>> i) Allocate memory for the reserved region and call
>>>>>>> memblock_mark_nomap() as needed.
>>>>>>> ii) Call the region specific initialization function using
>>>>>>> fdt_init_reserved_mem_node().
>>>>>>> iii) Save the region information in the reserved_mem array using
>>>>>>> fdt_reserved_mem_save_node().
>>>>>>>
>>>>>>> Step 2:
>>>>>>> 1) This stage of the reserved memory processing is now only used to
>>>>>>> add
>>>>>>> the statically-placed reserved memory regions into the
>>>>>>> reserved_mem
>>>>>>> array using fdt_scan_reserved_mem_reg_nodes(), as well as call
>>>>>>> their
>>>>>>> region specific initialization functions.
>>>>>>>
>>>>>>> 2) This step has also been moved to be after the page tables are
>>>>>>> setup. Moving this will allow us to replace the reserved_mem
>>>>>>> array with a dynamically sized array before storing the rest of
>>>>>>> these regions.
>>>>>> I am running into a call trace with this order change on armv7 chip
>>>>>> when
>>>>>> I tried to allocate dma coherent memory from the device reserved
>>>>>> memory.
>>>>>> The issue does not happen on armv8 chips.
>>>>>>
>>>>>> [ 0.000000] Reserved memory: created CMA memory pool at 0x1e000000,
>>>>>> size 32 MiB
>>>>>> [ 0.000000] OF: reserved mem: initialized node dt_reserved_cma,
>>>>>> compatible id shared-dma-pool
>>>>>> [ 0.000000] OF: reserved mem: 0x1e000000..0x1fffffff (32768 KiB) map
>>>>>> reusable dt_reserved_cma
>>>>>> ....
>>>>>>
>>>>>> [ 0.445322] ------------[ cut here ]------------
>>>>>> [ 0.445353] WARNING: CPU: 0 PID: 1 at mm/memory.c:3069
>>>>>> __apply_to_page_range+0x380/0x388
>>>>>> [ 0.488911] Modules linked in:
>>>>>> [ 0.492027] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted
>>>>>> 6.16.0-rc1-g27605c8c0f69-dirty #3 NONE
>>>>>> [ 0.501174] Hardware name: Generic DT based system
>>>>>> [ 0.505965] Call trace:
>>>>>> [ 0.505985] unwind_backtrace from show_stack+0x10/0x14
>>>>>> [ 0.513764] show_stack from dump_stack_lvl+0x54/0x68
>>>>>> [ 0.518834] dump_stack_lvl from __warn+0x7c/0x128
>>>>>> [ 0.523639] __warn from warn_slowpath_fmt+0x184/0x18c
>>>>>> [ 0.527676] Freeing initrd memory: 65536K
>>>>>> [ 0.532788] warn_slowpath_fmt from
>>>> __apply_to_page_range+0x380/0x388
>>>>>> [ 0.539242] __apply_to_page_range from
>>>> apply_to_page_range+0x1c/0x24
>>>>>> [ 0.545689] apply_to_page_range from
>>>> __alloc_from_contiguous+0xc0/0x14c
>>>>>> [ 0.552398] __alloc_from_contiguous from
>>>> cma_allocator_alloc+0x34/0x3c
>>>>>> [ 0.559016] cma_allocator_alloc from arch_dma_alloc+0x11c/0x2ac
>>>>>> [ 0.565025] arch_dma_alloc from dma_alloc_attrs+0x90/0x2e8
>>>>>> [ 0.570603] dma_alloc_attrs from dmydev_probe+0x8c/0xe8
>>>>>> [ 0.575919] dmydev_probe from platform_probe+0x5c/0xb0
>>>>>> [ 0.581152] platform_probe from really_probe+0xc8/0x2c8
>>>>>> [ 0.586467] really_probe from __driver_probe_device+0x88/0x19c
>>>>>> [ 0.592387] __driver_probe_device from
>>>>>> driver_probe_device+0x30/0x104
>>>>>> [ 0.598915] driver_probe_device from __driver_attach+0x90/0x178
>>>>>> [ 0.604921] __driver_attach from bus_for_each_dev+0x7c/0xcc
>>>>>> [ 0.610582] bus_for_each_dev from bus_add_driver+0xcc/0x1ec
>>>>>> [ 0.616241] bus_add_driver from driver_register+0x7c/0x114
>>>>>> [ 0.621814] driver_register from dmydev_init+0x20/0x28
>>>>>> [ 0.627045] dmydev_init from do_one_initcall+0x58/0x200
>>>>>> [ 0.632363] do_one_initcall from kernel_init_freeable+0x1cc/0x228
>>>>>> [ 0.638550] kernel_init_freeable from kernel_init+0x1c/0x12c
>>>>>> [ 0.644299] kernel_init from ret_from_fork+0x14/0x28
>>>>>> [ 0.649351] Exception stack(0xe0819fb0 to 0xe0819ff8)
>>>>>> [ 0.654401] 9fa0: 00000000
>>>>>> 00000000 00000000 00000000
>>>>>> [ 0.662575] 9fc0: 00000000 00000000 00000000 00000000 00000000
>>>>>> 00000000 00000000 00000000
>>>>>> [ 0.670747] 9fe0: 00000000 00000000 00000000 00000000 00000013
>>>> 00000000
>>>>>> [ 0.677403] ---[ end trace 0000000000000000 ]---
>>>>>> [ 0.682083] dmydev dmy_device: Allocate dma memory at 0xde000000 dma
>>>>>> addr 0x1e000000
>>>>>>
>>>>>> The reason is that now reserved memory's fixup function
>>>>>> dma_contiguous_early_fixup is called after the page table is
>>>>>> initialized. This fixup function increases the dma_mmu_remap count for
>>>>>> each reserved memory. And the dma_contiguous_remap function depends
>>>> on
>>>>>> it to properly set up the reserved memory mmu table entry. Before this
>>>>>> change, the paging_init function calls dma_contiguous_remap and it
>>>>>> founds the reserved memory and set it up properly. After the change,
>>>>>> this function found there is no reserved memory so skip any
>>>>>> initialization hence causes the crash later on when my driver tries to
>>>>>> allocate dma memory from the reserved memory.
>>>>>>
>>>>>> My workaround below is to move the dma_contiguous_remap out from the
>>>>>> paging_init function to the place right after unflatten_device_tree
>>>>>> where the dma_mmu_remap count is correctly set. But this is not ideal
>>>>>> solution and would like to see if you have any better way to solve the
>>>>>> issue.
>>>>>>
>>>>>> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
>>>>>> index a41c93988d2c..535d1bf44529 100644
>>>>>> --- a/arch/arm/kernel/setup.c
>>>>>> +++ b/arch/arm/kernel/setup.c
>>>>>> @@ -1079,6 +1079,7 @@ void __init hyp_mode_check(void)
>>>>>> #endif
>>>>>> }
>>>>>>
>>>>>> +void __init dma_contiguous_remap(void);
>>>>>> static void (*__arm_pm_restart)(enum reboot_mode reboot_mode, const
>>>>>> char *cmd);
>>>>>>
>>>>>> static int arm_restart(struct notifier_block *nb, unsigned long
>>>>>> action,
>>>>>> @@ -1164,6 +1165,7 @@ void __init setup_arch(char **cmdline_p)
>>>>>> }
>>>>>>
>>>>>> unflatten_device_tree();
>>>>>> + dma_contiguous_remap();
>>>>>>
>>>>>> arm_dt_init_cpu_maps();
>>>>>> psci_dt_init();
>>>>>> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
>>>>>> index edb7f56b7c91..1828c8737d70 100644
>>>>>> --- a/arch/arm/mm/mmu.c
>>>>>> +++ b/arch/arm/mm/mmu.c
>>>>>> @@ -1773,7 +1773,6 @@ void __init paging_init(const struct machine_desc
>>>>>> *mdesc)
>>>>>> * be used
>>>>>> */
>>>>>> map_kernel();
>>>>>> - dma_contiguous_remap();
>>>>>> early_fixmap_shutdown();
>>>>>> devicemaps_init(mdesc);
>>>>>> kmap_init();
>>>>>>
>>>>>> You can reproduce the issue on any v7 devices by adding these nodes to
>>>>>> the device tree
>>>>>> + reserved-memory {
>>>>>> + #address-cells = <1>;
>>>>>> + #size-cells = <1>;
>>>>>> + ranges;
>>>>>> +
>>>>>> + dt_reserved_cma: dt_reserved_cma {
>>>>>> + compatible = "shared-dma-pool";
>>>>>> + reusable;
>>>>>> +
>>>>>> + reg = <0x1e000000 0x2000000>;
>>>>>> + };
>>>>>> + };
>>>>>> +
>>>>>> + dmy_device {
>>>>>> + compatible = "xyz,dmydev";
>>>>>> + memory-region = <&dt_reserved_cma>;
>>>>>> + };
>>>>>>
>>>>>> And use this test driver to trigger the call stack:
>>>>>> diff --git a/drivers/char/dmydev.c b/drivers/char/dmydev.c
>>>>>> new file mode 100644
>>>>>> index 000000000000..1dd52ec492eb
>>>>>> --- /dev/null
>>>>>> +++ b/drivers/char/dmydev.c
>>>>>> @@ -0,0 +1,67 @@
>>>>>> +#include<linux/module.h>
>>>>>> +#include<linux/kernel.h>
>>>>>> +#include <linux/platform_device.h>
>>>>>> +#include <linux/of.h>
>>>>>> +#include <linux/of_reserved_mem.h>
>>>>>> +#include <linux/dma-mapping.h>
>>>>>> +
>>>>>> +static int dmydev_probe(struct platform_device *pdev)
>>>>>> +{
>>>>>> + void* virt_addr;
>>>>>> + dma_addr_t dma_addr;
>>>>>> + int ret;
>>>>>> +
>>>>>> + printk(KERN_ALERT "dmydev_probe called\n");
>>>>>> +
>>>>>> + ret = of_reserved_mem_device_init(&pdev->dev);
>>>>>> + if (ret && ret != -ENODEV) {
>>>>>> + dev_err(&pdev->dev, "Couldn't assign reserve memory to
>>>>>> device ret = %d\n", ret);
>>>>>> + return ret;
>>>>>> + }
>>>>>> +
>>>>>> + virt_addr = dma_alloc_coherent(&pdev->dev, 0x800000, &dma_addr,
>>>>>> GFP_KERNEL);
>>>>>> + if (virt_addr == NULL) {
>>>>>> + dev_err(&pdev->dev,"Failed to allocated cma memory\n");
>>>>>> + ret = -ENOMEM;
>>>>>> + }
>>>>>> + else
>>>>>> + dev_err(&pdev->dev,"Allocate dma memory at 0x%px dma
>>>>>> addr %pad\n", virt_addr, &dma_addr);
>>>>>> +
>>>>>> + return ret;
>>>>>> +}
>>>>>> +
>>>>>> +static void dmydev_remove(struct platform_device *pdev)
>>>>>> +{
>>>>>> +}
>>>>>> +
>>>>>> +static const struct of_device_id dmydev_of_match[] = {
>>>>>> + {.compatible = "xyz,dmydev"},
>>>>>> + {}
>>>>>> +};
>>>>>> +MODULE_DEVICE_TABLE(of, dmydev_of_match);
>>>>>>
>>>>>> Let me know if you need more info.
>>>>>>
>>>>>>> Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
>>>>>>> ---
>>>>>>> drivers/of/fdt.c | 5 +-
>>>>>>> drivers/of/of_private.h | 3 +-
>>>>>>> drivers/of/of_reserved_mem.c | 168
>>>>>>> ++++++++++++++++++++++++----------
>>>> -
>>>>>>> 3 files changed, 122 insertions(+), 54 deletions(-)
>>>>>>>
>>>>>>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
>>>>>>> index 4d528c10df3a..d0dbc8183ac4 100644
>>>>>>> --- a/drivers/of/fdt.c
>>>>>>> +++ b/drivers/of/fdt.c
>>>>>>> @@ -511,8 +511,6 @@ void __init early_init_fdt_scan_reserved_mem(void)
>>>>>>> break;
>>>>>>> memblock_reserve(base, size);
>>>>>>> }
>>>>>>> -
>>>>>>> - fdt_init_reserved_mem();
>>>>>>> }
>>>>>>>
>>>>>>> /**
>>>>>>> @@ -1212,6 +1210,9 @@ void __init unflatten_device_tree(void)
>>>>>>> {
>>>>>>> void *fdt = initial_boot_params;
>>>>>>>
>>>>>>> + /* Save the statically-placed regions in the reserved_mem array
>>>>>>> */
>>>>>>> + fdt_scan_reserved_mem_reg_nodes();
>>>>>>> +
>>>>>>> /* Don't use the bootloader provided DTB if ACPI is enabled */
>>>>>>> if (!acpi_disabled)
>>>>>>> fdt = NULL;
>>>>>>> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
>>>>>>> index 04aa2a91f851..29525c0b9939 100644
>>>>>>> --- a/drivers/of/of_private.h
>>>>>>> +++ b/drivers/of/of_private.h
>>>>>>> @@ -9,6 +9,7 @@
>>>>>>> */
>>>>>>>
>>>>>>> #define FDT_ALIGN_SIZE 8
>>>>>>> +#define MAX_RESERVED_REGIONS 64
>>>>>>>
>>>>>>> /**
>>>>>>> * struct alias_prop - Alias property in 'aliases' node
>>>>>>> @@ -180,7 +181,7 @@ static inline struct device_node
>>>> *__of_get_dma_parent(const struct device_node *
>>>>>>> #endif
>>>>>>>
>>>>>>> int fdt_scan_reserved_mem(void);
>>>>>>> -void fdt_init_reserved_mem(void);
>>>>>>> +void __init fdt_scan_reserved_mem_reg_nodes(void);
>>>>>>>
>>>>>>> bool of_fdt_device_is_available(const void *blob, unsigned long
>>>>>>> node);
>>>>>>>
>>>>>>> diff --git a/drivers/of/of_reserved_mem.c
>>>>>>> b/drivers/of/of_reserved_mem.c
>>>>>>> index 46e1c3fbc769..2011174211f9 100644
>>>>>>> --- a/drivers/of/of_reserved_mem.c
>>>>>>> +++ b/drivers/of/of_reserved_mem.c
>>>>>>> @@ -27,7 +27,6 @@
>>>>>>>
>>>>>>> #include "of_private.h"
>>>>>>>
>>>>>>> -#define MAX_RESERVED_REGIONS 64
>>>>>>> static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
>>>>>>> static int reserved_mem_count;
>>>>>>>
>>>>>>> @@ -56,6 +55,7 @@ static int __init
>>>> early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
>>>>>>> return err;
>>>>>>> }
>>>>>>>
>>>>>>> +static void __init fdt_init_reserved_mem_node(struct reserved_mem
>>>> *rmem);
>>>>>>> /*
>>>>>>> * fdt_reserved_mem_save_node() - save fdt node for second pass
>>>> initialization
>>>>>>> */
>>>>>>> @@ -74,6 +74,9 @@ static void __init
>>>> fdt_reserved_mem_save_node(unsigned long node, const char *un
>>>>>>> rmem->base = base;
>>>>>>> rmem->size = size;
>>>>>>>
>>>>>>> + /* Call the region specific initialization function */
>>>>>>> + fdt_init_reserved_mem_node(rmem);
>>>>>>> +
>>>>>>> reserved_mem_count++;
>>>>>>> return;
>>>>>>> }
>>>>>>> @@ -106,7 +109,6 @@ static int __init
>>>> __reserved_mem_reserve_reg(unsigned long node,
>>>>>>> phys_addr_t base, size;
>>>>>>> int len;
>>>>>>> const __be32 *prop;
>>>>>>> - int first = 1;
>>>>>>> bool nomap;
>>>>>>>
>>>>>>> prop = of_get_flat_dt_prop(node, "reg", &len);
>>>>>>> @@ -134,10 +136,6 @@ static int __init
>>>> __reserved_mem_reserve_reg(unsigned long node,
>>>>>>> uname, &base, (unsigned long)(size /
>>>>>>> SZ_1M));
>>>>>>>
>>>>>>> len -= t_len;
>>>>>>> - if (first) {
>>>>>>> - fdt_reserved_mem_save_node(node, uname, base,
>>>>>>> size);
>>>>>>> - first = 0;
>>>>>>> - }
>>>>>>> }
>>>>>>> return 0;
>>>>>>> }
>>>>>>> @@ -165,12 +163,77 @@ static int __init
>>>> __reserved_mem_check_root(unsigned long node)
>>>>>>> return 0;
>>>>>>> }
>>>>>>>
>>>>>>> +static void __init __rmem_check_for_overlap(void);
>>>>>>> +
>>>>>>> +/**
>>>>>>> + * fdt_scan_reserved_mem_reg_nodes() - Store info for the "reg"
>>>>>>> defined
>>>>>>> + * reserved memory regions.
