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WSL2-Linux-Kernel/mm/page_alloc.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* 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/highmem.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/interrupt.h>
#include <linux/pagemap.h>
#include <linux/jiffies.h>
#include <linux/memblock.h>
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/kasan.h>
#include <linux/kmsan.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/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/random.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/debugobjects.h>
#include <linux/kmemleak.h>
#include <linux/compaction.h>
#include <trace/events/kmem.h>
#include <trace/events/oom.h>
#include <linux/prefetch.h>
#include <linux/mm_inline.h>
#include <linux/mmu_notifier.h>
#include <linux/migrate.h>
#include <linux/hugetlb.h>
#include <linux/sched/rt.h>
#include <linux/sched/mm.h>
#include <linux/page_owner.h>
#include <linux/page_table_check.h>
#include <linux/kthread.h>
#include <linux/memcontrol.h>
#include <linux/ftrace.h>
#include <linux/lockdep.h>
#include <linux/nmi.h>
#include <linux/psi.h>
#include <linux/khugepaged.h>
#include <linux/delayacct.h>
#include <asm/sections.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
#include "internal.h"
#include "shuffle.h"
#include "page_reporting.h"
#include "swap.h"
/* Free Page Internal flags: for internal, non-pcp variants of free_pages(). */
typedef int __bitwise fpi_t;
/* No special request */
#define FPI_NONE ((__force fpi_t)0)
/*
* Skip free page reporting notification for the (possibly merged) page.
* This does not hinder free page reporting from grabbing the page,
* reporting it and marking it "reported" - it only skips notifying
* the free page reporting infrastructure about a newly freed page. For
* example, used when temporarily pulling a page from a freelist and
* putting it back unmodified.
*/
#define FPI_SKIP_REPORT_NOTIFY ((__force fpi_t)BIT(0))
/*
* Place the (possibly merged) page to the tail of the freelist. Will ignore
* page shuffling (relevant code - e.g., memory onlining - is expected to
* shuffle the whole zone).
*
* Note: No code should rely on this flag for correctness - it's purely
* to allow for optimizations when handing back either fresh pages
* (memory onlining) or untouched pages (page isolation, free page
* reporting).
*/
#define FPI_TO_TAIL ((__force fpi_t)BIT(1))
/* prevent >1 _updater_ of zone percpu pageset ->high and ->batch fields */
static DEFINE_MUTEX(pcp_batch_high_lock);
#define MIN_PERCPU_PAGELIST_HIGH_FRACTION (8)
#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)
/*
* On SMP, spin_trylock is sufficient protection.
* On PREEMPT_RT, spin_trylock is equivalent on both SMP and UP.
*/
#define pcp_trylock_prepare(flags) do { } while (0)
#define pcp_trylock_finish(flag) do { } while (0)
#else
/* UP spin_trylock always succeeds so disable IRQs to prevent re-entrancy. */
#define pcp_trylock_prepare(flags) local_irq_save(flags)
#define pcp_trylock_finish(flags) local_irq_restore(flags)
#endif
/*
* Locking a pcp requires a PCP lookup followed by a spinlock. To avoid
* a migration causing the wrong PCP to be locked and remote memory being
* potentially allocated, pin the task to the CPU for the lookup+lock.
* preempt_disable is used on !RT because it is faster than migrate_disable.
* migrate_disable is used on RT because otherwise RT spinlock usage is
* interfered with and a high priority task cannot preempt the allocator.
*/
#ifndef CONFIG_PREEMPT_RT
#define pcpu_task_pin() preempt_disable()
#define pcpu_task_unpin() preempt_enable()
#else
#define pcpu_task_pin() migrate_disable()
#define pcpu_task_unpin() migrate_enable()
#endif
/*
* Generic helper to lookup and a per-cpu variable with an embedded spinlock.
* Return value should be used with equivalent unlock helper.
