blob: 6903b695ebaef81ef890f4b5e41c749d89dce2e1 [file] [log] [blame]
/*
* linux/mm/page_alloc.c
*
* Manages the free list, the system allocates free pages here.
* Note that kmalloc() lives in slab.c
*
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
* Swap reorganised 29.12.95, Stephen Tweedie
* Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
* Reshaped it to be a zoned allocator, Ingo Molnar, Red Hat, 1999
* Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
* Zone balancing, Kanoj Sarcar, SGI, Jan 2000
* Per cpu hot/cold page lists, bulk allocation, Martin J. Bligh, Sept 2002
* (lots of bits borrowed from Ingo Molnar & Andrew Morton)
*/
#include <linux/stddef.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/interrupt.h>
#include <linux/pagemap.h>
#include <linux/jiffies.h>
#include <linux/bootmem.h>
#include <linux/memblock.h>
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/kmemcheck.h>
#include <linux/kasan.h>
#include <linux/module.h>
#include <linux/suspend.h>
#include <linux/pagevec.h>
#include <linux/blkdev.h>
#include <linux/slab.h>
#include <linux/ratelimit.h>
#include <linux/oom.h>
#include <linux/notifier.h>
#include <linux/topology.h>
#include <linux/sysctl.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/memory_hotplug.h>
#include <linux/nodemask.h>
#include <linux/vmalloc.h>
#include <linux/vmstat.h>
#include <linux/mempolicy.h>
#include <linux/memremap.h>
#include <linux/stop_machine.h>
#include <linux/sort.h>
#include <linux/pfn.h>
#include <linux/backing-dev.h>
#include <linux/fault-inject.h>
#include <linux/page-isolation.h>
#include <linux/page_ext.h>
#include <linux/debugobjects.h>
#include <linux/kmemleak.h>
#include <linux/compaction.h>
#include <trace/events/kmem.h>
#include <linux/prefetch.h>
#include <linux/mm_inline.h>
#include <linux/migrate.h>
#include <linux/page_ext.h>
#include <linux/hugetlb.h>
#include <linux/sched/rt.h>
#include <linux/page_owner.h>
#include <linux/kthread.h>
#include <asm/sections.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
#include "internal.h"
/* prevent >1 _updater_ of zone percpu pageset ->high and ->batch fields */
static DEFINE_MUTEX(pcp_batch_high_lock);
#define MIN_PERCPU_PAGELIST_FRACTION (8)
#ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID
DEFINE_PER_CPU(int, numa_node);
EXPORT_PER_CPU_SYMBOL(numa_node);
#endif
#ifdef CONFIG_HAVE_MEMORYLESS_NODES
/*
* N.B., Do NOT reference the '_numa_mem_' per cpu variable directly.
* It will not be defined when CONFIG_HAVE_MEMORYLESS_NODES is not defined.
* Use the accessor functions set_numa_mem(), numa_mem_id() and cpu_to_mem()
* defined in <linux/topology.h>.
*/
DEFINE_PER_CPU(int, _numa_mem_); /* Kernel "local memory" node */
EXPORT_PER_CPU_SYMBOL(_numa_mem_);
int _node_numa_mem_[MAX_NUMNODES];
#endif
/*
* Array of node states.
*/
nodemask_t node_states[NR_NODE_STATES] __read_mostly = {
[N_POSSIBLE] = NODE_MASK_ALL,
[N_ONLINE] = { { [0] = 1UL } },
#ifndef CONFIG_NUMA
[N_NORMAL_MEMORY] = { { [0] = 1UL } },
#ifdef CONFIG_HIGHMEM
[N_HIGH_MEMORY] = { { [0] = 1UL } },
#endif
#ifdef CONFIG_MOVABLE_NODE
[N_MEMORY] = { { [0] = 1UL } },
#endif
[N_CPU] = { { [0] = 1UL } },
#endif /* NUMA */
};
EXPORT_SYMBOL(node_states);
/* Protect totalram_pages and zone->managed_pages */
static DEFINE_SPINLOCK(managed_page_count_lock);
unsigned long totalram_pages __read_mostly;
unsigned long totalreserve_pages __read_mostly;
unsigned long totalcma_pages __read_mostly;
int percpu_pagelist_fraction;
gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
/*
* A cached value of the page's pageblock's migratetype, used when the page is
* put on a pcplist. Used to avoid the pageblock migratetype lookup when
* freeing from pcplists in most cases, at the cost of possibly becoming stale.
* Also the migratetype set in the page does not necessarily match the pcplist
* index, e.g. page might have MIGRATE_CMA set but be on a pcplist with any
* other index - this ensures that it will be put on the correct CMA freelist.
*/
static inline int get_pcppage_migratetype(struct page *page)
{
return page->index;
}
static inline void set_pcppage_migratetype(struct page *page, int migratetype)
{
page->index = migratetype;
}
#ifdef CONFIG_PM_SLEEP
/*
* The following functions are used by the suspend/hibernate code to temporarily
* change gfp_allowed_mask in order to avoid using I/O during memory allocations
* while devices are suspended. To avoid races with the suspend/hibernate code,
* they should always be called with pm_mutex held (gfp_allowed_mask also should
* only be modified with pm_mutex held, unless the suspend/hibernate code is
* guaranteed not to run in parallel with that modification).
*/
static gfp_t saved_gfp_mask;
void pm_restore_gfp_mask(void)
{
WARN_ON(!mutex_is_locked(&pm_mutex));
if (saved_gfp_mask) {
gfp_allowed_mask = saved_gfp_mask;
saved_gfp_mask = 0;
}
}
void pm_restrict_gfp_mask(void)
{
WARN_ON(!mutex_is_locked(&pm_mutex));
WARN_ON(saved_gfp_mask);
saved_gfp_mask = gfp_allowed_mask;
gfp_allowed_mask &= ~(__GFP_IO | __GFP_FS);
}
bool pm_suspended_storage(void)
{
if ((gfp_allowed_mask & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS))
return false;
return true;
}
#endif /* CONFIG_PM_SLEEP */
#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
unsigned int pageblock_order __read_mostly;
#endif
static void __free_pages_ok(struct page *page, unsigned int order);
/*
* results with 256, 32 in the lowmem_reserve sysctl:
* 1G machine -> (16M dma, 800M-16M normal, 1G-800M high)
* 1G machine -> (16M dma, 784M normal, 224M high)
* NORMAL allocation will leave 784M/256 of ram reserved in the ZONE_DMA
* HIGHMEM allocation will leave 224M/32 of ram reserved in ZONE_NORMAL
* HIGHMEM allocation will leave (224M+784M)/256 of ram reserved in ZONE_DMA
*
* TBD: should special case ZONE_DMA32 machines here - in those we normally
* don't need any ZONE_NORMAL reservation
*/
int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = {
#ifdef CONFIG_ZONE_DMA
256,
#endif
#ifdef CONFIG_ZONE_DMA32
256,
#endif
#ifdef CONFIG_HIGHMEM
32,
#endif
32,
};
EXPORT_SYMBOL(totalram_pages);
static char * const zone_names[MAX_NR_ZONES] = {
#ifdef CONFIG_ZONE_DMA
"DMA",
#endif
#ifdef CONFIG_ZONE_DMA32
"DMA32",
#endif
"Normal",
#ifdef CONFIG_HIGHMEM
"HighMem",
#endif
"Movable",
#ifdef CONFIG_ZONE_DEVICE
"Device",
#endif
};
char * const migratetype_names[MIGRATE_TYPES] = {
"Unmovable",
"Movable",
"Reclaimable",
"HighAtomic",
#ifdef CONFIG_CMA
"CMA",
#endif
#ifdef CONFIG_MEMORY_ISOLATION
"Isolate",
#endif
};
compound_page_dtor * const compound_page_dtors[] = {
NULL,
free_compound_page,
#ifdef CONFIG_HUGETLB_PAGE
free_huge_page,
#endif
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
free_transhuge_page,
#endif
};
int min_free_kbytes = 1024;
int user_min_free_kbytes = -1;
int watermark_scale_factor = 10;
static unsigned long __meminitdata nr_kernel_pages;
static unsigned long __meminitdata nr_all_pages;
static unsigned long __meminitdata dma_reserve;
#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
static unsigned long __meminitdata arch_zone_lowest_possible_pfn[MAX_NR_ZONES];
static unsigned long __meminitdata arch_zone_highest_possible_pfn[MAX_NR_ZONES];
static unsigned long __initdata required_kernelcore;
static unsigned long __initdata required_movablecore;
static unsigned long __meminitdata zone_movable_pfn[MAX_NUMNODES];
static bool mirrored_kernelcore;
/* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
int movable_zone;
EXPORT_SYMBOL(movable_zone);
#endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
#if MAX_NUMNODES > 1
int nr_node_ids __read_mostly = MAX_NUMNODES;
int nr_online_nodes __read_mostly = 1;
EXPORT_SYMBOL(nr_node_ids);
EXPORT_SYMBOL(nr_online_nodes);
#endif
int page_group_by_mobility_disabled __read_mostly;
#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
static inline void reset_deferred_meminit(pg_data_t *pgdat)
{
pgdat->first_deferred_pfn = ULONG_MAX;
}
/* Returns true if the struct page for the pfn is uninitialised */
static inline bool __meminit early_page_uninitialised(unsigned long pfn)
{
if (pfn >= NODE_DATA(early_pfn_to_nid(pfn))->first_deferred_pfn)
return true;
return false;
}
static inline bool early_page_nid_uninitialised(unsigned long pfn, int nid)
{
if (pfn >= NODE_DATA(nid)->first_deferred_pfn)
return true;
return false;
}
/*
* Returns false when the remaining initialisation should be deferred until
* later in the boot cycle when it can be parallelised.
*/
static inline bool update_defer_init(pg_data_t *pgdat,
unsigned long pfn, unsigned long zone_end,
unsigned long *nr_initialised)
{
unsigned long max_initialise;
/* Always populate low zones for address-contrained allocations */
if (zone_end < pgdat_end_pfn(pgdat))
return true;
/*
* Initialise at least 2G of a node but also take into account that
* two large system hashes that can take up 1GB for 0.25TB/node.
