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[PATCH v2 22/28] arch, mm: consolidate initialization of nodes, zones and memory map

Mike Rapoport posted 28 patches 1 month ago
There is a newer version of this series
[PATCH v2 22/28] arch, mm: consolidate initialization of nodes, zones and memory map
Posted by Mike Rapoport 1 month ago 
From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>

To initialize node, zone and memory map data structures every architecture
calls free_area_init() during setup_arch() and passes it an array of zone
limits.

Beside code duplication it creates "interesting" ordering cases between
allocation and initialization of hugetlb and the memory map. Some
architectures allocate hugetlb pages very early in setup_arch() in certain
cases, some only create hugetlb CMA areas in setup_arch() and sometimes
hugetlb allocations happen mm_core_init().

With arch_zone_limits_init() helper available now on all architectures it
is no longer necessary to call free_area_init() from architecture setup
code. Rather core MM initialization can call arch_zone_limits_init() in a
single place.

This allows to unify ordering of hugetlb vs memory map allocation and
initialization.

Remove the call to free_area_init() from architecture specific code and
place it in a new mm_core_init_early() function that is called immediately
after setup_arch().

After this refactoring it is possible to consolidate hugetlb allocations
and eliminate differences in ordering of hugetlb and memory map
initialization among different architectures.

As the first step of this consolidation move hugetlb_bootmem_alloc() to
mm_core_early_init().

Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
 arch/alpha/mm/init.c                 |  9 +--------
 arch/arc/mm/init.c                   |  5 -----
 arch/arm/mm/init.c                   | 16 ----------------
 arch/arm64/mm/init.c                 |  4 ----
 arch/csky/kernel/setup.c             |  4 ----
 arch/hexagon/mm/init.c               | 12 ------------
 arch/loongarch/include/asm/pgtable.h |  2 --
 arch/loongarch/kernel/setup.c        |  2 --
 arch/loongarch/mm/init.c             |  8 --------
 arch/m68k/mm/init.c                  |  3 ---
 arch/m68k/mm/mcfmmu.c                |  3 ---
 arch/m68k/mm/motorola.c              |  6 +-----
 arch/m68k/mm/sun3mmu.c               |  9 ---------
 arch/microblaze/mm/init.c            |  7 -------
 arch/mips/loongson64/numa.c          |  4 ----
 arch/mips/mm/init.c                  |  5 -----
 arch/mips/sgi-ip27/ip27-memory.c     |  4 ----
 arch/nios2/mm/init.c                 |  6 ------
 arch/openrisc/mm/init.c              | 10 ----------
 arch/parisc/mm/init.c                |  9 ---------
 arch/powerpc/mm/mem.c                |  4 ----
 arch/riscv/mm/init.c                 |  9 ---------
 arch/s390/mm/init.c                  |  5 -----
 arch/sh/mm/init.c                    |  5 -----
 arch/sparc/mm/init_64.c              | 11 -----------
 arch/sparc/mm/srmmu.c                |  7 -------
 arch/um/kernel/mem.c                 |  5 -----
 arch/x86/mm/init.c                   | 10 ----------
 arch/x86/mm/init_32.c                |  1 -
 arch/x86/mm/init_64.c                |  2 --
 arch/x86/mm/mm_internal.h            |  1 -
 arch/xtensa/mm/init.c                |  4 ----
 include/linux/mm.h                   |  4 ++--
 init/main.c                          |  1 +
 mm/mm_init.c                         | 18 ++++++++++--------
 35 files changed, 15 insertions(+), 200 deletions(-)

diff --git a/arch/alpha/mm/init.c b/arch/alpha/mm/init.c
index cd0cb1abde5f..9531cbc761c0 100644
--- a/arch/alpha/mm/init.c
+++ b/arch/alpha/mm/init.c
@@ -220,17 +220,10 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfn)
 }
 
 /*
- * paging_init() sets up the memory map.
+ * paging_init() initializes the kernel's ZERO_PGE.
  */
 void __init paging_init(void)
 {
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = {0, };
-
-	/* Initialize mem_map[].  */
-	arch_zone_limits_init(max_zone_pfn);
-	free_area_init(max_zone_pfn);
-
-	/* Initialize the kernel's ZERO_PGE. */
 	memset(absolute_pointer(ZERO_PGE), 0, PAGE_SIZE);
 }
 
diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
index ff7974d38011..a5e92f46e5d1 100644
--- a/arch/arc/mm/init.c
+++ b/arch/arc/mm/init.c
@@ -102,8 +102,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfn)
  */
 void __init setup_arch_memory(void)
 {
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
-
 	setup_initial_init_mm(_text, _etext, _edata, _end);
 
 	/* first page of system - kernel .vector starts here */
@@ -158,9 +156,6 @@ void __init setup_arch_memory(void)
 	arch_pfn_offset = min(min_low_pfn, min_high_pfn);
 	kmap_init();
 #endif /* CONFIG_HIGHMEM */
-
-	arch_zone_limits_init(max_zone_pfn);
-	free_area_init(max_zone_pfn);
 }
 
 void __init arch_mm_preinit(void)
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index bdcc3639681f..a8f7b4084715 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -118,15 +118,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfn)
 #endif
 }
 
-static void __init zone_sizes_init(unsigned long min, unsigned long max_low,
-	unsigned long max_high)
-{
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
-
-	arch_zone_limits_init(max_zone_pfn);
-	free_area_init(max_zone_pfn);
-}
-
 #ifdef CONFIG_HAVE_ARCH_PFN_VALID
 int pfn_valid(unsigned long pfn)
 {
@@ -222,13 +213,6 @@ void __init bootmem_init(void)
 	 * done after the fixed reservations
 	 */
 	sparse_init();
-
-	/*
-	 * Now free the memory - free_area_init needs
-	 * the sparse mem_map arrays initialized by sparse_init()
-	 * for memmap_init_zone(), otherwise all PFNs are invalid.
-	 */
-	zone_sizes_init(min_low_pfn, max_low_pfn, max_pfn);
 }
 
 /*
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 06815d34cc11..3641e88ea871 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -134,7 +134,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
 
 static void __init dma_limits_init(void)
 {
-	unsigned long max_zone_pfns[MAX_NR_ZONES]  = {0};
 	phys_addr_t __maybe_unused acpi_zone_dma_limit;
 	phys_addr_t __maybe_unused dt_zone_dma_limit;
 	phys_addr_t __maybe_unused dma32_phys_limit =
@@ -160,9 +159,6 @@ static void __init dma_limits_init(void)
 #endif
 	if (!arm64_dma_phys_limit)
 		arm64_dma_phys_limit = PHYS_MASK + 1;
-
-	arch_zone_limits_init(max_zone_pfns);
-	free_area_init(max_zone_pfns);
 }
 
 int pfn_is_map_memory(unsigned long pfn)
diff --git a/arch/csky/kernel/setup.c b/arch/csky/kernel/setup.c
index 8968815d93e6..4bf3c01ead3a 100644
--- a/arch/csky/kernel/setup.c
+++ b/arch/csky/kernel/setup.c
@@ -63,7 +63,6 @@ static void __init csky_memblock_init(void)
 {
 	unsigned long lowmem_size = PFN_DOWN(LOWMEM_LIMIT - PHYS_OFFSET_OFFSET);
 	unsigned long sseg_size = PFN_DOWN(SSEG_SIZE - PHYS_OFFSET_OFFSET);
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
 	signed long size;
 
 	memblock_reserve(__pa(_start), _end - _start);
@@ -101,9 +100,6 @@ static void __init csky_memblock_init(void)
 	memblock_set_current_limit(PFN_PHYS(max_low_pfn));
 
 	dma_contiguous_reserve(0);
-
-	arch_zone_limits_init(max_zone_pfn);
-	free_area_init(max_zone_pfn);
 }
 
 void __init setup_arch(char **cmdline_p)
diff --git a/arch/hexagon/mm/init.c b/arch/hexagon/mm/init.c
index e2c9487d8d34..07086dbd33fd 100644
--- a/arch/hexagon/mm/init.c
+++ b/arch/hexagon/mm/init.c
@@ -66,20 +66,8 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
 	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
 }
 
-/*
- * In order to set up page allocator "nodes",
- * somebody has to call free_area_init() for UMA.
- *
- * In this mode, we only have one pg_data_t
- * structure: contig_mem_data.
- */
 static void __init paging_init(void)
 {
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = {0, };
-
-	arch_zone_limits_init(max_zone_pfn);
-	free_area_init(max_zone_pfn);  /*  sets up the zonelists and mem_map  */
-
 	/*
 	 * Set the init_mm descriptors "context" value to point to the
 	 * initial kernel segment table's physical address.
diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h
index f41a648a3d9e..c33b3bcb733e 100644
--- a/arch/loongarch/include/asm/pgtable.h
+++ b/arch/loongarch/include/asm/pgtable.h
@@ -353,8 +353,6 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
 	return pte;
 }
 
-extern void paging_init(void);
-
 #define pte_none(pte)		(!(pte_val(pte) & ~_PAGE_GLOBAL))
 #define pte_present(pte)	(pte_val(pte) & (_PAGE_PRESENT | _PAGE_PROTNONE))
 #define pte_no_exec(pte)	(pte_val(pte) & _PAGE_NO_EXEC)
diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
index 20cb6f306456..708ac025db71 100644
--- a/arch/loongarch/kernel/setup.c
+++ b/arch/loongarch/kernel/setup.c
@@ -621,8 +621,6 @@ void __init setup_arch(char **cmdline_p)
 	prefill_possible_map();
 #endif
 
-	paging_init();
-
 #ifdef CONFIG_KASAN
 	kasan_init();
 #endif
diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c
index 17235f87eafb..c331bf69d2ec 100644
--- a/arch/loongarch/mm/init.c
+++ b/arch/loongarch/mm/init.c
@@ -68,14 +68,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
 	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
 }
 
-void __init paging_init(void)
-{
-	unsigned long max_zone_pfns[MAX_NR_ZONES];
-
-	arch_zone_limits_init(max_zone_pfns);
-	free_area_init(max_zone_pfns);
-}
-
 void __ref free_initmem(void)
 {
 	free_initmem_default(POISON_FREE_INITMEM);
diff --git a/arch/m68k/mm/init.c b/arch/m68k/mm/init.c
index 6b1d9d2434b5..53b71f786c27 100644
--- a/arch/m68k/mm/init.c
+++ b/arch/m68k/mm/init.c
@@ -69,13 +69,10 @@ void __init paging_init(void)
 	 * page_alloc get different views of the world.
 	 */
 	unsigned long end_mem = memory_end & PAGE_MASK;
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0, };
 
 	high_memory = (void *) end_mem;
 
 	empty_zero_page = memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
-	arch_zone_limits_init(max_zone_pfn);
-	free_area_init(max_zone_pfn);
 }
 
 #endif /* CONFIG_MMU */
diff --git a/arch/m68k/mm/mcfmmu.c b/arch/m68k/mm/mcfmmu.c
index 24a6f7bbd1ce..3418fd864237 100644
--- a/arch/m68k/mm/mcfmmu.c
+++ b/arch/m68k/mm/mcfmmu.c
@@ -39,7 +39,6 @@ void __init paging_init(void)
 	pte_t *pg_table;
 	unsigned long address, size;
 	unsigned long next_pgtable;
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
 	int i;
 
 	empty_zero_page = memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
@@ -73,8 +72,6 @@ void __init paging_init(void)
 	}
 
 	current->mm = NULL;
-	arch_zone_limits_init(max_zone_pfn);
-	free_area_init(max_zone_pfn);
 }
 
 int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
diff --git a/arch/m68k/mm/motorola.c b/arch/m68k/mm/motorola.c
index d6ccd23caf61..127a3fa69f4c 100644
--- a/arch/m68k/mm/motorola.c
+++ b/arch/m68k/mm/motorola.c
@@ -429,7 +429,6 @@ DECLARE_VM_GET_PAGE_PROT
  */
 void __init paging_init(void)
 {
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0, };
 	unsigned long min_addr, max_addr;
 	unsigned long addr;
 	int i;
@@ -511,12 +510,9 @@ void __init paging_init(void)
 	set_fc(USER_DATA);
 