*/
#define pcpu_spin_lock(type, member, ptr) \
({ \
type *_ret; \
pcpu_task_pin(); \
_ret = this_cpu_ptr(ptr); \
spin_lock(&_ret->member); \
_ret; \
})
#define pcpu_spin_trylock(type, member, ptr) \
({ \
type *_ret; \
pcpu_task_pin(); \
_ret = this_cpu_ptr(ptr); \
if (!spin_trylock(&_ret->member)) { \
pcpu_task_unpin(); \
_ret = NULL; \
} \
_ret; \
})
#define pcpu_spin_unlock(member, ptr) \
({ \
spin_unlock(&ptr->member); \
pcpu_task_unpin(); \
})
/* struct per_cpu_pages specific helpers. */
#define pcp_spin_lock(ptr) \
pcpu_spin_lock(struct per_cpu_pages, lock, ptr)
#define pcp_spin_trylock(ptr) \
pcpu_spin_trylock(struct per_cpu_pages, lock, ptr)
#define pcp_spin_unlock(ptr) \
pcpu_spin_unlock(lock, ptr)
#ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID
DEFINE_PER_CPU(int, numa_node);
EXPORT_PER_CPU_SYMBOL(numa_node);
#endif
DEFINE_STATIC_KEY_TRUE(vm_numa_stat_key);
#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_);
#endif
static DEFINE_MUTEX(pcpu_drain_mutex);
#ifdef CONFIG_GCC_PLUGIN_LATENT_ENTROPY
volatile unsigned long latent_entropy __latent_entropy;
EXPORT_SYMBOL(latent_entropy);
#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
[N_MEMORY] = { { [0] = 1UL } },
[N_CPU] = { { [0] = 1UL } },
#endif /* NUMA */
};
EXPORT_SYMBOL(node_states);
atomic_long_t _totalram_pages __read_mostly;
EXPORT_SYMBOL(_totalram_pages);
unsigned long totalreserve_pages __read_mostly;
unsigned long totalcma_pages __read_mostly;
int percpu_pagelist_high_fraction;
gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
DEFINE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, init_on_alloc);
EXPORT_SYMBOL(init_on_alloc);
DEFINE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_FREE_DEFAULT_ON, init_on_free);
EXPORT_SYMBOL(init_on_free);
/*
* 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 system_transition_mutex held
* (gfp_allowed_mask also should only be modified with system_transition_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(&system_transition_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(&system_transition_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,
fpi_t fpi_flags);
/*
* 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] = {
#ifdef CONFIG_ZONE_DMA
[ZONE_DMA] = 256,
#endif
#ifdef CONFIG_ZONE_DMA32
[ZONE_DMA32] = 256,
#endif
[ZONE_NORMAL] = 32,
#ifdef CONFIG_HIGHMEM
[ZONE_HIGHMEM] = 0,
#endif
[ZONE_MOVABLE] = 0,
};
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
};
const 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[NR_COMPOUND_DTORS] = {
[NULL_COMPOUND_DTOR] = NULL,
[COMPOUND_PAGE_DTOR] = free_compound_page,
#ifdef CONFIG_HUGETLB_PAGE
[HUGETLB_PAGE_DTOR] = free_huge_page,
#endif
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
[TRANSHUGE_PAGE_DTOR] = free_transhuge_page,
#endif
};
int min_free_kbytes = 1024;
int user_min_free_kbytes = -1;
int watermark_boost_factor __read_mostly = 15000;
int watermark_scale_factor = 10;
bool mirrored_kernelcore __initdata_memblock;
/* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
int movable_zone;
EXPORT_SYMBOL(movable_zone);
#if MAX_NUMNODES > 1
unsigned int nr_node_ids __read_mostly = MAX_NUMNODES;
unsigned 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
/*
* During boot we initialize deferred pages on-demand, as needed, but once
* page_alloc_init_late() has finished, the deferred pages are all initialized,
* and we can permanently disable that path.
*/
DEFINE_STATIC_KEY_TRUE(deferred_pages);
static inline bool deferred_pages_enabled(void)
{
return static_branch_unlikely(&deferred_pages);
}
/*
* deferred_grow_zone() is __init, but it is called from
* get_page_from_freelist() during early boot until deferred_pages permanently
* disables this call. This is why we have refdata wrapper to avoid warning,
* and to ensure that the function body gets unloaded.