>>>>>>> + *
>>>>>>> + * This function is used to scan through the DT and store the
>>>>>>> + * information for the reserved memory regions that are defined using
>>>>>>> + * the "reg" property. The region node number, name, base address,
>>>>>>> and
>>>>>>> + * size are all stored in the reserved_mem array by calling the
>>>>>>> + * fdt_reserved_mem_save_node() function.
>>>>>>> + */
>>>>>>> +void __init fdt_scan_reserved_mem_reg_nodes(void)
>>>>>>> +{
>>>>>>> + int t_len = (dt_root_addr_cells + dt_root_size_cells) *
>>>>>>> sizeof(__be32);
>>>>>>> + const void *fdt = initial_boot_params;
>>>>>>> + phys_addr_t base, size;
>>>>>>> + const __be32 *prop;
>>>>>>> + int node, child;
>>>>>>> + int len;
>>>>>>> +
>>>>>>> + if (!fdt)
>>>>>>> + return;
>>>>>>> +
>>>>>>> + node = fdt_path_offset(fdt, "/reserved-memory");
>>>>>>> + if (node < 0) {
>>>>>>> + pr_info("Reserved memory: No reserved-memory node in the
>>>> DT\n");
>>>>>>> + return;
>>>>>>> + }
>>>>>>> +
>>>>>>> + if (__reserved_mem_check_root(node)) {
>>>>>>> + pr_err("Reserved memory: unsupported node format,
>>>>>>> ignoring\n");
>>>>>>> + return;
>>>>>>> + }
>>>>>>> +
>>>>>>> + fdt_for_each_subnode(child, fdt, node) {
>>>>>>> + const char *uname;
>>>>>>> +
>>>>>>> + prop = of_get_flat_dt_prop(child, "reg", &len);
>>>>>>> + if (!prop)
>>>>>>> + continue;
>>>>>>> + if (!of_fdt_device_is_available(fdt, child))
>>>>>>> + continue;
>>>>>>> +
>>>>>>> + uname = fdt_get_name(fdt, child, NULL);
>>>>>>> + if (len && len % t_len != 0) {
>>>>>>> + pr_err("Reserved memory: invalid reg property in
>>>>>>> '%s', skipping
>>>> node.\n",
>>>>>>> + uname);
>>>>>>> + continue;
>>>>>>> + }
>>>>>>> + base = dt_mem_next_cell(dt_root_addr_cells, &prop);
>>>>>>> + size = dt_mem_next_cell(dt_root_size_cells, &prop);
>>>>>>> +
>>>>>>> + if (size)
>>>>>>> + fdt_reserved_mem_save_node(child, uname, base,
>>>>>>> size);
>>>>>>> + }
>>>>>>> +
>>>>>>> + /* check for overlapping reserved regions */
>>>>>>> + __rmem_check_for_overlap();
>>>>>>> +}
>>>>>>> +
>>>>>>> +static int __init __reserved_mem_alloc_size(unsigned long node, const
>>>> char *uname);
>>>>>>> +
>>>>>>> /*
>>>>>>> * fdt_scan_reserved_mem() - scan a single FDT node for reserved
>>>>>>> memory
>>>>>>> */
>>>>>>> int __init fdt_scan_reserved_mem(void)
>>>>>>> {
>>>>>>> int node, child;
>>>>>>> + int dynamic_nodes_cnt = 0;
>>>>>>> + int dynamic_nodes[MAX_RESERVED_REGIONS];
>>>>>>> const void *fdt = initial_boot_params;
>>>>>>>
>>>>>>> node = fdt_path_offset(fdt, "/reserved-memory");
>>>>>>> @@ -192,8 +255,24 @@ int __init fdt_scan_reserved_mem(void)
>>>>>>> uname = fdt_get_name(fdt, child, NULL);
>>>>>>>
>>>>>>> err = __reserved_mem_reserve_reg(child, uname);
>>>>>>> - if (err == -ENOENT && of_get_flat_dt_prop(child, "size",
>>>>>>> NULL))
>>>>>>> - fdt_reserved_mem_save_node(child, uname, 0, 0);
>>>>>>> + /*
>>>>>>> + * Save the nodes for the dynamically-placed regions
>>>>>>> + * into an array which will be used for allocation right
>>>>>>> + * after all the statically-placed regions are reserved
>>>>>>> + * or marked as no-map. This is done to avoid
>>>>>>> dynamically
>>>>>>> + * allocating from one of the statically-placed regions.
>>>>>>> + */
>>>>>>> + if (err == -ENOENT && of_get_flat_dt_prop(child, "size",
>>>>>>> NULL)) {
>>>>>>> + dynamic_nodes[dynamic_nodes_cnt] = child;
>>>>>>> + dynamic_nodes_cnt++;
>>>>>>> + }
>>>>>>> + }
>>>>>>> + for (int i = 0; i < dynamic_nodes_cnt; i++) {
>>>>>>> + const char *uname;
>>>>>>> +
>>>>>>> + child = dynamic_nodes[i];
>>>>>>> + uname = fdt_get_name(fdt, child, NULL);
>>>>>>> + __reserved_mem_alloc_size(child, uname);
>>>>>>> }
>>>>>>> return 0;
>>>>>>> }
>>>>>>> @@ -253,8 +332,7 @@ static int __init
>>>> __reserved_mem_alloc_in_range(phys_addr_t size,
>>>>>>> * __reserved_mem_alloc_size() - allocate reserved memory described
>>>>>>> by
>>>>>>> * 'size', 'alignment' and 'alloc-ranges' properties.
>>>>>>> */
>>>>>>> -static int __init __reserved_mem_alloc_size(unsigned long node,
>>>>>>> - const char *uname, phys_addr_t *res_base, phys_addr_t *res_size)
>>>>>>> +static int __init __reserved_mem_alloc_size(unsigned long node, const
>>>> char *uname)
>>>>>>> {
>>>>>>> int t_len = (dt_root_addr_cells + dt_root_size_cells) *
>>>>>>> sizeof(__be32);
>>>>>>> phys_addr_t start = 0, end = 0;
>>>>>>> @@ -334,9 +412,8 @@ static int __init
>>>> __reserved_mem_alloc_size(unsigned long node,
>>>>>>> return -ENOMEM;
>>>>>>> }
>>>>>>>
>>>>>>> - *res_base = base;
>>>>>>> - *res_size = size;
>>>>>>> -
>>>>>>> + /* Save region in the reserved_mem array */
>>>>>>> + fdt_reserved_mem_save_node(node, uname, base, size);
>>>>>>> return 0;
>>>>>>> }
>>>>>>>
>>>>>>> @@ -425,48 +502,37 @@ static void __init
>>>> __rmem_check_for_overlap(void)
>>>>>>> }
>>>>>>>
>>>>>>> /**
>>>>>>> - * fdt_init_reserved_mem() - allocate and init all saved reserved
>>>>>>> memory
>>>> regions
>>>>>>> + * fdt_init_reserved_mem_node() - Initialize a reserved memory region
>>>>>>> + * @rmem: reserved_mem struct of the memory region to be initialized.
>>>>>>> + *
>>>>>>> + * This function is used to call the region specific initialization
>>>>>>> + * function for a reserved memory region.
>>>>>>> */
>>>>>>> -void __init fdt_init_reserved_mem(void)
>>>>>>> +static void __init fdt_init_reserved_mem_node(struct reserved_mem
>>>> *rmem)
>>>>>>> {
>>>>>>> - int i;
>>>>>>> -
>>>>>>> - /* check for overlapping reserved regions */
>>>>>>> - __rmem_check_for_overlap();
>>>>>>> -
>>>>>>> - for (i = 0; i < reserved_mem_count; i++) {
>>>>>>> - struct reserved_mem *rmem = &reserved_mem[i];
>>>>>>> - unsigned long node = rmem->fdt_node;
>>>>>>> - int err = 0;
>>>>>>> - bool nomap;
>>>>>>> + unsigned long node = rmem->fdt_node;
>>>>>>> + int err = 0;
>>>>>>> + bool nomap;
>>>>>>>
>>>>>>> - nomap = of_get_flat_dt_prop(node, "no-map", NULL) !=
>>>>>>> NULL;
>>>>>>> + nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
>>>>>>>
>>>>>>> - if (rmem->size == 0)
>>>>>>> - err = __reserved_mem_alloc_size(node,
>>>>>>> rmem->name,
>>>>>>> - &rmem->base,
>>>>>>> &rmem->size);
>>>>>>> - if (err == 0) {
>>>>>>> - err = __reserved_mem_init_node(rmem);
>>>>>>> - if (err != 0 && err != -ENOENT) {
>>>>>>> - pr_info("node %s compatible matching
>>>>>>> fail\n",
>>>>>>> - rmem->name);
>>>>>>> - if (nomap)
>>>>>>> - memblock_clear_nomap(rmem->base,
>>>>>>> rmem->size);
>>>>>>> - else
>>>>>>> - memblock_phys_free(rmem->base,
>>>>>>> - rmem->size);
>>>>>>> - } else {
>>>>>>> - phys_addr_t end = rmem->base +
>>>>>>> rmem->size - 1;
>>>>>>> - bool reusable =
>>>>>>> - (of_get_flat_dt_prop(node,
>>>>>>> "reusable", NULL)) !=
>>>> NULL;
>>>>>>> -
>>>>>>> - pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
>>>>>>> - &rmem->base, &end, (unsigned
>>>>>>> long)(rmem->size /
>>>> SZ_1K),
>>>>>>> - nomap ? "nomap" : "map",
>>>>>>> - reusable ? "reusable" :
>>>>>>> "non-reusable",
>>>>>>> - rmem->name ? rmem->name :
>>>>>>> "unknown");
>>>>>>> - }
>>>>>>> - }
>>>>>>> + err = __reserved_mem_init_node(rmem);
>>>>>>> + if (err != 0 && err != -ENOENT) {
>>>>>>> + pr_info("node %s compatible matching fail\n",
>>>>>>> rmem->name);
>>>>>>> + if (nomap)
>>>>>>> + memblock_clear_nomap(rmem->base, rmem->size);
>>>>>>> + else
>>>>>>> + memblock_phys_free(rmem->base, rmem->size);
>>>>>>> + } else {
>>>>>>> + phys_addr_t end = rmem->base + rmem->size - 1;
>>>>>>> + bool reusable =
>>>>>>> + (of_get_flat_dt_prop(node, "reusable", NULL)) !=
>>>>>>> NULL;
>>>>>>> +
>>>>>>> + pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
>>>>>>> + &rmem->base, &end, (unsigned long)(rmem->size /
>>>>>>> SZ_1K),
>>>>>>> + nomap ? "nomap" : "map",
>>>>>>> + reusable ? "reusable" : "non-reusable",
>>>>>>> + rmem->name ? rmem->name : "unknown");
>>>>>>> }
>>>>>>> }
>>>>>>>
>>>>> Just want to follow up on this issue. Do you need any further detail
>>>>> or clarification?
>>>>> Any ARM memory manage guru on this thread can comment?
>>>>> Or is my workaround acceptable as a patch?
>>>>
>>>> Hi William,
>>>>
>>>> Sorry about the delay in getting back to you.
>>>>
>>>> Instead of moving dma_contiguous_remap(), I suggest moving
>>>> dma_contiguous_early_fixup()
>>>> to the function that parses the reserved regions so that it is done before
>>>> paging_init.
>>>>
>>>> Here is what that could look like. Can you please give this a try?
>>>>
>>>> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
>>>> index 77016c0cc296..132d2c66cafc 100644
>>>> --- a/drivers/of/of_reserved_mem.c
>>>> +++ b/drivers/of/of_reserved_mem.c
>>>> @@ -25,6 +25,7 @@
>>>> #include <linux/memblock.h>
>>>> #include <linux/kmemleak.h>
>>>> #include <linux/cma.h>
>>>> +#include <linux/dma-map-ops.h>
>>>>
>>>> #include "of_private.h"
>>>>
>>>> @@ -175,13 +176,17 @@ static int __init
>>>> __reserved_mem_reserve_reg(unsigned long node,
>>>> base = dt_mem_next_cell(dt_root_addr_cells, &prop);
>>>> size = dt_mem_next_cell(dt_root_size_cells, &prop);
>>>>
>>>> - if (size &&
>>>> - early_init_dt_reserve_memory(base, size, nomap) == 0)
>>>> + if (size && early_init_dt_reserve_memory(base, size,
>>>> nomap) == 0) {
>>>> + /* Architecture specific contiguous memory fixup.
>>>> */
>>>> + if (of_flat_dt_is_compatible(node,
>>>> "shared-dma-pool"))
>>>> + dma_contiguous_early_fixup(base, size);
>>>> +
>>>> pr_debug("Reserved memory: reserved region for
>>>> node '%s':
>>>> base %pa, size %lu MiB\n",
>>>> uname, &base, (unsigned long)(size /
>>>> SZ_1M));
>>>> - else
>>>> + } else {
>>>> pr_err("Reserved memory: failed to reserve memory
>>>> for node '%s':
>>>> base %pa, size %lu MiB\n",
>>>> uname, &base, (unsigned long)(size /
>>>> SZ_1M));
>>>> + }
>>>>
>>>> len -= t_len;
>>>> }
>>>> @@ -472,6 +477,9 @@ static int __init __reserved_mem_alloc_size(unsigned
>>>> long node, const char *unam
>>>> uname, (unsigned long)(size / SZ_1M));
>>>> return -ENOMEM;
>>>> }
>>>> + /* Architecture specific contiguous memory fixup. */
>>>> + if (of_flat_dt_is_compatible(node, "shared-dma-pool"))
>>>> + dma_contiguous_early_fixup(base, size);
>>>> /* Save region in the reserved_mem array */
>>>> fdt_reserved_mem_save_node(node, uname, base, size);
>>>> diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
>>>> index 8df0dfaaca18..9e5d63efe7c5 100644
>>>> --- a/kernel/dma/contiguous.c
>>>> +++ b/kernel/dma/contiguous.c
>>>> @@ -480,8 +480,6 @@ static int __init rmem_cma_setup(struct reserved_mem
>>>> *rmem)
>>>> pr_err("Reserved memory: unable to setup CMA region\n");
>>>> return err;
>>>> }
>>>> - /* Architecture specific contiguous memory fixup. */
>>>> - dma_contiguous_early_fixup(rmem->base, rmem->size);
>>>>
>>>> if (default_cma)
>>>> dma_contiguous_default_area = cma;
>>>>
>>>> Regards,
>>>> Oreoluwa
>>> Thank you Oreoluwa! Your patch fixed the issue too and it looks a more
>>> localized and better fix!
>> Thank you for testing it out! I'm glad it worked for you.
>> I can work on an offical patch for this and submit it in
>> the next few days.
>
> I'm waiting for the final patch then.
>
> Best regards
I have uploaded the final patch here:
https://lore.kernel.org/all/20250708165627.845295-1-oreoluwa.babatunde@oss.qualcomm.com/
Thanks!
Hi,
On 24-10-08, Oreoluwa Babatunde wrote:
> Reserved memory regions defined in the devicetree can be broken up into
> two groups:
> i) Statically-placed reserved memory regions
> i.e. regions defined with a static start address and size using the
> "reg" property.
> ii) Dynamically-placed reserved memory regions.
> i.e. regions defined by specifying an address range where they can be
> placed in memory using the "alloc_ranges" and "size" properties.
>
> These regions are processed and set aside at boot time.
> This is done in two stages as seen below:
>
> Stage 1:
> At this stage, fdt_scan_reserved_mem() scans through the child nodes of
> the reserved_memory node using the flattened devicetree and does the
> following:
>
> 1) If the node represents a statically-placed reserved memory region,
> i.e. if it is defined using the "reg" property:
> - Call memblock_reserve() or memblock_mark_nomap() as needed.
> - Add the information for that region into the reserved_mem array
> using fdt_reserved_mem_save_node().
> i.e. fdt_reserved_mem_save_node(node, name, base, size).
>
> 2) If the node represents a dynamically-placed reserved memory region,
> i.e. if it is defined using "alloc-ranges" and "size" properties:
> - Add the information for that region to the reserved_mem array with
> the starting address and size set to 0.
> i.e. fdt_reserved_mem_save_node(node, name, 0, 0).
> Note: This region is saved to the array with a starting address of 0
> because a starting address is not yet allocated for it.
>
> Stage 2:
> After iterating through all the reserved memory nodes and storing their
> relevant information in the reserved_mem array,fdt_init_reserved_mem() is
> called and does the following:
>
> 1) For statically-placed reserved memory regions:
> - Call the region specific init function using
> __reserved_mem_init_node().