 #ifdef DEBUG
-	printk ("before free_area_init\n");
+	printk ("before node_set_state\n");
 #endif
 	for (i = 0; i < m68k_num_memory; i++)
 		if (node_present_pages(i))
 			node_set_state(i, N_NORMAL_MEMORY);
-
-	arch_zone_limits_init(max_zone_pfn);
-	free_area_init(max_zone_pfn);
 }
diff --git a/arch/m68k/mm/sun3mmu.c b/arch/m68k/mm/sun3mmu.c
index fdd69cc4240c..c801677f7df8 100644
--- a/arch/m68k/mm/sun3mmu.c
+++ b/arch/m68k/mm/sun3mmu.c
@@ -41,7 +41,6 @@ void __init paging_init(void)
 	unsigned long address;
 	unsigned long next_pgtable;
 	unsigned long bootmem_end;
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0, };
 	unsigned long size;
 
 	empty_zero_page = memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
@@ -80,14 +79,6 @@ void __init paging_init(void)
 	mmu_emu_init(bootmem_end);
 
 	current->mm = NULL;
-
-	/* memory sizing is a hack stolen from motorola.c..  hope it works for us */
-	arch_zone_limits_init(max_zone_pfn);
-
-	/* I really wish I knew why the following change made things better...  -- Sam */
-	free_area_init(max_zone_pfn);
-
-
 }
 
 static const pgprot_t protection_map[16] = {
diff --git a/arch/microblaze/mm/init.c b/arch/microblaze/mm/init.c
index 54da60b81094..848cdee1380c 100644
--- a/arch/microblaze/mm/init.c
+++ b/arch/microblaze/mm/init.c
@@ -69,22 +69,15 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
  */
 static void __init paging_init(void)
 {
-	unsigned long zones_size[MAX_NR_ZONES];
 	int idx;
 
 	/* Setup fixmaps */
 	for (idx = 0; idx < __end_of_fixed_addresses; idx++)
 		clear_fixmap(idx);
 
-	/* Clean every zones */
-	memset(zones_size, 0, sizeof(zones_size));
-
 #ifdef CONFIG_HIGHMEM
 	highmem_init();
 #endif
-	arch_zone_limits_init(zones_size);
-	/* We don't have holes in memory map */
-	free_area_init(zones_size);
 }
 
 void __init setup_memory(void)
diff --git a/arch/mips/loongson64/numa.c b/arch/mips/loongson64/numa.c
index f72a58f87878..2cd95020df08 100644
--- a/arch/mips/loongson64/numa.c
+++ b/arch/mips/loongson64/numa.c
@@ -162,11 +162,7 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
 
 void __init paging_init(void)
 {
-	unsigned long zones_size[MAX_NR_ZONES] = {0, };
-
 	pagetable_init();
-	arch_zone_limits_init(zones_size);
-	free_area_init(zones_size);
 }
 
 /* All PCI device belongs to logical Node-0 */
diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index ab08249cfede..c479c42141c3 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -417,12 +417,7 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
 
 void __init paging_init(void)
 {
-	unsigned long max_zone_pfns[MAX_NR_ZONES];
-
 	pagetable_init();
-
-	arch_zone_limits_init(max_zone_pfns);
-	free_area_init(max_zone_pfns);
 }
 
 #ifdef CONFIG_64BIT
diff --git a/arch/mips/sgi-ip27/ip27-memory.c b/arch/mips/sgi-ip27/ip27-memory.c
index babeb0e07687..082651facf4f 100644
--- a/arch/mips/sgi-ip27/ip27-memory.c
+++ b/arch/mips/sgi-ip27/ip27-memory.c
@@ -413,9 +413,5 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
 
 void __init paging_init(void)
 {
-	unsigned long zones_size[MAX_NR_ZONES] = {0, };
-
 	pagetable_init();
-	arch_zone_limits_init(zones_size);
-	free_area_init(zones_size);
 }
diff --git a/arch/nios2/mm/init.c b/arch/nios2/mm/init.c
index 2cb666a65d9e..6b22f1995c16 100644
--- a/arch/nios2/mm/init.c
+++ b/arch/nios2/mm/init.c
@@ -51,15 +51,9 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
  */
 void __init paging_init(void)
 {
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
-
 	pagetable_init();
 	pgd_current = swapper_pg_dir;
 
-	arch_zone_limits_init(max_zone_pfn);
-	/* pass the memory from the bootmem allocator to the main allocator */
-	free_area_init(max_zone_pfn);
-
 	flush_dcache_range((unsigned long)empty_zero_page,
 			(unsigned long)empty_zero_page + PAGE_SIZE);
 }
diff --git a/arch/openrisc/mm/init.c b/arch/openrisc/mm/init.c
index 67de93e7a685..78fb0734cdbc 100644
--- a/arch/openrisc/mm/init.c
+++ b/arch/openrisc/mm/init.c
@@ -47,14 +47,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
 	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
 }
 
-static void __init zone_sizes_init(void)
-{
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
-
-	arch_zone_limits_init(max_zone_pfn);
-	free_area_init(max_zone_pfn);
-}
-
 extern const char _s_kernel_ro[], _e_kernel_ro[];
 
 /*
@@ -145,8 +137,6 @@ void __init paging_init(void)
 
 	map_ram();
 
-	zone_sizes_init();
-
 	/* self modifying code ;) */
 	/* Since the old TLB miss handler has been running up until now,
 	 * the kernel pages are still all RW, so we can still modify the
diff --git a/arch/parisc/mm/init.c b/arch/parisc/mm/init.c
index dc5bd3efe738..ce6f09ab7a90 100644
--- a/arch/parisc/mm/init.c
+++ b/arch/parisc/mm/init.c
@@ -698,14 +698,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
 	max_zone_pfns[ZONE_NORMAL] = PFN_DOWN(memblock_end_of_DRAM());
 }
 
-static void __init parisc_bootmem_free(void)
-{
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0, };
-
-	arch_zone_limits_init(max_zone_pfn);
-	free_area_init(max_zone_pfn);
-}
-
 void __init paging_init(void)
 {
 	setup_bootmem();
@@ -716,7 +708,6 @@ void __init paging_init(void)
 	flush_tlb_all_local(NULL);
 
 	sparse_init();
-	parisc_bootmem_free();
 }
 
 static void alloc_btlb(unsigned long start, unsigned long end, int *slot,
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 32c496bfab4f..72d4993192a6 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -237,7 +237,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
  */
 void __init paging_init(void)
 {
-	unsigned long max_zone_pfns[MAX_NR_ZONES];
 	unsigned long long total_ram = memblock_phys_mem_size();
 	phys_addr_t top_of_ram = memblock_end_of_DRAM();
 	int zone_dma_bits;
@@ -269,9 +268,6 @@ void __init paging_init(void)
 
 	zone_dma_limit = DMA_BIT_MASK(zone_dma_bits);
 
-	arch_zone_limits_init(max_zone_pfns);
-	free_area_init(max_zone_pfns);
-
 	mark_nonram_nosave();
 }
 
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 97e8661fbcff..79b4792578c4 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -87,14 +87,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
 	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
 }
 
-static void __init zone_sizes_init(void)
-{
-	unsigned long max_zone_pfns[MAX_NR_ZONES] = { 0, };
-
-	arch_zone_limits_init(max_zone_pfns);
-	free_area_init(max_zone_pfns);
-}
-
 #if defined(CONFIG_MMU) && defined(CONFIG_DEBUG_VM)
 
 #define LOG2_SZ_1K  ilog2(SZ_1K)
@@ -1443,7 +1435,6 @@ void __init misc_mem_init(void)
 	/* The entire VMEMMAP region has been populated. Flush TLB for this region */
 	local_flush_tlb_kernel_range(VMEMMAP_START, VMEMMAP_END);
 #endif
-	zone_sizes_init();
 	arch_reserve_crashkernel();
 	memblock_dump_all();
 }
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 1c11ad84dddb..9ec608b5cbb1 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -97,14 +97,9 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
  */
 void __init paging_init(void)
 {
-	unsigned long max_zone_pfns[MAX_NR_ZONES];
-
 	vmem_map_init();
 	sparse_init();
 	zone_dma_limit = DMA_BIT_MASK(31);
-	memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
-	arch_zone_limits_init(max_zone_pfns);
-	free_area_init(max_zone_pfns);
 }
 
 void mark_rodata_ro(void)
diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
index 5e7e63642611..3edee854b755 100644
--- a/arch/sh/mm/init.c
+++ b/arch/sh/mm/init.c
@@ -271,7 +271,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
 
 void __init paging_init(void)
 {
-	unsigned long max_zone_pfns[MAX_NR_ZONES];
 	unsigned long vaddr, end;
 
 	sh_mv.mv_mem_init();
@@ -325,10 +324,6 @@ void __init paging_init(void)
 	page_table_range_init(vaddr, end, swapper_pg_dir);
 
 	kmap_coherent_init();
-
-	memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
-	arch_zone_limits_init(max_zone_pfns);
-	free_area_init(max_zone_pfns);
 }
 
 unsigned int mem_init_done = 0;
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index fbaad449dfc9..931f872ce84a 100644
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -2459,17 +2459,6 @@ void __init paging_init(void)
 
 	kernel_physical_mapping_init();
 
-	{
-		unsigned long max_zone_pfns[MAX_NR_ZONES];
-
-		memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
-
-		max_zone_pfns[ZONE_NORMAL] = end_pfn;
-
-		arch_zone_limits_init(max_zone_pfns);
-		free_area_init(max_zone_pfns);
-	}
-
 	printk("Booting Linux...\n");
 }
 
diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c
index 81e90151db90..1b24c5e8d73d 100644
--- a/arch/sparc/mm/srmmu.c
+++ b/arch/sparc/mm/srmmu.c
@@ -970,13 +970,6 @@ void __init srmmu_paging_init(void)
 	flush_tlb_all();
 
 	sparc_context_init(num_contexts);
-
-	{
-		unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
-
-		arch_zone_limits_init(max_zone_pfn);
-		free_area_init(max_zone_pfn);
-	}
 }
 
 void mmu_info(struct seq_file *m)
diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index 2ac4e9debedd..89c8c8b94a79 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -91,16 +91,11 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
 
 void __init paging_init(void)
 {
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
-
 	empty_zero_page = (unsigned long *) memblock_alloc_low(PAGE_SIZE,
 							       PAGE_SIZE);
 	if (!empty_zero_page)
 		panic("%s: Failed to allocate %lu bytes align=%lx\n",
 		      __func__, PAGE_SIZE, PAGE_SIZE);
-
-	arch_zone_limits_init(max_zone_pfn);
-	free_area_init(max_zone_pfn);
 }
 
 /*
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index e7ef605a18d6..e52a262d3207 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -1011,16 +1011,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
 #endif
 }
 
-void __init zone_sizes_init(void)
-{
-	unsigned long max_zone_pfns[MAX_NR_ZONES];
-
-	memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
-
-	arch_zone_limits_init(max_zone_pfns);
-	free_area_init(max_zone_pfns);
-}
-
 __visible DEFINE_PER_CPU_ALIGNED(struct tlb_state, cpu_tlbstate) = {
 	.loaded_mm = &init_mm,
 	.next_asid = 1,
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 8a34fff6ab2b..b55172118c91 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -655,7 +655,6 @@ void __init paging_init(void)
 	 */
 	olpc_dt_build_devicetree();
 	sparse_init();
-	zone_sizes_init();
 }
 
 /*
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 9983017ecbe0..4daa40071c9f 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -843,8 +843,6 @@ void __init paging_init(void)
 	 */
 	node_clear_state(0, N_MEMORY);
 	node_clear_state(0, N_NORMAL_MEMORY);
-
-	zone_sizes_init();
 }
 