*/
static bool __ref
_deferred_grow_zone(struct zone *zone, unsigned int order)
{
return deferred_grow_zone(zone, order);
}
#else
static inline bool deferred_pages_enabled(void)
{
return false;
}
#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
/* Return a pointer to the bitmap storing bits affecting a block of pages */
static inline unsigned long *get_pageblock_bitmap(const struct page *page,
unsigned long pfn)
{
#ifdef CONFIG_SPARSEMEM
return section_to_usemap(__pfn_to_section(pfn));
#else
return page_zone(page)->pageblock_flags;
#endif /* CONFIG_SPARSEMEM */
}
static inline int pfn_to_bitidx(const struct page *page, unsigned long pfn)
{
#ifdef CONFIG_SPARSEMEM
pfn &= (PAGES_PER_SECTION-1);
#else
pfn = pfn - pageblock_start_pfn(page_zone(page)->zone_start_pfn);
#endif /* CONFIG_SPARSEMEM */
return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
}
static __always_inline
unsigned long __get_pfnblock_flags_mask(const struct page *page,
unsigned long pfn,
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);
/*
* This races, without locks, with set_pfnblock_flags_mask(). Ensure
* a consistent read of the memory array, so that results, even though
* racy, are not corrupted.
*/
word = READ_ONCE(bitmap[word_bitidx]);
return (word >> bitidx) & mask;
}
/**
* 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
* @mask: mask of bits that the caller is interested in
*
* Return: pageblock_bits flags
*/
unsigned long get_pfnblock_flags_mask(const struct page *page,
unsigned long pfn, unsigned long mask)
{
return __get_pfnblock_flags_mask(page, pfn, mask);
}
static __always_inline int get_pfnblock_migratetype(const struct page *page,
unsigned long pfn)
{
return __get_pfnblock_flags_mask(page, pfn, 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
* @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 mask)
{
unsigned long *bitmap;
unsigned long bitidx, word_bitidx;
unsigned long word;
BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4);
BUILD_BUG_ON(MIGRATE_TYPES > (1 << PB_migratetype_bits));
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);
mask <<= bitidx;
flags <<= bitidx;
word = READ_ONCE(bitmap[word_bitidx]);
do {
} while (!try_cmpxchg(&bitmap[word_bitidx], &word, (word & ~mask) | flags));
}
void set_pageblock_migratetype(struct page *page, int migratetype)
{
if (unlikely(page_group_by_mobility_disabled &&
migratetype < MIGRATE_PCPTYPES))
migratetype = MIGRATE_UNMOVABLE;
set_pfnblock_flags_mask(page, (unsigned long)migratetype,
page_to_pfn(page), MIGRATETYPE_MASK);
}
#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 (zone != page_zone(page))
return 0;
return 1;
}
/*
* Temporary debugging check for pages not lying within a given zone.
*/
static int __maybe_unused 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 __maybe_unused bad_range(struct zone *zone, struct page *page)
{
return 0;
}
#endif
static void bad_page(struct page *page, const char *reason)
{
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);
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);
}
static inline unsigned int order_to_pindex(int migratetype, int order)
{
int base = order;
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
if (order > PAGE_ALLOC_COSTLY_ORDER) {
VM_BUG_ON(order != pageblock_order);
return NR_LOWORDER_PCP_LISTS;
}
#else
VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);
#endif
return (MIGRATE_PCPTYPES * base) + migratetype;
}
static inline int pindex_to_order(unsigned int pindex)
{
int order = pindex / MIGRATE_PCPTYPES;
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
if (pindex == NR_LOWORDER_PCP_LISTS)
order = pageblock_order;
#else
VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);
#endif
return order;
}
static inline bool pcp_allowed_order(unsigned int order)
{
if (order <= PAGE_ALLOC_COSTLY_ORDER)
return true;
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
if (order == pageblock_order)
return true;
#endif
return false;
}
static inline void free_the_page(struct page *page, unsigned int order)
{
if (pcp_allowed_order(order)) /* Via pcp? */
free_unref_page(page, order);
else
__free_pages_ok(page, order, FPI_NONE);
}
/*
* 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)
{
mem_cgroup_uncharge(page_folio(page));
