Eliminate the core KHO notifier API
functions (`register_kho_notifier`, `unregister_kho_notifier`), the
`kho_event` enum, and the notifier chain head from KHO internal
structures.
This infrastructure was used to support the now-removed finalize and
abort states and is no longer required. Client subsystems now interact
with KHO through direct API calls.
Signed-off-by: Jason Miu <jasonmiu@google.com>
---
include/linux/kexec_handover.h | 22 ----------------------
kernel/kexec_handover.c | 15 ---------------
2 files changed, 37 deletions(-)
diff --git a/include/linux/kexec_handover.h b/include/linux/kexec_handover.h
index 9566c90a3501..09e8f0b0fcab 100644
--- a/include/linux/kexec_handover.h
+++ b/include/linux/kexec_handover.h
@@ -10,16 +10,7 @@ struct kho_scratch {
phys_addr_t size;
};
-/* KHO Notifier index */
-enum kho_event {
- KEXEC_KHO_FINALIZE = 0,
- KEXEC_KHO_ABORT = 1,
-};
-
struct folio;
-struct notifier_block;
-
-struct kho_serialization;
#ifdef CONFIG_KEXEC_HANDOVER
bool kho_is_enabled(void);
@@ -30,9 +21,6 @@ struct folio *kho_restore_folio(phys_addr_t phys);
int kho_add_subtree(const char *name, void *fdt);
int kho_retrieve_subtree(const char *name, phys_addr_t *phys);
-int register_kho_notifier(struct notifier_block *nb);
-int unregister_kho_notifier(struct notifier_block *nb);
-
void kho_memory_init(void);
void kho_populate(phys_addr_t fdt_phys, u64 fdt_len, phys_addr_t scratch_phys,
@@ -68,16 +56,6 @@ static inline int kho_retrieve_subtree(const char *name, phys_addr_t *phys)
return -EOPNOTSUPP;
}
-static inline int register_kho_notifier(struct notifier_block *nb)
-{
- return -EOPNOTSUPP;
-}
-
-static inline int unregister_kho_notifier(struct notifier_block *nb)
-{
- return -EOPNOTSUPP;
-}
-
static inline void kho_memory_init(void)
{
}
diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c
index ee4f430dfae0..fc290226e58b 100644
--- a/kernel/kexec_handover.c
+++ b/kernel/kexec_handover.c
@@ -16,7 +16,6 @@
#include <linux/libfdt.h>
#include <linux/list.h>
#include <linux/memblock.h>
-#include <linux/notifier.h>
#include <linux/page-isolation.h>
#include <linux/rwsem.h>
@@ -641,13 +640,11 @@ static int kho_debugfs_fdt_add(struct list_head *list, struct dentry *dir,
}
struct kho_out {
- struct blocking_notifier_head chain_head;
struct dentry *dir;
struct kho_serialization ser;
};
static struct kho_out kho_out = {
- .chain_head = BLOCKING_NOTIFIER_INIT(kho_out.chain_head),
.ser = {
.fdt_list = LIST_HEAD_INIT(kho_out.ser.fdt_list),
},
@@ -697,18 +694,6 @@ int kho_add_subtree(const char *name, void *fdt)
}
EXPORT_SYMBOL_GPL(kho_add_subtree);
-int register_kho_notifier(struct notifier_block *nb)
-{
- return blocking_notifier_chain_register(&kho_out.chain_head, nb);
-}
-EXPORT_SYMBOL_GPL(register_kho_notifier);
-
-int unregister_kho_notifier(struct notifier_block *nb)
-{
- return blocking_notifier_chain_unregister(&kho_out.chain_head, nb);
-}
-EXPORT_SYMBOL_GPL(unregister_kho_notifier);
-
/**
* kho_preserve_folio - preserve a folio across kexec.
* @folio: folio to preserve.