 #define PAGE_UNUSED 0xFD
diff --git a/arch/x86/mm/mm_internal.h b/arch/x86/mm/mm_internal.h
index 097aadc250f7..7c4a41235323 100644
--- a/arch/x86/mm/mm_internal.h
+++ b/arch/x86/mm/mm_internal.h
@@ -17,7 +17,6 @@ unsigned long kernel_physical_mapping_init(unsigned long start,
 unsigned long kernel_physical_mapping_change(unsigned long start,
 					     unsigned long end,
 					     unsigned long page_size_mask);
-void zone_sizes_init(void);
 
 extern int after_bootmem;
 
diff --git a/arch/xtensa/mm/init.c b/arch/xtensa/mm/init.c
index 60299f359a3c..fe83a68335da 100644
--- a/arch/xtensa/mm/init.c
+++ b/arch/xtensa/mm/init.c
@@ -126,10 +126,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
 
 void __init zones_init(void)
 {
-	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0, };
-
-	arch_zone_limits_init(max_zone_pfn);
-	free_area_init(max_zone_pfn);
 	print_vm_layout();
 }
 
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 628c0e0ac313..64d6f9c15ef1 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -45,6 +45,7 @@ struct pt_regs;
 struct folio_batch;
 
 void arch_mm_preinit(void);
+void mm_core_init_early(void);
 void mm_core_init(void);
 void init_mm_internals(void);
 
@@ -3536,7 +3537,7 @@ static inline unsigned long get_num_physpages(void)
 }
 
 /*
- * Using memblock node mappings, an architecture may initialise its
+ * FIXME: Using memblock node mappings, an architecture may initialise its
  * zones, allocate the backing mem_map and account for memory holes in an
  * architecture independent manner.
  *
@@ -3551,7 +3552,6 @@ static inline unsigned long get_num_physpages(void)
  *	memblock_add_node(base, size, nid, MEMBLOCK_NONE)
  * free_area_init(max_zone_pfns);
  */
-void free_area_init(unsigned long *max_zone_pfn);
 void arch_zone_limits_init(unsigned long *max_zone_pfn);
 unsigned long node_map_pfn_alignment(void);
 extern unsigned long absent_pages_in_range(unsigned long start_pfn,
diff --git a/init/main.c b/init/main.c
index b84818ad9685..445b5643ecec 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1025,6 +1025,7 @@ void start_kernel(void)
 	page_address_init();
 	pr_notice("%s", linux_banner);
 	setup_arch(&command_line);
+	mm_core_init_early();
 	/* Static keys and static calls are needed by LSMs */
 	jump_label_init();
 	static_call_init();
diff --git a/mm/mm_init.c b/mm/mm_init.c
index fc2a6f1e518f..ffc4a0f1fee9 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -1810,7 +1810,6 @@ static void __init set_high_memory(void)
 
 /**
  * free_area_init - Initialise all pg_data_t and zone data
- * @max_zone_pfn: an array of max PFNs for each zone
  *
  * This will call free_area_init_node() for each active node in the system.
  * Using the page ranges provided by memblock_set_node(), the size of each
@@ -1821,17 +1820,14 @@ static void __init set_high_memory(void)
  * starts where the previous one ended. For example, ZONE_DMA32 starts
  * at arch_max_dma_pfn.
  */
-void __init free_area_init(unsigned long *max_zone_pfn)
+static void __init free_area_init(void)
 {
+	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
 	unsigned long start_pfn, end_pfn;
 	int i, nid, zone;
 	bool descending;
 
-	/* Record where the zone boundaries are */
-	memset(arch_zone_lowest_possible_pfn, 0,
-				sizeof(arch_zone_lowest_possible_pfn));
-	memset(arch_zone_highest_possible_pfn, 0,
-				sizeof(arch_zone_highest_possible_pfn));
+	arch_zone_limits_init(max_zone_pfn);
 
 	start_pfn = PHYS_PFN(memblock_start_of_DRAM());
 	descending = arch_has_descending_max_zone_pfns();
@@ -2681,13 +2677,19 @@ void __init __weak mem_init(void)
 {
 }
 
+void __init mm_core_init_early(void)
+{
+	hugetlb_bootmem_alloc();
+
+	free_area_init();
+}
+
 /*
  * Set up kernel memory allocators
  */
 void __init mm_core_init(void)
 {
 	arch_mm_preinit();
-	hugetlb_bootmem_alloc();
 