> 2) For dynamically-placed reserved memory regions:
> - Call __reserved_mem_alloc_size() which is used to allocate memory
> for each of these regions, and mark them as nomap if they have the
> nomap property specified in the DT.
> - Call the region specific init function.
>
> The current size of the resvered_mem array is 64 as is defined by
> MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for
> how many reserved memory regions can be specified on a system.
> As systems continue to grow more and more complex, the number of
> reserved memory regions needed are also growing and are starting to hit
> this 64 count limit, hence the need to make the reserved_mem array
> dynamically sized (i.e. dynamically allocating memory for the
> reserved_mem array using membock_alloc_*).
>
> On architectures such as arm64, memory allocated using memblock is
> writable only after the page tables have been setup. This means that if
> the reserved_mem array is going to be dynamically allocated, it needs to
> happen after the page tables have been setup, not before.
>
> Since the reserved memory regions are currently being processed and
> added to the array before the page tables are setup, there is a need to
> change the order in which some of the processing is done to allow for
> the reserved_mem array to be dynamically sized.
>
> It is possible to process the statically-placed reserved memory regions
> without needing to store them in the reserved_mem array until after the
> page tables have been setup because all the information stored in the
> array is readily available in the devicetree and can be referenced at
> any time.
> Dynamically-placed reserved memory regions on the other hand get
> assigned a start address only at runtime, and hence need a place to be
> stored once they are allocated since there is no other referrence to the
> start address for these regions.
>
> Hence this patch changes the processing order of the reserved memory
> regions in the following ways:
>
> Step 1:
> fdt_scan_reserved_mem() scans through the child nodes of
> the reserved_memory node using the flattened devicetree and does the
> following:
>
> 1) If the node represents a statically-placed reserved memory region,
> i.e. if it is defined using the "reg" property:
> - Call memblock_reserve() or memblock_mark_nomap() as needed.
>
> 2) If the node represents a dynamically-placed reserved memory region,
> i.e. if it is defined using "alloc-ranges" and "size" properties:
> - Call __reserved_mem_alloc_size() which will:
> i) Allocate memory for the reserved region and call
> memblock_mark_nomap() as needed.
> ii) Call the region specific initialization function using
> fdt_init_reserved_mem_node().
> iii) Save the region information in the reserved_mem array using
> fdt_reserved_mem_save_node().
>
> Step 2:
> 1) This stage of the reserved memory processing is now only used to add
> the statically-placed reserved memory regions into the reserved_mem
> array using fdt_scan_reserved_mem_reg_nodes(), as well as call their
> region specific initialization functions.
>
> 2) This step has also been moved to be after the page tables are
> setup. Moving this will allow us to replace the reserved_mem
> array with a dynamically sized array before storing the rest of
> these regions.
>
> Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
> ---
> drivers/of/fdt.c | 5 +-
> drivers/of/of_private.h | 3 +-
> drivers/of/of_reserved_mem.c | 168 ++++++++++++++++++++++++-----------
> 3 files changed, 122 insertions(+), 54 deletions(-)
this patch got into stable kernel 6.12.13++ as part of Stable-dep-of.
The stable kernel commit is: 9a0fe62f93ede02c27aaca81112af1e59c8c0979.
With the patch applied I see that the cma area pool is misplaced which
cause my 4G device to fail to activate the cma pool. Below are some
logs:
*** Good case (6.12)
root@test:~# dmesg|grep -i cma
[ 0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool
[ 0.000000] OF: reserved mem: 0x0000000044200000..0x00000000541fffff (262144 KiB) map reusable linux,cma
[ 0.056915] Memory: 3695024K/4194304K available (15552K kernel code, 2510K rwdata, 5992K rodata, 6016K init, 489K bss, 231772K reserved, 262144K cma-reserved)
*** Bad (6.12.16)
root@test:~# dmesg|grep -i cma
[ 0.000000] Reserved memory: created CMA memory pool at 0x00000000f2000000, size 256 MiB
[ 0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool
[ 0.000000] OF: reserved mem: 0x00000000f2000000..0x0000000101ffffff (262144 KiB) map reusable linux,cma
[ 0.056968] Memory: 3694896K/4194304K available (15616K kernel code, 2512K rwdata, 6012K rodata, 6080K init, 491K bss, 231900K reserved, 262144K cma-reserved)
[ 0.116920] cma: CMA area linux,cma could not be activated
*** Good (6.12.16, revert 9a0fe62f93ed)
root@test:~# dmesg|grep -i cma
[ 0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool
[ 0.000000] OF: reserved mem: 0x0000000044200000..0x00000000541fffff (262144 KiB) map reusable linux,cma
[ 0.060976] Memory: 3694896K/4194304K available (15616K kernel code, 2512K rwdata, 6012K rodata, 6080K init, 491K bss, 231900K reserved, 262144K cma-reserved)
Below is our reserved-memory dts node:
reserved-memory {
#address-cells = <2>;
#size-cells = <2>;
ranges;
linux,cma {
compatible = "shared-dma-pool";
reusable;
/*
* The CMA area must be in the lower 32-bit address range.
*/
alloc-ranges = <0x0 0x42000000 0 0xc0000000>;
size = <0x0 0x10000000>;
alignment = <0 0x2000>;
linux,cma-default;
};
optee-core@40000000 {
reg = <0 0x40000000 0 0x1e00000>;
no-map;
};
optee-shm@41e00000 {
reg = <0 0x41e00000 0 0x200000>;
no-map;
};
m7_reserved: m7@80000000 {
reg = <0 0x80000000 0 0x1000000>;
no-map;
};
vdev0vring0: vdev0vring0@55000000 {
reg = <0 0x55000000 0 0x8000>;
no-map;
};
vdev0vring1: vdev0vring1@55008000 {
reg = <0 0x55008000 0 0x8000>;
no-map;
};
rsc_table: rsc-table@550ff000 {
reg = <0 0x550ff000 0 0x1000>;
no-map;
};
ram_console_buffer: ram-console-buffer@55100000 {
reg = <0 0x55100000 0 0x1000>;
no-map;
};
vdev0buffer: vdev0buffer@55400000 {
compatible = "shared-dma-pool";
reg = <0 0x55400000 0 0x100000>;
no-map;
};
};
My current workaround is to revert commit 9a0fe62f93ed and the
dep-chain: 2d1d620ff27b444 8de4e5a92282. But I would like to get a
proper solution without having revert commits in my downstream
patchstack.
Regards,
Marco
On Wed, Feb 26, 2025 at 5:51 AM Marco Felsch <m.felsch@pengutronix.de> wrote: > > Hi, > > On 24-10-08, Oreoluwa Babatunde wrote: > > Reserved memory regions defined in the devicetree can be broken up into > > two groups: > > i) Statically-placed reserved memory regions > > i.e. regions defined with a static start address and size using the > > "reg" property. > > ii) Dynamically-placed reserved memory regions. > > i.e. regions defined by specifying an address range where they can be > > placed in memory using the "alloc_ranges" and "size" properties. > > > > These regions are processed and set aside at boot time. > > This is done in two stages as seen below: > > > > Stage 1: > > At this stage, fdt_scan_reserved_mem() scans through the child nodes of > > the reserved_memory node using the flattened devicetree and does the > > following: > > > > 1) If the node represents a statically-placed reserved memory region, > > i.e. if it is defined using the "reg" property: > > - Call memblock_reserve() or memblock_mark_nomap() as needed. > > - Add the information for that region into the reserved_mem array > > using fdt_reserved_mem_save_node(). > > i.e. fdt_reserved_mem_save_node(node, name, base, size). > > > > 2) If the node represents a dynamically-placed reserved memory region, > > i.e. if it is defined using "alloc-ranges" and "size" properties: > > - Add the information for that region to the reserved_mem array with > > the starting address and size set to 0. > > i.e. fdt_reserved_mem_save_node(node, name, 0, 0). > > Note: This region is saved to the array with a starting address of 0 > > because a starting address is not yet allocated for it. > > > > Stage 2: > > After iterating through all the reserved memory nodes and storing their > > relevant information in the reserved_mem array,fdt_init_reserved_mem() is > > called and does the following: > > > > 1) For statically-placed reserved memory regions: > > - Call the region specific init function using > > __reserved_mem_init_node(). > > 2) For dynamically-placed reserved memory regions: > > - Call __reserved_mem_alloc_size() which is used to allocate memory > > for each of these regions, and mark them as nomap if they have the > > nomap property specified in the DT. > > - Call the region specific init function. > > > > The current size of the resvered_mem array is 64 as is defined by > > MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for > > how many reserved memory regions can be specified on a system. > > As systems continue to grow more and more complex, the number of > > reserved memory regions needed are also growing and are starting to hit > > this 64 count limit, hence the need to make the reserved_mem array > > dynamically sized (i.e. dynamically allocating memory for the > > reserved_mem array using membock_alloc_*). > > > > On architectures such as arm64, memory allocated using memblock is > > writable only after the page tables have been setup. This means that if > > the reserved_mem array is going to be dynamically allocated, it needs to > > happen after the page tables have been setup, not before. > > > > Since the reserved memory regions are currently being processed and > > added to the array before the page tables are setup, there is a need to > > change the order in which some of the processing is done to allow for > > the reserved_mem array to be dynamically sized. > > > > It is possible to process the statically-placed reserved memory regions > > without needing to store them in the reserved_mem array until after the > > page tables have been setup because all the information stored in the > > array is readily available in the devicetree and can be referenced at > > any time. > > Dynamically-placed reserved memory regions on the other hand get > > assigned a start address only at runtime, and hence need a place to be > > stored once they are allocated since there is no other referrence to the > > start address for these regions. > > > > Hence this patch changes the processing order of the reserved memory > > regions in the following ways: > > > > Step 1: > > fdt_scan_reserved_mem() scans through the child nodes of > > the reserved_memory node using the flattened devicetree and does the > > following: > > > > 1) If the node represents a statically-placed reserved memory region, > > i.e. if it is defined using the "reg" property: > > - Call memblock_reserve() or memblock_mark_nomap() as needed. > > > > 2) If the node represents a dynamically-placed reserved memory region, > > i.e. if it is defined using "alloc-ranges" and "size" properties: > > - Call __reserved_mem_alloc_size() which will: > > i) Allocate memory for the reserved region and call > > memblock_mark_nomap() as needed. > > ii) Call the region specific initialization function using > > fdt_init_reserved_mem_node(). > > iii) Save the region information in the reserved_mem array using > > fdt_reserved_mem_save_node(). > > > > Step 2: > > 1) This stage of the reserved memory processing is now only used to add > > the statically-placed reserved memory regions into the reserved_mem > > array using fdt_scan_reserved_mem_reg_nodes(), as well as call their > > region specific initialization functions. > > > > 2) This step has also been moved to be after the page tables are > > setup. Moving this will allow us to replace the reserved_mem > > array with a dynamically sized array before storing the rest of > > these regions. > > > > Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com> > > --- > > drivers/of/fdt.c | 5 +- > > drivers/of/of_private.h | 3 +- > > drivers/of/of_reserved_mem.c | 168 ++++++++++++++++++++++++----------- > > 3 files changed, 122 insertions(+), 54 deletions(-) > > this patch got into stable kernel 6.12.13++ as part of Stable-dep-of. > The stable kernel commit is: 9a0fe62f93ede02c27aaca81112af1e59c8c0979. > > With the patch applied I see that the cma area pool is misplaced which > cause my 4G device to fail to activate the cma pool. Below are some > logs: > > *** Good case (6.12) > > root@test:~# dmesg|grep -i cma > [ 0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool > [ 0.000000] OF: reserved mem: 0x0000000044200000..0x00000000541fffff (262144 KiB) map reusable linux,cma > [ 0.056915] Memory: 3695024K/4194304K available (15552K kernel code, 2510K rwdata, 5992K rodata, 6016K init, 489K bss, 231772K reserved, 262144K cma-reserved) > > *** Bad (6.12.16) > > root@test:~# dmesg|grep -i cma > [ 0.000000] Reserved memory: created CMA memory pool at 0x00000000f2000000, size 256 MiB > [ 0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool > [ 0.000000] OF: reserved mem: 0x00000000f2000000..0x0000000101ffffff (262144 KiB) map reusable linux,cma > /* > * The CMA area must be in the lower 32-bit address range. > */ > alloc-ranges = <0x0 0x42000000 0 0xc0000000>; Are you expecting that 0xc0000000 is the end address rather than the size? Because your range ends at 0x1_0200_0000. Looks to me like the kernel correctly followed what the DT said was allowed. Why it moved, I don't know. If you change 0xc0000000 to 0xbe000000, does it work? Rob
On 25-02-28, Rob Herring wrote: > On Wed, Feb 26, 2025 at 5:51 AM Marco Felsch <m.felsch@pengutronix.de> wrote: > > > > Hi, > > > > On 24-10-08, Oreoluwa Babatunde wrote: > > > Reserved memory regions defined in the devicetree can be broken up into > > > two groups: > > > i) Statically-placed reserved memory regions > > > i.e. regions defined with a static start address and size using the > > > "reg" property. > > > ii) Dynamically-placed reserved memory regions. > > > i.e. regions defined by specifying an address range where they can be > > > placed in memory using the "alloc_ranges" and "size" properties. > > > > > > These regions are processed and set aside at boot time. > > > This is done in two stages as seen below: > > > > > > Stage 1: > > > At this stage, fdt_scan_reserved_mem() scans through the child nodes of > > > the reserved_memory node using the flattened devicetree and does the > > > following: > > > > > > 1) If the node represents a statically-placed reserved memory region, > > > i.e. if it is defined using the "reg" property: > > > - Call memblock_reserve() or memblock_mark_nomap() as needed. > > > - Add the information for that region into the reserved_mem array > > > using fdt_reserved_mem_save_node(). > > > i.e. fdt_reserved_mem_save_node(node, name, base, size). > > > > > > 2) If the node represents a dynamically-placed reserved memory region, > > > i.e. if it is defined using "alloc-ranges" and "size" properties: > > > - Add the information for that region to the reserved_mem array with > > > the starting address and size set to 0. > > > i.e. fdt_reserved_mem_save_node(node, name, 0, 0). > > > Note: This region is saved to the array with a starting address of 0 > > > because a starting address is not yet allocated for it. > > > > > > Stage 2: > > > After iterating through all the reserved memory nodes and storing their > > > relevant information in the reserved_mem array,fdt_init_reserved_mem() is > > > called and does the following: > > > > > > 1) For statically-placed reserved memory regions: > > > - Call the region specific init function using > > > __reserved_mem_init_node(). > > > 2) For dynamically-placed reserved memory regions: > > > - Call __reserved_mem_alloc_size() which is used to allocate memory > > > for each of these regions, and mark them as nomap if they have the > > > nomap property specified in the DT. > > > - Call the region specific init function. > > > > > > The current size of the resvered_mem array is 64 as is defined by > > > MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for > > > how many reserved memory regions can be specified on a system. > > > As systems continue to grow more and more complex, the number of > > > reserved memory regions needed are also growing and are starting to hit > > > this 64 count limit, hence the need to make the reserved_mem array > > > dynamically sized (i.e. dynamically allocating memory for the > > > reserved_mem array using membock_alloc_*). > > > > > > On architectures such as arm64, memory allocated using memblock is > > > writable only after the page tables have been setup. This means that if > > > the reserved_mem array is going to be dynamically allocated, it needs to > > > happen after the page tables have been setup, not before. > > > > > > Since the reserved memory regions are currently being processed and > > > added to the array before the page tables are setup, there is a need to > > > change the order in which some of the processing is done to allow for > > > the reserved_mem array to be dynamically sized. > > > > > > It is possible to process the statically-placed reserved memory regions > > > without needing to store them in the reserved_mem array until after the > > > page tables have been setup because all the information stored in the > > > array is readily available in the devicetree and can be referenced at > > > any time. > > > Dynamically-placed reserved memory regions on the other hand get > > > assigned a start address only at runtime, and hence need a place to be > > > stored once they are allocated since there is no other referrence to the > > > start address for these regions. > > > > > > Hence this patch changes the processing order of the reserved memory > > > regions in the following ways: > > > > > > Step 1: > > > fdt_scan_reserved_mem() scans through the child nodes of > > > the reserved_memory node using the flattened devicetree and does the > > > following: > > > > > > 1) If the node represents a statically-placed reserved memory region, > > > i.e. if it is defined using the "reg" property: > > > - Call memblock_reserve() or memblock_mark_nomap() as needed. > > > > > > 2) If the node represents a dynamically-placed reserved memory region, > > > i.e. if it is defined using "alloc-ranges" and "size" properties: > > > - Call __reserved_mem_alloc_size() which will: > > > i) Allocate memory for the reserved region and call > > > memblock_mark_nomap() as needed. > > > ii) Call the region specific initialization function using > > > fdt_init_reserved_mem_node(). > > > iii) Save the region information in the reserved_mem array using > > > fdt_reserved_mem_save_node(). > > > > > > Step 2: > > > 1) This stage of the reserved memory processing is now only used to add > > > the statically-placed reserved memory regions into the reserved_mem > > > array using fdt_scan_reserved_mem_reg_nodes(), as well as call their > > > region specific initialization functions. > > > > > > 2) This step has also been moved to be after the page tables are > > > setup. Moving this will allow us to replace the reserved_mem > > > array with a dynamically sized array before storing the rest of > > > these regions. > > > > > > Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com> > > > --- > > > drivers/of/fdt.c | 5 +- > > > drivers/of/of_private.h | 3 +- > > > drivers/of/of_reserved_mem.c | 168 ++++++++++++++++++++++++----------- > > > 3 files changed, 122 insertions(+), 54 deletions(-) > > > > this patch got into stable kernel 6.12.13++ as part of Stable-dep-of. > > The stable kernel commit is: 9a0fe62f93ede02c27aaca81112af1e59c8c0979. > > > > With the patch applied I see that the cma area pool is misplaced which > > cause my 4G device to fail to activate the cma pool. Below are some > > logs: > > > > *** Good case (6.12) > > > > root@test:~# dmesg|grep -i cma > > [ 0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool > > [ 0.000000] OF: reserved mem: 0x0000000044200000..0x00000000541fffff (262144 KiB) map reusable linux,cma > > [ 0.056915] Memory: 3695024K/4194304K available (15552K kernel code, 2510K rwdata, 5992K rodata, 6016K init, 489K bss, 231772K reserved, 262144K cma-reserved) > > > > *** Bad (6.12.16) > > > > root@test:~# dmesg|grep -i cma > > [ 0.000000] Reserved memory: created CMA memory pool at 0x00000000f2000000, size 256 MiB > > [ 0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool > > [ 0.000000] OF: reserved mem: 0x00000000f2000000..0x0000000101ffffff (262144 KiB) map reusable linux,cma > > > /* > > * The CMA area must be in the lower 32-bit address range. > > */ > > alloc-ranges = <0x0 0x42000000 0 0xc0000000>; > > Are you expecting that 0xc0000000 is the end address rather than the > size? Because your range ends at 0x1_0200_0000. Looks to me like the > kernel correctly followed what the DT said was allowed. Why it moved, > I don't know. If you change 0xc0000000 to 0xbe000000, does it work? Argh.. you're absolutely right, we had the wrong size specified and didn't noticed it till the kernel update :/ I don't know why I didn't noticed this earlier. With the length/size set to 0xbe000000, the cma is now allocated correctly: root@test:~# dmesg|grep cma [ 0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool [ 0.000000] OF: reserved mem: 0x00000000f0000000..0x00000000ffffffff (262144 KiB) map reusable linux,cma [ 0.060910] Memory: 3694896K/4194304K available (15616K kernel code, 2512K rwdata, 6016K rodata, 6080K init, 491K bss, 231900K reserved, 262144K cma-reserved) As you said the the placing was changed too, not sure why but that's okay. To be honest, placing it at the end and not somewhere in between sounds far more reasonable to me. Thanks for the support, Marco
On 25-02-26, Marco Felsch wrote:
> Hi,
>
> On 24-10-08, Oreoluwa Babatunde wrote:
> > Reserved memory regions defined in the devicetree can be broken up into
> > two groups:
> > i) Statically-placed reserved memory regions
> > i.e. regions defined with a static start address and size using the
> > "reg" property.