--
2.51.0.618.g983fd99d29-googHi Jason,
kernel test robot noticed the following build errors:
[auto build test ERROR on rppt-memblock/for-next]
[also build test ERROR on linus/master v6.17]
[cannot apply to rppt-memblock/fixes akpm-mm/mm-everything next-20250929]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Jason-Miu/kho-Adopt-KHO-radix-tree-data-structures/20251001-092230
base: https://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock.git for-next
patch link: https://lore.kernel.org/r/20251001011941.1513050-4-jasonmiu%40google.com
patch subject: [PATCH v1 3/3] kho: Remove notifier system infrastructure
config: x86_64-randconfig-003-20251001 (https://download.01.org/0day-ci/archive/20251002/202510020105.a05LM8TX-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251002/202510020105.a05LM8TX-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510020105.a05LM8TX-lkp@intel.com/
All errors (new ones prefixed by >>):
>> lib/test_kho.c:49:7: error: use of undeclared identifier 'KEXEC_KHO_ABORT'
49 | case KEXEC_KHO_ABORT:
| ^
>> lib/test_kho.c:51:7: error: use of undeclared identifier 'KEXEC_KHO_FINALIZE'
51 | case KEXEC_KHO_FINALIZE:
| ^
lib/test_kho.c:59:44: error: too many arguments to function call, expected 2, have 3
59 | err |= kho_add_subtree(ser, KHO_TEST_FDT, folio_address(state->fdt));
| ~~~~~~~~~~~~~~~ ^~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/kexec_handover.h:21:5: note: 'kho_add_subtree' declared here
21 | int kho_add_subtree(const char *name, void *fdt);
| ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> lib/test_kho.c:194:9: error: call to undeclared function 'register_kho_notifier'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
194 | return register_kho_notifier(&kho_test_nb);
| ^
lib/test_kho.c:194:9: note: did you mean 'register_module_notifier'?
include/linux/module.h:745:5: note: 'register_module_notifier' declared here
745 | int register_module_notifier(struct notifier_block *nb);
| ^
>> lib/test_kho.c:298:2: error: call to undeclared function 'unregister_kho_notifier'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
298 | unregister_kho_notifier(&kho_test_nb);
| ^
lib/test_kho.c:298:2: note: did you mean 'unregister_module_notifier'?
include/linux/module.h:746:5: note: 'unregister_module_notifier' declared here
746 | int unregister_module_notifier(struct notifier_block *nb);
| ^
5 errors generated.
vim +/KEXEC_KHO_ABORT +49 lib/test_kho.c
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 40)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 41) static int kho_test_notifier(struct notifier_block *self, unsigned long cmd,
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 42) void *v)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 43) {
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 44) struct kho_test_state *state = &kho_test_state;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 45) struct kho_serialization *ser = v;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 46) int err = 0;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 47)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 48) switch (cmd) {
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 @49) case KEXEC_KHO_ABORT:
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 50) return NOTIFY_DONE;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 @51) case KEXEC_KHO_FINALIZE:
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 52) /* Handled below */
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 53) break;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 54) default:
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 55) return NOTIFY_BAD;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 56) }
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 57)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 58) err |= kho_preserve_folio(state->fdt);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 59) err |= kho_add_subtree(ser, KHO_TEST_FDT, folio_address(state->fdt));
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 60)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 61) return err ? NOTIFY_BAD : NOTIFY_DONE;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 62) }
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 63)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 64) static struct notifier_block kho_test_nb = {
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 65) .notifier_call = kho_test_notifier,
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 66) };
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 67)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 68) static int kho_test_save_data(struct kho_test_state *state, void *fdt)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 69) {
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 70) phys_addr_t *folios_info __free(kvfree) = NULL;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 71) int err = 0;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 72)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 73) folios_info = kvmalloc_array(state->nr_folios, sizeof(*folios_info),
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 74) GFP_KERNEL);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 75) if (!folios_info)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 76) return -ENOMEM;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 77)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 78) for (int i = 0; i < state->nr_folios; i++) {
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 79) struct folio *folio = state->folios[i];
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 80) unsigned int order = folio_order(folio);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 81)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 82) folios_info[i] = virt_to_phys(folio_address(folio)) | order;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 83)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 84) err = kho_preserve_folio(folio);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 85) if (err)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 86) return err;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 87) }
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 88)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 89) err |= fdt_begin_node(fdt, "data");
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 90) err |= fdt_property(fdt, "nr_folios", &state->nr_folios,
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 91) sizeof(state->nr_folios));
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 92) err |= fdt_property(fdt, "folios_info", folios_info,
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 93) state->nr_folios * sizeof(*folios_info));
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 94) err |= fdt_property(fdt, "csum", &state->csum, sizeof(state->csum));
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 95) err |= fdt_end_node(fdt);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 96)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 97) return err;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 98) }
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 99)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 100) static int kho_test_prepare_fdt(struct kho_test_state *state)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 101) {