*/
max_initialise = max(2UL << (30 - PAGE_SHIFT),
(pgdat->node_spanned_pages >> 8));
(*nr_initialised)++;
if ((*nr_initialised > max_initialise) &&
(pfn & (PAGES_PER_SECTION - 1)) == 0) {
pgdat->first_deferred_pfn = pfn;
return false;
}
return true;
}
#else
static inline void reset_deferred_meminit(pg_data_t *pgdat)
{
}
static inline bool early_page_uninitialised(unsigned long pfn)
{
return false;
}
static inline bool early_page_nid_uninitialised(unsigned long pfn, int nid)
{
return false;
}
static inline bool update_defer_init(pg_data_t *pgdat,
unsigned long pfn, unsigned long zone_end,
unsigned long *nr_initialised)
{
return true;
}
#endif
/* Return a pointer to the bitmap storing bits affecting a block of pages */
static inline unsigned long *get_pageblock_bitmap(struct page *page,
unsigned long pfn)
{
#ifdef CONFIG_SPARSEMEM
return __pfn_to_section(pfn)->pageblock_flags;
#else
return page_zone(page)->pageblock_flags;
#endif /* CONFIG_SPARSEMEM */
}
static inline int pfn_to_bitidx(struct page *page, unsigned long pfn)
{
#ifdef CONFIG_SPARSEMEM
pfn &= (PAGES_PER_SECTION-1);
return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
#else
pfn = pfn - round_down(page_zone(page)->zone_start_pfn, pageblock_nr_pages);
return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
#endif /* CONFIG_SPARSEMEM */
}
/**
* get_pfnblock_flags_mask - Return the requested group of flags for the pageblock_nr_pages block of pages
* @page: The page within the block of interest
* @pfn: The target page frame number
* @end_bitidx: The last bit of interest to retrieve
* @mask: mask of bits that the caller is interested in
*
* Return: pageblock_bits flags
*/
static __always_inline unsigned long __get_pfnblock_flags_mask(struct page *page,
unsigned long pfn,
unsigned long end_bitidx,
unsigned long mask)
{
unsigned long *bitmap;
unsigned long bitidx, word_bitidx;
unsigned long word;
bitmap = get_pageblock_bitmap(page, pfn);
bitidx = pfn_to_bitidx(page, pfn);
word_bitidx = bitidx / BITS_PER_LONG;
bitidx &= (BITS_PER_LONG-1);
word = bitmap[word_bitidx];
bitidx += end_bitidx;
return (word >> (BITS_PER_LONG - bitidx - 1)) & mask;
}
unsigned long get_pfnblock_flags_mask(struct page *page, unsigned long pfn,
unsigned long end_bitidx,
unsigned long mask)
{
return __get_pfnblock_flags_mask(page, pfn, end_bitidx, mask);
}
static __always_inline int get_pfnblock_migratetype(struct page *page, unsigned long pfn)
{
return __get_pfnblock_flags_mask(page, pfn, PB_migrate_end, MIGRATETYPE_MASK);
}
/**
* set_pfnblock_flags_mask - Set the requested group of flags for a pageblock_nr_pages block of pages
* @page: The page within the block of interest
* @flags: The flags to set
* @pfn: The target page frame number
* @end_bitidx: The last bit of interest
* @mask: mask of bits that the caller is interested in
*/
void set_pfnblock_flags_mask(struct page *page, unsigned long flags,
unsigned long pfn,
unsigned long end_bitidx,
unsigned long mask)
{
unsigned long *bitmap;
unsigned long bitidx, word_bitidx;
unsigned long old_word, word;
BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4);
bitmap = get_pageblock_bitmap(page, pfn);
bitidx = pfn_to_bitidx(page, pfn);
word_bitidx = bitidx / BITS_PER_LONG;
bitidx &= (BITS_PER_LONG-1);
VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);
bitidx += end_bitidx;
mask <<= (BITS_PER_LONG - bitidx - 1);
flags <<= (BITS_PER_LONG - bitidx - 1);
word = READ_ONCE(bitmap[word_bitidx]);
for (;;) {
old_word = cmpxchg(&bitmap[word_bitidx], word, (word & ~mask) | flags);
if (word == old_word)
break;
word = old_word;
}
}
void set_pageblock_migratetype(struct page *page, int migratetype)
{
if (unlikely(page_group_by_mobility_disabled &&
migratetype < MIGRATE_PCPTYPES))
migratetype = MIGRATE_UNMOVABLE;
set_pageblock_flags_group(page, (unsigned long)migratetype,
PB_migrate, PB_migrate_end);
}
#ifdef CONFIG_DEBUG_VM
static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
{
int ret = 0;
unsigned seq;
unsigned long pfn = page_to_pfn(page);
unsigned long sp, start_pfn;
do {
seq = zone_span_seqbegin(zone);
start_pfn = zone->zone_start_pfn;
sp = zone->spanned_pages;
if (!zone_spans_pfn(zone, pfn))
ret = 1;
} while (zone_span_seqretry(zone, seq));
if (ret)
pr_err("page 0x%lx outside node %d zone %s [ 0x%lx - 0x%lx ]\n",
pfn, zone_to_nid(zone), zone->name,
start_pfn, start_pfn + sp);
return ret;
}
static int page_is_consistent(struct zone *zone, struct page *page)
{
if (!pfn_valid_within(page_to_pfn(page)))
return 0;
if (zone != page_zone(page))
return 0;
return 1;
}
/*
* Temporary debugging check for pages not lying within a given zone.
*/
static int bad_range(struct zone *zone, struct page *page)
{
if (page_outside_zone_boundaries(zone, page))
return 1;
if (!page_is_consistent(zone, page))
return 1;
return 0;
}
#else
static inline int bad_range(struct zone *zone, struct page *page)
{
return 0;
}
#endif
static void bad_page(struct page *page, const char *reason,
unsigned long bad_flags)
{
static unsigned long resume;
static unsigned long nr_shown;
static unsigned long nr_unshown;
/*
* Allow a burst of 60 reports, then keep quiet for that minute;
* or allow a steady drip of one report per second.
*/
if (nr_shown == 60) {
if (time_before(jiffies, resume)) {
nr_unshown++;
goto out;
}
if (nr_unshown) {
pr_alert(
"BUG: Bad page state: %lu messages suppressed\n",
nr_unshown);
nr_unshown = 0;
}
nr_shown = 0;
}
if (nr_shown++ == 0)
resume = jiffies + 60 * HZ;
pr_alert("BUG: Bad page state in process %s pfn:%05lx\n",
current->comm, page_to_pfn(page));
__dump_page(page, reason);
bad_flags &= page->flags;
if (bad_flags)
pr_alert("bad because of flags: %#lx(%pGp)\n",
bad_flags, &bad_flags);
dump_page_owner(page);
print_modules();
dump_stack();
out:
/* Leave bad fields for debug, except PageBuddy could make trouble */
page_mapcount_reset(page); /* remove PageBuddy */
add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
}
/*
* Higher-order pages are called "compound pages". They are structured thusly:
*
* The first PAGE_SIZE page is called the "head page" and have PG_head set.
*
* The remaining PAGE_SIZE pages are called "tail pages". PageTail() is encoded
* in bit 0 of page->compound_head. The rest of bits is pointer to head page.
*
* The first tail page's ->compound_dtor holds the offset in array of compound
* page destructors. See compound_page_dtors.
*
* The first tail page's ->compound_order holds the order of allocation.
* This usage means that zero-order pages may not be compound.
*/
void free_compound_page(struct page *page)
{
__free_pages_ok(page, compound_order(page));
}
void prep_compound_page(struct page *page, unsigned int order)
{
int i;
int nr_pages = 1 << order;
set_compound_page_dtor(page, COMPOUND_PAGE_DTOR);
set_compound_order(page, order);
__SetPageHead(page);
for (i = 1; i < nr_pages; i++) {
struct page *p = page + i;
set_page_count(p, 0);
p->mapping = TAIL_MAPPING;
set_compound_head(p, page);
}
atomic_set(compound_mapcount_ptr(page), -1);
}
#ifdef CONFIG_DEBUG_PAGEALLOC
unsigned int _debug_guardpage_minorder;
bool _debug_pagealloc_enabled __read_mostly
= IS_ENABLED(CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT);
EXPORT_SYMBOL(_debug_pagealloc_enabled);
bool _debug_guardpage_enabled __read_mostly;
static int __init early_debug_pagealloc(char *buf)
{
if (!buf)
return -EINVAL;
return kstrtobool(buf, &_debug_pagealloc_enabled);
}
early_param("debug_pagealloc", early_debug_pagealloc);
static bool need_debug_guardpage(void)
{
/* If we don't use debug_pagealloc, we don't need guard page */
if (!debug_pagealloc_enabled())
return false;
return true;
}
static void init_debug_guardpage(void)
{
if (!debug_pagealloc_enabled())
return;
_debug_guardpage_enabled = true;
}
struct page_ext_operations debug_guardpage_ops = {
.need = need_debug_guardpage,
.init = init_debug_guardpage,
};
static int __init debug_guardpage_minorder_setup(char *buf)
{
unsigned long res;
if (kstrtoul(buf, 10, &res) < 0 || res > MAX_ORDER / 2) {
pr_err("Bad debug_guardpage_minorder value\n");
return 0;
}
_debug_guardpage_minorder = res;
pr_info("Setting debug_guardpage_minorder to %lu\n", res);
return 0;
}
__setup("debug_guardpage_minorder=", debug_guardpage_minorder_setup);
static inline void set_page_guard(struct zone *zone, struct page *page,
unsigned int order, int migratetype)
{
struct page_ext *page_ext;
if (!debug_guardpage_enabled())
return;
page_ext = lookup_page_ext(page);
if (unlikely(!page_ext))
return;
__set_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);
INIT_LIST_HEAD(&page->lru);
set_page_private(page, order);
/* Guard pages are not available for any usage */
__mod_zone_freepage_state(zone, -(1 << order), migratetype);
}
static inline void clear_page_guard(struct zone *zone, struct page *page,
unsigned int order, int migratetype)
{
struct page_ext *page_ext;
if (!debug_guardpage_enabled())
return;
page_ext = lookup_page_ext(page);
if (unlikely(!page_ext))
return;
__clear_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);
set_page_private(page, 0);
if (!is_migrate_isolate(migratetype))
__mod_zone_freepage_state(zone, (1 << order), migratetype);
}
#else
struct page_ext_operations debug_guardpage_ops = { NULL, };
static inline void set_page_guard(struct zone *zone, struct page *page,
unsigned int order, int migratetype) {}
static inline void clear_page_guard(struct zone *zone, struct page *page,
unsigned int order, int migratetype) {}
#endif
static inline void set_page_order(struct page *page, unsigned int order)
{
set_page_private(page, order);
__SetPageBuddy(page);
}
static inline void rmv_page_order(struct page *page)
{
__ClearPageBuddy(page);
set_page_private(page, 0);
}
/*
* This function checks whether a page is free && is the buddy
* we can do coalesce a page and its buddy if
* (a) the buddy is not in a hole &&
* (b) the buddy is in the buddy system &&
* (c) a page and its buddy have the same order &&
* (d) a page and its buddy are in the same zone.
*
* For recording whether a page is in the buddy system, we set ->_mapcount
* PAGE_BUDDY_MAPCOUNT_VALUE.
* Setting, clearing, and testing _mapcount PAGE_BUDDY_MAPCOUNT_VALUE is
* serialized by zone->lock.
*
* For recording page's order, we use page_private(page).
*/
static inline int page_is_buddy(struct page *page, struct page *buddy,
unsigned int order)
{
if (!pfn_valid_within(page_to_pfn(buddy)))
return 0;
if (page_is_guard(buddy) && page_order(buddy) == order) {
if (page_zone_id(page) != page_zone_id(buddy))
return 0;
VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
return 1;
}
if (PageBuddy(buddy) && page_order(buddy) == order) {
/*
* zone check is done late to avoid uselessly
* calculating zone/node ids for pages that could
* never merge.
*/
if (page_zone_id(page) != page_zone_id(buddy))
return 0;
VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
return 1;
}
return 0;
}
/*
* Freeing function for a buddy system allocator.
*
* The concept of a buddy system is to maintain direct-mapped table
* (containing bit values) for memory blocks of various "orders".
* The bottom level table contains the map for the smallest allocatable
* units of memory (here, pages), and each level above it describes
* pairs of units from the levels below, hence, "buddies".
* At a high level, all that happens here is marking the table entry
* at the bottom level available, and propagating the changes upward
* as necessary, plus some accounting needed to play nicely with other
* parts of the VM system.
* At each level, we keep a list of pages, which are heads of continuous
* free pages of length of (1 << order) and marked with _mapcount
* PAGE_BUDDY_MAPCOUNT_VALUE. Page's order is recorded in page_private(page)
* field.
* So when we are allocating or freeing one, we can derive the state of the
* other. That is, if we allocate a small block, and both were
* free, the remainder of the region must be split into blocks.
* If a block is freed, and its buddy is also free, then this
* triggers coalescing into a block of larger size.