> > ii) Dynamically-placed reserved memory regions.
> > i.e. regions defined by specifying an address range where they can be
> > placed in memory using the "alloc_ranges" and "size" properties.
> >
> > These regions are processed and set aside at boot time.
> > This is done in two stages as seen below:
> >
> > Stage 1:
> > At this stage, fdt_scan_reserved_mem() scans through the child nodes of
> > the reserved_memory node using the flattened devicetree and does the
> > following:
> >
> > 1) If the node represents a statically-placed reserved memory region,
> > i.e. if it is defined using the "reg" property:
> > - Call memblock_reserve() or memblock_mark_nomap() as needed.
> > - Add the information for that region into the reserved_mem array
> > using fdt_reserved_mem_save_node().
> > i.e. fdt_reserved_mem_save_node(node, name, base, size).
> >
> > 2) If the node represents a dynamically-placed reserved memory region,
> > i.e. if it is defined using "alloc-ranges" and "size" properties:
> > - Add the information for that region to the reserved_mem array with
> > the starting address and size set to 0.
> > i.e. fdt_reserved_mem_save_node(node, name, 0, 0).
> > Note: This region is saved to the array with a starting address of 0
> > because a starting address is not yet allocated for it.
> >
> > Stage 2:
> > After iterating through all the reserved memory nodes and storing their
> > relevant information in the reserved_mem array,fdt_init_reserved_mem() is
> > called and does the following:
> >
> > 1) For statically-placed reserved memory regions:
> > - Call the region specific init function using
> > __reserved_mem_init_node().
> > 2) For dynamically-placed reserved memory regions:
> > - Call __reserved_mem_alloc_size() which is used to allocate memory
> > for each of these regions, and mark them as nomap if they have the
> > nomap property specified in the DT.
> > - Call the region specific init function.
> >
> > The current size of the resvered_mem array is 64 as is defined by
> > MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for
> > how many reserved memory regions can be specified on a system.
> > As systems continue to grow more and more complex, the number of
> > reserved memory regions needed are also growing and are starting to hit
> > this 64 count limit, hence the need to make the reserved_mem array
> > dynamically sized (i.e. dynamically allocating memory for the
> > reserved_mem array using membock_alloc_*).
> >
> > On architectures such as arm64, memory allocated using memblock is
> > writable only after the page tables have been setup. This means that if
> > the reserved_mem array is going to be dynamically allocated, it needs to
> > happen after the page tables have been setup, not before.
> >
> > Since the reserved memory regions are currently being processed and
> > added to the array before the page tables are setup, there is a need to
> > change the order in which some of the processing is done to allow for
> > the reserved_mem array to be dynamically sized.
> >
> > It is possible to process the statically-placed reserved memory regions
> > without needing to store them in the reserved_mem array until after the
> > page tables have been setup because all the information stored in the
> > array is readily available in the devicetree and can be referenced at
> > any time.
> > Dynamically-placed reserved memory regions on the other hand get
> > assigned a start address only at runtime, and hence need a place to be
> > stored once they are allocated since there is no other referrence to the
> > start address for these regions.
> >
> > Hence this patch changes the processing order of the reserved memory
> > regions in the following ways:
> >
> > Step 1:
> > fdt_scan_reserved_mem() scans through the child nodes of
> > the reserved_memory node using the flattened devicetree and does the
> > following:
> >
> > 1) If the node represents a statically-placed reserved memory region,
> > i.e. if it is defined using the "reg" property:
> > - Call memblock_reserve() or memblock_mark_nomap() as needed.
> >
> > 2) If the node represents a dynamically-placed reserved memory region,
> > i.e. if it is defined using "alloc-ranges" and "size" properties:
> > - Call __reserved_mem_alloc_size() which will:
> > i) Allocate memory for the reserved region and call
> > memblock_mark_nomap() as needed.
> > ii) Call the region specific initialization function using
> > fdt_init_reserved_mem_node().
> > iii) Save the region information in the reserved_mem array using
> > fdt_reserved_mem_save_node().
> >
> > Step 2:
> > 1) This stage of the reserved memory processing is now only used to add
> > the statically-placed reserved memory regions into the reserved_mem
> > array using fdt_scan_reserved_mem_reg_nodes(), as well as call their
> > region specific initialization functions.
> >
> > 2) This step has also been moved to be after the page tables are
> > setup. Moving this will allow us to replace the reserved_mem
> > array with a dynamically sized array before storing the rest of
> > these regions.
> >
> > Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
> > ---
> > drivers/of/fdt.c | 5 +-
> > drivers/of/of_private.h | 3 +-
> > drivers/of/of_reserved_mem.c | 168 ++++++++++++++++++++++++-----------
> > 3 files changed, 122 insertions(+), 54 deletions(-)
>
> this patch got into stable kernel 6.12.13++ as part of Stable-dep-of.
> The stable kernel commit is: 9a0fe62f93ede02c27aaca81112af1e59c8c0979.
>
> With the patch applied I see that the cma area pool is misplaced which
> cause my 4G device to fail to activate the cma pool. Below are some
> logs:
>
> *** Good case (6.12)
>
> root@test:~# dmesg|grep -i cma
> [ 0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool
> [ 0.000000] OF: reserved mem: 0x0000000044200000..0x00000000541fffff (262144 KiB) map reusable linux,cma
> [ 0.056915] Memory: 3695024K/4194304K available (15552K kernel code, 2510K rwdata, 5992K rodata, 6016K init, 489K bss, 231772K reserved, 262144K cma-reserved)
>
> *** Bad (6.12.16)
>
> root@test:~# dmesg|grep -i cma
> [ 0.000000] Reserved memory: created CMA memory pool at 0x00000000f2000000, size 256 MiB
> [ 0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool
> [ 0.000000] OF: reserved mem: 0x00000000f2000000..0x0000000101ffffff (262144 KiB) map reusable linux,cma
> [ 0.056968] Memory: 3694896K/4194304K available (15616K kernel code, 2512K rwdata, 6012K rodata, 6080K init, 491K bss, 231900K reserved, 262144K cma-reserved)
> [ 0.116920] cma: CMA area linux,cma could not be activated
>
> *** Good (6.12.16, revert 9a0fe62f93ed)
>
> root@test:~# dmesg|grep -i cma
> [ 0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool
> [ 0.000000] OF: reserved mem: 0x0000000044200000..0x00000000541fffff (262144 KiB) map reusable linux,cma
> [ 0.060976] Memory: 3694896K/4194304K available (15616K kernel code, 2512K rwdata, 6012K rodata, 6080K init, 491K bss, 231900K reserved, 262144K cma-reserved)
>
> Below is our reserved-memory dts node:
>
> reserved-memory {
> #address-cells = <2>;
> #size-cells = <2>;
> ranges;
>
> linux,cma {
> compatible = "shared-dma-pool";
> reusable;
> /*
> * The CMA area must be in the lower 32-bit address range.
> */
> alloc-ranges = <0x0 0x42000000 0 0xc0000000>;
> size = <0x0 0x10000000>;
> alignment = <0 0x2000>;
> linux,cma-default;
> };
>
> optee-core@40000000 {
> reg = <0 0x40000000 0 0x1e00000>;
> no-map;
> };
>
> optee-shm@41e00000 {
> reg = <0 0x41e00000 0 0x200000>;
> no-map;
> };
>
> m7_reserved: m7@80000000 {
> reg = <0 0x80000000 0 0x1000000>;
> no-map;
> };
>
> vdev0vring0: vdev0vring0@55000000 {
> reg = <0 0x55000000 0 0x8000>;
> no-map;
> };
>
> vdev0vring1: vdev0vring1@55008000 {
> reg = <0 0x55008000 0 0x8000>;
> no-map;
> };
>
> rsc_table: rsc-table@550ff000 {
> reg = <0 0x550ff000 0 0x1000>;
> no-map;
> };
>
> ram_console_buffer: ram-console-buffer@55100000 {
> reg = <0 0x55100000 0 0x1000>;
> no-map;
> };
>
> vdev0buffer: vdev0buffer@55400000 {
> compatible = "shared-dma-pool";
> reg = <0 0x55400000 0 0x100000>;
> no-map;
> };
> };
>
> My current workaround is to revert commit 9a0fe62f93ed and the
> dep-chain: 2d1d620ff27b444 8de4e5a92282. But I would like to get a
It's not 2d1d620ff27b444 but e61977c71494.
> proper solution without having revert commits in my downstream
> patchstack.
>
> Regards,
> Marco
>
>
Hi Oreoluwa,
On Wed, Oct 9, 2024 at 12:08 AM Oreoluwa Babatunde
<quic_obabatun@quicinc.com> wrote:
> Reserved memory regions defined in the devicetree can be broken up into
> two groups:
> i) Statically-placed reserved memory regions
> i.e. regions defined with a static start address and size using the
> "reg" property.
> ii) Dynamically-placed reserved memory regions.
> i.e. regions defined by specifying an address range where they can be
> placed in memory using the "alloc_ranges" and "size" properties.
>
> These regions are processed and set aside at boot time.
> This is done in two stages as seen below:
>
> Stage 1:
> At this stage, fdt_scan_reserved_mem() scans through the child nodes of
> the reserved_memory node using the flattened devicetree and does the
> following:
>
> 1) If the node represents a statically-placed reserved memory region,
> i.e. if it is defined using the "reg" property:
> - Call memblock_reserve() or memblock_mark_nomap() as needed.
> - Add the information for that region into the reserved_mem array
> using fdt_reserved_mem_save_node().
> i.e. fdt_reserved_mem_save_node(node, name, base, size).
>
> 2) If the node represents a dynamically-placed reserved memory region,
> i.e. if it is defined using "alloc-ranges" and "size" properties:
> - Add the information for that region to the reserved_mem array with
> the starting address and size set to 0.
> i.e. fdt_reserved_mem_save_node(node, name, 0, 0).
> Note: This region is saved to the array with a starting address of 0
> because a starting address is not yet allocated for it.
>
> Stage 2:
> After iterating through all the reserved memory nodes and storing their
> relevant information in the reserved_mem array,fdt_init_reserved_mem() is
> called and does the following:
>
> 1) For statically-placed reserved memory regions:
> - Call the region specific init function using
> __reserved_mem_init_node().
> 2) For dynamically-placed reserved memory regions:
> - Call __reserved_mem_alloc_size() which is used to allocate memory
> for each of these regions, and mark them as nomap if they have the
> nomap property specified in the DT.
> - Call the region specific init function.
>
> The current size of the resvered_mem array is 64 as is defined by
> MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for
> how many reserved memory regions can be specified on a system.
> As systems continue to grow more and more complex, the number of
> reserved memory regions needed are also growing and are starting to hit
> this 64 count limit, hence the need to make the reserved_mem array
> dynamically sized (i.e. dynamically allocating memory for the
> reserved_mem array using membock_alloc_*).
>
> On architectures such as arm64, memory allocated using memblock is
> writable only after the page tables have been setup. This means that if
> the reserved_mem array is going to be dynamically allocated, it needs to
> happen after the page tables have been setup, not before.
>
> Since the reserved memory regions are currently being processed and
> added to the array before the page tables are setup, there is a need to
> change the order in which some of the processing is done to allow for
> the reserved_mem array to be dynamically sized.
>
> It is possible to process the statically-placed reserved memory regions
> without needing to store them in the reserved_mem array until after the
> page tables have been setup because all the information stored in the
> array is readily available in the devicetree and can be referenced at
> any time.
> Dynamically-placed reserved memory regions on the other hand get
> assigned a start address only at runtime, and hence need a place to be
> stored once they are allocated since there is no other referrence to the
> start address for these regions.
>
> Hence this patch changes the processing order of the reserved memory
> regions in the following ways:
>
> Step 1:
> fdt_scan_reserved_mem() scans through the child nodes of
> the reserved_memory node using the flattened devicetree and does the
> following:
>
> 1) If the node represents a statically-placed reserved memory region,
> i.e. if it is defined using the "reg" property:
> - Call memblock_reserve() or memblock_mark_nomap() as needed.
>
> 2) If the node represents a dynamically-placed reserved memory region,
> i.e. if it is defined using "alloc-ranges" and "size" properties:
> - Call __reserved_mem_alloc_size() which will:
> i) Allocate memory for the reserved region and call
> memblock_mark_nomap() as needed.
> ii) Call the region specific initialization function using
> fdt_init_reserved_mem_node().
> iii) Save the region information in the reserved_mem array using
> fdt_reserved_mem_save_node().
>
> Step 2:
> 1) This stage of the reserved memory processing is now only used to add
> the statically-placed reserved memory regions into the reserved_mem
> array using fdt_scan_reserved_mem_reg_nodes(), as well as call their
> region specific initialization functions.
>
> 2) This step has also been moved to be after the page tables are
> setup. Moving this will allow us to replace the reserved_mem
> array with a dynamically sized array before storing the rest of
> these regions.
>
> Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
Thanks for your patch, which is now commit 8a6e02d0c00e7b62
("of: reserved_mem: Restructure how the reserved memory regions
are processed") in dt-rh/for-next.
I have bisected a boot issue on RZ/Five to this commit.
