The patch titled
Subject: arch, mm: set max_mapnr when allocating memory map for FLATMEM
has been added to the -mm mm-unstable branch. Its filename is
arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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and is updated there every 2-3 working days
------------------------------------------------------
From: "Mike Rapoport (Microsoft)" <rppt@xxxxxxxxxx>
Subject: arch, mm: set max_mapnr when allocating memory map for FLATMEM
Date: Thu, 13 Mar 2025 15:49:59 +0200
max_mapnr is essentially the size of the memory map for systems that use
FLATMEM. There is no reason to calculate it in each and every architecture
when it's anyway calculated in alloc_node_mem_map().
Drop setting of max_mapnr from architecture code and set it once in
alloc_node_mem_map().
While on it, move definition of mem_map and max_mapnr to mm/mm_init.c so
there won't be two copies for MMU and !MMU variants.
Link: https://lkml.kernel.org/r/20250313135003.836600-10-rppt@xxxxxxxxxx
Signed-off-by: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>
Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> [x86]
Tested-by: Mark Brown <broonie@xxxxxxxxxx>
Cc: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Cc: Andreas Larsson <andreas@xxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Borislav Betkov <bp@xxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Dinh Nguyen <dinguyen@xxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx>
Cc: Guo Ren (csky) <guoren@xxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Helge Deller <deller@xxxxxx>
Cc: Huacai Chen <chenhuacai@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>
Cc: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Cc: John Paul Adrian Glaubitz <glaubitz@xxxxxxxxxxxxxxxxxxx>
Cc: Madhavan Srinivasan <maddy@xxxxxxxxxxxxx>
Cc: Matt Turner <mattst88@xxxxxxxxx>
Cc: Max Filippov <jcmvbkbc@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Michal Simek <monstr@xxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>
Cc: Richard Weinberger <richard@xxxxxx>
Cc: Russel King <linux@xxxxxxxxxxxxxxx>
Cc: Stafford Horne <shorne@xxxxxxxxx>
Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Cc: Thomas Gleinxer <tglx@xxxxxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Vineet Gupta <vgupta@xxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/alpha/mm/init.c | 1 -
arch/arc/mm/init.c | 5 -----
arch/arm/mm/init.c | 2 --
arch/csky/mm/init.c | 4 ----
arch/loongarch/mm/init.c | 1 -
arch/microblaze/mm/init.c | 4 ----
arch/mips/mm/init.c | 8 --------
arch/nios2/kernel/setup.c | 1 -
arch/nios2/mm/init.c | 2 +-
arch/openrisc/mm/init.c | 1 -
arch/parisc/mm/init.c | 1 -
arch/powerpc/kernel/setup-common.c | 2 --
arch/riscv/mm/init.c | 1 -
arch/s390/mm/init.c | 1 -
arch/sh/mm/init.c | 1 -
arch/sparc/mm/init_32.c | 1 -
arch/um/include/shared/mem_user.h | 1 -
arch/um/kernel/physmem.c | 12 ------------
arch/um/kernel/um_arch.c | 1 -
arch/x86/mm/init_32.c | 3 ---
arch/xtensa/mm/init.c | 1 -
include/asm-generic/memory_model.h | 5 +++--
include/linux/mm.h | 11 -----------
mm/memory.c | 8 --------
mm/mm_init.c | 25 +++++++++++++++++--------
mm/nommu.c | 4 ----
26 files changed, 21 insertions(+), 86 deletions(-)
--- a/arch/alpha/mm/init.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/alpha/mm/init.c
@@ -276,7 +276,6 @@ srm_paging_stop (void)
void __init
mem_init(void)
{
- set_max_mapnr(max_low_pfn);
high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
memblock_free_all();
}
--- a/arch/arc/mm/init.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/arc/mm/init.c
@@ -154,11 +154,6 @@ void __init setup_arch_memory(void)
arch_pfn_offset = min(min_low_pfn, min_high_pfn);
kmap_init();
-
-#else /* CONFIG_HIGHMEM */
- /* pfn_valid() uses this when FLATMEM=y and HIGHMEM=n */
- max_mapnr = max_low_pfn - min_low_pfn;
-
#endif /* CONFIG_HIGHMEM */
free_area_init(max_zone_pfn);