 	/* Initializations relying on SMP setup */
 	BUILD_BUG_ON(MAX_ZONELISTS > 2);
-- 
2.51.0
Re: [PATCH v2 22/28] arch, mm: consolidate initialization of nodes, zones and memory map
Posted by Kalle Niemi 1 month ago 
On 1/2/26 08:59, Mike Rapoport wrote:
> From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
> 
> To initialize node, zone and memory map data structures every architecture
> calls free_area_init() during setup_arch() and passes it an array of zone
> limits.
> 
> Beside code duplication it creates "interesting" ordering cases between
> allocation and initialization of hugetlb and the memory map. Some
> architectures allocate hugetlb pages very early in setup_arch() in certain
> cases, some only create hugetlb CMA areas in setup_arch() and sometimes
> hugetlb allocations happen mm_core_init().
> 
> With arch_zone_limits_init() helper available now on all architectures it
> is no longer necessary to call free_area_init() from architecture setup
> code. Rather core MM initialization can call arch_zone_limits_init() in a
> single place.
> 
> This allows to unify ordering of hugetlb vs memory map allocation and
> initialization.
> 
> Remove the call to free_area_init() from architecture specific code and
> place it in a new mm_core_init_early() function that is called immediately
> after setup_arch().
> 
> After this refactoring it is possible to consolidate hugetlb allocations
> and eliminate differences in ordering of hugetlb and memory map
> initialization among different architectures.
> 
> As the first step of this consolidation move hugetlb_bootmem_alloc() to
> mm_core_early_init().
> 
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> ---
>   arch/alpha/mm/init.c                 |  9 +--------
>   arch/arc/mm/init.c                   |  5 -----
>   arch/arm/mm/init.c                   | 16 ----------------
>   arch/arm64/mm/init.c                 |  4 ----
>   arch/csky/kernel/setup.c             |  4 ----
>   arch/hexagon/mm/init.c               | 12 ------------
>   arch/loongarch/include/asm/pgtable.h |  2 --
>   arch/loongarch/kernel/setup.c        |  2 --
>   arch/loongarch/mm/init.c             |  8 --------
>   arch/m68k/mm/init.c                  |  3 ---
>   arch/m68k/mm/mcfmmu.c                |  3 ---
>   arch/m68k/mm/motorola.c              |  6 +-----
>   arch/m68k/mm/sun3mmu.c               |  9 ---------
>   arch/microblaze/mm/init.c            |  7 -------
>   arch/mips/loongson64/numa.c          |  4 ----
>   arch/mips/mm/init.c                  |  5 -----
>   arch/mips/sgi-ip27/ip27-memory.c     |  4 ----
>   arch/nios2/mm/init.c                 |  6 ------
>   arch/openrisc/mm/init.c              | 10 ----------
>   arch/parisc/mm/init.c                |  9 ---------
>   arch/powerpc/mm/mem.c                |  4 ----
>   arch/riscv/mm/init.c                 |  9 ---------
>   arch/s390/mm/init.c                  |  5 -----
>   arch/sh/mm/init.c                    |  5 -----
>   arch/sparc/mm/init_64.c              | 11 -----------
>   arch/sparc/mm/srmmu.c                |  7 -------
>   arch/um/kernel/mem.c                 |  5 -----
>   arch/x86/mm/init.c                   | 10 ----------
>   arch/x86/mm/init_32.c                |  1 -
>   arch/x86/mm/init_64.c                |  2 --
>   arch/x86/mm/mm_internal.h            |  1 -
>   arch/xtensa/mm/init.c                |  4 ----
>   include/linux/mm.h                   |  4 ++--
>   init/main.c                          |  1 +
>   mm/mm_init.c                         | 18 ++++++++++--------
>   35 files changed, 15 insertions(+), 200 deletions(-)
> 
> diff --git a/arch/alpha/mm/init.c b/arch/alpha/mm/init.c
> index cd0cb1abde5f..9531cbc761c0 100644
> --- a/arch/alpha/mm/init.c
> +++ b/arch/alpha/mm/init.c
> @@ -220,17 +220,10 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfn)
>   }
>   
>   /*
> - * paging_init() sets up the memory map.
> + * paging_init() initializes the kernel's ZERO_PGE.
>    */
>   void __init paging_init(void)
>   {
> -	unsigned long max_zone_pfn[MAX_NR_ZONES] = {0, };
> -
> -	/* Initialize mem_map[].  */
> -	arch_zone_limits_init(max_zone_pfn);
> -	free_area_init(max_zone_pfn);
> -
> -	/* Initialize the kernel's ZERO_PGE. */
>   	memset(absolute_pointer(ZERO_PGE), 0, PAGE_SIZE);
>   }
>   
> diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
> index ff7974d38011..a5e92f46e5d1 100644
> --- a/arch/arc/mm/init.c
> +++ b/arch/arc/mm/init.c
> @@ -102,8 +102,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfn)
>    */
>   void __init setup_arch_memory(void)
>   {
> -	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
> -
>   	setup_initial_init_mm(_text, _etext, _edata, _end);
>   
>   	/* first page of system - kernel .vector starts here */
> @@ -158,9 +156,6 @@ void __init setup_arch_memory(void)
>   	arch_pfn_offset = min(min_low_pfn, min_high_pfn);
>   	kmap_init();
>   #endif /* CONFIG_HIGHMEM */
> -
> -	arch_zone_limits_init(max_zone_pfn);
> -	free_area_init(max_zone_pfn);
>   }
>   
>   void __init arch_mm_preinit(void)
> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index bdcc3639681f..a8f7b4084715 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -118,15 +118,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfn)
>   #endif
>   }
>   
> -static void __init zone_sizes_init(unsigned long min, unsigned long max_low,
> -	unsigned long max_high)
> -{
> -	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
> -
> -	arch_zone_limits_init(max_zone_pfn);
> -	free_area_init(max_zone_pfn);
> -}
> -
>   #ifdef CONFIG_HAVE_ARCH_PFN_VALID
>   int pfn_valid(unsigned long pfn)
>   {
> @@ -222,13 +213,6 @@ void __init bootmem_init(void)
>   	 * done after the fixed reservations
>   	 */
>   	sparse_init();
> -
> -	/*
> -	 * Now free the memory - free_area_init needs
> -	 * the sparse mem_map arrays initialized by sparse_init()
> -	 * for memmap_init_zone(), otherwise all PFNs are invalid.
> -	 */
> -	zone_sizes_init(min_low_pfn, max_low_pfn, max_pfn);
>   }
>   
>   /*
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 06815d34cc11..3641e88ea871 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -134,7 +134,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
>   
>   static void __init dma_limits_init(void)
>   {
> -	unsigned long max_zone_pfns[MAX_NR_ZONES]  = {0};
>   	phys_addr_t __maybe_unused acpi_zone_dma_limit;
>   	phys_addr_t __maybe_unused dt_zone_dma_limit;
>   	phys_addr_t __maybe_unused dma32_phys_limit =
> @@ -160,9 +159,6 @@ static void __init dma_limits_init(void)
>   #endif
>   	if (!arm64_dma_phys_limit)
>   		arm64_dma_phys_limit = PHYS_MASK + 1;
> -
> -	arch_zone_limits_init(max_zone_pfns);
> -	free_area_init(max_zone_pfns);
>   }
>   
>   int pfn_is_map_memory(unsigned long pfn)
> diff --git a/arch/csky/kernel/setup.c b/arch/csky/kernel/setup.c
> index 8968815d93e6..4bf3c01ead3a 100644
> --- a/arch/csky/kernel/setup.c
> +++ b/arch/csky/kernel/setup.c
> @@ -63,7 +63,6 @@ static void __init csky_memblock_init(void)
>   {
>   	unsigned long lowmem_size = PFN_DOWN(LOWMEM_LIMIT - PHYS_OFFSET_OFFSET);
>   	unsigned long sseg_size = PFN_DOWN(SSEG_SIZE - PHYS_OFFSET_OFFSET);
> -	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
>   	signed long size;
>   
>   	memblock_reserve(__pa(_start), _end - _start);
> @@ -101,9 +100,6 @@ static void __init csky_memblock_init(void)
>   	memblock_set_current_limit(PFN_PHYS(max_low_pfn));
>   
>   	dma_contiguous_reserve(0);
> -
> -	arch_zone_limits_init(max_zone_pfn);
> -	free_area_init(max_zone_pfn);
>   }
>   
>   void __init setup_arch(char **cmdline_p)
> diff --git a/arch/hexagon/mm/init.c b/arch/hexagon/mm/init.c
> index e2c9487d8d34..07086dbd33fd 100644
> --- a/arch/hexagon/mm/init.c
> +++ b/arch/hexagon/mm/init.c
> @@ -66,20 +66,8 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
>   	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
>   }
>   
> -/*
> - * In order to set up page allocator "nodes",
> - * somebody has to call free_area_init() for UMA.
> - *
> - * In this mode, we only have one pg_data_t
> - * structure: contig_mem_data.
> - */
>   static void __init paging_init(void)
>   {
> -	unsigned long max_zone_pfn[MAX_NR_ZONES] = {0, };
> -
> -	arch_zone_limits_init(max_zone_pfn);
> -	free_area_init(max_zone_pfn);  /*  sets up the zonelists and mem_map  */
> -
>   	/*
>   	 * Set the init_mm descriptors "context" value to point to the
>   	 * initial kernel segment table's physical address.
> diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h
> index f41a648a3d9e..c33b3bcb733e 100644
> --- a/arch/loongarch/include/asm/pgtable.h
> +++ b/arch/loongarch/include/asm/pgtable.h
> @@ -353,8 +353,6 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
>   	return pte;
>   }
>   
> -extern void paging_init(void);
> -
>   #define pte_none(pte)		(!(pte_val(pte) & ~_PAGE_GLOBAL))
>   #define pte_present(pte)	(pte_val(pte) & (_PAGE_PRESENT | _PAGE_PROTNONE))
>   #define pte_no_exec(pte)	(pte_val(pte) & _PAGE_NO_EXEC)
> diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
> index 20cb6f306456..708ac025db71 100644
> --- a/arch/loongarch/kernel/setup.c
> +++ b/arch/loongarch/kernel/setup.c
> @@ -621,8 +621,6 @@ void __init setup_arch(char **cmdline_p)
>   	prefill_possible_map();
>   #endif
>   
> -	paging_init();
> -
>   #ifdef CONFIG_KASAN
>   	kasan_init();
>   #endif
> diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c
> index 17235f87eafb..c331bf69d2ec 100644
> --- a/arch/loongarch/mm/init.c
> +++ b/arch/loongarch/mm/init.c
> @@ -68,14 +68,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
>   	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
>   }
>   
> -void __init paging_init(void)
> -{
> -	unsigned long max_zone_pfns[MAX_NR_ZONES];
> -
> -	arch_zone_limits_init(max_zone_pfns);
> -	free_area_init(max_zone_pfns);
> -}
> -
>   void __ref free_initmem(void)
>   {
>   	free_initmem_default(POISON_FREE_INITMEM);
> diff --git a/arch/m68k/mm/init.c b/arch/m68k/mm/init.c
> index 6b1d9d2434b5..53b71f786c27 100644
> --- a/arch/m68k/mm/init.c
> +++ b/arch/m68k/mm/init.c
> @@ -69,13 +69,10 @@ void __init paging_init(void)
>   	 * page_alloc get different views of the world.
>   	 */
>   	unsigned long end_mem = memory_end & PAGE_MASK;
> -	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0, };
>   
>   	high_memory = (void *) end_mem;
>   
>   	empty_zero_page = memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
> -	arch_zone_limits_init(max_zone_pfn);
> -	free_area_init(max_zone_pfn);
>   }
>   
>   #endif /* CONFIG_MMU */
> diff --git a/arch/m68k/mm/mcfmmu.c b/arch/m68k/mm/mcfmmu.c
> index 24a6f7bbd1ce..3418fd864237 100644
> --- a/arch/m68k/mm/mcfmmu.c
> +++ b/arch/m68k/mm/mcfmmu.c
> @@ -39,7 +39,6 @@ void __init paging_init(void)
>   	pte_t *pg_table;
>   	unsigned long address, size;
>   	unsigned long next_pgtable;
> -	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
>   	int i;
>   
>   	empty_zero_page = memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
> @@ -73,8 +72,6 @@ void __init paging_init(void)
>   	}
>   
>   	current->mm = NULL;
> -	arch_zone_limits_init(max_zone_pfn);
> -	free_area_init(max_zone_pfn);
>   }
>   
>   int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
> diff --git a/arch/m68k/mm/motorola.c b/arch/m68k/mm/motorola.c
> index d6ccd23caf61..127a3fa69f4c 100644
> --- a/arch/m68k/mm/motorola.c
> +++ b/arch/m68k/mm/motorola.c
> @@ -429,7 +429,6 @@ DECLARE_VM_GET_PAGE_PROT
>    */
>   void __init paging_init(void)
>   {
> -	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0, };
>   	unsigned long min_addr, max_addr;
>   	unsigned long addr;
>   	int i;
> @@ -511,12 +510,9 @@ void __init paging_init(void)
>   	set_fc(USER_DATA);
>   
>   #ifdef DEBUG
> -	printk ("before free_area_init\n");
> +	printk ("before node_set_state\n");
>   #endif
>   	for (i = 0; i < m68k_num_memory; i++)
>   		if (node_present_pages(i))
>   			node_set_state(i, N_NORMAL_MEMORY);
> -
> -	arch_zone_limits_init(max_zone_pfn);
> -	free_area_init(max_zone_pfn);
>   }
> diff --git a/arch/m68k/mm/sun3mmu.c b/arch/m68k/mm/sun3mmu.c
> index fdd69cc4240c..c801677f7df8 100644
> --- a/arch/m68k/mm/sun3mmu.c
> +++ b/arch/m68k/mm/sun3mmu.c
> @@ -41,7 +41,6 @@ void __init paging_init(void)
>   	unsigned long address;
>   	unsigned long next_pgtable;
>   	unsigned long bootmem_end;
> -	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0, };
>   	unsigned long size;
>   
>   	empty_zero_page = memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
> @@ -80,14 +79,6 @@ void __init paging_init(void)
>   	mmu_emu_init(bootmem_end);
>   
>   	current->mm = NULL;
> -
> -	/* memory sizing is a hack stolen from motorola.c..  hope it works for us */
> -	arch_zone_limits_init(max_zone_pfn);
> -
> -	/* I really wish I knew why the following change made things better...  -- Sam */
> -	free_area_init(max_zone_pfn);
> -
> -
>   }
>   
>   static const pgprot_t protection_map[16] = {
> diff --git a/arch/microblaze/mm/init.c b/arch/microblaze/mm/init.c
> index 54da60b81094..848cdee1380c 100644
> --- a/arch/microblaze/mm/init.c
> +++ b/arch/microblaze/mm/init.c
> @@ -69,22 +69,15 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
>    */
>   static void __init paging_init(void)
>   {
> -	unsigned long zones_size[MAX_NR_ZONES];
>   	int idx;
>   
>   	/* Setup fixmaps */
>   	for (idx = 0; idx < __end_of_fixed_addresses; idx++)
>   		clear_fixmap(idx);
>   
> -	/* Clean every zones */
> -	memset(zones_size, 0, sizeof(zones_size));
> -
>   #ifdef CONFIG_HIGHMEM
>   	highmem_init();
>   #endif
> -	arch_zone_limits_init(zones_size);
> -	/* We don't have holes in memory map */
> -	free_area_init(zones_size);
>   }
>   
>   void __init setup_memory(void)
> diff --git a/arch/mips/loongson64/numa.c b/arch/mips/loongson64/numa.c
