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arch, mm: streamline HIGHMEM freeing

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All architectures that support HIGHMEM have their code that frees high
memory pages to the buddy allocator while __free_memory_core() is limited
to freeing only low memory.

There is no actual reason for that.  The memory map is completely ready by
the time memblock_free_all() is called and high pages can be released to
the buddy allocator along with low memory.

Remove low memory limit from __free_memory_core() and drop per-architecture
code that frees high memory pages.

Link: https://lkml.kernel.org/r/20250313135003.836600-12-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>	[x86]
Tested-by: Mark Brown <broonie@kernel.org>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Guo Ren (csky) <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Mike Rapoport (Microsoft) 2025-03-13 15:50:01 +02:00 • committed by Andrew Morton
parent e120d1bc12
commit 6faea3422e
16 changed files with 2 additions and 239 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
arch/arc/mm/init.c
View file

@ -160,11 +160,7 @@ void __init setup_arch_memory(void)
static void __init highmem_init(void)
{
#ifdef CONFIG_HIGHMEM
unsigned long tmp;
memblock_phys_free(high_mem_start, high_mem_sz);
for (tmp = min_high_pfn; tmp < max_high_pfn; tmp++)
free_highmem_page(pfn_to_page(tmp));
#endif
}
@ -176,8 +172,8 @@ static void __init highmem_init(void)
*/
void __init mem_init(void)
{
memblock_free_all();
highmem_init();
memblock_free_all();
BUILD_BUG_ON((PTRS_PER_PGD * sizeof(pgd_t)) > PAGE_SIZE);
BUILD_BUG_ON((PTRS_PER_PUD * sizeof(pud_t)) > PAGE_SIZE);

29
arch/arm/mm/init.c
View file

@ -237,33 +237,6 @@ static inline void poison_init_mem(void *s, size_t count)
*p++ = 0xe7fddef0;
}
static void __init free_highpages(void)
{
#ifdef CONFIG_HIGHMEM
unsigned long max_low = max_low_pfn;
phys_addr_t range_start, range_end;
u64 i;
/* set highmem page free */
for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE,
&range_start, &range_end, NULL) {
unsigned long start = PFN_UP(range_start);
unsigned long end = PFN_DOWN(range_end);
/* Ignore complete lowmem entries */
if (end <= max_low)
continue;
/* Truncate partial highmem entries */
if (start < max_low)
start = max_low;
for (; start < end; start++)
free_highmem_page(pfn_to_page(start));
}
#endif
}
/*
* mem_init() marks the free areas in the mem_map and tells us how much
* memory is free. This is done after various parts of the system have
@ -283,8 +256,6 @@ void __init mem_init(void)
/* this will put all unused low memory onto the freelists */
memblock_free_all();
free_highpages();
/*
* Check boundaries twice: Some fundamental inconsistencies can
* be detected at build time already.

14
arch/csky/mm/init.c
View file

@ -44,21 +44,7 @@ EXPORT_SYMBOL(empty_zero_page);
void __init mem_init(void)
{
#ifdef CONFIG_HIGHMEM
unsigned long tmp;
#endif
memblock_free_all();
#ifdef CONFIG_HIGHMEM
for (tmp = highstart_pfn; tmp < highend_pfn; tmp++) {
struct page *page = pfn_to_page(tmp);
/* FIXME not sure about */
if (!memblock_is_reserved(tmp << PAGE_SHIFT))
free_highmem_page(page);
}
#endif
}
void free_initmem(void)

16
arch/microblaze/mm/init.c
View file

@ -52,19 +52,6 @@ static void __init highmem_init(void)
map_page(PKMAP_BASE, 0, 0); /* XXX gross */
pkmap_page_table = virt_to_kpte(PKMAP_BASE);
}
static void __meminit highmem_setup(void)
{
unsigned long pfn;
for (pfn = max_low_pfn; pfn < max_pfn; ++pfn) {
struct page *page = pfn_to_page(pfn);
/* FIXME not sure about */
if (!memblock_is_reserved(pfn << PAGE_SHIFT))
free_highmem_page(page);
}
}
#endif /* CONFIG_HIGHMEM */
/*
@ -122,9 +109,6 @@ void __init mem_init(void)
{
/* this will put all memory onto the freelists */
memblock_free_all();
#ifdef CONFIG_HIGHMEM
highmem_setup();
#endif
mem_init_done = 1;
}