With "earlycon keep_bootcon" (else there is no output):
Oops - store (or AMO) access fault [#1]
CPU: 0 UID: 0 PID: 1 Comm: swapper Not tainted
6.12.0-rc1-00015-g8a6e02d0c00e #201
Hardware name: Renesas SMARC EVK based on r9a07g043f01 (DT)
epc : __memset+0x60/0x100
ra : __dma_alloc_from_coherent+0x150/0x17a
epc : ffffffff8062d2bc ra : ffffffff80053a94 sp : ffffffc60000ba20
gp : ffffffff812e9938 tp : ffffffd601920000 t0 : ffffffc6000d0000
t1 : 0000000000000000 t2 : ffffffffe9600000 s0 : ffffffc60000baa0
s1 : ffffffc6000d0000 a0 : ffffffc6000d0000 a1 : 0000000000000000
a2 : 0000000000001000 a3 : ffffffc6000d1000 a4 : 0000000000000000
a5 : 0000000000000000 a6 : ffffffd601adacc0 a7 : ffffffd601a841a8
s2 : ffffffd6018573c0 s3 : 0000000000001000 s4 : ffffffd6019541e0
s5 : 0000000200000022 s6 : ffffffd6018f8410 s7 : ffffffd6018573e8
s8 : 0000000000000001 s9 : 0000000000000001 s10: 0000000000000010
s11: 0000000000000000 t3 : 0000000000000000 t4 : ffffffffdefe62d1
t5 : 000000001cd6a3a9 t6 : ffffffd601b2aad6
status: 0000000200000120 badaddr: ffffffc6000d0000 cause: 0000000000000007
[<ffffffff8062d2bc>] __memset+0x60/0x100
[<ffffffff80053e1a>] dma_alloc_from_global_coherent+0x1c/0x28
[<ffffffff80053056>] dma_direct_alloc+0x98/0x112
[<ffffffff8005238c>] dma_alloc_attrs+0x78/0x86
[<ffffffff8035fdb4>] rz_dmac_probe+0x3f6/0x50a
[<ffffffff803a0694>] platform_probe+0x4c/0x8a
[<ffffffff8039ea16>] really_probe+0xe4/0x1c8
[<ffffffff8039ebc4>] __driver_probe_device+0xca/0xce
[<ffffffff8039ec48>] driver_probe_device+0x34/0x92
[<ffffffff8039ede8>] __driver_attach+0xb4/0xbe
[<ffffffff8039ce58>] bus_for_each_dev+0x60/0xa0
[<ffffffff8039e26a>] driver_attach+0x1a/0x22
[<ffffffff8039dc20>] bus_add_driver+0xa4/0x184
[<ffffffff8039f65c>] driver_register+0x8a/0xb4
[<ffffffff803a051c>] __platform_driver_register+0x1c/0x24
[<ffffffff808202f6>] rz_dmac_driver_init+0x1a/0x22
[<ffffffff80800ef6>] do_one_initcall+0x64/0x134
[<ffffffff8080122e>] kernel_init_freeable+0x200/0x202
[<ffffffff80638126>] kernel_init+0x1e/0x10a
[<ffffffff8063d58e>] ret_from_fork+0xe/0x18
Code: 1007 82b3 40e2 0797 0000 8793 00e7 8305 97ba 8782 (b023) 00b2
---[ end trace 0000000000000000 ]---
Kernel panic - not syncing: Fatal exception in interrupt
---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---
Nothing really stands out in the kernel log, except for a delayed
initialization of the reserved mem nodes (they are the same
before/after):
printk: debug: ignoring loglevel setting.
-OF: reserved mem: 0x0000000000030000..0x000000000003ffff (64 KiB)
nomap non-reusable mmode_resv0@30000
-OF: reserved mem: 0x0000000000040000..0x000000000004ffff (64 KiB)
nomap non-reusable mmode_resv1@40000
-OF: reserved mem: 0x0000000044000000..0x000000004403ffff (256 KiB)
nomap non-reusable mmode_resv3@44000000
-OF: reserved mem: 0x0000000044040000..0x000000004405ffff (128 KiB)
nomap non-reusable mmode_resv2@44040000
+earlycon: scif0 at MMIO 0x000000001004b800 (options '115200n8')
+printk: legacy bootconsole [scif0] enabled
+printk: debug: skip boot console de-registration.
Reserved memory: created DMA memory pool at 0x0000000058000000, size 128 MiB
OF: reserved mem: initialized node pma_resv0@58000000, compatible id
shared-dma-pool
OF: reserved mem: 0x0000000058000000..0x000000005fffffff (131072 KiB)
nomap non-reusable pma_resv0@58000000
+OF: reserved mem: 0x0000000000030000..0x000000000003ffff (64 KiB)
nomap non-reusable mmode_resv0@30000
+OF: reserved mem: 0x0000000000040000..0x000000000004ffff (64 KiB)
nomap non-reusable mmode_resv1@40000
+OF: reserved mem: 0x0000000044040000..0x000000004405ffff (128 KiB)
nomap non-reusable mmode_resv2@44040000
+OF: reserved mem: 0x0000000044000000..0x000000004403ffff (256 KiB)
nomap non-reusable mmode_resv3@44000000
Zone ranges:
DMA32 [mem 0x0000000048000000-0x000000007fffffff]
Normal empty
Reverting commits 00c9a452a235c61f ("of: reserved_mem: Add code to
dynamically allocate reserved_mem array") and 8a6e02d0c00e7b62 fixes
the issue.
root@smarc-rzfive:/sys/firmware/devicetree/base/reserved-memory# ls -l
total 0
-r--r--r-- 1 root root 4 Oct 29 12:37 #address-cells
-r--r--r-- 1 root root 4 Oct 29 12:37 #size-cells
drwxr-xr-x 2 root root 0 Oct 29 12:37 mmode_resv0@30000
drwxr-xr-x 2 root root 0 Oct 29 12:37 mmode_resv1@40000
drwxr-xr-x 2 root root 0 Oct 29 12:37 mmode_resv2@44040000
drwxr-xr-x 2 root root 0 Oct 29 12:37 mmode_resv3@44000000
-r--r--r-- 1 root root 16 Oct 29 12:37 name
drwxr-xr-x 2 root root 0 Oct 29 12:37 pma_resv0@58000000
-r--r--r-- 1 root root 0 Oct 29 12:37 ranges
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 4d528c10df3a..d0dbc8183ac4 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -511,8 +511,6 @@ void __init early_init_fdt_scan_reserved_mem(void)
> break;
> memblock_reserve(base, size);
> }
> -
> - fdt_init_reserved_mem();
> }
>
> /**
> @@ -1212,6 +1210,9 @@ void __init unflatten_device_tree(void)
> {
> void *fdt = initial_boot_params;
>
> + /* Save the statically-placed regions in the reserved_mem array */
> + fdt_scan_reserved_mem_reg_nodes();
> +
> /* Don't use the bootloader provided DTB if ACPI is enabled */
> if (!acpi_disabled)
> fdt = NULL;
> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
> index 04aa2a91f851..29525c0b9939 100644
> --- a/drivers/of/of_private.h
> +++ b/drivers/of/of_private.h
> @@ -9,6 +9,7 @@
> */
>
> #define FDT_ALIGN_SIZE 8
> +#define MAX_RESERVED_REGIONS 64
>
> /**
> * struct alias_prop - Alias property in 'aliases' node
> @@ -180,7 +181,7 @@ static inline struct device_node *__of_get_dma_parent(const struct device_node *
> #endif
>
> int fdt_scan_reserved_mem(void);
> -void fdt_init_reserved_mem(void);
> +void __init fdt_scan_reserved_mem_reg_nodes(void);
>
> bool of_fdt_device_is_available(const void *blob, unsigned long node);
>
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> index 46e1c3fbc769..2011174211f9 100644
> --- a/drivers/of/of_reserved_mem.c
> +++ b/drivers/of/of_reserved_mem.c
> @@ -27,7 +27,6 @@
>
> #include "of_private.h"
>
> -#define MAX_RESERVED_REGIONS 64
> static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
> static int reserved_mem_count;
>
> @@ -56,6 +55,7 @@ static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
> return err;
> }
>
> +static void __init fdt_init_reserved_mem_node(struct reserved_mem *rmem);
> /*
> * fdt_reserved_mem_save_node() - save fdt node for second pass initialization
> */
> @@ -74,6 +74,9 @@ static void __init fdt_reserved_mem_save_node(unsigned long node, const char *un
> rmem->base = base;
> rmem->size = size;
>
> + /* Call the region specific initialization function */
> + fdt_init_reserved_mem_node(rmem);
> +
> reserved_mem_count++;
> return;
> }
> @@ -106,7 +109,6 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
> phys_addr_t base, size;
> int len;
> const __be32 *prop;
> - int first = 1;
> bool nomap;
>
> prop = of_get_flat_dt_prop(node, "reg", &len);
> @@ -134,10 +136,6 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
> uname, &base, (unsigned long)(size / SZ_1M));
>
> len -= t_len;
> - if (first) {
> - fdt_reserved_mem_save_node(node, uname, base, size);
> - first = 0;
> - }
> }
> return 0;
> }
> @@ -165,12 +163,77 @@ static int __init __reserved_mem_check_root(unsigned long node)
> return 0;
> }
>
> +static void __init __rmem_check_for_overlap(void);
> +
> +/**
> + * fdt_scan_reserved_mem_reg_nodes() - Store info for the "reg" defined
> + * reserved memory regions.
> + *
> + * This function is used to scan through the DT and store the
> + * information for the reserved memory regions that are defined using
> + * the "reg" property. The region node number, name, base address, and
> + * size are all stored in the reserved_mem array by calling the
> + * fdt_reserved_mem_save_node() function.
> + */
> +void __init fdt_scan_reserved_mem_reg_nodes(void)
> +{
> + int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
> + const void *fdt = initial_boot_params;
> + phys_addr_t base, size;
> + const __be32 *prop;
> + int node, child;
> + int len;
> +
> + if (!fdt)
> + return;
> +
> + node = fdt_path_offset(fdt, "/reserved-memory");
> + if (node < 0) {
> + pr_info("Reserved memory: No reserved-memory node in the DT\n");
> + return;
> + }
> +
> + if (__reserved_mem_check_root(node)) {
> + pr_err("Reserved memory: unsupported node format, ignoring\n");
> + return;
> + }
> +
> + fdt_for_each_subnode(child, fdt, node) {
> + const char *uname;
> +
> + prop = of_get_flat_dt_prop(child, "reg", &len);
> + if (!prop)
> + continue;
> + if (!of_fdt_device_is_available(fdt, child))
> + continue;
> +
> + uname = fdt_get_name(fdt, child, NULL);
> + if (len && len % t_len != 0) {
> + pr_err("Reserved memory: invalid reg property in '%s', skipping node.\n",
> + uname);
> + continue;
> + }
> + base = dt_mem_next_cell(dt_root_addr_cells, &prop);
> + size = dt_mem_next_cell(dt_root_size_cells, &prop);
> +
> + if (size)
> + fdt_reserved_mem_save_node(child, uname, base, size);
> + }
> +
> + /* check for overlapping reserved regions */
> + __rmem_check_for_overlap();
> +}
> +
> +static int __init __reserved_mem_alloc_size(unsigned long node, const char *uname);
> +
> /*
> * fdt_scan_reserved_mem() - scan a single FDT node for reserved memory
> */
> int __init fdt_scan_reserved_mem(void)
> {
> int node, child;
> + int dynamic_nodes_cnt = 0;
> + int dynamic_nodes[MAX_RESERVED_REGIONS];
> const void *fdt = initial_boot_params;
>
> node = fdt_path_offset(fdt, "/reserved-memory");
> @@ -192,8 +255,24 @@ int __init fdt_scan_reserved_mem(void)
> uname = fdt_get_name(fdt, child, NULL);
>
> err = __reserved_mem_reserve_reg(child, uname);
> - if (err == -ENOENT && of_get_flat_dt_prop(child, "size", NULL))
> - fdt_reserved_mem_save_node(child, uname, 0, 0);
> + /*
> + * Save the nodes for the dynamically-placed regions
> + * into an array which will be used for allocation right
> + * after all the statically-placed regions are reserved
> + * or marked as no-map. This is done to avoid dynamically
> + * allocating from one of the statically-placed regions.
> + */
> + if (err == -ENOENT && of_get_flat_dt_prop(child, "size", NULL)) {
> + dynamic_nodes[dynamic_nodes_cnt] = child;
> + dynamic_nodes_cnt++;
> + }
> + }
> + for (int i = 0; i < dynamic_nodes_cnt; i++) {
> + const char *uname;
> +
> + child = dynamic_nodes[i];
> + uname = fdt_get_name(fdt, child, NULL);
> + __reserved_mem_alloc_size(child, uname);
> }
> return 0;
> }
> @@ -253,8 +332,7 @@ static int __init __reserved_mem_alloc_in_range(phys_addr_t size,
> * __reserved_mem_alloc_size() - allocate reserved memory described by
> * 'size', 'alignment' and 'alloc-ranges' properties.
> */
> -static int __init __reserved_mem_alloc_size(unsigned long node,
> - const char *uname, phys_addr_t *res_base, phys_addr_t *res_size)
> +static int __init __reserved_mem_alloc_size(unsigned long node, const char *uname)
> {
> int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
> phys_addr_t start = 0, end = 0;
> @@ -334,9 +412,8 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
> return -ENOMEM;
> }
>
> - *res_base = base;
> - *res_size = size;
> -
> + /* Save region in the reserved_mem array */
> + fdt_reserved_mem_save_node(node, uname, base, size);
> return 0;
> }
>
> @@ -425,48 +502,37 @@ static void __init __rmem_check_for_overlap(void)
> }
>
> /**
> - * fdt_init_reserved_mem() - allocate and init all saved reserved memory regions
> + * fdt_init_reserved_mem_node() - Initialize a reserved memory region
> + * @rmem: reserved_mem struct of the memory region to be initialized.
> + *
> + * This function is used to call the region specific initialization
> + * function for a reserved memory region.
> */
> -void __init fdt_init_reserved_mem(void)
> +static void __init fdt_init_reserved_mem_node(struct reserved_mem *rmem)
> {
> - int i;
> -
> - /* check for overlapping reserved regions */
> - __rmem_check_for_overlap();
> -
> - for (i = 0; i < reserved_mem_count; i++) {
> - struct reserved_mem *rmem = &reserved_mem[i];
> - unsigned long node = rmem->fdt_node;
> - int err = 0;
> - bool nomap;
> + unsigned long node = rmem->fdt_node;
> + int err = 0;
> + bool nomap;
>
> - nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
> + nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
>
> - if (rmem->size == 0)
> - err = __reserved_mem_alloc_size(node, rmem->name,
> - &rmem->base, &rmem->size);
> - if (err == 0) {
> - err = __reserved_mem_init_node(rmem);
> - if (err != 0 && err != -ENOENT) {
> - pr_info("node %s compatible matching fail\n",
> - rmem->name);
> - if (nomap)
> - memblock_clear_nomap(rmem->base, rmem->size);
> - else
> - memblock_phys_free(rmem->base,
> - rmem->size);
> - } else {
> - phys_addr_t end = rmem->base + rmem->size - 1;
> - bool reusable =
> - (of_get_flat_dt_prop(node, "reusable", NULL)) != NULL;
> -
> - pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
> - &rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
> - nomap ? "nomap" : "map",
> - reusable ? "reusable" : "non-reusable",
> - rmem->name ? rmem->name : "unknown");
> - }
> - }
> + err = __reserved_mem_init_node(rmem);
> + if (err != 0 && err != -ENOENT) {
> + pr_info("node %s compatible matching fail\n", rmem->name);
> + if (nomap)
> + memblock_clear_nomap(rmem->base, rmem->size);
> + else
> + memblock_phys_free(rmem->base, rmem->size);
> + } else {
> + phys_addr_t end = rmem->base + rmem->size - 1;
> + bool reusable =
> + (of_get_flat_dt_prop(node, "reusable", NULL)) != NULL;
> +
> + pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
> + &rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
> + nomap ? "nomap" : "map",
> + reusable ? "reusable" : "non-reusable",
> + rmem->name ? rmem->name : "unknown");
> }
> }
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
On 10/29/2024 5:41 AM, Geert Uytterhoeven wrote:
> Hi Oreoluwa,
>
> On Wed, Oct 9, 2024 at 12:08 AM Oreoluwa Babatunde
> <quic_obabatun@quicinc.com> wrote:
>> Reserved memory regions defined in the devicetree can be broken up into
>> two groups:
>> i) Statically-placed reserved memory regions
>> i.e. regions defined with a static start address and size using the
>> "reg" property.
>> ii) Dynamically-placed reserved memory regions.