*
* -- nyc
*/
static inline void __free_one_page(struct page *page,
unsigned long pfn,
struct zone *zone, unsigned int order,
int migratetype)
{
unsigned long page_idx;
unsigned long combined_idx;
unsigned long uninitialized_var(buddy_idx);
struct page *buddy;
unsigned int max_order;
max_order = min_t(unsigned int, MAX_ORDER, pageblock_order + 1);
VM_BUG_ON(!zone_is_initialized(zone));
VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP, page);
VM_BUG_ON(migratetype == -1);
if (likely(!is_migrate_isolate(migratetype)))
__mod_zone_freepage_state(zone, 1 << order, migratetype);
page_idx = pfn & ((1 << MAX_ORDER) - 1);
VM_BUG_ON_PAGE(page_idx & ((1 << order) - 1), page);
VM_BUG_ON_PAGE(bad_range(zone, page), page);
continue_merging:
while (order < max_order - 1) {
buddy_idx = __find_buddy_index(page_idx, order);
buddy = page + (buddy_idx - page_idx);
if (!page_is_buddy(page, buddy, order))
goto done_merging;
/*
* Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page,
* merge with it and move up one order.
*/
if (page_is_guard(buddy)) {
clear_page_guard(zone, buddy, order, migratetype);
} else {
list_del(&buddy->lru);
zone->free_area[order].nr_free--;
rmv_page_order(buddy);
}
combined_idx = buddy_idx & page_idx;
page = page + (combined_idx - page_idx);
page_idx = combined_idx;
order++;
}
if (max_order < MAX_ORDER) {
/* If we are here, it means order is >= pageblock_order.
* We want to prevent merge between freepages on isolate
* pageblock and normal pageblock. Without this, pageblock
* isolation could cause incorrect freepage or CMA accounting.
*
* We don't want to hit this code for the more frequent
* low-order merging.
*/
if (unlikely(has_isolate_pageblock(zone))) {
int buddy_mt;
buddy_idx = __find_buddy_index(page_idx, order);
buddy = page + (buddy_idx - page_idx);
buddy_mt = get_pageblock_migratetype(buddy);
if (migratetype != buddy_mt
&& (is_migrate_isolate(migratetype) ||
is_migrate_isolate(buddy_mt)))
goto done_merging;
}
max_order++;
goto continue_merging;
}
done_merging:
set_page_order(page, order);
/*
* If this is not the largest possible page, check if the buddy
* of the next-highest order is free. If it is, it's possible
* that pages are being freed that will coalesce soon. In case,
* that is happening, add the free page to the tail of the list
* so it's less likely to be used soon and more likely to be merged
* as a higher order page
*/
if ((order < MAX_ORDER-2) && pfn_valid_within(page_to_pfn(buddy))) {
struct page *higher_page, *higher_buddy;
combined_idx = buddy_idx & page_idx;
higher_page = page + (combined_idx - page_idx);
buddy_idx = __find_buddy_index(combined_idx, order + 1);
higher_buddy = higher_page + (buddy_idx - combined_idx);
if (page_is_buddy(higher_page, higher_buddy, order + 1)) {
list_add_tail(&page->lru,
&zone->free_area[order].free_list[migratetype]);
goto out;
}
}
list_add(&page->lru, &zone->free_area[order].free_list[migratetype]);
out:
zone->free_area[order].nr_free++;
}
/*
* A bad page could be due to a number of fields. Instead of multiple branches,
* try and check multiple fields with one check. The caller must do a detailed
* check if necessary.
*/
static inline bool page_expected_state(struct page *page,
unsigned long check_flags)
{
if (unlikely(atomic_read(&page->_mapcount) != -1))
return false;
if (unlikely((unsigned long)page->mapping |
page_ref_count(page) |
#ifdef CONFIG_MEMCG
(unsigned long)page->mem_cgroup |
#endif
(page->flags & check_flags)))
return false;
return true;
}
static void free_pages_check_bad(struct page *page)
{
const char *bad_reason;
unsigned long bad_flags;
bad_reason = NULL;
bad_flags = 0;
if (unlikely(atomic_read(&page->_mapcount) != -1))
bad_reason = "nonzero mapcount";
if (unlikely(page->mapping != NULL))
bad_reason = "non-NULL mapping";
if (unlikely(page_ref_count(page) != 0))
bad_reason = "nonzero _refcount";
if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_FREE)) {
bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
bad_flags = PAGE_FLAGS_CHECK_AT_FREE;
}
#ifdef CONFIG_MEMCG
if (unlikely(page->mem_cgroup))
bad_reason = "page still charged to cgroup";
#endif
bad_page(page, bad_reason, bad_flags);
}
static inline int free_pages_check(struct page *page)
{
if (likely(page_expected_state(page, PAGE_FLAGS_CHECK_AT_FREE)))
return 0;
/* Something has gone sideways, find it */
free_pages_check_bad(page);
return 1;
}
static int free_tail_pages_check(struct page *head_page, struct page *page)
{
int ret = 1;
/*
* We rely page->lru.next never has bit 0 set, unless the page
* is PageTail(). Let's make sure that's true even for poisoned ->lru.
*/
BUILD_BUG_ON((unsigned long)LIST_POISON1 & 1);
if (!IS_ENABLED(CONFIG_DEBUG_VM)) {
ret = 0;
goto out;
}
switch (page - head_page) {
case 1:
/* the first tail page: ->mapping is compound_mapcount() */
if (unlikely(compound_mapcount(page))) {
bad_page(page, "nonzero compound_mapcount", 0);
goto out;
}
break;
case 2:
/*
* the second tail page: ->mapping is
* page_deferred_list().next -- ignore value.
*/
break;
default:
if (page->mapping != TAIL_MAPPING) {
bad_page(page, "corrupted mapping in tail page", 0);
goto out;
}
break;
}
if (unlikely(!PageTail(page))) {
bad_page(page, "PageTail not set", 0);
goto out;
}
if (unlikely(compound_head(page) != head_page)) {
bad_page(page, "compound_head not consistent", 0);
goto out;
}
ret = 0;
out:
page->mapping = NULL;
clear_compound_head(page);
return ret;
}
static __always_inline bool free_pages_prepare(struct page *page,
unsigned int order, bool check_free)
{
int bad = 0;
VM_BUG_ON_PAGE(PageTail(page), page);
trace_mm_page_free(page, order);
kmemcheck_free_shadow(page, order);
/*
* Check tail pages before head page information is cleared to
* avoid checking PageCompound for order-0 pages.
*/
if (unlikely(order)) {
bool compound = PageCompound(page);
int i;
VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
for (i = 1; i < (1 << order); i++) {
if (compound)
bad += free_tail_pages_check(page, page + i);
if (unlikely(free_pages_check(page + i))) {
bad++;
continue;
}
(page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
}
}
if (PageAnonHead(page))
page->mapping = NULL;
if (check_free)
bad += free_pages_check(page);
if (bad)
return false;
page_cpupid_reset_last(page);
page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
reset_page_owner(page, order);
if (!PageHighMem(page)) {
debug_check_no_locks_freed(page_address(page),
PAGE_SIZE << order);
debug_check_no_obj_freed(page_address(page),
PAGE_SIZE << order);
}
arch_free_page(page, order);
kernel_poison_pages(page, 1 << order, 0);
kernel_map_pages(page, 1 << order, 0);
kasan_free_pages(page, order);
return true;
}
#ifdef CONFIG_DEBUG_VM
static inline bool free_pcp_prepare(struct page *page)
{
return free_pages_prepare(page, 0, true);
}
static inline bool bulkfree_pcp_prepare(struct page *page)
{
return false;
}
#else
static bool free_pcp_prepare(struct page *page)
{
return free_pages_prepare(page, 0, false);
}
static bool bulkfree_pcp_prepare(struct page *page)
{
return free_pages_check(page);
}
#endif /* CONFIG_DEBUG_VM */
/*
* Frees a number of pages from the PCP lists
* Assumes all pages on list are in same zone, and of same order.
* count is the number of pages to free.
*
* If the zone was previously in an "all pages pinned" state then look to
* see if this freeing clears that state.
*
* And clear the zone's pages_scanned counter, to hold off the "all pages are
* pinned" detection logic.
*/
static void free_pcppages_bulk(struct zone *zone, int count,
struct per_cpu_pages *pcp)
{
int migratetype = 0;
int batch_free = 0;
unsigned long nr_scanned;
bool isolated_pageblocks;
spin_lock(&zone->lock);
isolated_pageblocks = has_isolate_pageblock(zone);
nr_scanned = zone_page_state(zone, NR_PAGES_SCANNED);
if (nr_scanned)
__mod_zone_page_state(zone, NR_PAGES_SCANNED, -nr_scanned);
while (count) {
struct page *page;
struct list_head *list;
/*
* Remove pages from lists in a round-robin fashion. A
* batch_free count is maintained that is incremented when an
* empty list is encountered. This is so more pages are freed
* off fuller lists instead of spinning excessively around empty
* lists
*/
do {
batch_free++;
if (++migratetype == MIGRATE_PCPTYPES)
migratetype = 0;
list = &pcp->lists[migratetype];
} while (list_empty(list));
/* This is the only non-empty list. Free them all. */
if (batch_free == MIGRATE_PCPTYPES)
batch_free = count;
do {
int mt; /* migratetype of the to-be-freed page */
page = list_last_entry(list, struct page, lru);
/* must delete as __free_one_page list manipulates */
list_del(&page->lru);
mt = get_pcppage_migratetype(page);
/* MIGRATE_ISOLATE page should not go to pcplists */
VM_BUG_ON_PAGE(is_migrate_isolate(mt), page);
/* Pageblock could have been isolated meanwhile */
if (unlikely(isolated_pageblocks))
mt = get_pageblock_migratetype(page);
if (bulkfree_pcp_prepare(page))
continue;
__free_one_page(page, page_to_pfn(page), zone, 0, mt);
trace_mm_page_pcpu_drain(page, 0, mt);
} while (--count && --batch_free && !list_empty(list));
}
spin_unlock(&zone->lock);
}
static void free_one_page(struct zone *zone,
struct page *page, unsigned long pfn,
unsigned int order,
int migratetype)
{
unsigned long nr_scanned;
spin_lock(&zone->lock);
nr_scanned = zone_page_state(zone, NR_PAGES_SCANNED);
if (nr_scanned)
__mod_zone_page_state(zone, NR_PAGES_SCANNED, -nr_scanned);
if (unlikely(has_isolate_pageblock(zone) ||
is_migrate_isolate(migratetype))) {
migratetype = get_pfnblock_migratetype(page, pfn);
}
__free_one_page(page, pfn, zone, order, migratetype);
spin_unlock(&zone->lock);
}
static void __meminit __init_single_page(struct page *page, unsigned long pfn,
unsigned long zone, int nid)
{
set_page_links(page, zone, nid, pfn);
init_page_count(page);
page_mapcount_reset(page);
page_cpupid_reset_last(page);
INIT_LIST_HEAD(&page->lru);
#ifdef WANT_PAGE_VIRTUAL
/* The shift won't overflow because ZONE_NORMAL is below 4G. */
if (!is_highmem_idx(zone))
set_page_address(page, __va(pfn << PAGE_SHIFT));
#endif
}
static void __meminit __init_single_pfn(unsigned long pfn, unsigned long zone,
int nid)
{
return __init_single_page(pfn_to_page(pfn), pfn, zone, nid);
}
#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
static void init_reserved_page(unsigned long pfn)
{
pg_data_t *pgdat;
int nid, zid;
if (!early_page_uninitialised(pfn))
return;
nid = early_pfn_to_nid(pfn);
pgdat = NODE_DATA(nid);
for (zid = 0; zid < MAX_NR_ZONES; zid++) {
struct zone *zone = &pgdat->node_zones[zid];
if (pfn >= zone->zone_start_pfn && pfn < zone_end_pfn(zone))
break;
}
__init_single_pfn(pfn, zid, nid);
}
#else
static inline void init_reserved_page(unsigned long pfn)
{
}
#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
/*
* Initialised pages do not have PageReserved set. This function is
* called for each range allocated by the bootmem allocator and
* marks the pages PageReserved. The remaining valid pages are later
* sent to the buddy page allocator.