> index f72a58f87878..2cd95020df08 100644
> --- a/arch/mips/loongson64/numa.c
> +++ b/arch/mips/loongson64/numa.c
> @@ -162,11 +162,7 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
>   
>   void __init paging_init(void)
>   {
> -	unsigned long zones_size[MAX_NR_ZONES] = {0, };
> -
>   	pagetable_init();
> -	arch_zone_limits_init(zones_size);
> -	free_area_init(zones_size);
>   }
>   
>   /* All PCI device belongs to logical Node-0 */
> diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
> index ab08249cfede..c479c42141c3 100644
> --- a/arch/mips/mm/init.c
> +++ b/arch/mips/mm/init.c
> @@ -417,12 +417,7 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
>   
>   void __init paging_init(void)
>   {
> -	unsigned long max_zone_pfns[MAX_NR_ZONES];
> -
>   	pagetable_init();
> -
> -	arch_zone_limits_init(max_zone_pfns);
> -	free_area_init(max_zone_pfns);
>   }
>   
>   #ifdef CONFIG_64BIT
> diff --git a/arch/mips/sgi-ip27/ip27-memory.c b/arch/mips/sgi-ip27/ip27-memory.c
> index babeb0e07687..082651facf4f 100644
> --- a/arch/mips/sgi-ip27/ip27-memory.c
> +++ b/arch/mips/sgi-ip27/ip27-memory.c
> @@ -413,9 +413,5 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
>   
>   void __init paging_init(void)
>   {
> -	unsigned long zones_size[MAX_NR_ZONES] = {0, };
> -
>   	pagetable_init();
> -	arch_zone_limits_init(zones_size);
> -	free_area_init(zones_size);
>   }
> diff --git a/arch/nios2/mm/init.c b/arch/nios2/mm/init.c
> index 2cb666a65d9e..6b22f1995c16 100644
> --- a/arch/nios2/mm/init.c
> +++ b/arch/nios2/mm/init.c
> @@ -51,15 +51,9 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
>    */
>   void __init paging_init(void)
>   {
> -	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
> -
>   	pagetable_init();
>   	pgd_current = swapper_pg_dir;
>   
> -	arch_zone_limits_init(max_zone_pfn);
> -	/* pass the memory from the bootmem allocator to the main allocator */
> -	free_area_init(max_zone_pfn);
> -
>   	flush_dcache_range((unsigned long)empty_zero_page,
>   			(unsigned long)empty_zero_page + PAGE_SIZE);
>   }
> diff --git a/arch/openrisc/mm/init.c b/arch/openrisc/mm/init.c
> index 67de93e7a685..78fb0734cdbc 100644
> --- a/arch/openrisc/mm/init.c
> +++ b/arch/openrisc/mm/init.c
> @@ -47,14 +47,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
>   	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
>   }
>   
> -static void __init zone_sizes_init(void)
> -{
> -	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
> -
> -	arch_zone_limits_init(max_zone_pfn);
> -	free_area_init(max_zone_pfn);
> -}
> -
>   extern const char _s_kernel_ro[], _e_kernel_ro[];
>   
>   /*
> @@ -145,8 +137,6 @@ void __init paging_init(void)
>   
>   	map_ram();
>   
> -	zone_sizes_init();
> -
>   	/* self modifying code ;) */
>   	/* Since the old TLB miss handler has been running up until now,
>   	 * the kernel pages are still all RW, so we can still modify the
> diff --git a/arch/parisc/mm/init.c b/arch/parisc/mm/init.c
> index dc5bd3efe738..ce6f09ab7a90 100644
> --- a/arch/parisc/mm/init.c
> +++ b/arch/parisc/mm/init.c
> @@ -698,14 +698,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
>   	max_zone_pfns[ZONE_NORMAL] = PFN_DOWN(memblock_end_of_DRAM());
>   }
>   
> -static void __init parisc_bootmem_free(void)
> -{
> -	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0, };
> -
> -	arch_zone_limits_init(max_zone_pfn);
> -	free_area_init(max_zone_pfn);
> -}
> -
>   void __init paging_init(void)
>   {
>   	setup_bootmem();
> @@ -716,7 +708,6 @@ void __init paging_init(void)
>   	flush_tlb_all_local(NULL);
>   
>   	sparse_init();
> -	parisc_bootmem_free();
>   }
>   
>   static void alloc_btlb(unsigned long start, unsigned long end, int *slot,
> diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
> index 32c496bfab4f..72d4993192a6 100644
> --- a/arch/powerpc/mm/mem.c
> +++ b/arch/powerpc/mm/mem.c
> @@ -237,7 +237,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
>    */
>   void __init paging_init(void)
>   {
> -	unsigned long max_zone_pfns[MAX_NR_ZONES];
>   	unsigned long long total_ram = memblock_phys_mem_size();
>   	phys_addr_t top_of_ram = memblock_end_of_DRAM();
>   	int zone_dma_bits;
> @@ -269,9 +268,6 @@ void __init paging_init(void)
>   
>   	zone_dma_limit = DMA_BIT_MASK(zone_dma_bits);
>   
> -	arch_zone_limits_init(max_zone_pfns);
> -	free_area_init(max_zone_pfns);
> -
>   	mark_nonram_nosave();
>   }
>   
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 97e8661fbcff..79b4792578c4 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -87,14 +87,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
>   	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
>   }
>   
> -static void __init zone_sizes_init(void)
> -{
> -	unsigned long max_zone_pfns[MAX_NR_ZONES] = { 0, };
> -
> -	arch_zone_limits_init(max_zone_pfns);
> -	free_area_init(max_zone_pfns);
> -}
> -
>   #if defined(CONFIG_MMU) && defined(CONFIG_DEBUG_VM)
>   
>   #define LOG2_SZ_1K  ilog2(SZ_1K)
> @@ -1443,7 +1435,6 @@ void __init misc_mem_init(void)
>   	/* The entire VMEMMAP region has been populated. Flush TLB for this region */
>   	local_flush_tlb_kernel_range(VMEMMAP_START, VMEMMAP_END);
>   #endif
> -	zone_sizes_init();
>   	arch_reserve_crashkernel();
>   	memblock_dump_all();
>   }
> diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
> index 1c11ad84dddb..9ec608b5cbb1 100644
> --- a/arch/s390/mm/init.c
> +++ b/arch/s390/mm/init.c
> @@ -97,14 +97,9 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
>    */
>   void __init paging_init(void)
>   {
> -	unsigned long max_zone_pfns[MAX_NR_ZONES];
> -
>   	vmem_map_init();
>   	sparse_init();
>   	zone_dma_limit = DMA_BIT_MASK(31);
> -	memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
> -	arch_zone_limits_init(max_zone_pfns);
> -	free_area_init(max_zone_pfns);
>   }
>   
>   void mark_rodata_ro(void)
> diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
> index 5e7e63642611..3edee854b755 100644
> --- a/arch/sh/mm/init.c
> +++ b/arch/sh/mm/init.c
> @@ -271,7 +271,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
>   
>   void __init paging_init(void)
>   {
> -	unsigned long max_zone_pfns[MAX_NR_ZONES];
>   	unsigned long vaddr, end;
>   
>   	sh_mv.mv_mem_init();
> @@ -325,10 +324,6 @@ void __init paging_init(void)
>   	page_table_range_init(vaddr, end, swapper_pg_dir);
>   
>   	kmap_coherent_init();
> -
> -	memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
> -	arch_zone_limits_init(max_zone_pfns);
> -	free_area_init(max_zone_pfns);
>   }
>   
>   unsigned int mem_init_done = 0;
> diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
> index fbaad449dfc9..931f872ce84a 100644
> --- a/arch/sparc/mm/init_64.c
> +++ b/arch/sparc/mm/init_64.c
> @@ -2459,17 +2459,6 @@ void __init paging_init(void)
>   
>   	kernel_physical_mapping_init();
>   
> -	{
> -		unsigned long max_zone_pfns[MAX_NR_ZONES];
> -
> -		memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
> -
> -		max_zone_pfns[ZONE_NORMAL] = end_pfn;
> -
> -		arch_zone_limits_init(max_zone_pfns);
> -		free_area_init(max_zone_pfns);
> -	}
> -
>   	printk("Booting Linux...\n");
>   }
>   
> diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c
> index 81e90151db90..1b24c5e8d73d 100644
> --- a/arch/sparc/mm/srmmu.c
> +++ b/arch/sparc/mm/srmmu.c
> @@ -970,13 +970,6 @@ void __init srmmu_paging_init(void)
>   	flush_tlb_all();
>   
>   	sparc_context_init(num_contexts);
> -
> -	{
> -		unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
> -
> -		arch_zone_limits_init(max_zone_pfn);
> -		free_area_init(max_zone_pfn);
> -	}
>   }
>   
>   void mmu_info(struct seq_file *m)
> diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
> index 2ac4e9debedd..89c8c8b94a79 100644
> --- a/arch/um/kernel/mem.c
> +++ b/arch/um/kernel/mem.c
> @@ -91,16 +91,11 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
>   
>   void __init paging_init(void)
>   {
> -	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
> -
>   	empty_zero_page = (unsigned long *) memblock_alloc_low(PAGE_SIZE,
>   							       PAGE_SIZE);
>   	if (!empty_zero_page)
>   		panic("%s: Failed to allocate %lu bytes align=%lx\n",
>   		      __func__, PAGE_SIZE, PAGE_SIZE);
> -
> -	arch_zone_limits_init(max_zone_pfn);
> -	free_area_init(max_zone_pfn);
>   }
>   
>   /*
> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
> index e7ef605a18d6..e52a262d3207 100644
> --- a/arch/x86/mm/init.c
> +++ b/arch/x86/mm/init.c
> @@ -1011,16 +1011,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
>   #endif
>   }
>   
> -void __init zone_sizes_init(void)
> -{
> -	unsigned long max_zone_pfns[MAX_NR_ZONES];
> -
> -	memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
> -
> -	arch_zone_limits_init(max_zone_pfns);
> -	free_area_init(max_zone_pfns);
> -}
> -
>   __visible DEFINE_PER_CPU_ALIGNED(struct tlb_state, cpu_tlbstate) = {
>   	.loaded_mm = &init_mm,
>   	.next_asid = 1,
> diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
> index 8a34fff6ab2b..b55172118c91 100644
> --- a/arch/x86/mm/init_32.c
> +++ b/arch/x86/mm/init_32.c
> @@ -655,7 +655,6 @@ void __init paging_init(void)
>   	 */
>   	olpc_dt_build_devicetree();
>   	sparse_init();
> -	zone_sizes_init();
>   }
>   
>   /*
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index 9983017ecbe0..4daa40071c9f 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -843,8 +843,6 @@ void __init paging_init(void)
>   	 */
>   	node_clear_state(0, N_MEMORY);
>   	node_clear_state(0, N_NORMAL_MEMORY);
> -
> -	zone_sizes_init();
>   }
>   
>   #define PAGE_UNUSED 0xFD
> diff --git a/arch/x86/mm/mm_internal.h b/arch/x86/mm/mm_internal.h
> index 097aadc250f7..7c4a41235323 100644
> --- a/arch/x86/mm/mm_internal.h
> +++ b/arch/x86/mm/mm_internal.h
> @@ -17,7 +17,6 @@ unsigned long kernel_physical_mapping_init(unsigned long start,
>   unsigned long kernel_physical_mapping_change(unsigned long start,
>   					     unsigned long end,
>   					     unsigned long page_size_mask);
> -void zone_sizes_init(void);
>   
>   extern int after_bootmem;
>   
> diff --git a/arch/xtensa/mm/init.c b/arch/xtensa/mm/init.c
> index 60299f359a3c..fe83a68335da 100644
> --- a/arch/xtensa/mm/init.c
> +++ b/arch/xtensa/mm/init.c
> @@ -126,10 +126,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
>   
>   void __init zones_init(void)
>   {
> -	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0, };
> -
> -	arch_zone_limits_init(max_zone_pfn);
> -	free_area_init(max_zone_pfn);
>   	print_vm_layout();
>   }
>   
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 628c0e0ac313..64d6f9c15ef1 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -45,6 +45,7 @@ struct pt_regs;
>   struct folio_batch;
>   
>   void arch_mm_preinit(void);
> +void mm_core_init_early(void);
>   void mm_core_init(void);
>   void init_mm_internals(void);
>   
> @@ -3536,7 +3537,7 @@ static inline unsigned long get_num_physpages(void)
>   }
>   
>   /*
> - * Using memblock node mappings, an architecture may initialise its
> + * FIXME: Using memblock node mappings, an architecture may initialise its
>    * zones, allocate the backing mem_map and account for memory holes in an
>    * architecture independent manner.
>    *
> @@ -3551,7 +3552,6 @@ static inline unsigned long get_num_physpages(void)
>    *	memblock_add_node(base, size, nid, MEMBLOCK_NONE)
>    * free_area_init(max_zone_pfns);
>    */
> -void free_area_init(unsigned long *max_zone_pfn);
>   void arch_zone_limits_init(unsigned long *max_zone_pfn);
>   unsigned long node_map_pfn_alignment(void);
>   extern unsigned long absent_pages_in_range(unsigned long start_pfn,
> diff --git a/init/main.c b/init/main.c
> index b84818ad9685..445b5643ecec 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -1025,6 +1025,7 @@ void start_kernel(void)
>   	page_address_init();
>   	pr_notice("%s", linux_banner);
>   	setup_arch(&command_line);
> +	mm_core_init_early();
>   	/* Static keys and static calls are needed by LSMs */
>   	jump_label_init();
>   	static_call_init();
> diff --git a/mm/mm_init.c b/mm/mm_init.c
> index fc2a6f1e518f..ffc4a0f1fee9 100644
> --- a/mm/mm_init.c
> +++ b/mm/mm_init.c
> @@ -1810,7 +1810,6 @@ static void __init set_high_memory(void)
>   
>   /**
>    * free_area_init - Initialise all pg_data_t and zone data
> - * @max_zone_pfn: an array of max PFNs for each zone
>    *
>    * This will call free_area_init_node() for each active node in the system.
>    * Using the page ranges provided by memblock_set_node(), the size of each
> @@ -1821,17 +1820,14 @@ static void __init set_high_memory(void)
>    * starts where the previous one ended. For example, ZONE_DMA32 starts
>    * at arch_max_dma_pfn.
>    */
> -void __init free_area_init(unsigned long *max_zone_pfn)
> +static void __init free_area_init(void)
>   {
> +	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
>   	unsigned long start_pfn, end_pfn;
>   	int i, nid, zone;
>   	bool descending;
>   
> -	/* Record where the zone boundaries are */
> -	memset(arch_zone_lowest_possible_pfn, 0,
> -				sizeof(arch_zone_lowest_possible_pfn));
> -	memset(arch_zone_highest_possible_pfn, 0,
> -				sizeof(arch_zone_highest_possible_pfn));
> +	arch_zone_limits_init(max_zone_pfn);
>   
>   	start_pfn = PHYS_PFN(memblock_start_of_DRAM());
>   	descending = arch_has_descending_max_zone_pfns();
> @@ -2681,13 +2677,19 @@ void __init __weak mem_init(void)
>   {
>   }
>   
> +void __init mm_core_init_early(void)
> +{
> +	hugetlb_bootmem_alloc();
> +
> +	free_area_init();
> +}
> +
>   /*
>    * Set up kernel memory allocators
>    */
>   void __init mm_core_init(void)
>   {
>   	arch_mm_preinit();
> -	hugetlb_bootmem_alloc();
>   
>   	/* Initializations relying on SMP setup */
>   	BUILD_BUG_ON(MAX_ZONELISTS > 2);
Hello,