>> i.e. regions defined by specifying an address range where they can be
>> placed in memory using the "alloc_ranges" and "size" properties.
>>
>> These regions are processed and set aside at boot time.
>> This is done in two stages as seen below:
>>
>> Stage 1:
>> At this stage, fdt_scan_reserved_mem() scans through the child nodes of
>> the reserved_memory node using the flattened devicetree and does the
>> following:
>>
>> 1) If the node represents a statically-placed reserved memory region,
>> i.e. if it is defined using the "reg" property:
>> - Call memblock_reserve() or memblock_mark_nomap() as needed.
>> - Add the information for that region into the reserved_mem array
>> using fdt_reserved_mem_save_node().
>> i.e. fdt_reserved_mem_save_node(node, name, base, size).
>>
>> 2) If the node represents a dynamically-placed reserved memory region,
>> i.e. if it is defined using "alloc-ranges" and "size" properties:
>> - Add the information for that region to the reserved_mem array with
>> the starting address and size set to 0.
>> i.e. fdt_reserved_mem_save_node(node, name, 0, 0).
>> Note: This region is saved to the array with a starting address of 0
>> because a starting address is not yet allocated for it.
>>
>> Stage 2:
>> After iterating through all the reserved memory nodes and storing their
>> relevant information in the reserved_mem array,fdt_init_reserved_mem() is
>> called and does the following:
>>
>> 1) For statically-placed reserved memory regions:
>> - Call the region specific init function using
>> __reserved_mem_init_node().
>> 2) For dynamically-placed reserved memory regions:
>> - Call __reserved_mem_alloc_size() which is used to allocate memory
>> for each of these regions, and mark them as nomap if they have the
>> nomap property specified in the DT.
>> - Call the region specific init function.
>>
>> The current size of the resvered_mem array is 64 as is defined by
>> MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for
>> how many reserved memory regions can be specified on a system.
>> As systems continue to grow more and more complex, the number of
>> reserved memory regions needed are also growing and are starting to hit
>> this 64 count limit, hence the need to make the reserved_mem array
>> dynamically sized (i.e. dynamically allocating memory for the
>> reserved_mem array using membock_alloc_*).
>>
>> On architectures such as arm64, memory allocated using memblock is
>> writable only after the page tables have been setup. This means that if
>> the reserved_mem array is going to be dynamically allocated, it needs to
>> happen after the page tables have been setup, not before.
>>
>> Since the reserved memory regions are currently being processed and
>> added to the array before the page tables are setup, there is a need to
>> change the order in which some of the processing is done to allow for
>> the reserved_mem array to be dynamically sized.
>>
>> It is possible to process the statically-placed reserved memory regions
>> without needing to store them in the reserved_mem array until after the
>> page tables have been setup because all the information stored in the
>> array is readily available in the devicetree and can be referenced at
>> any time.
>> Dynamically-placed reserved memory regions on the other hand get
>> assigned a start address only at runtime, and hence need a place to be
>> stored once they are allocated since there is no other referrence to the
>> start address for these regions.
>>
>> Hence this patch changes the processing order of the reserved memory
>> regions in the following ways:
>>
>> Step 1:
>> fdt_scan_reserved_mem() scans through the child nodes of
>> the reserved_memory node using the flattened devicetree and does the
>> following:
>>
>> 1) If the node represents a statically-placed reserved memory region,
>> i.e. if it is defined using the "reg" property:
>> - Call memblock_reserve() or memblock_mark_nomap() as needed.
>>
>> 2) If the node represents a dynamically-placed reserved memory region,
>> i.e. if it is defined using "alloc-ranges" and "size" properties:
>> - Call __reserved_mem_alloc_size() which will:
>> i) Allocate memory for the reserved region and call
>> memblock_mark_nomap() as needed.
>> ii) Call the region specific initialization function using
>> fdt_init_reserved_mem_node().
>> iii) Save the region information in the reserved_mem array using
>> fdt_reserved_mem_save_node().
>>
>> Step 2:
>> 1) This stage of the reserved memory processing is now only used to add
>> the statically-placed reserved memory regions into the reserved_mem
>> array using fdt_scan_reserved_mem_reg_nodes(), as well as call their
>> region specific initialization functions.
>>
>> 2) This step has also been moved to be after the page tables are
>> setup. Moving this will allow us to replace the reserved_mem
>> array with a dynamically sized array before storing the rest of
>> these regions.
>>
>> Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
> Thanks for your patch, which is now commit 8a6e02d0c00e7b62
> ("of: reserved_mem: Restructure how the reserved memory regions
> are processed") in dt-rh/for-next.
>
> I have bisected a boot issue on RZ/Five to this commit.
> With "earlycon keep_bootcon" (else there is no output):
>
> Oops - store (or AMO) access fault [#1]
> CPU: 0 UID: 0 PID: 1 Comm: swapper Not tainted
> 6.12.0-rc1-00015-g8a6e02d0c00e #201
> Hardware name: Renesas SMARC EVK based on r9a07g043f01 (DT)
> epc : __memset+0x60/0x100
> ra : __dma_alloc_from_coherent+0x150/0x17a
> epc : ffffffff8062d2bc ra : ffffffff80053a94 sp : ffffffc60000ba20
> gp : ffffffff812e9938 tp : ffffffd601920000 t0 : ffffffc6000d0000
> t1 : 0000000000000000 t2 : ffffffffe9600000 s0 : ffffffc60000baa0
> s1 : ffffffc6000d0000 a0 : ffffffc6000d0000 a1 : 0000000000000000
> a2 : 0000000000001000 a3 : ffffffc6000d1000 a4 : 0000000000000000
> a5 : 0000000000000000 a6 : ffffffd601adacc0 a7 : ffffffd601a841a8
> s2 : ffffffd6018573c0 s3 : 0000000000001000 s4 : ffffffd6019541e0
> s5 : 0000000200000022 s6 : ffffffd6018f8410 s7 : ffffffd6018573e8
> s8 : 0000000000000001 s9 : 0000000000000001 s10: 0000000000000010
> s11: 0000000000000000 t3 : 0000000000000000 t4 : ffffffffdefe62d1
> t5 : 000000001cd6a3a9 t6 : ffffffd601b2aad6
> status: 0000000200000120 badaddr: ffffffc6000d0000 cause: 0000000000000007
> [<ffffffff8062d2bc>] __memset+0x60/0x100
> [<ffffffff80053e1a>] dma_alloc_from_global_coherent+0x1c/0x28
> [<ffffffff80053056>] dma_direct_alloc+0x98/0x112
> [<ffffffff8005238c>] dma_alloc_attrs+0x78/0x86
> [<ffffffff8035fdb4>] rz_dmac_probe+0x3f6/0x50a
> [<ffffffff803a0694>] platform_probe+0x4c/0x8a
> [<ffffffff8039ea16>] really_probe+0xe4/0x1c8
> [<ffffffff8039ebc4>] __driver_probe_device+0xca/0xce
> [<ffffffff8039ec48>] driver_probe_device+0x34/0x92
> [<ffffffff8039ede8>] __driver_attach+0xb4/0xbe
> [<ffffffff8039ce58>] bus_for_each_dev+0x60/0xa0
> [<ffffffff8039e26a>] driver_attach+0x1a/0x22
> [<ffffffff8039dc20>] bus_add_driver+0xa4/0x184
> [<ffffffff8039f65c>] driver_register+0x8a/0xb4
> [<ffffffff803a051c>] __platform_driver_register+0x1c/0x24
> [<ffffffff808202f6>] rz_dmac_driver_init+0x1a/0x22
> [<ffffffff80800ef6>] do_one_initcall+0x64/0x134
> [<ffffffff8080122e>] kernel_init_freeable+0x200/0x202
> [<ffffffff80638126>] kernel_init+0x1e/0x10a
> [<ffffffff8063d58e>] ret_from_fork+0xe/0x18
> Code: 1007 82b3 40e2 0797 0000 8793 00e7 8305 97ba 8782 (b023) 00b2
> ---[ end trace 0000000000000000 ]---
> Kernel panic - not syncing: Fatal exception in interrupt
> ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---
>
> Nothing really stands out in the kernel log, except for a delayed
> initialization of the reserved mem nodes (they are the same
> before/after):
>
> printk: debug: ignoring loglevel setting.
> -OF: reserved mem: 0x0000000000030000..0x000000000003ffff (64 KiB)
> nomap non-reusable mmode_resv0@30000
> -OF: reserved mem: 0x0000000000040000..0x000000000004ffff (64 KiB)
> nomap non-reusable mmode_resv1@40000
> -OF: reserved mem: 0x0000000044000000..0x000000004403ffff (256 KiB)
> nomap non-reusable mmode_resv3@44000000
> -OF: reserved mem: 0x0000000044040000..0x000000004405ffff (128 KiB)
> nomap non-reusable mmode_resv2@44040000
> +earlycon: scif0 at MMIO 0x000000001004b800 (options '115200n8')
> +printk: legacy bootconsole [scif0] enabled
> +printk: debug: skip boot console de-registration.
> Reserved memory: created DMA memory pool at 0x0000000058000000, size 128 MiB
> OF: reserved mem: initialized node pma_resv0@58000000, compatible id
> shared-dma-pool
> OF: reserved mem: 0x0000000058000000..0x000000005fffffff (131072 KiB)
> nomap non-reusable pma_resv0@58000000
> +OF: reserved mem: 0x0000000000030000..0x000000000003ffff (64 KiB)
> nomap non-reusable mmode_resv0@30000
> +OF: reserved mem: 0x0000000000040000..0x000000000004ffff (64 KiB)
> nomap non-reusable mmode_resv1@40000
> +OF: reserved mem: 0x0000000044040000..0x000000004405ffff (128 KiB)
> nomap non-reusable mmode_resv2@44040000
> +OF: reserved mem: 0x0000000044000000..0x000000004403ffff (256 KiB)
> nomap non-reusable mmode_resv3@44000000
> Zone ranges:
> DMA32 [mem 0x0000000048000000-0x000000007fffffff]
> Normal empty
>
> Reverting commits 00c9a452a235c61f ("of: reserved_mem: Add code to
> dynamically allocate reserved_mem array") and 8a6e02d0c00e7b62 fixes
> the issue.
>
> root@smarc-rzfive:/sys/firmware/devicetree/base/reserved-memory# ls -l
> total 0
> -r--r--r-- 1 root root 4 Oct 29 12:37 #address-cells
> -r--r--r-- 1 root root 4 Oct 29 12:37 #size-cells
> drwxr-xr-x 2 root root 0 Oct 29 12:37 mmode_resv0@30000
> drwxr-xr-x 2 root root 0 Oct 29 12:37 mmode_resv1@40000
> drwxr-xr-x 2 root root 0 Oct 29 12:37 mmode_resv2@44040000
> drwxr-xr-x 2 root root 0 Oct 29 12:37 mmode_resv3@44000000
> -r--r--r-- 1 root root 16 Oct 29 12:37 name
> drwxr-xr-x 2 root root 0 Oct 29 12:37 pma_resv0@58000000
> -r--r--r-- 1 root root 0 Oct 29 12:37 ranges
Hi Geert,
Thanks for reaching out and sorry you're seeing this issue.
Please can you provide reproduction steps? I tried booting up
risc-v arch with qemu but did not run into the issue you are
seeing.
Regards,
Oreoluwa
Hi Oreoluwa,
On Thu, Oct 31, 2024 at 10:06 PM Oreoluwa Babatunde
<quic_obabatun@quicinc.com> wrote:
> On 10/29/2024 5:41 AM, Geert Uytterhoeven wrote:
> > On Wed, Oct 9, 2024 at 12:08 AM Oreoluwa Babatunde
> > <quic_obabatun@quicinc.com> wrote:
> >> Reserved memory regions defined in the devicetree can be broken up into
> >> two groups:
> >> i) Statically-placed reserved memory regions
> >> i.e. regions defined with a static start address and size using the
> >> "reg" property.
> >> ii) Dynamically-placed reserved memory regions.
> >> i.e. regions defined by specifying an address range where they can be
> >> placed in memory using the "alloc_ranges" and "size" properties.
> >>
> >> These regions are processed and set aside at boot time.
> >> This is done in two stages as seen below:
> >>
> >> Stage 1:
> >> At this stage, fdt_scan_reserved_mem() scans through the child nodes of
> >> the reserved_memory node using the flattened devicetree and does the
> >> following:
> >>
> >> 1) If the node represents a statically-placed reserved memory region,
> >> i.e. if it is defined using the "reg" property:
> >> - Call memblock_reserve() or memblock_mark_nomap() as needed.
> >> - Add the information for that region into the reserved_mem array
> >> using fdt_reserved_mem_save_node().
> >> i.e. fdt_reserved_mem_save_node(node, name, base, size).
> >>
> >> 2) If the node represents a dynamically-placed reserved memory region,
> >> i.e. if it is defined using "alloc-ranges" and "size" properties:
> >> - Add the information for that region to the reserved_mem array with
> >> the starting address and size set to 0.
> >> i.e. fdt_reserved_mem_save_node(node, name, 0, 0).
> >> Note: This region is saved to the array with a starting address of 0
> >> because a starting address is not yet allocated for it.
> >>
> >> Stage 2:
> >> After iterating through all the reserved memory nodes and storing their
> >> relevant information in the reserved_mem array,fdt_init_reserved_mem() is
> >> called and does the following:
> >>
> >> 1) For statically-placed reserved memory regions:
> >> - Call the region specific init function using
> >> __reserved_mem_init_node().
> >> 2) For dynamically-placed reserved memory regions:
> >> - Call __reserved_mem_alloc_size() which is used to allocate memory
> >> for each of these regions, and mark them as nomap if they have the
> >> nomap property specified in the DT.
> >> - Call the region specific init function.
> >>
> >> The current size of the resvered_mem array is 64 as is defined by
> >> MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for
> >> how many reserved memory regions can be specified on a system.
> >> As systems continue to grow more and more complex, the number of
> >> reserved memory regions needed are also growing and are starting to hit
> >> this 64 count limit, hence the need to make the reserved_mem array
> >> dynamically sized (i.e. dynamically allocating memory for the
> >> reserved_mem array using membock_alloc_*).
> >>
> >> On architectures such as arm64, memory allocated using memblock is
> >> writable only after the page tables have been setup. This means that if
> >> the reserved_mem array is going to be dynamically allocated, it needs to
> >> happen after the page tables have been setup, not before.
> >>
> >> Since the reserved memory regions are currently being processed and
> >> added to the array before the page tables are setup, there is a need to
> >> change the order in which some of the processing is done to allow for
> >> the reserved_mem array to be dynamically sized.
> >>
> >> It is possible to process the statically-placed reserved memory regions
> >> without needing to store them in the reserved_mem array until after the
> >> page tables have been setup because all the information stored in the
> >> array is readily available in the devicetree and can be referenced at
> >> any time.
> >> Dynamically-placed reserved memory regions on the other hand get
> >> assigned a start address only at runtime, and hence need a place to be
> >> stored once they are allocated since there is no other referrence to the
> >> start address for these regions.
> >>
> >> Hence this patch changes the processing order of the reserved memory
> >> regions in the following ways:
> >>
> >> Step 1:
> >> fdt_scan_reserved_mem() scans through the child nodes of
> >> the reserved_memory node using the flattened devicetree and does the
> >> following:
> >>
> >> 1) If the node represents a statically-placed reserved memory region,
> >> i.e. if it is defined using the "reg" property:
> >> - Call memblock_reserve() or memblock_mark_nomap() as needed.
> >>
> >> 2) If the node represents a dynamically-placed reserved memory region,
> >> i.e. if it is defined using "alloc-ranges" and "size" properties:
> >> - Call __reserved_mem_alloc_size() which will:
> >> i) Allocate memory for the reserved region and call
> >> memblock_mark_nomap() as needed.
> >> ii) Call the region specific initialization function using
> >> fdt_init_reserved_mem_node().
> >> iii) Save the region information in the reserved_mem array using
> >> fdt_reserved_mem_save_node().
> >>
> >> Step 2:
> >> 1) This stage of the reserved memory processing is now only used to add
> >> the statically-placed reserved memory regions into the reserved_mem
> >> array using fdt_scan_reserved_mem_reg_nodes(), as well as call their
> >> region specific initialization functions.
> >>
> >> 2) This step has also been moved to be after the page tables are
> >> setup. Moving this will allow us to replace the reserved_mem
> >> array with a dynamically sized array before storing the rest of
> >> these regions.
> >>
> >> Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
> > Thanks for your patch, which is now commit 8a6e02d0c00e7b62
> > ("of: reserved_mem: Restructure how the reserved memory regions
> > are processed") in dt-rh/for-next.
> >
> > I have bisected a boot issue on RZ/Five to this commit.