free_the_page(page, compound_order(page));
}
void prep_compound_page(struct page *page, unsigned int order)
{
int i;
int nr_pages = 1 << order;
__SetPageHead(page);
for (i = 1; i < nr_pages; i++)
prep_compound_tail(page, i);
prep_compound_head(page, order);
}
void destroy_large_folio(struct folio *folio)
{
enum compound_dtor_id dtor = folio->_folio_dtor;
VM_BUG_ON_FOLIO(dtor >= NR_COMPOUND_DTORS, folio);
compound_page_dtors[dtor](&folio->page);
}
#ifdef CONFIG_DEBUG_PAGEALLOC
unsigned int _debug_guardpage_minorder;
bool _debug_pagealloc_enabled_early __read_mostly
= IS_ENABLED(CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT);
EXPORT_SYMBOL(_debug_pagealloc_enabled_early);
DEFINE_STATIC_KEY_FALSE(_debug_pagealloc_enabled);
EXPORT_SYMBOL(_debug_pagealloc_enabled);
DEFINE_STATIC_KEY_FALSE(_debug_guardpage_enabled);
static int __init early_debug_pagealloc(char *buf)
{
return kstrtobool(buf, &_debug_pagealloc_enabled_early);
}
early_param("debug_pagealloc", early_debug_pagealloc);
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;
}
early_param("debug_guardpage_minorder", debug_guardpage_minorder_setup);
static inline bool set_page_guard(struct zone *zone, struct page *page,
unsigned int order, int migratetype)
{
if (!debug_guardpage_enabled())
return false;
if (order >= debug_guardpage_minorder())
return false;
__SetPageGuard(page);
INIT_LIST_HEAD(&page->buddy_list);
set_page_private(page, order);
/* Guard pages are not available for any usage */
if (!is_migrate_isolate(migratetype))
__mod_zone_freepage_state(zone, -(1 << order), migratetype);
return true;
}
static inline void clear_page_guard(struct zone *zone, struct page *page,
unsigned int order, int migratetype)
{
if (!debug_guardpage_enabled())
return;
__ClearPageGuard(page);
set_page_private(page, 0);
if (!is_migrate_isolate(migratetype))
__mod_zone_freepage_state(zone, (1 << order), migratetype);
}
#else
static inline bool set_page_guard(struct zone *zone, struct page *page,
unsigned int order, int migratetype) { return false; }
static inline void clear_page_guard(struct zone *zone, struct page *page,
unsigned int order, int migratetype) {}
#endif
static inline void set_buddy_order(struct page *page, unsigned int order)
{
set_page_private(page, order);
__SetPageBuddy(page);
}
#ifdef CONFIG_COMPACTION
static inline struct capture_control *task_capc(struct zone *zone)
{
struct capture_control *capc = current->capture_control;
return unlikely(capc) &&
!(current->flags & PF_KTHREAD) &&
!capc->page &&
capc->cc->zone == zone ? capc : NULL;
}
static inline bool
compaction_capture(struct capture_control *capc, struct page *page,
int order, int migratetype)
{
if (!capc || order != capc->cc->order)
return false;
/* Do not accidentally pollute CMA or isolated regions*/
if (is_migrate_cma(migratetype) ||
is_migrate_isolate(migratetype))
return false;
/*
* Do not let lower order allocations pollute a movable pageblock.
* This might let an unmovable request use a reclaimable pageblock
* and vice-versa but no more than normal fallback logic which can
* have trouble finding a high-order free page.
*/
if (order < pageblock_order && migratetype == MIGRATE_MOVABLE)
return false;
capc->page = page;
return true;
}
#else
static inline struct capture_control *task_capc(struct zone *zone)
{
return NULL;
}
static inline bool
compaction_capture(struct capture_control *capc, struct page *page,
int order, int migratetype)
{
return false;
}
#endif /* CONFIG_COMPACTION */
/* Used for pages not on another list */
static inline void add_to_free_list(struct page *page, struct zone *zone,
unsigned int order, int migratetype)
{
struct free_area *area = &zone->free_area[order];
list_add(&page->buddy_list, &area->free_list[migratetype]);
area->nr_free++;
}
/* Used for pages not on another list */
static inline void add_to_free_list_tail(struct page *page, struct zone *zone,
unsigned int order, int migratetype)
{
struct free_area *area = &zone->free_area[order];
list_add_tail(&page->buddy_list, &area->free_list[migratetype]);
area->nr_free++;
}
/*
* Used for pages which are on another list. Move the pages to the tail
* of the list - so the moved pages won't immediately be considered for
* allocation again (e.g., optimization for memory onlining).