--- a/arch/arm/mm/init.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/arm/mm/init.c
@@ -275,8 +275,6 @@ void __init mem_init(void)
swiotlb_init(max_pfn > arm_dma_pfn_limit, SWIOTLB_VERBOSE);
#endif
- set_max_mapnr(pfn_to_page(max_pfn) - mem_map);
-
#ifdef CONFIG_SA1111
/* now that our DMA memory is actually so designated, we can free it */
memblock_phys_free(PHYS_OFFSET, __pa(swapper_pg_dir) - PHYS_OFFSET);
--- a/arch/csky/mm/init.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/csky/mm/init.c
@@ -46,10 +46,6 @@ void __init mem_init(void)
{
#ifdef CONFIG_HIGHMEM
unsigned long tmp;
-
- set_max_mapnr(highend_pfn - ARCH_PFN_OFFSET);
-#else
- set_max_mapnr(max_low_pfn - ARCH_PFN_OFFSET);
#endif
high_memory = (void *) __va(max_low_pfn << PAGE_SHIFT);
--- a/arch/loongarch/mm/init.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/loongarch/mm/init.c
@@ -78,7 +78,6 @@ void __init paging_init(void)
void __init mem_init(void)
{
- max_mapnr = max_low_pfn;
high_memory = (void *) __va(max_low_pfn << PAGE_SHIFT);
memblock_free_all();
--- a/arch/microblaze/mm/init.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/microblaze/mm/init.c
@@ -104,17 +104,13 @@ void __init setup_memory(void)
*
* min_low_pfn - the first page (mm/bootmem.c - node_boot_start)
* max_low_pfn
- * max_mapnr - the first unused page (mm/bootmem.c - node_low_pfn)
*/
/* memory start is from the kernel end (aligned) to higher addr */
min_low_pfn = memory_start >> PAGE_SHIFT; /* minimum for allocation */
- /* RAM is assumed contiguous */
- max_mapnr = memory_size >> PAGE_SHIFT;
max_low_pfn = ((u64)memory_start + (u64)lowmem_size) >> PAGE_SHIFT;
max_pfn = ((u64)memory_start + (u64)memory_size) >> PAGE_SHIFT;
- pr_info("%s: max_mapnr: %#lx\n", __func__, max_mapnr);
pr_info("%s: min_low_pfn: %#lx\n", __func__, min_low_pfn);
pr_info("%s: max_low_pfn: %#lx\n", __func__, max_low_pfn);
pr_info("%s: max_pfn: %#lx\n", __func__, max_pfn);
--- a/arch/mips/mm/init.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/mips/mm/init.c
@@ -415,15 +415,7 @@ void __init paging_init(void)
" %ldk highmem ignored\n",
(highend_pfn - max_low_pfn) << (PAGE_SHIFT - 10));
max_zone_pfns[ZONE_HIGHMEM] = max_low_pfn;
-
- max_mapnr = max_low_pfn;
- } else if (highend_pfn) {
- max_mapnr = highend_pfn;
- } else {
- max_mapnr = max_low_pfn;
}
-#else
- max_mapnr = max_low_pfn;
#endif
high_memory = (void *) __va(max_low_pfn << PAGE_SHIFT);
--- a/arch/nios2/kernel/setup.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/nios2/kernel/setup.c
@@ -158,7 +158,6 @@ void __init setup_arch(char **cmdline_p)
*cmdline_p = boot_command_line;
find_limits(&min_low_pfn, &max_low_pfn, &max_pfn);
- max_mapnr = max_low_pfn;
memblock_reserve(__pa_symbol(_stext), _end - _stext);
#ifdef CONFIG_BLK_DEV_INITRD
--- a/arch/nios2/mm/init.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/nios2/mm/init.c
@@ -51,7 +51,7 @@ void __init paging_init(void)
pagetable_init();
pgd_current = swapper_pg_dir;
- max_zone_pfn[ZONE_NORMAL] = max_mapnr;
+ max_zone_pfn[ZONE_NORMAL] = max_low_pfn;
/* pass the memory from the bootmem allocator to the main allocator */
free_area_init(max_zone_pfn);
--- a/arch/openrisc/mm/init.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/openrisc/mm/init.c
@@ -193,7 +193,6 @@ void __init mem_init(void)
{
BUG_ON(!mem_map);
- max_mapnr = max_low_pfn;
high_memory = (void *)__va(max_low_pfn * PAGE_SIZE);
/* clear the zero-page */
--- a/arch/parisc/mm/init.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/parisc/mm/init.c
@@ -563,7 +563,6 @@ void __init mem_init(void)
#endif
high_memory = __va((max_pfn << PAGE_SHIFT));
- set_max_mapnr(max_low_pfn);
memblock_free_all();
#ifdef CONFIG_PA11
--- a/arch/powerpc/kernel/setup-common.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/powerpc/kernel/setup-common.c
@@ -957,8 +957,6 @@ void __init setup_arch(char **cmdline_p)
/* Parse memory topology */
mem_topology_setup();