> > With "earlycon keep_bootcon" (else there is no output):
> >
> > Oops - store (or AMO) access fault [#1]
> > CPU: 0 UID: 0 PID: 1 Comm: swapper Not tainted
> > 6.12.0-rc1-00015-g8a6e02d0c00e #201
> > Hardware name: Renesas SMARC EVK based on r9a07g043f01 (DT)
> > epc : __memset+0x60/0x100
> > ra : __dma_alloc_from_coherent+0x150/0x17a
> > epc : ffffffff8062d2bc ra : ffffffff80053a94 sp : ffffffc60000ba20
> > gp : ffffffff812e9938 tp : ffffffd601920000 t0 : ffffffc6000d0000
> > t1 : 0000000000000000 t2 : ffffffffe9600000 s0 : ffffffc60000baa0
> > s1 : ffffffc6000d0000 a0 : ffffffc6000d0000 a1 : 0000000000000000
> > a2 : 0000000000001000 a3 : ffffffc6000d1000 a4 : 0000000000000000
> > a5 : 0000000000000000 a6 : ffffffd601adacc0 a7 : ffffffd601a841a8
> > s2 : ffffffd6018573c0 s3 : 0000000000001000 s4 : ffffffd6019541e0
> > s5 : 0000000200000022 s6 : ffffffd6018f8410 s7 : ffffffd6018573e8
> > s8 : 0000000000000001 s9 : 0000000000000001 s10: 0000000000000010
> > s11: 0000000000000000 t3 : 0000000000000000 t4 : ffffffffdefe62d1
> > t5 : 000000001cd6a3a9 t6 : ffffffd601b2aad6
> > status: 0000000200000120 badaddr: ffffffc6000d0000 cause: 0000000000000007
> > [<ffffffff8062d2bc>] __memset+0x60/0x100
> > [<ffffffff80053e1a>] dma_alloc_from_global_coherent+0x1c/0x28
> > [<ffffffff80053056>] dma_direct_alloc+0x98/0x112
> > [<ffffffff8005238c>] dma_alloc_attrs+0x78/0x86
> > [<ffffffff8035fdb4>] rz_dmac_probe+0x3f6/0x50a
> > [<ffffffff803a0694>] platform_probe+0x4c/0x8a
> > [<ffffffff8039ea16>] really_probe+0xe4/0x1c8
> > [<ffffffff8039ebc4>] __driver_probe_device+0xca/0xce
> > [<ffffffff8039ec48>] driver_probe_device+0x34/0x92
> > [<ffffffff8039ede8>] __driver_attach+0xb4/0xbe
> > [<ffffffff8039ce58>] bus_for_each_dev+0x60/0xa0
> > [<ffffffff8039e26a>] driver_attach+0x1a/0x22
> > [<ffffffff8039dc20>] bus_add_driver+0xa4/0x184
> > [<ffffffff8039f65c>] driver_register+0x8a/0xb4
> > [<ffffffff803a051c>] __platform_driver_register+0x1c/0x24
> > [<ffffffff808202f6>] rz_dmac_driver_init+0x1a/0x22
> > [<ffffffff80800ef6>] do_one_initcall+0x64/0x134
> > [<ffffffff8080122e>] kernel_init_freeable+0x200/0x202
> > [<ffffffff80638126>] kernel_init+0x1e/0x10a
> > [<ffffffff8063d58e>] ret_from_fork+0xe/0x18
> > Code: 1007 82b3 40e2 0797 0000 8793 00e7 8305 97ba 8782 (b023) 00b2
> > ---[ end trace 0000000000000000 ]---
> > Kernel panic - not syncing: Fatal exception in interrupt
> > ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---
> >
> > Nothing really stands out in the kernel log, except for a delayed
> > initialization of the reserved mem nodes (they are the same
> > before/after):
> >
> > printk: debug: ignoring loglevel setting.
> > -OF: reserved mem: 0x0000000000030000..0x000000000003ffff (64 KiB)
> > nomap non-reusable mmode_resv0@30000
> > -OF: reserved mem: 0x0000000000040000..0x000000000004ffff (64 KiB)
> > nomap non-reusable mmode_resv1@40000
> > -OF: reserved mem: 0x0000000044000000..0x000000004403ffff (256 KiB)
> > nomap non-reusable mmode_resv3@44000000
> > -OF: reserved mem: 0x0000000044040000..0x000000004405ffff (128 KiB)
> > nomap non-reusable mmode_resv2@44040000
> > +earlycon: scif0 at MMIO 0x000000001004b800 (options '115200n8')
> > +printk: legacy bootconsole [scif0] enabled
> > +printk: debug: skip boot console de-registration.
> > Reserved memory: created DMA memory pool at 0x0000000058000000, size 128 MiB
> > OF: reserved mem: initialized node pma_resv0@58000000, compatible id
> > shared-dma-pool
> > OF: reserved mem: 0x0000000058000000..0x000000005fffffff (131072 KiB)
> > nomap non-reusable pma_resv0@58000000
> > +OF: reserved mem: 0x0000000000030000..0x000000000003ffff (64 KiB)
> > nomap non-reusable mmode_resv0@30000
> > +OF: reserved mem: 0x0000000000040000..0x000000000004ffff (64 KiB)
> > nomap non-reusable mmode_resv1@40000
> > +OF: reserved mem: 0x0000000044040000..0x000000004405ffff (128 KiB)
> > nomap non-reusable mmode_resv2@44040000
> > +OF: reserved mem: 0x0000000044000000..0x000000004403ffff (256 KiB)
> > nomap non-reusable mmode_resv3@44000000
> > Zone ranges:
> > DMA32 [mem 0x0000000048000000-0x000000007fffffff]
> > Normal empty
> >
> > Reverting commits 00c9a452a235c61f ("of: reserved_mem: Add code to
> > dynamically allocate reserved_mem array") and 8a6e02d0c00e7b62 fixes
> > the issue.
> >
> > root@smarc-rzfive:/sys/firmware/devicetree/base/reserved-memory# ls -l
> > total 0
> > -r--r--r-- 1 root root 4 Oct 29 12:37 #address-cells
> > -r--r--r-- 1 root root 4 Oct 29 12:37 #size-cells
> > drwxr-xr-x 2 root root 0 Oct 29 12:37 mmode_resv0@30000
> > drwxr-xr-x 2 root root 0 Oct 29 12:37 mmode_resv1@40000
> > drwxr-xr-x 2 root root 0 Oct 29 12:37 mmode_resv2@44040000
> > drwxr-xr-x 2 root root 0 Oct 29 12:37 mmode_resv3@44000000
> > -r--r--r-- 1 root root 16 Oct 29 12:37 name
> > drwxr-xr-x 2 root root 0 Oct 29 12:37 pma_resv0@58000000
> > -r--r--r-- 1 root root 0 Oct 29 12:37 ranges
> Thanks for reaching out and sorry you're seeing this issue.
>
> Please can you provide reproduction steps? I tried booting up
> risc-v arch with qemu but did not run into the issue you are
> seeing.
It indeed doesn't happen on other RISC-V platforms (tried MPFS/Icicle).
RZ/Five is special in that it is DMA non-coherent, and the crash
happens in dma_alloc_from_global_coherent().
According to the logs, the DMA pool at 0x58000000 is still being created.
I'll try to debug this further next week...
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
Hi Oreoluwa,
On Fri, Nov 1, 2024 at 1:45 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> On Thu, Oct 31, 2024 at 10:06 PM Oreoluwa Babatunde
> <quic_obabatun@quicinc.com> wrote:
> > On 10/29/2024 5:41 AM, Geert Uytterhoeven wrote:
> > > On Wed, Oct 9, 2024 at 12:08 AM Oreoluwa Babatunde
> > > <quic_obabatun@quicinc.com> wrote:
> > >> Reserved memory regions defined in the devicetree can be broken up into
> > >> two groups:
> > >> i) Statically-placed reserved memory regions
> > >> i.e. regions defined with a static start address and size using the
> > >> "reg" property.
> > >> ii) Dynamically-placed reserved memory regions.
> > >> i.e. regions defined by specifying an address range where they can be
> > >> placed in memory using the "alloc_ranges" and "size" properties.
[...]
> > >> Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
> > > Thanks for your patch, which is now commit 8a6e02d0c00e7b62
> > > ("of: reserved_mem: Restructure how the reserved memory regions
> > > are processed") in dt-rh/for-next.
> > >
> > > I have bisected a boot issue on RZ/Five to this commit.
> > > With "earlycon keep_bootcon" (else there is no output):
> > >
> > > Oops - store (or AMO) access fault [#1]
> > > CPU: 0 UID: 0 PID: 1 Comm: swapper Not tainted
> > > 6.12.0-rc1-00015-g8a6e02d0c00e #201
> > > Hardware name: Renesas SMARC EVK based on r9a07g043f01 (DT)
> > > epc : __memset+0x60/0x100
> > > ra : __dma_alloc_from_coherent+0x150/0x17a
> > > epc : ffffffff8062d2bc ra : ffffffff80053a94 sp : ffffffc60000ba20
> > > gp : ffffffff812e9938 tp : ffffffd601920000 t0 : ffffffc6000d0000
> > > t1 : 0000000000000000 t2 : ffffffffe9600000 s0 : ffffffc60000baa0
> > > s1 : ffffffc6000d0000 a0 : ffffffc6000d0000 a1 : 0000000000000000
> > > a2 : 0000000000001000 a3 : ffffffc6000d1000 a4 : 0000000000000000
> > > a5 : 0000000000000000 a6 : ffffffd601adacc0 a7 : ffffffd601a841a8
> > > s2 : ffffffd6018573c0 s3 : 0000000000001000 s4 : ffffffd6019541e0
> > > s5 : 0000000200000022 s6 : ffffffd6018f8410 s7 : ffffffd6018573e8
> > > s8 : 0000000000000001 s9 : 0000000000000001 s10: 0000000000000010
> > > s11: 0000000000000000 t3 : 0000000000000000 t4 : ffffffffdefe62d1
> > > t5 : 000000001cd6a3a9 t6 : ffffffd601b2aad6
> > > status: 0000000200000120 badaddr: ffffffc6000d0000 cause: 0000000000000007
> > > [<ffffffff8062d2bc>] __memset+0x60/0x100
> > > [<ffffffff80053e1a>] dma_alloc_from_global_coherent+0x1c/0x28
> > > [<ffffffff80053056>] dma_direct_alloc+0x98/0x112
> > > [<ffffffff8005238c>] dma_alloc_attrs+0x78/0x86
> > > [<ffffffff8035fdb4>] rz_dmac_probe+0x3f6/0x50a
> > Please can you provide reproduction steps? I tried booting up
> > risc-v arch with qemu but did not run into the issue you are
> > seeing.
>
> It indeed doesn't happen on other RISC-V platforms (tried MPFS/Icicle).
> RZ/Five is special in that it is DMA non-coherent, and the crash
> happens in dma_alloc_from_global_coherent().
> According to the logs, the DMA pool at 0x58000000 is still being created.
> I'll try to debug this further next week...
I found the issue, and have sent a fix
https://lore.kernel.org/r/f8cef6845a6141f0277e31a71fe153612daae776.1731436631.git.geert+renesas@glider.be
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
CC linux-renesas-soc
On Tue, Oct 29, 2024 at 1:41 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> On Wed, Oct 9, 2024 at 12:08 AM Oreoluwa Babatunde
> <quic_obabatun@quicinc.com> wrote:
> > Reserved memory regions defined in the devicetree can be broken up into
> > two groups:
> > i) Statically-placed reserved memory regions
> > i.e. regions defined with a static start address and size using the
> > "reg" property.
> > ii) Dynamically-placed reserved memory regions.
> > i.e. regions defined by specifying an address range where they can be
> > placed in memory using the "alloc_ranges" and "size" properties.
> >
> > These regions are processed and set aside at boot time.
> > This is done in two stages as seen below:
> >
> > Stage 1:
> > At this stage, fdt_scan_reserved_mem() scans through the child nodes of
> > the reserved_memory node using the flattened devicetree and does the
> > following:
> >
> > 1) If the node represents a statically-placed reserved memory region,
> > i.e. if it is defined using the "reg" property:
> > - Call memblock_reserve() or memblock_mark_nomap() as needed.
> > - Add the information for that region into the reserved_mem array
> > using fdt_reserved_mem_save_node().
> > i.e. fdt_reserved_mem_save_node(node, name, base, size).
> >
> > 2) If the node represents a dynamically-placed reserved memory region,
> > i.e. if it is defined using "alloc-ranges" and "size" properties:
> > - Add the information for that region to the reserved_mem array with
> > the starting address and size set to 0.
> > i.e. fdt_reserved_mem_save_node(node, name, 0, 0).
> > Note: This region is saved to the array with a starting address of 0
> > because a starting address is not yet allocated for it.
> >
> > Stage 2:
> > After iterating through all the reserved memory nodes and storing their
> > relevant information in the reserved_mem array,fdt_init_reserved_mem() is
> > called and does the following:
> >
> > 1) For statically-placed reserved memory regions:
> > - Call the region specific init function using
> > __reserved_mem_init_node().
> > 2) For dynamically-placed reserved memory regions:
> > - Call __reserved_mem_alloc_size() which is used to allocate memory
> > for each of these regions, and mark them as nomap if they have the
> > nomap property specified in the DT.
> > - Call the region specific init function.
> >
> > The current size of the resvered_mem array is 64 as is defined by
> > MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for
> > how many reserved memory regions can be specified on a system.
> > As systems continue to grow more and more complex, the number of
> > reserved memory regions needed are also growing and are starting to hit
> > this 64 count limit, hence the need to make the reserved_mem array
> > dynamically sized (i.e. dynamically allocating memory for the
> > reserved_mem array using membock_alloc_*).
> >
> > On architectures such as arm64, memory allocated using memblock is
> > writable only after the page tables have been setup. This means that if
> > the reserved_mem array is going to be dynamically allocated, it needs to
> > happen after the page tables have been setup, not before.
> >
> > Since the reserved memory regions are currently being processed and
> > added to the array before the page tables are setup, there is a need to
> > change the order in which some of the processing is done to allow for
> > the reserved_mem array to be dynamically sized.
> >
> > It is possible to process the statically-placed reserved memory regions
> > without needing to store them in the reserved_mem array until after the
> > page tables have been setup because all the information stored in the
> > array is readily available in the devicetree and can be referenced at
> > any time.
> > Dynamically-placed reserved memory regions on the other hand get
> > assigned a start address only at runtime, and hence need a place to be
> > stored once they are allocated since there is no other referrence to the
> > start address for these regions.
> >
> > Hence this patch changes the processing order of the reserved memory
> > regions in the following ways:
> >
> > Step 1:
> > fdt_scan_reserved_mem() scans through the child nodes of
> > the reserved_memory node using the flattened devicetree and does the
> > following:
> >
> > 1) If the node represents a statically-placed reserved memory region,
> > i.e. if it is defined using the "reg" property:
> > - Call memblock_reserve() or memblock_mark_nomap() as needed.
> >
> > 2) If the node represents a dynamically-placed reserved memory region,
> > i.e. if it is defined using "alloc-ranges" and "size" properties:
> > - Call __reserved_mem_alloc_size() which will:
> > i) Allocate memory for the reserved region and call
> > memblock_mark_nomap() as needed.
> > ii) Call the region specific initialization function using
> > fdt_init_reserved_mem_node().
> > iii) Save the region information in the reserved_mem array using
> > fdt_reserved_mem_save_node().
> >
> > Step 2:
> > 1) This stage of the reserved memory processing is now only used to add
> > the statically-placed reserved memory regions into the reserved_mem
> > array using fdt_scan_reserved_mem_reg_nodes(), as well as call their
> > region specific initialization functions.
> >
> > 2) This step has also been moved to be after the page tables are
> > setup. Moving this will allow us to replace the reserved_mem
> > array with a dynamically sized array before storing the rest of
> > these regions.
> >
> > Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
>
> Thanks for your patch, which is now commit 8a6e02d0c00e7b62
> ("of: reserved_mem: Restructure how the reserved memory regions
> are processed") in dt-rh/for-next.
>
> I have bisected a boot issue on RZ/Five to this commit.