20
arch/mips/mm/init.c
View file

@ -425,25 +425,6 @@ void __init paging_init(void)
static struct kcore_list kcore_kseg0;
#endif
static inline void __init mem_init_free_highmem(void)
{
#ifdef CONFIG_HIGHMEM
unsigned long tmp;
if (cpu_has_dc_aliases)
return;
for (tmp = highstart_pfn; tmp < highend_pfn; tmp++) {
struct page *page = pfn_to_page(tmp);
if (!memblock_is_memory(PFN_PHYS(tmp)))
SetPageReserved(page);
else
free_highmem_page(page);
}
#endif
}
void __init mem_init(void)
{
/*
@ -454,7 +435,6 @@ void __init mem_init(void)
maar_init();
setup_zero_pages(); /* Setup zeroed pages. */
mem_init_free_highmem();
memblock_free_all();
#ifdef CONFIG_64BIT

14
arch/powerpc/mm/mem.c
View file

@ -297,20 +297,6 @@ void __init mem_init(void)
memblock_free_all();
#ifdef CONFIG_HIGHMEM
{
unsigned long pfn, highmem_mapnr;
highmem_mapnr = lowmem_end_addr >> PAGE_SHIFT;
for (pfn = highmem_mapnr; pfn < max_mapnr; ++pfn) {
phys_addr_t paddr = (phys_addr_t)pfn << PAGE_SHIFT;
struct page *page = pfn_to_page(pfn);
if (memblock_is_memory(paddr) && !memblock_is_reserved(paddr))
free_highmem_page(page);
}
}
#endif /* CONFIG_HIGHMEM */
#if defined(CONFIG_PPC_E500) && !defined(CONFIG_SMP)
/*
* If smp is enabled, next_tlbcam_idx is initialized in the cpu up

25
arch/sparc/mm/init_32.c
View file

@ -232,18 +232,6 @@ static void __init taint_real_pages(void)
}
}
static void map_high_region(unsigned long start_pfn, unsigned long end_pfn)
{
unsigned long tmp;
#ifdef CONFIG_DEBUG_HIGHMEM
printk("mapping high region %08lx - %08lx\n", start_pfn, end_pfn);
#endif
for (tmp = start_pfn; tmp < end_pfn; tmp++)
free_highmem_page(pfn_to_page(tmp));
}
void __init mem_init(void)
{
int i;
@ -276,19 +264,6 @@ void __init mem_init(void)
taint_real_pages();
memblock_free_all();
for (i = 0; sp_banks[i].num_bytes != 0; i++) {
unsigned long start_pfn = sp_banks[i].base_addr >> PAGE_SHIFT;
unsigned long end_pfn = (sp_banks[i].base_addr + sp_banks[i].num_bytes) >> PAGE_SHIFT;
if (end_pfn <= highstart_pfn)
continue;
if (start_pfn < highstart_pfn)
start_pfn = highstart_pfn;
map_high_region(start_pfn, end_pfn);
}
}
void sparc_flush_page_to_ram(struct page *page)

3
arch/x86/include/asm/highmem.h
View file

@ -69,9 +69,6 @@ extern unsigned long highstart_pfn, highend_pfn;
arch_flush_lazy_mmu_mode(); \
} while (0)
extern void add_highpages_with_active_regions(int nid, unsigned long start_pfn,
unsigned long end_pfn);
#endif /* __KERNEL__ */
#endif /* _ASM_X86_HIGHMEM_H */

4
arch/x86/include/asm/numa.h
View file

@ -41,10 +41,6 @@ static inline int numa_cpu_node(int cpu)
}
#endif /* CONFIG_NUMA */
#ifdef CONFIG_X86_32
# include <asm/numa_32.h>
#endif
#ifdef CONFIG_NUMA
extern void numa_set_node(int cpu, int node);
extern void numa_clear_node(int cpu);

13
arch/x86/include/asm/numa_32.h
View file

@ -1,13 +0,0 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_NUMA_32_H
#define _ASM_X86_NUMA_32_H
#ifdef CONFIG_HIGHMEM
extern void set_highmem_pages_init(void);
#else
static inline void set_highmem_pages_init(void)
{
}
#endif
#endif /* _ASM_X86_NUMA_32_H */

2
arch/x86/mm/Makefile
View file

@ -42,8 +42,6 @@ obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
obj-$(CONFIG_PTDUMP) += dump_pagetables.o
obj-$(CONFIG_PTDUMP_DEBUGFS) += debug_pagetables.o
obj-$(CONFIG_HIGHMEM) += highmem_32.o
KASAN_SANITIZE_kasan_init_$(BITS).o := n
obj-$(CONFIG_KASAN) += kasan_init_$(BITS).o