*/
static inline void move_to_free_list(struct page *page, struct zone *zone,
unsigned int order, int migratetype)
{
struct free_area *area = &zone->free_area[order];
list_move_tail(&page->buddy_list, &area->free_list[migratetype]);
}
static inline void del_page_from_free_list(struct page *page, struct zone *zone,
unsigned int order)
{
/* clear reported state and update reported page count */
if (page_reported(page))
__ClearPageReported(page);
list_del(&page->buddy_list);
__ClearPageBuddy(page);
set_page_private(page, 0);
zone->free_area[order].nr_free--;
}
static inline struct page *get_page_from_free_area(struct free_area *area,
int migratetype)
{
return list_first_entry_or_null(&area->free_list[migratetype],
struct page, lru);
}
/*
* 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
*/
static inline bool
buddy_merge_likely(unsigned long pfn, unsigned long buddy_pfn,
struct page *page, unsigned int order)
{
unsigned long higher_page_pfn;
struct page *higher_page;
if (order >= MAX_ORDER - 1)
return false;
higher_page_pfn = buddy_pfn & pfn;
higher_page = page + (higher_page_pfn - pfn);
return find_buddy_page_pfn(higher_page, higher_page_pfn, order + 1,
NULL) != NULL;
}
/*
* 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 PageBuddy.
* 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, fpi_t fpi_flags)
{
struct capture_control *capc = task_capc(zone);
unsigned long buddy_pfn = 0;
unsigned long combined_pfn;
struct page *buddy;
bool to_tail;
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);
VM_BUG_ON_PAGE(pfn & ((1 << order) - 1), page);
VM_BUG_ON_PAGE(bad_range(zone, page), page);
while (order < MAX_ORDER) {
if (compaction_capture(capc, page, order, migratetype)) {
__mod_zone_freepage_state(zone, -(1 << order),
migratetype);
return;
}
buddy = find_buddy_page_pfn(page, pfn, order, &buddy_pfn);
if (!buddy)
goto done_merging;
if (unlikely(order >= pageblock_order)) {
/*
* We want to prevent merge between freepages on pageblock
* without fallbacks and normal pageblock. Without this,
* pageblock isolation could cause incorrect freepage or CMA
* accounting or HIGHATOMIC accounting.
*/
int buddy_mt = get_pageblock_migratetype(buddy);
if (migratetype != buddy_mt
&& (!migratetype_is_mergeable(migratetype) ||
!migratetype_is_mergeable(buddy_mt)))
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
del_page_from_free_list(buddy, zone, order);
combined_pfn = buddy_pfn & pfn;
page = page + (combined_pfn - pfn);
pfn = combined_pfn;
order++;
}
done_merging:
set_buddy_order(page, order);
if (fpi_flags & FPI_TO_TAIL)
to_tail = true;
else if (is_shuffle_order(order))
to_tail = shuffle_pick_tail();
else
to_tail = buddy_merge_likely(pfn, buddy_pfn, page, order);
if (to_tail)
add_to_free_list_tail(page, zone, order, migratetype);
else
add_to_free_list(page, zone, order, migratetype);
/* Notify page reporting subsystem of freed page */
if (!(fpi_flags & FPI_SKIP_REPORT_NOTIFY))
page_reporting_notify_free(order);
}
/**
* split_free_page() -- split a free page at split_pfn_offset
* @free_page: the original free page
* @order: the order of the page
* @split_pfn_offset: split offset within the page
*
* Return -ENOENT if the free page is changed, otherwise 0
*
* It is used when the free page crosses two pageblocks with different migratetypes
* at split_pfn_offset within the page. The split free page will be put into
* separate migratetype lists afterwards. Otherwise, the function achieves
* nothing.