> With "earlycon keep_bootcon" (else there is no output):
>
> Oops - store (or AMO) access fault [#1]
> CPU: 0 UID: 0 PID: 1 Comm: swapper Not tainted
> 6.12.0-rc1-00015-g8a6e02d0c00e #201
> Hardware name: Renesas SMARC EVK based on r9a07g043f01 (DT)
> epc : __memset+0x60/0x100
> ra : __dma_alloc_from_coherent+0x150/0x17a
> epc : ffffffff8062d2bc ra : ffffffff80053a94 sp : ffffffc60000ba20
> gp : ffffffff812e9938 tp : ffffffd601920000 t0 : ffffffc6000d0000
> t1 : 0000000000000000 t2 : ffffffffe9600000 s0 : ffffffc60000baa0
> s1 : ffffffc6000d0000 a0 : ffffffc6000d0000 a1 : 0000000000000000
> a2 : 0000000000001000 a3 : ffffffc6000d1000 a4 : 0000000000000000
> a5 : 0000000000000000 a6 : ffffffd601adacc0 a7 : ffffffd601a841a8
> s2 : ffffffd6018573c0 s3 : 0000000000001000 s4 : ffffffd6019541e0
> s5 : 0000000200000022 s6 : ffffffd6018f8410 s7 : ffffffd6018573e8
> s8 : 0000000000000001 s9 : 0000000000000001 s10: 0000000000000010
> s11: 0000000000000000 t3 : 0000000000000000 t4 : ffffffffdefe62d1
> t5 : 000000001cd6a3a9 t6 : ffffffd601b2aad6
> status: 0000000200000120 badaddr: ffffffc6000d0000 cause: 0000000000000007
> [<ffffffff8062d2bc>] __memset+0x60/0x100
> [<ffffffff80053e1a>] dma_alloc_from_global_coherent+0x1c/0x28
> [<ffffffff80053056>] dma_direct_alloc+0x98/0x112
> [<ffffffff8005238c>] dma_alloc_attrs+0x78/0x86
> [<ffffffff8035fdb4>] rz_dmac_probe+0x3f6/0x50a
> [<ffffffff803a0694>] platform_probe+0x4c/0x8a
> [<ffffffff8039ea16>] really_probe+0xe4/0x1c8
> [<ffffffff8039ebc4>] __driver_probe_device+0xca/0xce
> [<ffffffff8039ec48>] driver_probe_device+0x34/0x92
> [<ffffffff8039ede8>] __driver_attach+0xb4/0xbe
> [<ffffffff8039ce58>] bus_for_each_dev+0x60/0xa0
> [<ffffffff8039e26a>] driver_attach+0x1a/0x22
> [<ffffffff8039dc20>] bus_add_driver+0xa4/0x184
> [<ffffffff8039f65c>] driver_register+0x8a/0xb4
> [<ffffffff803a051c>] __platform_driver_register+0x1c/0x24
> [<ffffffff808202f6>] rz_dmac_driver_init+0x1a/0x22
> [<ffffffff80800ef6>] do_one_initcall+0x64/0x134
> [<ffffffff8080122e>] kernel_init_freeable+0x200/0x202
> [<ffffffff80638126>] kernel_init+0x1e/0x10a
> [<ffffffff8063d58e>] ret_from_fork+0xe/0x18
> Code: 1007 82b3 40e2 0797 0000 8793 00e7 8305 97ba 8782 (b023) 00b2
> ---[ end trace 0000000000000000 ]---
> Kernel panic - not syncing: Fatal exception in interrupt
> ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---
>
> Nothing really stands out in the kernel log, except for a delayed
> initialization of the reserved mem nodes (they are the same
> before/after):
>
> printk: debug: ignoring loglevel setting.
> -OF: reserved mem: 0x0000000000030000..0x000000000003ffff (64 KiB)
> nomap non-reusable mmode_resv0@30000
> -OF: reserved mem: 0x0000000000040000..0x000000000004ffff (64 KiB)
> nomap non-reusable mmode_resv1@40000
> -OF: reserved mem: 0x0000000044000000..0x000000004403ffff (256 KiB)
> nomap non-reusable mmode_resv3@44000000
> -OF: reserved mem: 0x0000000044040000..0x000000004405ffff (128 KiB)
> nomap non-reusable mmode_resv2@44040000
> +earlycon: scif0 at MMIO 0x000000001004b800 (options '115200n8')
> +printk: legacy bootconsole [scif0] enabled
> +printk: debug: skip boot console de-registration.
> Reserved memory: created DMA memory pool at 0x0000000058000000, size 128 MiB
> OF: reserved mem: initialized node pma_resv0@58000000, compatible id
> shared-dma-pool
> OF: reserved mem: 0x0000000058000000..0x000000005fffffff (131072 KiB)
> nomap non-reusable pma_resv0@58000000
> +OF: reserved mem: 0x0000000000030000..0x000000000003ffff (64 KiB)
> nomap non-reusable mmode_resv0@30000
> +OF: reserved mem: 0x0000000000040000..0x000000000004ffff (64 KiB)
> nomap non-reusable mmode_resv1@40000
> +OF: reserved mem: 0x0000000044040000..0x000000004405ffff (128 KiB)
> nomap non-reusable mmode_resv2@44040000
> +OF: reserved mem: 0x0000000044000000..0x000000004403ffff (256 KiB)
> nomap non-reusable mmode_resv3@44000000
> Zone ranges:
> DMA32 [mem 0x0000000048000000-0x000000007fffffff]
> Normal empty
>
> Reverting commits 00c9a452a235c61f ("of: reserved_mem: Add code to
> dynamically allocate reserved_mem array") and 8a6e02d0c00e7b62 fixes
> the issue.
>
> root@smarc-rzfive:/sys/firmware/devicetree/base/reserved-memory# ls -l
> total 0
> -r--r--r-- 1 root root 4 Oct 29 12:37 #address-cells
> -r--r--r-- 1 root root 4 Oct 29 12:37 #size-cells
> drwxr-xr-x 2 root root 0 Oct 29 12:37 mmode_resv0@30000
> drwxr-xr-x 2 root root 0 Oct 29 12:37 mmode_resv1@40000
> drwxr-xr-x 2 root root 0 Oct 29 12:37 mmode_resv2@44040000
> drwxr-xr-x 2 root root 0 Oct 29 12:37 mmode_resv3@44000000
> -r--r--r-- 1 root root 16 Oct 29 12:37 name
> drwxr-xr-x 2 root root 0 Oct 29 12:37 pma_resv0@58000000
> -r--r--r-- 1 root root 0 Oct 29 12:37 ranges
>
> > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> > index 4d528c10df3a..d0dbc8183ac4 100644
> > --- a/drivers/of/fdt.c
> > +++ b/drivers/of/fdt.c
> > @@ -511,8 +511,6 @@ void __init early_init_fdt_scan_reserved_mem(void)
> > break;
> > memblock_reserve(base, size);
> > }
> > -
> > - fdt_init_reserved_mem();
> > }
> >
> > /**
> > @@ -1212,6 +1210,9 @@ void __init unflatten_device_tree(void)
> > {
> > void *fdt = initial_boot_params;
> >
> > + /* Save the statically-placed regions in the reserved_mem array */
> > + fdt_scan_reserved_mem_reg_nodes();
> > +
> > /* Don't use the bootloader provided DTB if ACPI is enabled */
> > if (!acpi_disabled)
> > fdt = NULL;
> > diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
> > index 04aa2a91f851..29525c0b9939 100644
> > --- a/drivers/of/of_private.h
> > +++ b/drivers/of/of_private.h
> > @@ -9,6 +9,7 @@
> > */
> >
> > #define FDT_ALIGN_SIZE 8
> > +#define MAX_RESERVED_REGIONS 64
> >
> > /**
> > * struct alias_prop - Alias property in 'aliases' node
> > @@ -180,7 +181,7 @@ static inline struct device_node *__of_get_dma_parent(const struct device_node *
> > #endif
> >
> > int fdt_scan_reserved_mem(void);
> > -void fdt_init_reserved_mem(void);
> > +void __init fdt_scan_reserved_mem_reg_nodes(void);
> >
> > bool of_fdt_device_is_available(const void *blob, unsigned long node);
> >
> > diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> > index 46e1c3fbc769..2011174211f9 100644
> > --- a/drivers/of/of_reserved_mem.c
> > +++ b/drivers/of/of_reserved_mem.c
> > @@ -27,7 +27,6 @@
> >
> > #include "of_private.h"
> >
> > -#define MAX_RESERVED_REGIONS 64
> > static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
> > static int reserved_mem_count;
> >
> > @@ -56,6 +55,7 @@ static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
> > return err;
> > }
> >
> > +static void __init fdt_init_reserved_mem_node(struct reserved_mem *rmem);
> > /*
> > * fdt_reserved_mem_save_node() - save fdt node for second pass initialization
> > */
> > @@ -74,6 +74,9 @@ static void __init fdt_reserved_mem_save_node(unsigned long node, const char *un
> > rmem->base = base;
> > rmem->size = size;
> >
> > + /* Call the region specific initialization function */
> > + fdt_init_reserved_mem_node(rmem);
> > +
> > reserved_mem_count++;
> > return;
> > }
> > @@ -106,7 +109,6 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
> > phys_addr_t base, size;
> > int len;
> > const __be32 *prop;
> > - int first = 1;
> > bool nomap;
> >
> > prop = of_get_flat_dt_prop(node, "reg", &len);
> > @@ -134,10 +136,6 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
> > uname, &base, (unsigned long)(size / SZ_1M));
> >
> > len -= t_len;
> > - if (first) {
> > - fdt_reserved_mem_save_node(node, uname, base, size);
> > - first = 0;
> > - }
> > }
> > return 0;
> > }
> > @@ -165,12 +163,77 @@ static int __init __reserved_mem_check_root(unsigned long node)
> > return 0;
> > }
> >
> > +static void __init __rmem_check_for_overlap(void);
> > +
> > +/**
> > + * fdt_scan_reserved_mem_reg_nodes() - Store info for the "reg" defined
> > + * reserved memory regions.
> > + *
> > + * This function is used to scan through the DT and store the
> > + * information for the reserved memory regions that are defined using
> > + * the "reg" property. The region node number, name, base address, and
> > + * size are all stored in the reserved_mem array by calling the
> > + * fdt_reserved_mem_save_node() function.
> > + */
> > +void __init fdt_scan_reserved_mem_reg_nodes(void)
> > +{
> > + int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
> > + const void *fdt = initial_boot_params;
> > + phys_addr_t base, size;
> > + const __be32 *prop;
> > + int node, child;
> > + int len;
> > +
> > + if (!fdt)
> > + return;
> > +
> > + node = fdt_path_offset(fdt, "/reserved-memory");
> > + if (node < 0) {
> > + pr_info("Reserved memory: No reserved-memory node in the DT\n");
> > + return;
> > + }
> > +
> > + if (__reserved_mem_check_root(node)) {
> > + pr_err("Reserved memory: unsupported node format, ignoring\n");
> > + return;
> > + }
> > +
> > + fdt_for_each_subnode(child, fdt, node) {
> > + const char *uname;
> > +
> > + prop = of_get_flat_dt_prop(child, "reg", &len);
> > + if (!prop)
> > + continue;
> > + if (!of_fdt_device_is_available(fdt, child))
> > + continue;
> > +
> > + uname = fdt_get_name(fdt, child, NULL);
> > + if (len && len % t_len != 0) {
> > + pr_err("Reserved memory: invalid reg property in '%s', skipping node.\n",
> > + uname);
> > + continue;
> > + }
> > + base = dt_mem_next_cell(dt_root_addr_cells, &prop);
> > + size = dt_mem_next_cell(dt_root_size_cells, &prop);
> > +
> > + if (size)
> > + fdt_reserved_mem_save_node(child, uname, base, size);
> > + }
> > +
> > + /* check for overlapping reserved regions */
> > + __rmem_check_for_overlap();
> > +}
> > +
> > +static int __init __reserved_mem_alloc_size(unsigned long node, const char *uname);
> > +
> > /*
> > * fdt_scan_reserved_mem() - scan a single FDT node for reserved memory
> > */
> > int __init fdt_scan_reserved_mem(void)
> > {
> > int node, child;
> > + int dynamic_nodes_cnt = 0;
> > + int dynamic_nodes[MAX_RESERVED_REGIONS];
> > const void *fdt = initial_boot_params;
> >
> > node = fdt_path_offset(fdt, "/reserved-memory");
> > @@ -192,8 +255,24 @@ int __init fdt_scan_reserved_mem(void)
> > uname = fdt_get_name(fdt, child, NULL);
> >
> > err = __reserved_mem_reserve_reg(child, uname);
> > - if (err == -ENOENT && of_get_flat_dt_prop(child, "size", NULL))
> > - fdt_reserved_mem_save_node(child, uname, 0, 0);
> > + /*
> > + * Save the nodes for the dynamically-placed regions
> > + * into an array which will be used for allocation right
> > + * after all the statically-placed regions are reserved
> > + * or marked as no-map. This is done to avoid dynamically
> > + * allocating from one of the statically-placed regions.
> > + */
> > + if (err == -ENOENT && of_get_flat_dt_prop(child, "size", NULL)) {
> > + dynamic_nodes[dynamic_nodes_cnt] = child;
> > + dynamic_nodes_cnt++;
> > + }
> > + }
> > + for (int i = 0; i < dynamic_nodes_cnt; i++) {
> > + const char *uname;
> > +
> > + child = dynamic_nodes[i];
> > + uname = fdt_get_name(fdt, child, NULL);
> > + __reserved_mem_alloc_size(child, uname);
> > }
> > return 0;
> > }
> > @@ -253,8 +332,7 @@ static int __init __reserved_mem_alloc_in_range(phys_addr_t size,
> > * __reserved_mem_alloc_size() - allocate reserved memory described by
> > * 'size', 'alignment' and 'alloc-ranges' properties.
> > */
> > -static int __init __reserved_mem_alloc_size(unsigned long node,
> > - const char *uname, phys_addr_t *res_base, phys_addr_t *res_size)
> > +static int __init __reserved_mem_alloc_size(unsigned long node, const char *uname)
> > {
> > int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
> > phys_addr_t start = 0, end = 0;
> > @@ -334,9 +412,8 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
> > return -ENOMEM;
> > }
> >
> > - *res_base = base;
> > - *res_size = size;
> > -
> > + /* Save region in the reserved_mem array */
> > + fdt_reserved_mem_save_node(node, uname, base, size);
> > return 0;
> > }
> >
> > @@ -425,48 +502,37 @@ static void __init __rmem_check_for_overlap(void)
> > }
> >
> > /**
> > - * fdt_init_reserved_mem() - allocate and init all saved reserved memory regions
> > + * fdt_init_reserved_mem_node() - Initialize a reserved memory region
> > + * @rmem: reserved_mem struct of the memory region to be initialized.
> > + *
> > + * This function is used to call the region specific initialization
> > + * function for a reserved memory region.
> > */
> > -void __init fdt_init_reserved_mem(void)
> > +static void __init fdt_init_reserved_mem_node(struct reserved_mem *rmem)
> > {
> > - int i;
> > -
> > - /* check for overlapping reserved regions */
> > - __rmem_check_for_overlap();
> > -
> > - for (i = 0; i < reserved_mem_count; i++) {
> > - struct reserved_mem *rmem = &reserved_mem[i];
> > - unsigned long node = rmem->fdt_node;
> > - int err = 0;
> > - bool nomap;
> > + unsigned long node = rmem->fdt_node;
> > + int err = 0;
> > + bool nomap;
> >
> > - nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
> > + nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
> >
> > - if (rmem->size == 0)
> > - err = __reserved_mem_alloc_size(node, rmem->name,
> > - &rmem->base, &rmem->size);
> > - if (err == 0) {
> > - err = __reserved_mem_init_node(rmem);
> > - if (err != 0 && err != -ENOENT) {
> > - pr_info("node %s compatible matching fail\n",
> > - rmem->name);
> > - if (nomap)
> > - memblock_clear_nomap(rmem->base, rmem->size);
> > - else
> > - memblock_phys_free(rmem->base,
> > - rmem->size);
> > - } else {
> > - phys_addr_t end = rmem->base + rmem->size - 1;
> > - bool reusable =
> > - (of_get_flat_dt_prop(node, "reusable", NULL)) != NULL;
> > -
> > - pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
> > - &rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
> > - nomap ? "nomap" : "map",
> > - reusable ? "reusable" : "non-reusable",
> > - rmem->name ? rmem->name : "unknown");
> > - }
> > - }
> > + err = __reserved_mem_init_node(rmem);
> > + if (err != 0 && err != -ENOENT) {
> > + pr_info("node %s compatible matching fail\n", rmem->name);
> > + if (nomap)
> > + memblock_clear_nomap(rmem->base, rmem->size);
> > + else
> > + memblock_phys_free(rmem->base, rmem->size);
> > + } else {
> > + phys_addr_t end = rmem->base + rmem->size - 1;
> > + bool reusable =
> > + (of_get_flat_dt_prop(node, "reusable", NULL)) != NULL;
> > +
> > + pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
> > + &rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
> > + nomap ? "nomap" : "map",
> > + reusable ? "reusable" : "non-reusable",
> > + rmem->name ? rmem->name : "unknown");
> > }
> > }
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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