*/
void __meminit reserve_bootmem_region(phys_addr_t start, phys_addr_t end)
{
unsigned long start_pfn = PFN_DOWN(start);
unsigned long end_pfn = PFN_UP(end);
for (; start_pfn < end_pfn; start_pfn++) {
if (pfn_valid(start_pfn)) {
struct page *page = pfn_to_page(start_pfn);
init_reserved_page(start_pfn);
/* Avoid false-positive PageTail() */
INIT_LIST_HEAD(&page->lru);
SetPageReserved(page);
}
}
}
static void __free_pages_ok(struct page *page, unsigned int order)
{
unsigned long flags;
int migratetype;
unsigned long pfn = page_to_pfn(page);
if (!free_pages_prepare(page, order, true))
return;
migratetype = get_pfnblock_migratetype(page, pfn);
local_irq_save(flags);
__count_vm_events(PGFREE, 1 << order);
free_one_page(page_zone(page), page, pfn, order, migratetype);
local_irq_restore(flags);
}
static void __init __free_pages_boot_core(struct page *page, unsigned int order)
{
unsigned int nr_pages = 1 << order;
struct page *p = page;
unsigned int loop;
prefetchw(p);
for (loop = 0; loop < (nr_pages - 1); loop++, p++) {
prefetchw(p + 1);
__ClearPageReserved(p);
set_page_count(p, 0);
}
__ClearPageReserved(p);
set_page_count(p, 0);
page_zone(page)->managed_pages += nr_pages;
set_page_refcounted(page);
__free_pages(page, order);
}
#if defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID) || \
defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
static struct mminit_pfnnid_cache early_pfnnid_cache __meminitdata;
int __meminit early_pfn_to_nid(unsigned long pfn)
{
static DEFINE_SPINLOCK(early_pfn_lock);
int nid;
spin_lock(&early_pfn_lock);
nid = __early_pfn_to_nid(pfn, &early_pfnnid_cache);
if (nid < 0)
nid = 0;
spin_unlock(&early_pfn_lock);
return nid;
}
#endif
#ifdef CONFIG_NODES_SPAN_OTHER_NODES
static inline bool __meminit meminit_pfn_in_nid(unsigned long pfn, int node,
struct mminit_pfnnid_cache *state)
{
int nid;
nid = __early_pfn_to_nid(pfn, state);
if (nid >= 0 && nid != node)
return false;
return true;
}
/* Only safe to use early in boot when initialisation is single-threaded */
static inline bool __meminit early_pfn_in_nid(unsigned long pfn, int node)
{
return meminit_pfn_in_nid(pfn, node, &early_pfnnid_cache);
}
#else
static inline bool __meminit early_pfn_in_nid(unsigned long pfn, int node)
{
return true;
}
static inline bool __meminit meminit_pfn_in_nid(unsigned long pfn, int node,
struct mminit_pfnnid_cache *state)
{
return true;
}
#endif
void __init __free_pages_bootmem(struct page *page, unsigned long pfn,
unsigned int order)
{
if (early_page_uninitialised(pfn))
return;
return __free_pages_boot_core(page, order);
}
/*
* Check that the whole (or subset of) a pageblock given by the interval of
* [start_pfn, end_pfn) is valid and within the same zone, before scanning it
* with the migration of free compaction scanner. The scanners then need to
* use only pfn_valid_within() check for arches that allow holes within
* pageblocks.
*
* Return struct page pointer of start_pfn, or NULL if checks were not passed.
*
* It's possible on some configurations to have a setup like node0 node1 node0
* i.e. it's possible that all pages within a zones range of pages do not
* belong to a single zone. We assume that a border between node0 and node1
* can occur within a single pageblock, but not a node0 node1 node0
* interleaving within a single pageblock. It is therefore sufficient to check
* the first and last page of a pageblock and avoid checking each individual
* page in a pageblock.
*/
struct page *__pageblock_pfn_to_page(unsigned long start_pfn,
unsigned long end_pfn, struct zone *zone)
{
struct page *start_page;
struct page *end_page;
/* end_pfn is one past the range we are checking */
end_pfn--;
if (!pfn_valid(start_pfn) || !pfn_valid(end_pfn))
return NULL;
start_page = pfn_to_page(start_pfn);
if (page_zone(start_page) != zone)
return NULL;
end_page = pfn_to_page(end_pfn);
/* This gives a shorter code than deriving page_zone(end_page) */
if (page_zone_id(start_page) != page_zone_id(end_page))
return NULL;
return start_page;
}
void set_zone_contiguous(struct zone *zone)
{
unsigned long block_start_pfn = zone->zone_start_pfn;
unsigned long block_end_pfn;
block_end_pfn = ALIGN(block_start_pfn + 1, pageblock_nr_pages);
for (; block_start_pfn < zone_end_pfn(zone);
block_start_pfn = block_end_pfn,
block_end_pfn += pageblock_nr_pages) {
block_end_pfn = min(block_end_pfn, zone_end_pfn(zone));
if (!__pageblock_pfn_to_page(block_start_pfn,
block_end_pfn, zone))
return;
}
/* We confirm that there is no hole */
zone->contiguous = true;
}
void clear_zone_contiguous(struct zone *zone)
{
zone->contiguous = false;
}
#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
static void __init deferred_free_range(struct page *page,
unsigned long pfn, int nr_pages)
{
int i;
if (!page)
return;
/* Free a large naturally-aligned chunk if possible */
if (nr_pages == MAX_ORDER_NR_PAGES &&
(pfn & (MAX_ORDER_NR_PAGES-1)) == 0) {
set_pageblock_migratetype(page, MIGRATE_MOVABLE);
__free_pages_boot_core(page, MAX_ORDER-1);
return;
}
for (i = 0; i < nr_pages; i++, page++)
__free_pages_boot_core(page, 0);
}
/* Completion tracking for deferred_init_memmap() threads */
static atomic_t pgdat_init_n_undone __initdata;
static __initdata DECLARE_COMPLETION(pgdat_init_all_done_comp);
static inline void __init pgdat_init_report_one_done(void)
{
if (atomic_dec_and_test(&pgdat_init_n_undone))
complete(&pgdat_init_all_done_comp);
}
/* Initialise remaining memory on a node */
static int __init deferred_init_memmap(void *data)
{
pg_data_t *pgdat = data;
int nid = pgdat->node_id;
struct mminit_pfnnid_cache nid_init_state = { };
unsigned long start = jiffies;
unsigned long nr_pages = 0;
unsigned long walk_start, walk_end;
int i, zid;
struct zone *zone;
unsigned long first_init_pfn = pgdat->first_deferred_pfn;
const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
if (first_init_pfn == ULONG_MAX) {
pgdat_init_report_one_done();
return 0;
}
/* Bind memory initialisation thread to a local node if possible */
if (!cpumask_empty(cpumask))
set_cpus_allowed_ptr(current, cpumask);
/* Sanity check boundaries */
BUG_ON(pgdat->first_deferred_pfn < pgdat->node_start_pfn);
BUG_ON(pgdat->first_deferred_pfn > pgdat_end_pfn(pgdat));
pgdat->first_deferred_pfn = ULONG_MAX;
/* Only the highest zone is deferred so find it */
for (zid = 0; zid < MAX_NR_ZONES; zid++) {
zone = pgdat->node_zones + zid;
if (first_init_pfn < zone_end_pfn(zone))
break;
}
for_each_mem_pfn_range(i, nid, &walk_start, &walk_end, NULL) {
unsigned long pfn, end_pfn;
struct page *page = NULL;
struct page *free_base_page = NULL;
unsigned long free_base_pfn = 0;
int nr_to_free = 0;
end_pfn = min(walk_end, zone_end_pfn(zone));
pfn = first_init_pfn;
if (pfn < walk_start)
pfn = walk_start;
if (pfn < zone->zone_start_pfn)
pfn = zone->zone_start_pfn;
for (; pfn < end_pfn; pfn++) {
if (!pfn_valid_within(pfn))
goto free_range;
/*
* Ensure pfn_valid is checked every
* MAX_ORDER_NR_PAGES for memory holes
*/
if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0) {
if (!pfn_valid(pfn)) {
page = NULL;
goto free_range;
}
}
if (!meminit_pfn_in_nid(pfn, nid, &nid_init_state)) {
page = NULL;
goto free_range;
}
/* Minimise pfn page lookups and scheduler checks */
if (page && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0) {
page++;
} else {
nr_pages += nr_to_free;
deferred_free_range(free_base_page,
free_base_pfn, nr_to_free);
free_base_page = NULL;
free_base_pfn = nr_to_free = 0;
page = pfn_to_page(pfn);
cond_resched();
}
if (page->flags) {
VM_BUG_ON(page_zone(page) != zone);
goto free_range;
}
__init_single_page(page, pfn, zid, nid);
if (!free_base_page) {
free_base_page = page;
free_base_pfn = pfn;
nr_to_free = 0;
}
nr_to_free++;
/* Where possible, batch up pages for a single free */
continue;
free_range:
/* Free the current block of pages to allocator */
nr_pages += nr_to_free;
deferred_free_range(free_base_page, free_base_pfn,
nr_to_free);
free_base_page = NULL;
free_base_pfn = nr_to_free = 0;
}
first_init_pfn = max(end_pfn, first_init_pfn);
}
/* Sanity check that the next zone really is unpopulated */
WARN_ON(++zid < MAX_NR_ZONES && populated_zone(++zone));
pr_info("node %d initialised, %lu pages in %ums\n", nid, nr_pages,
jiffies_to_msecs(jiffies - start));
pgdat_init_report_one_done();
return 0;
}
#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
void __init page_alloc_init_late(void)
{
struct zone *zone;
#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
int nid;
/* There will be num_node_state(N_MEMORY) threads */
atomic_set(&pgdat_init_n_undone, num_node_state(N_MEMORY));
for_each_node_state(nid, N_MEMORY) {
kthread_run(deferred_init_memmap, NODE_DATA(nid), "pgdatinit%d", nid);
}
/* Block until all are initialised */
wait_for_completion(&pgdat_init_all_done_comp);
/* Reinit limits that are based on free pages after the kernel is up */
files_maxfiles_init();
#endif
for_each_populated_zone(zone)
set_zone_contiguous(zone);
}
#ifdef CONFIG_CMA
/* Free whole pageblock and set its migration type to MIGRATE_CMA. */
void __init init_cma_reserved_pageblock(struct page *page)
{
unsigned i = pageblock_nr_pages;
struct page *p = page;
do {
__ClearPageReserved(p);
set_page_count(p, 0);
} while (++p, --i);
set_pageblock_migratetype(page, MIGRATE_CMA);
if (pageblock_order >= MAX_ORDER) {
i = pageblock_nr_pages;
p = page;
do {
set_page_refcounted(p);
__free_pages(p, MAX_ORDER - 1);
p += MAX_ORDER_NR_PAGES;
} while (i -= MAX_ORDER_NR_PAGES);
} else {
set_page_refcounted(page);
__free_pages(page, pageblock_order);
}
adjust_managed_page_count(page, pageblock_nr_pages);
}
#endif
/*
* The order of subdivision here is critical for the IO subsystem.