- /* Set max_mapnr before paging_init() */
- set_max_mapnr(max_pfn);
high_memory = (void *)__va(max_low_pfn * PAGE_SIZE);
/*
--- a/arch/riscv/mm/init.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/riscv/mm/init.c
@@ -298,7 +298,6 @@ static void __init setup_bootmem(void)
high_memory = (void *)(__va(PFN_PHYS(max_low_pfn)));
dma32_phys_limit = min(4UL * SZ_1G, (unsigned long)PFN_PHYS(max_low_pfn));
- set_max_mapnr(max_low_pfn - ARCH_PFN_OFFSET);
reserve_initrd_mem();
--- a/arch/s390/mm/init.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/s390/mm/init.c
@@ -159,7 +159,6 @@ void __init mem_init(void)
cpumask_set_cpu(0, &init_mm.context.cpu_attach_mask);
cpumask_set_cpu(0, mm_cpumask(&init_mm));
- set_max_mapnr(max_low_pfn);
high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
pv_init();
--- a/arch/sh/mm/init.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/sh/mm/init.c
@@ -290,7 +290,6 @@ void __init paging_init(void)
*/
max_low_pfn = max_pfn = memblock_end_of_DRAM() >> PAGE_SHIFT;
min_low_pfn = __MEMORY_START >> PAGE_SHIFT;
- set_max_mapnr(max_low_pfn - min_low_pfn);
nodes_clear(node_online_map);
--- a/arch/sparc/mm/init_32.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/sparc/mm/init_32.c
@@ -275,7 +275,6 @@ void __init mem_init(void)
taint_real_pages();
- max_mapnr = last_valid_pfn - pfn_base;
high_memory = __va(max_low_pfn << PAGE_SHIFT);
memblock_free_all();
--- a/arch/um/include/shared/mem_user.h~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/um/include/shared/mem_user.h
@@ -47,7 +47,6 @@ extern int iomem_size;
#define ROUND_4M(n) ((((unsigned long) (n)) + (1 << 22)) & ~((1 << 22) - 1))
extern unsigned long find_iomem(char *driver, unsigned long *len_out);
-extern void mem_total_pages(unsigned long physmem, unsigned long iomem);
extern void setup_physmem(unsigned long start, unsigned long usable,
unsigned long len);
extern void map_memory(unsigned long virt, unsigned long phys,
--- a/arch/um/kernel/physmem.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/um/kernel/physmem.c
@@ -22,18 +22,6 @@ static int physmem_fd = -1;
unsigned long high_physmem;
EXPORT_SYMBOL(high_physmem);
-void __init mem_total_pages(unsigned long physmem, unsigned long iomem)
-{
- unsigned long phys_pages, iomem_pages, total_pages;
-
- phys_pages = physmem >> PAGE_SHIFT;
- iomem_pages = iomem >> PAGE_SHIFT;
-
- total_pages = phys_pages + iomem_pages;
-
- max_mapnr = total_pages;
-}
-
void map_memory(unsigned long virt, unsigned long phys, unsigned long len,
int r, int w, int x)
{
--- a/arch/um/kernel/um_arch.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/um/kernel/um_arch.c
@@ -419,7 +419,6 @@ void __init setup_arch(char **cmdline_p)
stack_protections((unsigned long) init_task.stack);
setup_physmem(uml_physmem, uml_reserved, physmem_size);
- mem_total_pages(physmem_size, iomem_size);
uml_dtb_init();
read_initrd();
--- a/arch/x86/mm/init_32.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/x86/mm/init_32.c
@@ -650,9 +650,6 @@ void __init initmem_init(void)
memblock_set_node(0, PHYS_ADDR_MAX, &memblock.memory, 0);
-#ifdef CONFIG_FLATMEM
- max_mapnr = IS_ENABLED(CONFIG_HIGHMEM) ? highend_pfn : max_low_pfn;
-#endif
__vmalloc_start_set = true;
printk(KERN_NOTICE "%ldMB LOWMEM available.\n",
--- a/arch/xtensa/mm/init.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/arch/xtensa/mm/init.c
@@ -164,7 +164,6 @@ void __init mem_init(void)
{
free_highpages();
- max_mapnr = max_pfn - ARCH_PFN_OFFSET;
high_memory = (void *)__va(max_low_pfn << PAGE_SHIFT);
memblock_free_all();
--- a/include/asm-generic/memory_model.h~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/include/asm-generic/memory_model.h
@@ -19,11 +19,12 @@
#define __page_to_pfn(page) ((unsigned long)((page) - mem_map) + \
ARCH_PFN_OFFSET)
+/* avoid <linux/mm.h> include hell */
+extern unsigned long max_mapnr;
+
#ifndef pfn_valid
static inline int pfn_valid(unsigned long pfn)