This patch got bisected to cause BeagleBone Black boot failure in 
linux-next version next-20260107.

At the moment I cannot provide any helpful information about this.

BR
Kalle
Re: [PATCH v2 22/28] arch, mm: consolidate initialization of nodes, zones and memory map
Posted by Mike Rapoport 1 month ago 
Hi,

On Thu, Jan 08, 2026 at 11:24:07AM +0200, Kalle Niemi wrote:
> On 1/2/26 08:59, Mike Rapoport wrote:
> > From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
> > 
> Hello,
> 
> This patch got bisected to cause BeagleBone Black boot failure in linux-next
> version next-20260107.

Can you check if this patch fixes it?

https://lore.kernel.org/all/aVpWpLV4Dut5Muo2@kernel.org/
 
> At the moment I cannot provide any helpful information about this.
> 
> BR
> Kalle

-- 
Sincerely yours,
Mike.
Re: [PATCH v2 22/28] arch, mm: consolidate initialization of nodes, zones and memory map
Posted by Klara Modin 1 month ago 
Hi,

On 2026-01-02 08:59:58 +0200, Mike Rapoport wrote:
> From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
> 
> To initialize node, zone and memory map data structures every architecture
> calls free_area_init() during setup_arch() and passes it an array of zone
> limits.
> 
> Beside code duplication it creates "interesting" ordering cases between
> allocation and initialization of hugetlb and the memory map. Some
> architectures allocate hugetlb pages very early in setup_arch() in certain
> cases, some only create hugetlb CMA areas in setup_arch() and sometimes
> hugetlb allocations happen mm_core_init().
> 
> With arch_zone_limits_init() helper available now on all architectures it
> is no longer necessary to call free_area_init() from architecture setup
> code. Rather core MM initialization can call arch_zone_limits_init() in a
> single place.
> 
> This allows to unify ordering of hugetlb vs memory map allocation and
> initialization.
> 
> Remove the call to free_area_init() from architecture specific code and
> place it in a new mm_core_init_early() function that is called immediately
> after setup_arch().
> 
> After this refactoring it is possible to consolidate hugetlb allocations
> and eliminate differences in ordering of hugetlb and memory map
> initialization among different architectures.
> 
> As the first step of this consolidation move hugetlb_bootmem_alloc() to
> mm_core_early_init().
> 
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

This breaks boot on my Raspberry Pi 1. The reason seems to be the use of
page_folio() when initializing the dynamically allocated zero page in
arm, which doesn't work when free_area_init() hasn't been called yet.

The following oopses are generated:

 Booting Linux on physical CPU 0x0
 Linux version 6.19.0-rc3-03898-g7975b0084358 (klara@soda.int.kasm.eu) (armv6j-unknown-linux-gnueabihf-gcc (Gentoo 15.2.1_p20251122 p3) 15.2.1 20251122, GNU ld (Gentoo 2.45.1 p1) 2.45.1) #451 Fri Jan  2 20:26:00 CET 2026
 CPU: ARMv6-compatible processor [410fb767] revision 7 (ARMv7), cr=00c5387d
 CPU: PIPT / VIPT nonaliasing data cache, VIPT nonaliasing instruction cache
 OF: fdt: Machine model: Raspberry Pi Model B Rev 2
 earlycon: pl11 at MMIO32 0x20201000 (options '')
 printk: legacy bootconsole [pl11] enabled
 Memory policy: Data cache writeback
 Reserved memory: created CMA memory pool at 0x19400000, size 64 MiB
 OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool
 OF: reserved mem: 0x19400000..0x1d3fffff (65536 KiB) map reusable linux,cma
 8<--- cut here ---
 Unable to handle kernel paging request at virtual address 003dfb44 when read
 [003dfb44] *pgd=00000000
 Internal error: Oops: 5 [#1] ARM
 CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 6.19.0-rc3-03898-g7975b0084358 #451 NONE
 Hardware name: BCM2835
 PC is at paging_init (include/linux/page-flags.h:284 (discriminator 2) arch/arm/mm/mmu.c:1790 (discriminator 2))
 LR is at paging_init (arch/arm/mm/mmu.c:1789 (discriminator 1))
 pc :    lr :    psr: 600000d3
 sp : c0d01ef8  ip : defdb000  fp : 0000000b
 r10: 00200000  r9 : d9400000  r8 : ffe00000
 r7 : c0d09050  r6 : c0d0902c  r5 : c0d43d40  r4 : 0001efda
 r3 : c0dab20c  r2 : 00000000  r1 : 003dfb40  r0 : 00000000
 Flags: nZCv  IRQs off  FIQs off  Mode SVC_32  ISA ARM  Segment none
 Control: 00c5387d  Table: 00004008  DAC: 00000051
 Register r0 information: NULL pointer
 Register r1 information: non-paged memory
 Register r2 information: NULL pointer
 Register r3 information:
 8<--- cut here ---
 Unable to handle kernel paging request at virtual address 0001b564 when read
 [0001b564] *pgd=00000000
 Internal error: Oops: 5 [#2] ARM
 CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 6.19.0-rc3-03898-g7975b0084358 #451 NONE
 Hardware name: BCM2835
 PC is at kmem_dump_obj (mm/slab.h:142 (discriminator 2) mm/slab.h:178 (discriminator 2) mm/slab_common.c:609 (discriminator 2))
 LR is at 0x1
 pc :    lr :    psr: 200001d3
 sp : c0d01cc8  ip : 00000000  fp : 0000000b
 r10: 00200000  r9 : c0dab1dc  r8 : 00000000
 r7 : 00000005  r6 : 00000dab  r5 : 0001b560  r4 : c0dab20c
 r3 : c0dc2058  r2 : 1f000000  r1 : 00c00000  r0 : 00000001
 Flags: nzCv  IRQs off  FIQs off  Mode SVC_32  ISA ARM  Segment none
 Control: 00c5387d  Table: 00004008  DAC: 00000051
 Register r0 information: non-paged memory
 Register r1 information: non-paged memory
 Register r2 information: non-paged memory
 Register r3 information:
 8<--- cut here ---

and the second one repeats for some time afterwards.

I experimented a little by allocating the zero page statically as many
other arches do which fixes the issue as it does not need to be
initialized at this point anymore, though I have no idea if that's
appropriate.

Regards,
Klara Modin

...

> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index bdcc3639681f..a8f7b4084715 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -118,15 +118,6 @@ void __init arch_zone_limits_init(unsigned long *max_zone_pfn)
>  #endif
>  }
>  
> -static void __init zone_sizes_init(unsigned long min, unsigned long max_low,
> -	unsigned long max_high)
> -{
> -	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
> -
> -	arch_zone_limits_init(max_zone_pfn);
> -	free_area_init(max_zone_pfn);
> -}
> -
>  #ifdef CONFIG_HAVE_ARCH_PFN_VALID
>  int pfn_valid(unsigned long pfn)
>  {
> @@ -222,13 +213,6 @@ void __init bootmem_init(void)
>  	 * done after the fixed reservations
>  	 */
>  	sparse_init();
> -
> -	/*
> -	 * Now free the memory - free_area_init needs
> -	 * the sparse mem_map arrays initialized by sparse_init()
> -	 * for memmap_init_zone(), otherwise all PFNs are invalid.
> -	 */
> -	zone_sizes_init(min_low_pfn, max_low_pfn, max_pfn);
>  }
>  
>  /*

...

> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 628c0e0ac313..64d6f9c15ef1 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -45,6 +45,7 @@ struct pt_regs;
>  struct folio_batch;
>  
>  void arch_mm_preinit(void);
> +void mm_core_init_early(void);
>  void mm_core_init(void);
>  void init_mm_internals(void);
>  
> @@ -3536,7 +3537,7 @@ static inline unsigned long get_num_physpages(void)
>  }
>  
>  /*
> - * Using memblock node mappings, an architecture may initialise its
> + * FIXME: Using memblock node mappings, an architecture may initialise its
>   * zones, allocate the backing mem_map and account for memory holes in an
>   * architecture independent manner.
>   *
> @@ -3551,7 +3552,6 @@ static inline unsigned long get_num_physpages(void)
>   *	memblock_add_node(base, size, nid, MEMBLOCK_NONE)
>   * free_area_init(max_zone_pfns);
>   */
> -void free_area_init(unsigned long *max_zone_pfn);
>  void arch_zone_limits_init(unsigned long *max_zone_pfn);
>  unsigned long node_map_pfn_alignment(void);
>  extern unsigned long absent_pages_in_range(unsigned long start_pfn,
> diff --git a/init/main.c b/init/main.c
> index b84818ad9685..445b5643ecec 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -1025,6 +1025,7 @@ void start_kernel(void)
>  	page_address_init();
>  	pr_notice("%s", linux_banner);
>  	setup_arch(&command_line);
> +	mm_core_init_early();
>  	/* Static keys and static calls are needed by LSMs */
>  	jump_label_init();
>  	static_call_init();
> diff --git a/mm/mm_init.c b/mm/mm_init.c
> index fc2a6f1e518f..ffc4a0f1fee9 100644
> --- a/mm/mm_init.c
> +++ b/mm/mm_init.c
> @@ -1810,7 +1810,6 @@ static void __init set_high_memory(void)
>  
>  /**
>   * free_area_init - Initialise all pg_data_t and zone data
> - * @max_zone_pfn: an array of max PFNs for each zone
>   *
>   * This will call free_area_init_node() for each active node in the system.
>   * Using the page ranges provided by memblock_set_node(), the size of each
> @@ -1821,17 +1820,14 @@ static void __init set_high_memory(void)
>   * starts where the previous one ended. For example, ZONE_DMA32 starts
>   * at arch_max_dma_pfn.
>   */
> -void __init free_area_init(unsigned long *max_zone_pfn)
> +static void __init free_area_init(void)
>  {
> +	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
>  	unsigned long start_pfn, end_pfn;
>  	int i, nid, zone;
>  	bool descending;
>  
> -	/* Record where the zone boundaries are */
> -	memset(arch_zone_lowest_possible_pfn, 0,
> -				sizeof(arch_zone_lowest_possible_pfn));
> -	memset(arch_zone_highest_possible_pfn, 0,
> -				sizeof(arch_zone_highest_possible_pfn));
> +	arch_zone_limits_init(max_zone_pfn);
>  
>  	start_pfn = PHYS_PFN(memblock_start_of_DRAM());
>  	descending = arch_has_descending_max_zone_pfns();
> @@ -2681,13 +2677,19 @@ void __init __weak mem_init(void)
>  {
>  }
>  
> +void __init mm_core_init_early(void)
> +{
> +	hugetlb_bootmem_alloc();
> +
> +	free_area_init();
> +}
> +
>  /*
>   * Set up kernel memory allocators
>   */
>  void __init mm_core_init(void)
>  {
>  	arch_mm_preinit();
> -	hugetlb_bootmem_alloc();
>  
>  	/* Initializations relying on SMP setup */
>  	BUILD_BUG_ON(MAX_ZONELISTS > 2);
> -- 
> 2.51.0
>
Re: [PATCH v2 22/28] arch, mm: consolidate initialization of nodes, zones and memory map
Posted by Mike Rapoport 1 month ago 
Hi,

On Sat, Jan 03, 2026 at 12:33:29AM +0100, Klara Modin wrote:
> On 2026-01-02 08:59:58 +0200, Mike Rapoport wrote:
> > From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
> > 
> > To initialize node, zone and memory map data structures every architecture
> > calls free_area_init() during setup_arch() and passes it an array of zone
> > limits.
> > 
> > Beside code duplication it creates "interesting" ordering cases between
> > allocation and initialization of hugetlb and the memory map. Some
> > architectures allocate hugetlb pages very early in setup_arch() in certain
> > cases, some only create hugetlb CMA areas in setup_arch() and sometimes
> > hugetlb allocations happen mm_core_init().
> > 
> > With arch_zone_limits_init() helper available now on all architectures it
> > is no longer necessary to call free_area_init() from architecture setup
> > code. Rather core MM initialization can call arch_zone_limits_init() in a
> > single place.
> > 
> > This allows to unify ordering of hugetlb vs memory map allocation and
> > initialization.
> > 
> > Remove the call to free_area_init() from architecture specific code and
> > place it in a new mm_core_init_early() function that is called immediately
> > after setup_arch().
> > 
> > After this refactoring it is possible to consolidate hugetlb allocations
> > and eliminate differences in ordering of hugetlb and memory map
> > initialization among different architectures.
> > 
> > As the first step of this consolidation move hugetlb_bootmem_alloc() to
> > mm_core_early_init().
> > 
> > Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> 
> This breaks boot on my Raspberry Pi 1. The reason seems to be the use of
> page_folio() when initializing the dynamically allocated zero page in
> arm, which doesn't work when free_area_init() hasn't been called yet.

I believe the reason is rather the use of virt_to_phys() that now happens
before the memory map is ready.