* Please do not alter this order without good reasons and regression
* testing. Specifically, as large blocks of memory are subdivided,
* the order in which smaller blocks are delivered depends on the order
* they're subdivided in this function. This is the primary factor
* influencing the order in which pages are delivered to the IO
* subsystem according to empirical testing, and this is also justified
* by considering the behavior of a buddy system containing a single
* large block of memory acted on by a series of small allocations.
* This behavior is a critical factor in sglist merging's success.
*
* -- nyc
*/
static inline void expand(struct zone *zone, struct page *page,
int low, int high, struct free_area *area,
int migratetype)
{
unsigned long size = 1 << high;
while (high > low) {
area--;
high--;
size >>= 1;
VM_BUG_ON_PAGE(bad_range(zone, &page[size]), &page[size]);
if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC) &&
debug_guardpage_enabled() &&
high < debug_guardpage_minorder()) {
/*
* Mark as guard pages (or page), that will allow to
* merge back to allocator when buddy will be freed.
* Corresponding page table entries will not be touched,
* pages will stay not present in virtual address space
*/
set_page_guard(zone, &page[size], high, migratetype);
continue;
}
list_add(&page[size].lru, &area->free_list[migratetype]);
area->nr_free++;
set_page_order(&page[size], high);
}
}
static void check_new_page_bad(struct page *page)
{
const char *bad_reason = NULL;
unsigned long bad_flags = 0;
if (unlikely(atomic_read(&page->_mapcount) != -1))
bad_reason = "nonzero mapcount";
if (unlikely(page->mapping != NULL))
bad_reason = "non-NULL mapping";
if (unlikely(page_ref_count(page) != 0))
bad_reason = "nonzero _count";
if (unlikely(page->flags & __PG_HWPOISON)) {
bad_reason = "HWPoisoned (hardware-corrupted)";
bad_flags = __PG_HWPOISON;
/* Don't complain about hwpoisoned pages */
page_mapcount_reset(page); /* remove PageBuddy */
return;
}
if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_PREP)) {
bad_reason = "PAGE_FLAGS_CHECK_AT_PREP flag set";
bad_flags = PAGE_FLAGS_CHECK_AT_PREP;
}
#ifdef CONFIG_MEMCG
if (unlikely(page->mem_cgroup))
bad_reason = "page still charged to cgroup";
#endif
bad_page(page, bad_reason, bad_flags);
}
/*
* This page is about to be returned from the page allocator
*/
static inline int check_new_page(struct page *page)
{
if (likely(page_expected_state(page,
PAGE_FLAGS_CHECK_AT_PREP|__PG_HWPOISON)))
return 0;
check_new_page_bad(page);
return 1;
}
static inline bool free_pages_prezeroed(bool poisoned)
{
return IS_ENABLED(CONFIG_PAGE_POISONING_ZERO) &&
page_poisoning_enabled() && poisoned;
}
#ifdef CONFIG_DEBUG_VM
static bool check_pcp_refill(struct page *page)
{
return false;
}
static bool check_new_pcp(struct page *page)
{
return check_new_page(page);
}
#else
static bool check_pcp_refill(struct page *page)
{
return check_new_page(page);
}
static bool check_new_pcp(struct page *page)
{
return false;
}
#endif /* CONFIG_DEBUG_VM */
static bool check_new_pages(struct page *page, unsigned int order)
{
int i;
for (i = 0; i < (1 << order); i++) {
struct page *p = page + i;
if (unlikely(check_new_page(p)))
return true;
}
return false;
}
static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
unsigned int alloc_flags)
{
int i;
bool poisoned = true;
for (i = 0; i < (1 << order); i++) {
struct page *p = page + i;
if (poisoned)
poisoned &= page_is_poisoned(p);
}
set_page_private(page, 0);
set_page_refcounted(page);
arch_alloc_page(page, order);
kernel_map_pages(page, 1 << order, 1);
kernel_poison_pages(page, 1 << order, 1);
kasan_alloc_pages(page, order);
if (!free_pages_prezeroed(poisoned) && (gfp_flags & __GFP_ZERO))
for (i = 0; i < (1 << order); i++)
clear_highpage(page + i);
if (order && (gfp_flags & __GFP_COMP))
prep_compound_page(page, order);
set_page_owner(page, order, gfp_flags);
/*
* page is set pfmemalloc when ALLOC_NO_WATERMARKS was necessary to
* allocate the page. The expectation is that the caller is taking
* steps that will free more memory. The caller should avoid the page
* being used for !PFMEMALLOC purposes.
*/
if (alloc_flags & ALLOC_NO_WATERMARKS)
set_page_pfmemalloc(page);
else
clear_page_pfmemalloc(page);
}
/*
* Go through the free lists for the given migratetype and remove
* the smallest available page from the freelists
*/
static inline
struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
int migratetype)
{
unsigned int current_order;
struct free_area *area;
struct page *page;
/* Find a page of the appropriate size in the preferred list */
for (current_order = order; current_order < MAX_ORDER; ++current_order) {
area = &(zone->free_area[current_order]);
page = list_first_entry_or_null(&area->free_list[migratetype],
struct page, lru);
if (!page)
continue;
list_del(&page->lru);
rmv_page_order(page);
area->nr_free--;
expand(zone, page, order, current_order, area, migratetype);
set_pcppage_migratetype(page, migratetype);
return page;
}
return NULL;
}
/*
* This array describes the order lists are fallen back to when
* the free lists for the desirable migrate type are depleted
*/
static int fallbacks[MIGRATE_TYPES][4] = {
[MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE, MIGRATE_TYPES },
[MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE, MIGRATE_TYPES },
[MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_TYPES },
#ifdef CONFIG_CMA
[MIGRATE_CMA] = { MIGRATE_TYPES }, /* Never used */
#endif
#ifdef CONFIG_MEMORY_ISOLATION
[MIGRATE_ISOLATE] = { MIGRATE_TYPES }, /* Never used */
#endif
};
#ifdef CONFIG_CMA
static struct page *__rmqueue_cma_fallback(struct zone *zone,
unsigned int order)
{
return __rmqueue_smallest(zone, order, MIGRATE_CMA);
}
#else
static inline struct page *__rmqueue_cma_fallback(struct zone *zone,
unsigned int order) { return NULL; }
#endif
/*
* Move the free pages in a range to the free lists of the requested type.
* Note that start_page and end_pages are not aligned on a pageblock
* boundary. If alignment is required, use move_freepages_block()
*/
int move_freepages(struct zone *zone,
struct page *start_page, struct page *end_page,
int migratetype)
{
struct page *page;
unsigned int order;
int pages_moved = 0;
#ifndef CONFIG_HOLES_IN_ZONE
/*
* page_zone is not safe to call in this context when
* CONFIG_HOLES_IN_ZONE is set. This bug check is probably redundant
* anyway as we check zone boundaries in move_freepages_block().
* Remove at a later date when no bug reports exist related to
* grouping pages by mobility
*/
VM_BUG_ON(page_zone(start_page) != page_zone(end_page));
#endif
for (page = start_page; page <= end_page;) {
/* Make sure we are not inadvertently changing nodes */
VM_BUG_ON_PAGE(page_to_nid(page) != zone_to_nid(zone), page);
if (!pfn_valid_within(page_to_pfn(page))) {
page++;
continue;
}
if (!PageBuddy(page)) {
page++;
continue;
}
order = page_order(page);
list_move(&page->lru,
&zone->free_area[order].free_list[migratetype]);
page += 1 << order;
pages_moved += 1 << order;
}
return pages_moved;
}
int move_freepages_block(struct zone *zone, struct page *page,
int migratetype)
{
unsigned long start_pfn, end_pfn;
struct page *start_page, *end_page;
start_pfn = page_to_pfn(page);
start_pfn = start_pfn & ~(pageblock_nr_pages-1);
start_page = pfn_to_page(start_pfn);
end_page = start_page + pageblock_nr_pages - 1;
end_pfn = start_pfn + pageblock_nr_pages - 1;
/* Do not cross zone boundaries */
if (!zone_spans_pfn(zone, start_pfn))
start_page = page;
if (!zone_spans_pfn(zone, end_pfn))
return 0;
return move_freepages(zone, start_page, end_page, migratetype);
}
static void change_pageblock_range(struct page *pageblock_page,
int start_order, int migratetype)
{
int nr_pageblocks = 1 << (start_order - pageblock_order);
while (nr_pageblocks--) {
set_pageblock_migratetype(pageblock_page, migratetype);
pageblock_page += pageblock_nr_pages;
}
}
/*
* When we are falling back to another migratetype during allocation, try to
* steal extra free pages from the same pageblocks to satisfy further
* allocations, instead of polluting multiple pageblocks.
*
* If we are stealing a relatively large buddy page, it is likely there will
* be more free pages in the pageblock, so try to steal them all. For
* reclaimable and unmovable allocations, we steal regardless of page size,
* as fragmentation caused by those allocations polluting movable pageblocks
* is worse than movable allocations stealing from unmovable and reclaimable
* pageblocks.
*/
static bool can_steal_fallback(unsigned int order, int start_mt)
{
/*
* Leaving this order check is intended, although there is
* relaxed order check in next check. The reason is that
* we can actually steal whole pageblock if this condition met,
* but, below check doesn't guarantee it and that is just heuristic
* so could be changed anytime.
*/
if (order >= pageblock_order)
return true;
if (order >= pageblock_order / 2 ||
start_mt == MIGRATE_RECLAIMABLE ||
start_mt == MIGRATE_UNMOVABLE ||
page_group_by_mobility_disabled)
return true;
return false;
}
/*
* This function implements actual steal behaviour. If order is large enough,
* we can steal whole pageblock. If not, we first move freepages in this
* pageblock and check whether half of pages are moved or not. If half of
* pages are moved, we can change migratetype of pageblock and permanently
* use it's pages as requested migratetype in the future.
*/
static void steal_suitable_fallback(struct zone *zone, struct page *page,
int start_type)
{
unsigned int current_order = page_order(page);
int pages;
/* Take ownership for orders >= pageblock_order */
if (current_order >= pageblock_order) {
change_pageblock_range(page, current_order, start_type);
return;
}
pages = move_freepages_block(zone, page, start_type);
/* Claim the whole block if over half of it is free */
if (pages >= (1 << (pageblock_order-1)) ||
page_group_by_mobility_disabled)
set_pageblock_migratetype(page, start_type);
}
/*
* Check whether there is a suitable fallback freepage with requested order.
* If only_stealable is true, this function returns fallback_mt only if
* we can steal other freepages all together. This would help to reduce
* fragmentation due to mixed migratetype pages in one pageblock.
*/
int find_suitable_fallback(struct free_area *area, unsigned int order,
int migratetype, bool only_stealable, bool *can_steal)
{
int i;
int fallback_mt;
if (area->nr_free == 0)
return -1;
*can_steal = false;
for (i = 0;; i++) {
fallback_mt = fallbacks[migratetype][i];
if (fallback_mt == MIGRATE_TYPES)
break;
if (list_empty(&area->free_list[fallback_mt]))
continue;
if (can_steal_fallback(order, migratetype))
*can_steal = true;
if (!only_stealable)
return fallback_mt;
if (*can_steal)
return fallback_mt;
}
return -1;
}
/*
* Reserve a pageblock for exclusive use of high-order atomic allocations if
* there are no empty page blocks that contain a page with a suitable order
*/
static void reserve_highatomic_pageblock(struct page *page, struct zone *zone,
unsigned int alloc_order)
{
int mt;
unsigned long max_managed, flags;
/*
* Limit the number reserved to 1 pageblock or roughly 1% of a zone.