34
arch/x86/mm/highmem_32.c
View file

@ -1,34 +0,0 @@
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/highmem.h>
#include <linux/export.h>
#include <linux/swap.h> /* for totalram_pages */
#include <linux/memblock.h>
#include <asm/numa.h>
void __init set_highmem_pages_init(void)
{
struct zone *zone;
int nid;
/*
* Explicitly reset zone->managed_pages because set_highmem_pages_init()
* is invoked before memblock_free_all()
*/
reset_all_zones_managed_pages();
for_each_zone(zone) {
unsigned long zone_start_pfn, zone_end_pfn;
if (!is_highmem(zone))
continue;
zone_start_pfn = zone->zone_start_pfn;
zone_end_pfn = zone_start_pfn + zone->spanned_pages;
nid = zone_to_nid(zone);
printk(KERN_INFO "Initializing %s for node %d (%08lx:%08lx)\n",
zone->name, nid, zone_start_pfn, zone_end_pfn);
add_highpages_with_active_regions(nid, zone_start_pfn,
zone_end_pfn);
}
}

28
arch/x86/mm/init_32.c
View file

@ -394,23 +394,6 @@ static void __init permanent_kmaps_init(pgd_t *pgd_base)
pkmap_page_table = virt_to_kpte(vaddr);
}
void __init add_highpages_with_active_regions(int nid,
unsigned long start_pfn, unsigned long end_pfn)
{
phys_addr_t start, end;
u64 i;
for_each_free_mem_range(i, nid, MEMBLOCK_NONE, &start, &end, NULL) {
unsigned long pfn = clamp_t(unsigned long, PFN_UP(start),
start_pfn, end_pfn);
unsigned long e_pfn = clamp_t(unsigned long, PFN_DOWN(end),
start_pfn, end_pfn);
for ( ; pfn < e_pfn; pfn++)
if (pfn_valid(pfn))
free_highmem_page(pfn_to_page(pfn));
}
}
#else
static inline void permanent_kmaps_init(pgd_t *pgd_base)
{
@ -715,17 +698,6 @@ void __init mem_init(void)
#ifdef CONFIG_FLATMEM
BUG_ON(!mem_map);
#endif
/*
* With CONFIG_DEBUG_PAGEALLOC initialization of highmem pages has to
* be done before memblock_free_all(). Memblock use free low memory for
* temporary data (see find_range_array()) and for this purpose can use
* pages that was already passed to the buddy allocator, hence marked as
* not accessible in the page tables when compiled with
* CONFIG_DEBUG_PAGEALLOC. Otherwise order of initialization is not
* important here.
*/
set_highmem_pages_init();
/* this will put all low memory onto the freelists */
memblock_free_all();

29
arch/xtensa/mm/init.c
View file

@ -129,41 +129,12 @@ void __init zones_init(void)
print_vm_layout();
}
static void __init free_highpages(void)
{
#ifdef CONFIG_HIGHMEM
unsigned long max_low = max_low_pfn;
phys_addr_t range_start, range_end;
u64 i;
/* set highmem page free */
for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE,
&range_start, &range_end, NULL) {
unsigned long start = PFN_UP(range_start);
unsigned long end = PFN_DOWN(range_end);
/* Ignore complete lowmem entries */
if (end <= max_low)
continue;
/* Truncate partial highmem entries */
if (start < max_low)
start = max_low;
for (; start < end; start++)
free_highmem_page(pfn_to_page(start));
}
#endif
}
/*
* Initialize memory pages.
*/
void __init mem_init(void)
{
free_highpages();
memblock_free_all();
}

1
include/linux/mm.h
View file

@ -3275,7 +3275,6 @@ extern void reserve_bootmem_region(phys_addr_t start,
/* Free the reserved page into the buddy system, so it gets managed. */
void free_reserved_page(struct page *page);
#define free_highmem_page(page) free_reserved_page(page)
static inline void mark_page_reserved(struct page *page)
{

3
mm/memblock.c
View file

@ -2164,8 +2164,7 @@ static unsigned long __init __free_memory_core(phys_addr_t start,
phys_addr_t end)
{
unsigned long start_pfn = PFN_UP(start);
unsigned long end_pfn = min_t(unsigned long,
PFN_DOWN(end), max_low_pfn);
unsigned long end_pfn = PFN_DOWN(end);
if (start_pfn >= end_pfn)
return 0;