*/
int split_free_page(struct page *free_page,
unsigned int order, unsigned long split_pfn_offset)
{
struct zone *zone = page_zone(free_page);
unsigned long free_page_pfn = page_to_pfn(free_page);
unsigned long pfn;
unsigned long flags;
int free_page_order;
int mt;
int ret = 0;
if (split_pfn_offset == 0)
return ret;
spin_lock_irqsave(&zone->lock, flags);
if (!PageBuddy(free_page) || buddy_order(free_page) != order) {
ret = -ENOENT;
goto out;
}
mt = get_pageblock_migratetype(free_page);
if (likely(!is_migrate_isolate(mt)))
__mod_zone_freepage_state(zone, -(1UL << order), mt);
del_page_from_free_list(free_page, zone, order);
for (pfn = free_page_pfn;
pfn < free_page_pfn + (1UL << order);) {
int mt = get_pfnblock_migratetype(pfn_to_page(pfn), pfn);
free_page_order = min_t(unsigned int,
pfn ? __ffs(pfn) : order,
__fls(split_pfn_offset));
__free_one_page(pfn_to_page(pfn), pfn, zone, free_page_order,
mt, FPI_NONE);
pfn += 1UL << free_page_order;
split_pfn_offset -= (1UL << free_page_order);
/* we have done the first part, now switch to second part */
if (split_pfn_offset == 0)
split_pfn_offset = (1UL << order) - (pfn - free_page_pfn);
}
out:
spin_unlock_irqrestore(&zone->lock, flags);
return ret;
}
/*
* 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
page->memcg_data |
#endif
(page->flags & check_flags)))
return false;
return true;
}
static const char *page_bad_reason(struct page *page, unsigned long flags)
{
const char *bad_reason = NULL;
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 & flags)) {
if (flags == PAGE_FLAGS_CHECK_AT_PREP)
bad_reason = "PAGE_FLAGS_CHECK_AT_PREP flag(s) set";
else
bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
}
#ifdef CONFIG_MEMCG
if (unlikely(page->memcg_data))
bad_reason = "page still charged to cgroup";
#endif
return bad_reason;
}
static void free_page_is_bad_report(struct page *page)
{
bad_page(page,
page_bad_reason(page, PAGE_FLAGS_CHECK_AT_FREE));
}
static inline bool free_page_is_bad(struct page *page)
{
if (likely(page_expected_state(page, PAGE_FLAGS_CHECK_AT_FREE)))
return false;
/* Something has gone sideways, find it */
free_page_is_bad_report(page);
return true;
}
static int free_tail_page_prepare(struct page *head_page, struct page *page)
{
struct folio *folio = (struct folio *)head_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 (!static_branch_unlikely(&check_pages_enabled)) {
ret = 0;
goto out;
}
switch (page - head_page) {
case 1:
/* the first tail page: these may be in place of ->mapping */
if (unlikely(folio_entire_mapcount(folio))) {
bad_page(page, "nonzero entire_mapcount");
goto out;
}
if (unlikely(atomic_read(&folio->_nr_pages_mapped))) {
bad_page(page, "nonzero nr_pages_mapped");
goto out;
}
if (unlikely(atomic_read(&folio->_pincount))) {
bad_page(page, "nonzero pincount");
goto out;
}
break;
case 2:
/*
* the second tail page: ->mapping is
* deferred_list.next -- ignore value.
*/
break;
default:
if (page->mapping != TAIL_MAPPING) {
bad_page(page, "corrupted mapping in tail page");
goto out;
}
break;
}
if (unlikely(!PageTail(page))) {
bad_page(page, "PageTail not set");
goto out;
}
if (unlikely(compound_head(page) != head_page)) {
bad_page(page, "compound_head not consistent");
goto out;
}
ret = 0;
out:
page->mapping = NULL;
clear_compound_head(page);
return ret;
}
/*
* Skip KASAN memory poisoning when either:
*
* 1. For generic KASAN: deferred memory initialization has not yet completed.
* Tag-based KASAN modes skip pages freed via deferred memory initialization
* using page tags instead (see below).
* 2. For tag-based KASAN modes: the page has a match-all KASAN tag, indicating
* that error detection is disabled for accesses via the page address.