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 102) const char compatible[] = KHO_TEST_COMPAT;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 103) unsigned int magic = KHO_TEST_MAGIC;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 104) ssize_t fdt_size;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 105) int err = 0;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 106) void *fdt;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 107)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 108) fdt_size = state->nr_folios * sizeof(phys_addr_t) + PAGE_SIZE;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 109) state->fdt = folio_alloc(GFP_KERNEL, get_order(fdt_size));
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 110) if (!state->fdt)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 111) return -ENOMEM;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 112)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 113) fdt = folio_address(state->fdt);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 114)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 115) err |= fdt_create(fdt, fdt_size);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 116) err |= fdt_finish_reservemap(fdt);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 117)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 118) err |= fdt_begin_node(fdt, "");
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 119) err |= fdt_property(fdt, "compatible", compatible, sizeof(compatible));
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 120) err |= fdt_property(fdt, "magic", &magic, sizeof(magic));
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 121) err |= kho_test_save_data(state, fdt);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 122) err |= fdt_end_node(fdt);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 123)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 124) err |= fdt_finish(fdt);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 125)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 126) if (err)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 127) folio_put(state->fdt);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 128)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 129) return err;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 130) }
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 131)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 132) static int kho_test_generate_data(struct kho_test_state *state)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 133) {
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 134) size_t alloc_size = 0;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 135) __wsum csum = 0;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 136)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 137) while (alloc_size < max_mem) {
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 138) int order = get_random_u32() % NR_PAGE_ORDERS;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 139) struct folio *folio;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 140) unsigned int size;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 141) void *addr;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 142)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 143) /* cap allocation so that we won't exceed max_mem */
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 144) if (alloc_size + (PAGE_SIZE << order) > max_mem) {
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 145) order = get_order(max_mem - alloc_size);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 146) if (order)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 147) order--;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 148) }
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 149) size = PAGE_SIZE << order;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 150)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 151) folio = folio_alloc(GFP_KERNEL | __GFP_NORETRY, order);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 152) if (!folio)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 153) goto err_free_folios;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 154)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 155) state->folios[state->nr_folios++] = folio;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 156) addr = folio_address(folio);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 157) get_random_bytes(addr, size);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 158) csum = csum_partial(addr, size, csum);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 159) alloc_size += size;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 160) }
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 161)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 162) state->csum = csum;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 163) return 0;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 164)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 165) err_free_folios:
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 166) for (int i = 0; i < state->nr_folios; i++)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 167) folio_put(state->folios[i]);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 168) return -ENOMEM;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 169) }
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 170)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 171) static int kho_test_save(void)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 172) {
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 173) struct kho_test_state *state = &kho_test_state;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 174) struct folio **folios __free(kvfree) = NULL;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 175) unsigned long max_nr;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 176) int err;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 177)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 178) max_mem = PAGE_ALIGN(max_mem);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 179) max_nr = max_mem >> PAGE_SHIFT;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 180)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 181) folios = kvmalloc_array(max_nr, sizeof(*state->folios), GFP_KERNEL);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 182) if (!folios)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 183) return -ENOMEM;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 184) state->folios = folios;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 185)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 186) err = kho_test_generate_data(state);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 187) if (err)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 188) return err;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 189)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 190) err = kho_test_prepare_fdt(state);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 191) if (err)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 192) return err;
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 193)
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 @194) return register_kho_notifier(&kho_test_nb);
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 195) }
b753522bed0b7e Mike Rapoport (Microsoft 2025-07-27 196)
--
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