> The following oopses are generated:
> 
>  8<--- cut here ---
>  Unable to handle kernel paging request at virtual address 003dfb44 when read
>  [003dfb44] *pgd=00000000
>  Internal error: Oops: 5 [#1] ARM
>  CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 6.19.0-rc3-03898-g7975b0084358 #451 NONE
>  Hardware name: BCM2835
>  PC is at paging_init (include/linux/page-flags.h:284 (discriminator 2) arch/arm/mm/mmu.c:1790 (discriminator 2))
>  LR is at paging_init (arch/arm/mm/mmu.c:1789 (discriminator 1))

...

>  8<--- cut here ---
> 
> and the second one repeats for some time afterwards.
> 
> I experimented a little by allocating the zero page statically as many
> other arches do which fixes the issue as it does not need to be
> initialized at this point anymore, though I have no idea if that's
> appropriate.

Do you mean putting the zero in the BSS like, e.g. arm64? I don't see a
reason why this shouldn't work.

I also have a patch with some minor changes that still keeps
empty_zero_page allocated, but avoids virt_to_page() and folio_page()
dance. Can you please test it in your setup?

From 8a213c13211106d592fbe96b68ee29879ed739f8 Mon Sep 17 00:00:00 2001
From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
Date: Sat, 3 Jan 2026 20:40:09 +0200
Subject: [PATCH] arm: make initialization of zero page independent of the
 memory map

Unlike most architectures, arm keeps a struct page pointer to the
empty_zero_page and to initialize it requires conversion of a virtual
address to page which makes it necessary to have memory map initialized
before creating the empty_zero_page.

Make empty_zero_page a void * to decouple it's initialization from the
initialization of the memory map.

Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
 arch/arm/include/asm/pgtable.h |  4 ++--
 arch/arm/mm/mmu.c              | 10 +++-------
 arch/arm/mm/nommu.c            | 10 +++-------
 3 files changed, 8 insertions(+), 16 deletions(-)

diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 86378eec7757..08bbd2aed6c9 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -15,8 +15,8 @@
  * ZERO_PAGE is a global shared page that is always zero: used
  * for zero-mapped memory areas etc..
  */
-extern struct page *empty_zero_page;
-#define ZERO_PAGE(vaddr)	(empty_zero_page)
+extern void *empty_zero_page;
+#define ZERO_PAGE(vaddr)	(virt_to_page(empty_zero_page))
 #endif
 
 #include <asm-generic/pgtable-nopud.h>
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 8bac96e205ac..867258f1ae09 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -45,7 +45,7 @@ extern unsigned long __atags_pointer;
  * empty_zero_page is a special page that is used for
  * zero-initialized data and COW.
  */
-struct page *empty_zero_page;
+void *empty_zero_page;
 EXPORT_SYMBOL(empty_zero_page);
 
 /*
@@ -1754,8 +1754,6 @@ static void __init early_fixmap_shutdown(void)
  */
 void __init paging_init(const struct machine_desc *mdesc)
 {
-	void *zero_page;
-
 #ifdef CONFIG_XIP_KERNEL
 	/* Store the kernel RW RAM region start/end in these variables */
 	kernel_sec_start = CONFIG_PHYS_OFFSET & SECTION_MASK;
@@ -1782,12 +1780,10 @@ void __init paging_init(const struct machine_desc *mdesc)
 	top_pmd = pmd_off_k(0xffff0000);
 
 	/* allocate the zero page. */
-	zero_page = early_alloc(PAGE_SIZE);
+	empty_zero_page = early_alloc(PAGE_SIZE);
+	__cpuc_flush_dcache_area(empty_zero_page, PAGE_SIZE);
 
 	bootmem_init();
-
-	empty_zero_page = virt_to_page(zero_page);
-	__flush_dcache_folio(NULL, page_folio(empty_zero_page));
 }
 
 void __init early_mm_init(const struct machine_desc *mdesc)
diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c
index d638cc87807e..f80ff5a69fbb 100644
--- a/arch/arm/mm/nommu.c
+++ b/arch/arm/mm/nommu.c
@@ -31,7 +31,7 @@ unsigned long vectors_base;
  * empty_zero_page is a special page that is used for
  * zero-initialized data and COW.
  */
-struct page *empty_zero_page;
+void *empty_zero_page;
 EXPORT_SYMBOL(empty_zero_page);
 
 #ifdef CONFIG_ARM_MPU
@@ -156,18 +156,14 @@ void __init adjust_lowmem_bounds(void)
  */
 void __init paging_init(const struct machine_desc *mdesc)
 {
-	void *zero_page;
-
 	early_trap_init((void *)vectors_base);
 	mpu_setup();
 
 	/* allocate the zero page. */
-	zero_page = (void *)memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
+	empty_zero_page = memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
+	__cpuc_flush_dcache_area(empty_zero_page, PAGE_SIZE);
 
 	bootmem_init();
-
-	empty_zero_page = virt_to_page(zero_page);
-	flush_dcache_page(empty_zero_page);
 }
 
 /*
-- 
2.51.0

 
> Regards,
> Klara Modin
> 

-- 
Sincerely yours,
Mike.
Re: [PATCH v2 22/28] arch, mm: consolidate initialization of nodes, zones and memory map
Posted by Klara Modin 1 month ago 
Hi,

On 2026-01-03 20:54:23 +0200, Mike Rapoport wrote:
> Hi,
> 
> On Sat, Jan 03, 2026 at 12:33:29AM +0100, Klara Modin wrote:
> > On 2026-01-02 08:59:58 +0200, Mike Rapoport wrote:
> > > From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
> > > 
> > > To initialize node, zone and memory map data structures every architecture
> > > calls free_area_init() during setup_arch() and passes it an array of zone
> > > limits.
> > > 
> > > Beside code duplication it creates "interesting" ordering cases between
> > > allocation and initialization of hugetlb and the memory map. Some
> > > architectures allocate hugetlb pages very early in setup_arch() in certain
> > > cases, some only create hugetlb CMA areas in setup_arch() and sometimes
> > > hugetlb allocations happen mm_core_init().
> > > 
> > > With arch_zone_limits_init() helper available now on all architectures it
> > > is no longer necessary to call free_area_init() from architecture setup
> > > code. Rather core MM initialization can call arch_zone_limits_init() in a
> > > single place.
> > > 
> > > This allows to unify ordering of hugetlb vs memory map allocation and
> > > initialization.
> > > 
> > > Remove the call to free_area_init() from architecture specific code and
> > > place it in a new mm_core_init_early() function that is called immediately
> > > after setup_arch().
> > > 
> > > After this refactoring it is possible to consolidate hugetlb allocations
> > > and eliminate differences in ordering of hugetlb and memory map
> > > initialization among different architectures.
> > > 
> > > As the first step of this consolidation move hugetlb_bootmem_alloc() to
> > > mm_core_early_init().
> > > 
> > > Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> > 
> > This breaks boot on my Raspberry Pi 1. The reason seems to be the use of
> > page_folio() when initializing the dynamically allocated zero page in
> > arm, which doesn't work when free_area_init() hasn't been called yet.
> 
> I believe the reason is rather the use of virt_to_phys() that now happens
> before the memory map is ready.
> 

Right, that makes sense, the fault just becomes apparent when
page_folio() is called on some bogus address then?

> > The following oopses are generated:
> > 
> >  8<--- cut here ---
> >  Unable to handle kernel paging request at virtual address 003dfb44 when read
> >  [003dfb44] *pgd=00000000
> >  Internal error: Oops: 5 [#1] ARM
> >  CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 6.19.0-rc3-03898-g7975b0084358 #451 NONE
> >  Hardware name: BCM2835
> >  PC is at paging_init (include/linux/page-flags.h:284 (discriminator 2) arch/arm/mm/mmu.c:1790 (discriminator 2))
> >  LR is at paging_init (arch/arm/mm/mmu.c:1789 (discriminator 1))
> 
> ...
> 
> >  8<--- cut here ---
> > 
> > and the second one repeats for some time afterwards.
> > 
> > I experimented a little by allocating the zero page statically as many
> > other arches do which fixes the issue as it does not need to be
> > initialized at this point anymore, though I have no idea if that's
> > appropriate.
> 
> Do you mean putting the zero in the BSS like, e.g. arm64? I don't see a
> reason why this shouldn't work.
> 

Yes, exactly that. The diff I had was:

diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 86378eec7757..6fa9acd6a7f5 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -15,8 +15,8 @@
  * ZERO_PAGE is a global shared page that is always zero: used
  * for zero-mapped memory areas etc..
  */
-extern struct page *empty_zero_page;
-#define ZERO_PAGE(vaddr)	(empty_zero_page)
+extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
+#define ZERO_PAGE(vaddr)	(virt_to_page(empty_zero_page))
 #endif
 
 #include <asm-generic/pgtable-nopud.h>
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 8bac96e205ac..518def8314e7 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -45,7 +45,7 @@ extern unsigned long __atags_pointer;
  * empty_zero_page is a special page that is used for
  * zero-initialized data and COW.
  */
-struct page *empty_zero_page;
+unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss;
 EXPORT_SYMBOL(empty_zero_page);
 
 /*
@@ -1754,8 +1754,6 @@ static void __init early_fixmap_shutdown(void)
  */
 void __init paging_init(const struct machine_desc *mdesc)
 {
-	void *zero_page;
-
 #ifdef CONFIG_XIP_KERNEL
 	/* Store the kernel RW RAM region start/end in these variables */
 	kernel_sec_start = CONFIG_PHYS_OFFSET & SECTION_MASK;
@@ -1781,13 +1779,7 @@ void __init paging_init(const struct machine_desc *mdesc)
 
 	top_pmd = pmd_off_k(0xffff0000);
 
-	/* allocate the zero page. */
-	zero_page = early_alloc(PAGE_SIZE);
-
 	bootmem_init();
-
-	empty_zero_page = virt_to_page(zero_page);
-	__flush_dcache_folio(NULL, page_folio(empty_zero_page));
 }
 
 void __init early_mm_init(const struct machine_desc *mdesc)
diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c
index d638cc87807e..7e42d8accec6 100644
--- a/arch/arm/mm/nommu.c
+++ b/arch/arm/mm/nommu.c
@@ -31,7 +31,7 @@ unsigned long vectors_base;
  * empty_zero_page is a special page that is used for
  * zero-initialized data and COW.
  */
-struct page *empty_zero_page;
+unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss;
 EXPORT_SYMBOL(empty_zero_page);
 
 #ifdef CONFIG_ARM_MPU
@@ -156,18 +156,10 @@ void __init adjust_lowmem_bounds(void)
  */
 void __init paging_init(const struct machine_desc *mdesc)
 {
-	void *zero_page;
-
 	early_trap_init((void *)vectors_base);
 	mpu_setup();
 
-	/* allocate the zero page. */
-	zero_page = (void *)memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
-
 	bootmem_init();
-
-	empty_zero_page = virt_to_page(zero_page);
-	flush_dcache_page(empty_zero_page);
 }
 