* Check is race-prone but harmless.
*/
max_managed = (zone->managed_pages / 100) + pageblock_nr_pages;
if (zone->nr_reserved_highatomic >= max_managed)
return;
spin_lock_irqsave(&zone->lock, flags);
/* Recheck the nr_reserved_highatomic limit under the lock */
if (zone->nr_reserved_highatomic >= max_managed)
goto out_unlock;
/* Yoink! */
mt = get_pageblock_migratetype(page);
if (mt != MIGRATE_HIGHATOMIC &&
!is_migrate_isolate(mt) && !is_migrate_cma(mt)) {
zone->nr_reserved_highatomic += pageblock_nr_pages;
set_pageblock_migratetype(page, MIGRATE_HIGHATOMIC);
move_freepages_block(zone, page, MIGRATE_HIGHATOMIC);
}
out_unlock:
spin_unlock_irqrestore(&zone->lock, flags);
}
/*
* Used when an allocation is about to fail under memory pressure. This
* potentially hurts the reliability of high-order allocations when under
* intense memory pressure but failed atomic allocations should be easier
* to recover from than an OOM.
*/
static void unreserve_highatomic_pageblock(const struct alloc_context *ac)
{
struct zonelist *zonelist = ac->zonelist;
unsigned long flags;
struct zoneref *z;
struct zone *zone;
struct page *page;
int order;
for_each_zone_zonelist_nodemask(zone, z, zonelist, ac->high_zoneidx,
ac->nodemask) {
/* Preserve at least one pageblock */
if (zone->nr_reserved_highatomic <= pageblock_nr_pages)
continue;
spin_lock_irqsave(&zone->lock, flags);
for (order = 0; order < MAX_ORDER; order++) {
struct free_area *area = &(zone->free_area[order]);
page = list_first_entry_or_null(
&area->free_list[MIGRATE_HIGHATOMIC],
struct page, lru);
if (!page)
continue;
/*
* It should never happen but changes to locking could
* inadvertently allow a per-cpu drain to add pages
* to MIGRATE_HIGHATOMIC while unreserving so be safe
* and watch for underflows.
*/
zone->nr_reserved_highatomic -= min(pageblock_nr_pages,
zone->nr_reserved_highatomic);
/*
* Convert to ac->migratetype and avoid the normal
* pageblock stealing heuristics. Minimally, the caller
* is doing the work and needs the pages. More
* importantly, if the block was always converted to
* MIGRATE_UNMOVABLE or another type then the number
* of pageblocks that cannot be completely freed
* may increase.
*/
set_pageblock_migratetype(page, ac->migratetype);
move_freepages_block(zone, page, ac->migratetype);
spin_unlock_irqrestore(&zone->lock, flags);
return;
}
spin_unlock_irqrestore(&zone->lock, flags);
}
}
/* Remove an element from the buddy allocator from the fallback list */
static inline struct page *
__rmqueue_fallback(struct zone *zone, unsigned int order, int start_migratetype)
{
struct free_area *area;
unsigned int current_order;
struct page *page;
int fallback_mt;
bool can_steal;
/* Find the largest possible block of pages in the other list */
for (current_order = MAX_ORDER-1;
current_order >= order && current_order <= MAX_ORDER-1;
--current_order) {
area = &(zone->free_area[current_order]);
fallback_mt = find_suitable_fallback(area, current_order,
start_migratetype, false, &can_steal);
if (fallback_mt == -1)
continue;
page = list_first_entry(&area->free_list[fallback_mt],
struct page, lru);
if (can_steal)
steal_suitable_fallback(zone, page, start_migratetype);
/* Remove the page from the freelists */
area->nr_free--;
list_del(&page->lru);
rmv_page_order(page);
expand(zone, page, order, current_order, area,
start_migratetype);
/*
* The pcppage_migratetype may differ from pageblock's
* migratetype depending on the decisions in
* find_suitable_fallback(). This is OK as long as it does not
* differ for MIGRATE_CMA pageblocks. Those can be used as
* fallback only via special __rmqueue_cma_fallback() function
*/
set_pcppage_migratetype(page, start_migratetype);
trace_mm_page_alloc_extfrag(page, order, current_order,
start_migratetype, fallback_mt);
return page;
}
return NULL;
}
/*
* Do the hard work of removing an element from the buddy allocator.
* Call me with the zone->lock already held.
*/
static struct page *__rmqueue(struct zone *zone, unsigned int order,
int migratetype)
{
struct page *page;
page = __rmqueue_smallest(zone, order, migratetype);
if (unlikely(!page)) {
if (migratetype == MIGRATE_MOVABLE)
page = __rmqueue_cma_fallback(zone, order);
if (!page)
page = __rmqueue_fallback(zone, order, migratetype);
}
trace_mm_page_alloc_zone_locked(page, order, migratetype);
return page;
}
/*
* Obtain a specified number of elements from the buddy allocator, all under
* a single hold of the lock, for efficiency. Add them to the supplied list.
* Returns the number of new pages which were placed at *list.
*/
static int rmqueue_bulk(struct zone *zone, unsigned int order,
unsigned long count, struct list_head *list,
int migratetype, bool cold)
{
int i;
spin_lock(&zone->lock);
for (i = 0; i < count; ++i) {
struct page *page = __rmqueue(zone, order, migratetype);
if (unlikely(page == NULL))
break;
if (unlikely(check_pcp_refill(page)))
continue;
/*
* Split buddy pages returned by expand() are received here
* in physical page order. The page is added to the callers and
* list and the list head then moves forward. From the callers
* perspective, the linked list is ordered by page number in
* some conditions. This is useful for IO devices that can
* merge IO requests if the physical pages are ordered
* properly.
*/
if (likely(!cold))
list_add(&page->lru, list);
else
list_add_tail(&page->lru, list);
list = &page->lru;
if (is_migrate_cma(get_pcppage_migratetype(page)))
__mod_zone_page_state(zone, NR_FREE_CMA_PAGES,
-(1 << order));
}
__mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order));
spin_unlock(&zone->lock);
return i;
}
#ifdef CONFIG_NUMA
/*
* Called from the vmstat counter updater to drain pagesets of this
* currently executing processor on remote nodes after they have
* expired.
*
* Note that this function must be called with the thread pinned to
* a single processor.
*/
void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
{
unsigned long flags;
int to_drain, batch;
local_irq_save(flags);
batch = READ_ONCE(pcp->batch);
to_drain = min(pcp->count, batch);
if (to_drain > 0) {
free_pcppages_bulk(zone, to_drain, pcp);
pcp->count -= to_drain;
}
local_irq_restore(flags);
}
#endif
/*
* Drain pcplists of the indicated processor and zone.
*
* The processor must either be the current processor and the
* thread pinned to the current processor or a processor that
* is not online.
*/
static void drain_pages_zone(unsigned int cpu, struct zone *zone)
{
unsigned long flags;
struct per_cpu_pageset *pset;
struct per_cpu_pages *pcp;
local_irq_save(flags);
pset = per_cpu_ptr(zone->pageset, cpu);
pcp = &pset->pcp;
if (pcp->count) {
free_pcppages_bulk(zone, pcp->count, pcp);
pcp->count = 0;
}
local_irq_restore(flags);
}
/*
* Drain pcplists of all zones on the indicated processor.
*
* The processor must either be the current processor and the
* thread pinned to the current processor or a processor that
* is not online.
*/
static void drain_pages(unsigned int cpu)
{
struct zone *zone;
for_each_populated_zone(zone) {
drain_pages_zone(cpu, zone);
}
}
/*
* Spill all of this CPU's per-cpu pages back into the buddy allocator.
*
* The CPU has to be pinned. When zone parameter is non-NULL, spill just
* the single zone's pages.
*/
void drain_local_pages(struct zone *zone)
{
int cpu = smp_processor_id();
if (zone)
drain_pages_zone(cpu, zone);
else
drain_pages(cpu);
}
/*
* Spill all the per-cpu pages from all CPUs back into the buddy allocator.
*
* When zone parameter is non-NULL, spill just the single zone's pages.
*
* Note that this code is protected against sending an IPI to an offline
* CPU but does not guarantee sending an IPI to newly hotplugged CPUs:
* on_each_cpu_mask() blocks hotplug and won't talk to offlined CPUs but
* nothing keeps CPUs from showing up after we populated the cpumask and
* before the call to on_each_cpu_mask().
*/
void drain_all_pages(struct zone *zone)
{
int cpu;
/*
* Allocate in the BSS so we wont require allocation in
* direct reclaim path for CONFIG_CPUMASK_OFFSTACK=y
*/
static cpumask_t cpus_with_pcps;
/*
* We don't care about racing with CPU hotplug event
* as offline notification will cause the notified
* cpu to drain that CPU pcps and on_each_cpu_mask
* disables preemption as part of its processing
*/
for_each_online_cpu(cpu) {
struct per_cpu_pageset *pcp;
struct zone *z;
bool has_pcps = false;
if (zone) {
pcp = per_cpu_ptr(zone->pageset, cpu);
if (pcp->pcp.count)
has_pcps = true;
} else {
for_each_populated_zone(z) {
pcp = per_cpu_ptr(z->pageset, cpu);
if (pcp->pcp.count) {
has_pcps = true;
break;
}
}
}
if (has_pcps)
cpumask_set_cpu(cpu, &cpus_with_pcps);
else
cpumask_clear_cpu(cpu, &cpus_with_pcps);
}
on_each_cpu_mask(&cpus_with_pcps, (smp_call_func_t) drain_local_pages,
zone, 1);
}
#ifdef CONFIG_HIBERNATION
void mark_free_pages(struct zone *zone)
{
unsigned long pfn, max_zone_pfn;
unsigned long flags;
unsigned int order, t;
struct page *page;
if (zone_is_empty(zone))
return;
spin_lock_irqsave(&zone->lock, flags);
max_zone_pfn = zone_end_pfn(zone);
for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
if (pfn_valid(pfn)) {
page = pfn_to_page(pfn);
if (page_zone(page) != zone)
continue;
if (!swsusp_page_is_forbidden(page))
swsusp_unset_page_free(page);
}
for_each_migratetype_order(order, t) {
list_for_each_entry(page,
&zone->free_area[order].free_list[t], lru) {
unsigned long i;
pfn = page_to_pfn(page);
for (i = 0; i < (1UL << order); i++)
swsusp_set_page_free(pfn_to_page(pfn + i));
}
}
spin_unlock_irqrestore(&zone->lock, flags);
}
#endif /* CONFIG_PM */
/*
* Free a 0-order page
* cold == true ? free a cold page : free a hot page
*/
void free_hot_cold_page(struct page *page, bool cold)
{
struct zone *zone = page_zone(page);
struct per_cpu_pages *pcp;
unsigned long flags;
unsigned long pfn = page_to_pfn(page);
int migratetype;
if (!free_pcp_prepare(page))
return;
migratetype = get_pfnblock_migratetype(page, pfn);
set_pcppage_migratetype(page, migratetype);
local_irq_save(flags);
__count_vm_event(PGFREE);
/*
* We only track unmovable, reclaimable and movable on pcp lists.