{
- /* avoid <linux/mm.h> include hell */
- extern unsigned long max_mapnr;
unsigned long pfn_offset = ARCH_PFN_OFFSET;
return pfn >= pfn_offset && (pfn - pfn_offset) < max_mapnr;
--- a/include/linux/mm.h~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/include/linux/mm.h
@@ -46,17 +46,6 @@ extern int sysctl_page_lock_unfairness;
void mm_core_init(void);
void init_mm_internals(void);
-#ifndef CONFIG_NUMA /* Don't use mapnrs, do it properly */
-extern unsigned long max_mapnr;
-
-static inline void set_max_mapnr(unsigned long limit)
-{
- max_mapnr = limit;
-}
-#else
-static inline void set_max_mapnr(unsigned long limit) { }
-#endif
-
extern atomic_long_t _totalram_pages;
static inline unsigned long totalram_pages(void)
{
--- a/mm/memory.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/mm/memory.c
@@ -95,14 +95,6 @@
#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
#endif
-#ifndef CONFIG_NUMA
-unsigned long max_mapnr;
-EXPORT_SYMBOL(max_mapnr);
-
-struct page *mem_map;
-EXPORT_SYMBOL(mem_map);
-#endif
-
static vm_fault_t do_fault(struct vm_fault *vmf);
static vm_fault_t do_anonymous_page(struct vm_fault *vmf);
static bool vmf_pte_changed(struct vm_fault *vmf);
--- a/mm/mm_init.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/mm/mm_init.c
@@ -37,6 +37,14 @@
#include <asm/setup.h>
+#ifndef CONFIG_NUMA
+unsigned long max_mapnr;
+EXPORT_SYMBOL(max_mapnr);
+
+struct page *mem_map;
+EXPORT_SYMBOL(mem_map);
+#endif
+
#ifdef CONFIG_DEBUG_MEMORY_INIT
int __meminitdata mminit_loglevel;
@@ -1639,7 +1647,7 @@ static void __init alloc_node_mem_map(st
start = pgdat->node_start_pfn & ~(MAX_ORDER_NR_PAGES - 1);
offset = pgdat->node_start_pfn - start;
/*
- * The zone's endpoints aren't required to be MAX_PAGE_ORDER
+ * The zone's endpoints aren't required to be MAX_PAGE_ORDER
* aligned but the node_mem_map endpoints must be in order
* for the buddy allocator to function correctly.
*/
@@ -1655,14 +1663,15 @@ static void __init alloc_node_mem_map(st
pr_debug("%s: node %d, pgdat %08lx, node_mem_map %08lx\n",
__func__, pgdat->node_id, (unsigned long)pgdat,
(unsigned long)pgdat->node_mem_map);
-#ifndef CONFIG_NUMA
+
/* the global mem_map is just set as node 0's */
- if (pgdat == NODE_DATA(0)) {
- mem_map = NODE_DATA(0)->node_mem_map;
- if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
- mem_map -= offset;
- }
-#endif
+ WARN_ON(pgdat != NODE_DATA(0));
+
+ mem_map = pgdat->node_mem_map;
+ if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
+ mem_map -= offset;
+
+ max_mapnr = end - start;
}
#else
static inline void alloc_node_mem_map(struct pglist_data *pgdat) { }
--- a/mm/nommu.c~arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem
+++ a/mm/nommu.c
@@ -44,16 +44,12 @@
void *high_memory;
EXPORT_SYMBOL(high_memory);
-struct page *mem_map;
-unsigned long max_mapnr;
-EXPORT_SYMBOL(max_mapnr);
unsigned long highest_memmap_pfn;
int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
int heap_stack_gap = 0;
atomic_long_t mmap_pages_allocated;
-EXPORT_SYMBOL(mem_map);
/* list of mapped, potentially shareable regions */
static struct kmem_cache *vm_region_jar;
_
Patches currently in -mm which might be from rppt@xxxxxxxxxx are
arm-mem_init-use-memblock_phys_free-to-free-dma-memory-on-sa1111.patch
csky-move-setup_initrd-to-setupc.patch
hexagon-move-initialization-of-init_mmcontext-init-to-paging_init.patch
mips-consolidate-mem_init-for-numa-machines.patch
mips-make-setup_zero_pages-use-memblock.patch
nios2-move-pr_debug-about-memory-start-and-end-to-setup_arch.patch
s390-make-setup_zero_pages-use-memblock.patch
xtensa-split-out-printing-of-virtual-memory-layout-to-a-function.patch
arch-mm-set-max_mapnr-when-allocating-memory-map-for-flatmem.patch
arch-mm-set-high_memory-in-free_area_init.patch
arch-mm-streamline-highmem-freeing.patch
arch-mm-introduce-arch_mm_preinit.patch
arch-mm-make-releasing-of-memory-to-page-allocator-more-explicit.patch