 /*

> I also have a patch with some minor changes that still keeps
> empty_zero_page allocated, but avoids virt_to_page() and folio_page()
> dance. Can you please test it in your setup?
> 
> From 8a213c13211106d592fbe96b68ee29879ed739f8 Mon Sep 17 00:00:00 2001
> From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
> Date: Sat, 3 Jan 2026 20:40:09 +0200
> Subject: [PATCH] arm: make initialization of zero page independent of the
>  memory map
> 
> Unlike most architectures, arm keeps a struct page pointer to the
> empty_zero_page and to initialize it requires conversion of a virtual
> address to page which makes it necessary to have memory map initialized
> before creating the empty_zero_page.
> 
> Make empty_zero_page a void * to decouple it's initialization from the
> initialization of the memory map.
> 
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> ---
>  arch/arm/include/asm/pgtable.h |  4 ++--
>  arch/arm/mm/mmu.c              | 10 +++-------
>  arch/arm/mm/nommu.c            | 10 +++-------
>  3 files changed, 8 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
> index 86378eec7757..08bbd2aed6c9 100644
> --- a/arch/arm/include/asm/pgtable.h
> +++ b/arch/arm/include/asm/pgtable.h
> @@ -15,8 +15,8 @@
>   * ZERO_PAGE is a global shared page that is always zero: used
>   * for zero-mapped memory areas etc..
>   */
> -extern struct page *empty_zero_page;
> -#define ZERO_PAGE(vaddr)	(empty_zero_page)
> +extern void *empty_zero_page;
> +#define ZERO_PAGE(vaddr)	(virt_to_page(empty_zero_page))
>  #endif
>  
>  #include <asm-generic/pgtable-nopud.h>
> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> index 8bac96e205ac..867258f1ae09 100644
> --- a/arch/arm/mm/mmu.c
> +++ b/arch/arm/mm/mmu.c
> @@ -45,7 +45,7 @@ extern unsigned long __atags_pointer;
>   * empty_zero_page is a special page that is used for
>   * zero-initialized data and COW.
>   */
> -struct page *empty_zero_page;
> +void *empty_zero_page;
>  EXPORT_SYMBOL(empty_zero_page);
>  
>  /*
> @@ -1754,8 +1754,6 @@ static void __init early_fixmap_shutdown(void)
>   */
>  void __init paging_init(const struct machine_desc *mdesc)
>  {
> -	void *zero_page;
> -
>  #ifdef CONFIG_XIP_KERNEL
>  	/* Store the kernel RW RAM region start/end in these variables */
>  	kernel_sec_start = CONFIG_PHYS_OFFSET & SECTION_MASK;
> @@ -1782,12 +1780,10 @@ void __init paging_init(const struct machine_desc *mdesc)
>  	top_pmd = pmd_off_k(0xffff0000);
>  
>  	/* allocate the zero page. */
> -	zero_page = early_alloc(PAGE_SIZE);
> +	empty_zero_page = early_alloc(PAGE_SIZE);
> +	__cpuc_flush_dcache_area(empty_zero_page, PAGE_SIZE);
>  
>  	bootmem_init();
> -
> -	empty_zero_page = virt_to_page(zero_page);
> -	__flush_dcache_folio(NULL, page_folio(empty_zero_page));
>  }
>  
>  void __init early_mm_init(const struct machine_desc *mdesc)
> diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c
> index d638cc87807e..f80ff5a69fbb 100644
> --- a/arch/arm/mm/nommu.c
> +++ b/arch/arm/mm/nommu.c
> @@ -31,7 +31,7 @@ unsigned long vectors_base;
>   * empty_zero_page is a special page that is used for
>   * zero-initialized data and COW.
>   */
> -struct page *empty_zero_page;
> +void *empty_zero_page;
>  EXPORT_SYMBOL(empty_zero_page);
>  
>  #ifdef CONFIG_ARM_MPU
> @@ -156,18 +156,14 @@ void __init adjust_lowmem_bounds(void)
>   */
>  void __init paging_init(const struct machine_desc *mdesc)
>  {
> -	void *zero_page;
> -
>  	early_trap_init((void *)vectors_base);
>  	mpu_setup();
>  
>  	/* allocate the zero page. */
> -	zero_page = (void *)memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
> +	empty_zero_page = memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
> +	__cpuc_flush_dcache_area(empty_zero_page, PAGE_SIZE);
>  
>  	bootmem_init();
> -
> -	empty_zero_page = virt_to_page(zero_page);
> -	flush_dcache_page(empty_zero_page);
>  }
>  
>  /*
> -- 
> 2.51.0
> 

This also works for me.

Thanks,
Tested-by: Klara Modin <klarasmodin@gmail.com>

>  
> > Regards,
> > Klara Modin
> > 
> 
> -- 
> Sincerely yours,
> Mike.
[PATCH 3.5] arm: make initialization of zero page independent of the memory map (was Re: [PATCH v2 22/28] arch, mm: consolidate initialization of nodes, zones and memory map)
Posted by Mike Rapoport 1 month ago 
Andrew,

Can you please stick this between patch 3 (arm: introduce
arch_zone_limits_init()) and patch 4 (arm64: introduce
arch_zone_limits_init())?

From 35d016bbf5da7c08cc5c5547c85558fc50cb63aa Mon Sep 17 00:00:00 2001
From: Klara Modin <klarasmodin@gmail.com>
Date: Sat, 3 Jan 2026 20:40:09 +0200
Subject: [PATCH] arm: make initialization of zero page independent of the
 memory map

Unlike most architectures, arm keeps a struct page pointer to the
empty_zero_page and to initialize it requires conversion of a virtual
address to page which makes it necessary to have memory map initialized
before creating the empty_zero_page.

Make empty_zero_page a stataic array in BSS to decouple it's
initialization from the initialization of the memory map.

This also aligns arm with vast majorty of architectures.

Signed-off-by: Klara Modin <klarasmodin@gmail.com>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
 arch/arm/include/asm/pgtable.h |  4 ++--
 arch/arm/mm/mmu.c              | 10 +---------
 arch/arm/mm/nommu.c            | 10 +---------
 3 files changed, 4 insertions(+), 20 deletions(-)

diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 86378eec7757..6fa9acd6a7f5 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -15,8 +15,8 @@
  * ZERO_PAGE is a global shared page that is always zero: used
  * for zero-mapped memory areas etc..
  */
-extern struct page *empty_zero_page;
-#define ZERO_PAGE(vaddr)	(empty_zero_page)
+extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
+#define ZERO_PAGE(vaddr)	(virt_to_page(empty_zero_page))
 #endif
 
 #include <asm-generic/pgtable-nopud.h>
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 8bac96e205ac..518def8314e7 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -45,7 +45,7 @@ extern unsigned long __atags_pointer;
  * empty_zero_page is a special page that is used for
  * zero-initialized data and COW.
  */
-struct page *empty_zero_page;
+unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss;
 EXPORT_SYMBOL(empty_zero_page);
 
 /*
@@ -1754,8 +1754,6 @@ static void __init early_fixmap_shutdown(void)
  */
 void __init paging_init(const struct machine_desc *mdesc)
 {
-	void *zero_page;
-
 #ifdef CONFIG_XIP_KERNEL
 	/* Store the kernel RW RAM region start/end in these variables */
 	kernel_sec_start = CONFIG_PHYS_OFFSET & SECTION_MASK;
@@ -1781,13 +1779,7 @@ void __init paging_init(const struct machine_desc *mdesc)
 
 	top_pmd = pmd_off_k(0xffff0000);
 
-	/* allocate the zero page. */
-	zero_page = early_alloc(PAGE_SIZE);
-
 	bootmem_init();
-
-	empty_zero_page = virt_to_page(zero_page);
-	__flush_dcache_folio(NULL, page_folio(empty_zero_page));
 }
 
 void __init early_mm_init(const struct machine_desc *mdesc)
diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c
index d638cc87807e..7e42d8accec6 100644
--- a/arch/arm/mm/nommu.c
+++ b/arch/arm/mm/nommu.c
@@ -31,7 +31,7 @@ unsigned long vectors_base;
  * empty_zero_page is a special page that is used for
  * zero-initialized data and COW.
  */
-struct page *empty_zero_page;
+unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss;
 EXPORT_SYMBOL(empty_zero_page);
 
 #ifdef CONFIG_ARM_MPU
@@ -156,18 +156,10 @@ void __init adjust_lowmem_bounds(void)
  */
 void __init paging_init(const struct machine_desc *mdesc)
 {
-	void *zero_page;
-
 	early_trap_init((void *)vectors_base);
 	mpu_setup();
 
-	/* allocate the zero page. */
-	zero_page = (void *)memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
-
 	bootmem_init();
-
-	empty_zero_page = virt_to_page(zero_page);
-	flush_dcache_page(empty_zero_page);
 }
 
 /*
-- 
2.51.0
Re: [PATCH 3.5] arm: make initialization of zero page independent of the memory map (was Re: [PATCH v2 22/28] arch, mm: consolidate initialization of nodes, zones and memory map)
Posted by Andrew Morton 1 month ago 
On Sun, 4 Jan 2026 14:01:40 +0200 Mike Rapoport <rppt@kernel.org> wrote:

> Can you please stick this between patch 3 (arm: introduce
> arch_zone_limits_init()) and patch 4 (arm64: introduce
> arch_zone_limits_init())?

Did, thanks.  I made this a standalone patch rather than  a
squashable -fix.

> >From 35d016bbf5da7c08cc5c5547c85558fc50cb63aa Mon Sep 17 00:00:00 2001
> From: Klara Modin <klarasmodin@gmail.com>
> Date: Sat, 3 Jan 2026 20:40:09 +0200
> Subject: [PATCH] arm: make initialization of zero page independent of the
>  memory map
> 
> Unlike most architectures, arm keeps a struct page pointer to the
> empty_zero_page and to initialize it requires conversion of a virtual
> address to page which makes it necessary to have memory map initialized
> before creating the empty_zero_page.
> 
> Make empty_zero_page a stataic array in BSS to decouple it's
> initialization from the initialization of the memory map.
> 
> This also aligns arm with vast majorty of architectures.

Russell, can you please update us on your concerns with this change?
Re: [PATCH 3.5] arm: make initialization of zero page independent of the memory map (was Re: [PATCH v2 22/28] arch, mm: consolidate initialization of nodes, zones and memory map)
Posted by Russell King (Oracle) 1 month ago 
On Sun, Jan 04, 2026 at 02:01:40PM +0200, Mike Rapoport wrote:
> From 35d016bbf5da7c08cc5c5547c85558fc50cb63aa Mon Sep 17 00:00:00 2001
> From: Klara Modin <klarasmodin@gmail.com>
> Date: Sat, 3 Jan 2026 20:40:09 +0200
> Subject: [PATCH] arm: make initialization of zero page independent of the
>  memory map
> 
> Unlike most architectures, arm keeps a struct page pointer to the
> empty_zero_page and to initialize it requires conversion of a virtual
> address to page which makes it necessary to have memory map initialized
> before creating the empty_zero_page.
> 
> Make empty_zero_page a stataic array in BSS to decouple it's
> initialization from the initialization of the memory map.

I see you haven't considered _why_ ARM does this.

You are getting rid of the flush_dcache_page() call, which ensures
that the zeroed contents of the page are pushed out of the cache
into memory. This is necessary.

BSS is very similar. It's memset() during the kernel boot _after_
the caches are enabled. Without an explicit flush, nothing
guarantees that those writes will be visible to userspace.

To me, this seems like a bad idea, which will cause userspace to
break.

We need to call flush_dcache_page(), and _that_ requires a struct
page.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!
Re: [PATCH 3.5] arm: make initialization of zero page independent of the memory map (was Re: [PATCH v2 22/28] arch, mm: consolidate initialization of nodes, zones and memory map)
Posted by Mike Rapoport 1 month ago 
On Sun, Jan 04, 2026 at 08:56:45PM +0000, Russell King (Oracle) wrote:
> On Sun, Jan 04, 2026 at 02:01:40PM +0200, Mike Rapoport wrote:
> > From 35d016bbf5da7c08cc5c5547c85558fc50cb63aa Mon Sep 17 00:00:00 2001
> > From: Klara Modin <klarasmodin@gmail.com>
> > Date: Sat, 3 Jan 2026 20:40:09 +0200
> > Subject: [PATCH] arm: make initialization of zero page independent of the
> >  memory map
> > 
> > Unlike most architectures, arm keeps a struct page pointer to the
> > empty_zero_page and to initialize it requires conversion of a virtual
> > address to page which makes it necessary to have memory map initialized
> > before creating the empty_zero_page.
> > 
> > Make empty_zero_page a stataic array in BSS to decouple it's
> > initialization from the initialization of the memory map.
> 
> I see you haven't considered _why_ ARM does this.
> 
> You are getting rid of the flush_dcache_page() call, which ensures
> that the zeroed contents of the page are pushed out of the cache
> into memory. This is necessary.
> 
> BSS is very similar. It's memset() during the kernel boot _after_
> the caches are enabled. Without an explicit flush, nothing
> guarantees that those writes will be visible to userspace.

There's a call to flush_cache_all() paging_init()->devicemaps_init() that
will guarantee that those writes are flushed long before userspace starts.
 
> To me, this seems like a bad idea, which will cause userspace to
> break.
> 
> We need to call flush_dcache_page(), and _that_ requires a struct
> page.

Right now there's __flush_dcache_folio() that will break anyway when folio
divorces from struct page.   

-- 
Sincerely yours,
Mike.

Patchew 2.1-devel-b67e4c2

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