* Free ISOLATE pages back to the allocator because they are being
* offlined but treat RESERVE as movable pages so we can get those
* areas back if necessary. Otherwise, we may have to free
* excessively into the page allocator
*/
if (migratetype >= MIGRATE_PCPTYPES) {
if (unlikely(is_migrate_isolate(migratetype))) {
free_one_page(zone, page, pfn, 0, migratetype);
goto out;
}
migratetype = MIGRATE_MOVABLE;
}
pcp = &this_cpu_ptr(zone->pageset)->pcp;
if (!cold)
list_add(&page->lru, &pcp->lists[migratetype]);
else
list_add_tail(&page->lru, &pcp->lists[migratetype]);
pcp->count++;
if (pcp->count >= pcp->high) {
unsigned long batch = READ_ONCE(pcp->batch);
free_pcppages_bulk(zone, batch, pcp);
pcp->count -= batch;
}
out:
local_irq_restore(flags);
}
/*
* Free a list of 0-order pages
*/
void free_hot_cold_page_list(struct list_head *list, bool cold)
{
struct page *page, *next;
list_for_each_entry_safe(page, next, list, lru) {
trace_mm_page_free_batched(page, cold);
free_hot_cold_page(page, cold);
}
}
/*
* split_page takes a non-compound higher-order page, and splits it into
* n (1<<order) sub-pages: page[0..n]
* Each sub-page must be freed individually.
*
* Note: this is probably too low level an operation for use in drivers.
* Please consult with lkml before using this in your driver.
*/
void split_page(struct page *page, unsigned int order)
{
int i;
gfp_t gfp_mask;
VM_BUG_ON_PAGE(PageCompound(page), page);
VM_BUG_ON_PAGE(!page_count(page), page);
#ifdef CONFIG_KMEMCHECK
/*
* Split shadow pages too, because free(page[0]) would
* otherwise free the whole shadow.
*/
if (kmemcheck_page_is_tracked(page))
split_page(virt_to_page(page[0].shadow), order);
#endif
gfp_mask = get_page_owner_gfp(page);
set_page_owner(page, 0, gfp_mask);
for (i = 1; i < (1 << order); i++) {
set_page_refcounted(page + i);
set_page_owner(page + i, 0, gfp_mask);
}
}
EXPORT_SYMBOL_GPL(split_page);
int __isolate_free_page(struct page *page, unsigned int order)
{
unsigned long watermark;
struct zone *zone;
int mt;
BUG_ON(!PageBuddy(page));
zone = page_zone(page);
mt = get_pageblock_migratetype(page);
if (!is_migrate_isolate(mt)) {
/* Obey watermarks as if the page was being allocated */
watermark = low_wmark_pages(zone) + (1 << order);
if (!zone_watermark_ok(zone, 0, watermark, 0, 0))
return 0;
__mod_zone_freepage_state(zone, -(1UL << order), mt);
}
/* Remove page from free list */
list_del(&page->lru);
zone->free_area[order].nr_free--;
rmv_page_order(page);
set_page_owner(page, order, __GFP_MOVABLE);
/* Set the pageblock if the isolated page is at least a pageblock */
if (order >= pageblock_order - 1) {
struct page *endpage = page + (1 << order) - 1;
for (; page < endpage; page += pageblock_nr_pages) {
int mt = get_pageblock_migratetype(page);
if (!is_migrate_isolate(mt) && !is_migrate_cma(mt))
set_pageblock_migratetype(page,
MIGRATE_MOVABLE);
}
}
return 1UL << order;
}
/*
* Similar to split_page except the page is already free. As this is only
* being used for migration, the migratetype of the block also changes.
* As this is called with interrupts disabled, the caller is responsible
* for calling arch_alloc_page() and kernel_map_page() after interrupts
* are enabled.
*
* Note: this is probably too low level an operation for use in drivers.
* Please consult with lkml before using this in your driver.
*/
int split_free_page(struct page *page)
{
unsigned int order;
int nr_pages;
order = page_order(page);
nr_pages = __isolate_free_page(page, order);
if (!nr_pages)
return 0;
/* Split into individual pages */
set_page_refcounted(page);
split_page(page, order);
return nr_pages;
}
/*
* Update NUMA hit/miss statistics
*
* Must be called with interrupts disabled.
*
* When __GFP_OTHER_NODE is set assume the node of the preferred
* zone is the local node. This is useful for daemons who allocate
* memory on behalf of other processes.
*/
static inline void zone_statistics(struct zone *preferred_zone, struct zone *z,
gfp_t flags)
{
#ifdef CONFIG_NUMA
int local_nid = numa_node_id();
enum zone_stat_item local_stat = NUMA_LOCAL;
if (unlikely(flags & __GFP_OTHER_NODE)) {
local_stat = NUMA_OTHER;
local_nid = preferred_zone->node;
}
if (z->node == local_nid) {
__inc_zone_state(z, NUMA_HIT);
__inc_zone_state(z, local_stat);
} else {
__inc_zone_state(z, NUMA_MISS);
__inc_zone_state(preferred_zone, NUMA_FOREIGN);
}
#endif
}
/*
* Allocate a page from the given zone. Use pcplists for order-0 allocations.
*/
static inline
struct page *buffered_rmqueue(struct zone *preferred_zone,
struct zone *zone, unsigned int order,
gfp_t gfp_flags, unsigned int alloc_flags,
int migratetype)
{
unsigned long flags;
struct page *page;
bool cold = ((gfp_flags & __GFP_COLD) != 0);
if (likely(order == 0)) {
struct per_cpu_pages *pcp;
struct list_head *list;
local_irq_save(flags);
do {
pcp = &this_cpu_ptr(zone->pageset)->pcp;
list = &pcp->lists[migratetype];
if (list_empty(list)) {
pcp->count += rmqueue_bulk(zone, 0,
pcp->batch, list,
migratetype, cold);
if (unlikely(list_empty(list)))
goto failed;
}
if (cold)
page = list_last_entry(list, struct page, lru);
else
page = list_first_entry(list, struct page, lru);
__dec_zone_state(zone, NR_ALLOC_BATCH);
list_del(&page->lru);
pcp->count--;
} while (check_new_pcp(page));
} else {
/*
* We most definitely don't want callers attempting to
* allocate greater than order-1 page units with __GFP_NOFAIL.
*/
WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1));
spin_lock_irqsave(&zone->lock, flags);
do {
page = NULL;
if (alloc_flags & ALLOC_HARDER) {
page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
if (page)
trace_mm_page_alloc_zone_locked(page, order, migratetype);
}
if (!page)
page = __rmqueue(zone, order, migratetype);
} while (page && check_new_pages(page, order));
spin_unlock(&zone->lock);
if (!page)
goto failed;
__mod_zone_page_state(zone, NR_ALLOC_BATCH, -(1 << order));
__mod_zone_freepage_state(zone, -(1 << order),
get_pcppage_migratetype(page));
}
if (atomic_long_read(&zone->vm_stat[NR_ALLOC_BATCH]) <= 0 &&
!test_bit(ZONE_FAIR_DEPLETED, &zone->flags))
set_bit(ZONE_FAIR_DEPLETED, &zone->flags);
__count_zone_vm_events(PGALLOC, zone, 1 << order);
zone_statistics(preferred_zone, zone, gfp_flags);
local_irq_restore(flags);
VM_BUG_ON_PAGE(bad_range(zone, page), page);
return page;
failed:
local_irq_restore(flags);
return NULL;
}
#ifdef CONFIG_FAIL_PAGE_ALLOC
static struct {
struct fault_attr attr;
bool ignore_gfp_highmem;
bool ignore_gfp_reclaim;
u32 min_order;
} fail_page_alloc = {
.attr = FAULT_ATTR_INITIALIZER,
.ignore_gfp_reclaim = true,
.ignore_gfp_highmem = true,
.min_order = 1,
};
static int __init setup_fail_page_alloc(char *str)
{
return setup_fault_attr(&fail_page_alloc.attr, str);
}
__setup("fail_page_alloc=", setup_fail_page_alloc);
static bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
{
if (order < fail_page_alloc.min_order)
return false;
if (gfp_mask & __GFP_NOFAIL)
return false;
if (fail_page_alloc.ignore_gfp_highmem && (gfp_mask & __GFP_HIGHMEM))
return false;
if (fail_page_alloc.ignore_gfp_reclaim &&
(gfp_mask & __GFP_DIRECT_RECLAIM))
return false;
return should_fail(&fail_page_alloc.attr, 1 << order);
}
#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
static int __init fail_page_alloc_debugfs(void)
{
umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
struct dentry *dir;
dir = fault_create_debugfs_attr("fail_page_alloc", NULL,
&fail_page_alloc.attr);
if (IS_ERR(dir))
return PTR_ERR(dir);
if (!debugfs_create_bool("ignore-gfp-wait", mode, dir,
&fail_page_alloc.ignore_gfp_reclaim))
goto fail;
if (!debugfs_create_bool("ignore-gfp-highmem", mode, dir,
&fail_page_alloc.ignore_gfp_highmem))
goto fail;
if (!debugfs_create_u32("min-order", mode, dir,
&fail_page_alloc.min_order))
goto fail;
return 0;
fail:
debugfs_remove_recursive(dir);
return -ENOMEM;
}
late_initcall(fail_page_alloc_debugfs);
#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
#else /* CONFIG_FAIL_PAGE_ALLOC */
static inline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
{
return false;
}
#endif /* CONFIG_FAIL_PAGE_ALLOC */
/*
* Return true if free base pages are above 'mark'. For high-order checks it
* will return true of the order-0 watermark is reached and there is at least
* one free page of a suitable size. Checking now avoids taking the zone lock
* to check in the allocation paths if no pages are free.
*/
bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
int classzone_idx, unsigned int alloc_flags,
long free_pages)
{
long min = mark;
int o;
const bool alloc_harder = (alloc_flags & ALLOC_HARDER);
/* free_pages may go negative - that's OK */
free_pages -= (1 << order) - 1;
if (alloc_flags & ALLOC_HIGH)
min -= min / 2;
/*
* If the caller does not have rights to ALLOC_HARDER then subtract
* the high-atomic reserves. This will over-estimate the size of the
* atomic reserve but it avoids a search.
*/
if (likely(!alloc_harder))
free_pages -= z->nr_reserved_highatomic;
else
min -= min / 4;
#ifdef CONFIG_CMA
/* If allocation can't use CMA areas don't use free CMA pages */
if (!(alloc_flags & ALLOC_CMA))
free_pages -= zone_page_state(z, NR_FREE_CMA_PAGES);
#endif
/*
* Check watermarks for an order-0 allocation request. If these
* are not met, then a high-order request also cannot go ahead
* even if a suitable page happened to be free.
*/
if (free_pages <= min + z->lowmem_reserve[classzone_idx])
return false;
/* If this is an order-0 request then the watermark is fine */
if (!order)
return true;
/* For a high-order request, check at least one suitable page is free */
for (o = order; o < MAX_ORDER; o++) {
struct free_area *area = &z->free_area[o];
int mt;
if (!area->nr_free)
continue;
if (alloc_harder)
return true;
for (mt = 0; mt < MIGRATE_PCPTYPES; mt++) {
if (!list_empty(&area->free_list[mt]))
return true;
}
#ifdef CONFIG_CMA
if ((alloc_flags & ALLOC_CMA) &&
!list_empty(&area->free_list[MIGRATE_CMA])) {
return true;
}
#endif
}
return false;
}
bool zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
int classzone_idx, unsigned int alloc_flags)
{
return __zone_watermark_ok(z, order, mark, classzone_idx, alloc_flags,
zone_page_state(z, NR_FREE_PAGES));
}
static inline bool zone_watermark_fast(struct zone *z, unsigned int order,
unsigned long mark, int classzone_idx, unsigned int alloc_flags)
{
long free_pages = zone_page_state(z, NR_FREE_PAGES);
long cma_pages = 0;
#ifdef CONFIG_CMA
/* If allocation can't use CMA areas don't use free CMA pages */
if (!(alloc_flags & ALLOC_CMA))
cma_pages = zone_page_state(z, NR_FREE_CMA_PAGES);
#endif
/*
* Fast check for order-0 only. If this fails then the reserves
* need to be calculated. There is a corner case where the check
* passes but only the high-order atomic reserve are free. If
* the caller is !atomic then it'll uselessly search the free
* list. That corner case is then slower but it is harmless.
*/
if (!order && (free_pages - cma_pages) > mark + z->lowmem_reserve[classzone_idx])
return true;
return __zone_watermark_ok(z, order, mark, classzone_idx, alloc_flags,
free_pages);
}
bool zone_watermark_ok_safe(struct zone *z, unsigned int order,
unsigned long mark, int classzone_idx)
{
long free_pages = zone_page_state(z, NR_FREE_PAGES);
if (z->percpu_drift_mark && free_pages < z->percpu_drift_mark)
free_pages = zone_page_state_snapshot(z, NR_FREE_PAGES);
return __zone_watermark_ok(z, order, mark, classzone_idx, 0,
free_pages);
}
#ifdef CONFIG_NUMA
static bool zone_local(struct zone *local_zone, struct zone *zone)
{
return local_zone->node == zone->node;
}
static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
{
return node_distance(zone_to_nid(local_zone), zone_to_nid(zone)) <
RECLAIM_DISTANCE;
}
#else /* CONFIG_NUMA */
static bool zone_local(struct zone *local_zone, struct zone *zone)
{
return true;
}
static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
{
return true;
}
#endif /* CONFIG_NUMA */
static void reset_alloc_batches(struct zone *preferred_zone)
{
struct zone *zone = preferred_zone->zone_pgdat->node_zones;
do {
mod_zone_page_state(zone, NR_ALLOC_BATCH,
high_wmark_pages(zone) - low_wmark_pages(zone) -
atomic_long_read(&zone->vm_stat[NR_ALLOC_BATCH]));
clear_bit(ZONE_FAIR_DEPLETED, &zone->flags);
} while (zone++ != preferred_zone);
}
/*
* get_page_from_freelist goes through the zonelist trying to allocate
* a page.
*/
static struct page *
get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
const struct alloc_context *ac)
{
struct zoneref *z = ac->preferred_zoneref;
struct zone *zone;
bool fair_skipped = false;
bool apply_fair = (alloc_flags & ALLOC_FAIR);
zonelist_scan:
/*
* Scan zonelist, looking for a zone with enough free.
* See also __cpuset_node_allowed() comment in kernel/cpuset.c.
*/
for_next_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx,
ac->nodemask) {
struct page *page;
unsigned long mark;
if (cpusets_enabled() &&
(alloc_flags & ALLOC_CPUSET) &&
!__cpuset_zone_allowed(zone, gfp_mask))
continue;
/*
* Distribute pages in proportion to the individual
* zone size to ensure fair page aging. The zone a
* page was allocated in should have no effect on the
* time the page has in memory before being reclaimed.
*/
if (apply_fair) {
if (test_bit(ZONE_FAIR_DEPLETED, &zone->flags)) {
fair_skipped = true;
continue;
}
if (!zone_local(ac->preferred_zoneref->zone, zone)) {
if (fair_skipped)
goto reset_fair;
apply_fair = false;
}
}
/*
* When allocating a page cache page for writing, we
* want to get it from a zone that is within its dirty
* limit, such that no single zone holds more than its
* proportional share of globally allowed dirty pages.
* The dirty limits take into account the zone's
* lowmem reserves and high watermark so that kswapd
* should be able to balance it without having to
* write pages from its LRU list.
*
* This may look like it could increase pressure on
* lower zones by failing allocations in higher zones
* before they are full. But the pages that do spill
* over are limited as the lower zones are protected
* by this very same mechanism. It should not become
* a practical burden to them.
*
* XXX: For now, allow allocations to potentially
* exceed the per-zone dirty limit in the slowpath
* (spread_dirty_pages unset) before going into reclaim,
* which is important when on a NUMA setup the allowed
* zones are together not big enough to reach the
* global limit. The proper fix for these situations
* will require awareness of zones in the
* dirty-throttling and the flusher threads.
*/
if (ac->spread_dirty_pages && !zone_dirty_ok(zone))
continue;
mark = zone->watermark[alloc_flags & ALLOC_WMARK_MASK];
if (!zone_watermark_fast(zone, order, mark,
ac_classzone_idx(ac), alloc_flags)) {
int ret;
/* Checked here to keep the fast path fast */
BUILD_BUG_ON(ALLOC_NO_WATERMARKS < NR_WMARK);
if (alloc_flags & ALLOC_NO_WATERMARKS)
goto try_this_zone;
if (zone_reclaim_mode == 0 ||
!zone_allows_reclaim(ac->preferred_zoneref->zone, zone))
continue;
ret = zone_reclaim(zone, gfp_mask, order);
switch (ret) {
case ZONE_RECLAIM_NOSCAN:
/* did not scan */
continue;
case ZONE_RECLAIM_FULL:
/* scanned but unreclaimable */
continue;
default:
/* did we reclaim enough */
if (zone_watermark_ok(zone, order, mark,
ac_classzone_idx(ac), alloc_flags))
goto try_this_zone;
continue;
}
}
try_this_zone:
page = buffered_rmqueue(ac->preferred_zoneref->zone, zone, order,
gfp_mask, alloc_flags, ac->migratetype);
if (page) {
prep_new_page(page, order, gfp_mask, alloc_flags);
/*
* If this is a high-order atomic allocation then check
* if the pageblock should be reserved for the future
*/
if (unlikely(order && (alloc_flags & ALLOC_HARDER)))
reserve_highatomic_pageblock(page, zone, order);
return page;
}
}
/*
* The first pass makes sure allocations are spread fairly within the
* local node. However, the local node might have free pages left
* after the fairness batches are exhausted, and remote zones haven't
* even been considered yet. Try once more without fairness, and
* include remote zones now, before entering the slowpath and waking
* kswapd: prefer spilling to a remote zone over swapping locally.
*/
if (fair_skipped) {
reset_fair:
apply_fair = false;
fair_skipped = false;
reset_alloc_batches(ac->preferred_zoneref->zone);
z = ac->preferred_zoneref;
goto zonelist_scan;
}
return NULL;
}
/*
* Large machines with many possible nodes should not always dump per-node
* meminfo in irq context.
*/
static inline bool should_suppress_show_mem(void)
{
bool ret = false;
#if NODES_SHIFT > 8
ret = in_interrupt();
#endif
return ret;
}
static DEFINE_RATELIMIT_STATE(nopage_rs,
DEFAULT_RATELIMIT_INTERVAL,
DEFAULT_RATELIMIT_BURST);
void warn_alloc_failed(gfp_t gfp_mask, unsigned int order, const char *fmt, ...)
{
unsigned int filter = SHOW_MEM_FILTER_NODES;
if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs) ||
debug_guardpage_minorder() > 0)
return;
/*
* This documents exceptions given to allocations in certain
* contexts that are allowed to allocate outside current's set
* of allowed nodes.
*/
if (!(gfp_mask & __GFP_NOMEMALLOC))
if (test_thread_flag(TIF_MEMDIE) ||
(current->flags & (PF_MEMALLOC | PF_EXITING)))
filter &= ~SHOW_MEM_FILTER_NODES;
if (in_interrupt() || !(gfp_mask & __GFP_DIRECT_RECLAIM))
filter &= ~SHOW_MEM_FILTER_NODES;
if (fmt) {
struct va_format vaf;
va_list args;
va_start(args, fmt);
vaf.fmt = fmt;
vaf.va = &args;
pr_warn("%pV", &vaf);
va_end(args);
}
pr_warn("%s: page allocation failure: order:%u, mode:%#x(%pGg)\n",
current->comm, order, gfp_mask, &gfp_mask);
dump_stack();
if (!should_suppress_show_mem())
show_mem(filter);
}
static inline struct page *
__alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
const struct alloc_context *ac, unsigned long *did_some_progress)
{
struct oom_control oc = {
.zonelist = ac->zonelist,
.nodemask = ac->nodemask,
.gfp_mask = gfp_mask,
.order = order,
};
struct page *page;
*did_some_progress = 0;
/*
* Acquire the oom lock. If that fails, somebody else is
* making progress for us.
*/
if (!mutex_trylock(&oom_lock)) {
*did_some_progress = 1;
schedule_timeout_uninterruptible(1);
return NULL;
}
/*
* Go through the zonelist yet one more time, keep very high watermark
* here, this is only to catch a parallel oom killing, we must fail if
* we're still under heavy pressure.
*/
page = get_page_from_freelist(gfp_mask | __GFP_HARDWALL, order,
ALLOC_WMARK_HIGH|ALLOC_CPUSET, ac);
if (page)
goto out;
if (!(gfp_mask & __GFP_NOFAIL)) {
/* Coredumps can quickly deplete all memory reserves */
if (current->flags & PF_DUMPCORE)
goto out;
/* The OOM killer will not help higher order allocs */
if (order > PAGE_ALLOC_COSTLY_ORDER)
goto out;
/* The OOM killer does not needlessly kill tasks for lowmem */
if (ac->high_zoneidx < ZONE_NORMAL)
goto out;
if (pm_suspended_storage())
goto out;
/*
* XXX: GFP_NOFS allocations should rather fail than rely on
* other request to make a forward progress.
* We are in an unfortunate situation where out_of_memory cannot
* do much for this context but let's try it to at least get
* access to memory reserved if the current task is killed (see
* out_of_memory). Once filesystems are ready to handle allocation
* failures more gracefully we should just bail out here.
*/
/* The OOM killer may not free memory on a specific node */
if (gfp_mask & __GFP_THISNODE)
goto out;
}
/* Exhausted what can be done so it's blamo time */
if (out_of_memory(&oc) || WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL)) {
*did_some_progress = 1;
if (gfp_mask & __GFP_NOFAIL) {
page = get_page_from_freelist(gfp_mask, order,
ALLOC_NO_WATERMARKS|ALLOC_CPUSET, ac);
/*
* fallback to ignore cpuset restriction if our nodes
* are depleted
*/
if (!page)
page = get_page_from_freelist(gfp_mask, order,
ALLOC_NO_WATERMARKS, ac);
}
}
out:
mutex_unlock(&oom_lock);
return page;
}
/*
* Maximum number of compaction retries wit a progress before OOM
* killer is consider as the only way to move forward.
*/
#define MAX_COMPACT_RETRIES 16
#ifdef CONFIG_COMPACTION
/* Try memory compaction for high-order allocations before reclaim */
static struct page *
__alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
unsigned int alloc_flags, const struct alloc_context *ac,
enum migrate_mode mode, enum compact_result *compact_result)
{
struct page *page;
int contended_compaction;
if (!order)
return NULL;
current->flags |= PF_MEMALLOC;
*compact_result = try_to_compact_pages(gfp_mask, order, alloc_flags, ac,
mode, &contended_compaction);
current->flags &= ~PF_MEMALLOC;
if (*compact_result <= COMPACT_INACTIVE)
return NULL;
/*
* At least in one zone compaction wasn't deferred or skipped, so let's
* count a compaction stall
*/
count_vm_event(COMPACTSTALL);
page = get_page_from_freelist(gfp_mask, order,
alloc_flags & ~ALLOC_NO_WATERMARKS, ac);
if (page) {
struct zone *zone = page_zone(page);
zone->compact_blockskip_flush = false;
compaction_defer_reset(zone, order, true);
count_vm_ev