*
* Pages will have match-all tags in the following circumstances:
*
* 1. Pages are being initialized for the first time, including during deferred
* memory init; see the call to page_kasan_tag_reset in __init_single_page.
* 2. The allocation was not unpoisoned due to __GFP_SKIP_KASAN, with the
* exception of pages unpoisoned by kasan_unpoison_vmalloc.
* 3. The allocation was excluded from being checked due to sampling,
* see the call to kasan_unpoison_pages.
*
* Poisoning pages during deferred memory init will greatly lengthen the
* process and cause problem in large memory systems as the deferred pages
* initialization is done with interrupt disabled.
*
* Assuming that there will be no reference to those newly initialized
* pages before they are ever allocated, this should have no effect on
* KASAN memory tracking as the poison will be properly inserted at page
* allocation time. The only corner case is when pages are allocated by
* on-demand allocation and then freed again before the deferred pages
* initialization is done, but this is not likely to happen.
*/
static inline bool should_skip_kasan_poison(struct page *page, fpi_t fpi_flags)
{
if (IS_ENABLED(CONFIG_KASAN_GENERIC))
return deferred_pages_enabled();
return page_kasan_tag(page) == 0xff;
}
static void kernel_init_pages(struct page *page, int numpages)
{
int i;
/* s390's use of memset() could override KASAN redzones. */
kasan_disable_current();
for (i = 0; i < numpages; i++)
clear_highpage_kasan_tagged(page + i);
kasan_enable_current();
}
static __always_inline bool free_pages_prepare(struct page *page,
unsigned int order, fpi_t fpi_flags)
{
int bad = 0;
bool skip_kasan_poison = should_skip_kasan_poison(page, fpi_flags);
bool init = want_init_on_free();
VM_BUG_ON_PAGE(PageTail(page), page);
trace_mm_page_free(page, order);
kmsan_free_page(page, order);
if (unlikely(PageHWPoison(page)) && !order) {
/*
* Do not let hwpoison pages hit pcplists/buddy
* Untie memcg state and reset page's owner
*/
if (memcg_kmem_online() && PageMemcgKmem(page))
__memcg_kmem_uncharge_page(page, order);
reset_page_owner(page, order);
page_table_check_free(page, order);
return false;
}
/*
* 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);
if (compound)
ClearPageHasHWPoisoned(page);
for (i = 1; i < (1 << order); i++) {
if (compound)
bad += free_tail_page_prepare(page, page + i);
if (is_check_pages_enabled()) {
if (free_page_is_bad(page + i)) {
bad++;
continue;
}
}
(page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
}
}
if (PageMappingFlags(page))
page->mapping = NULL;
if (memcg_kmem_online() && PageMemcgKmem(page))
__memcg_kmem_uncharge_page(page, order);
if (is_check_pages_enabled()) {
if (free_page_is_bad(page))
bad++;
if (bad)
return false;
}
page_cpupid_reset_last(page);
page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
reset_page_owner(page, order);
page_table_check_free(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);
}
kernel_poison_pages(page, 1 << order);
/*
* As memory initialization might be integrated into KASAN,
* KASAN poisoning and memory initialization code must be
* kept together to avoid discrepancies in behavior.
*
* With hardware tag-based KASAN, memory tags must be set before the
* page becomes unavailable via debug_pagealloc or arch_free_page.
*/
if (!skip_kasan_poison) {
kasan_poison_pages(page, order, init);
/* Memory is already initialized if KASAN did it internally. */
if (kasan_has_integrated_init())
init = false;
}
if (init)
kernel_init_pages(page, 1 << order);
/*
* arch_free_page() can make the page's contents inaccessible. s390
* does this. So nothing which can access the page's contents should
* happen after this.
*/
arch_free_page(page, order);
debug_pagealloc_unmap_pages(page, 1 << order);
return true;
}
/*
* Frees a number of pages from the PCP lists
* Assumes all pages on list are in same zone.
* count is the number of pages to free.
*/
static void free_pcppages_bulk(struct zone *zone, int count,
struct per_cpu_pages *pcp,
int pindex)
{
unsigned long flags;
int min_pindex = 0;
int max_pindex = NR_PCP_LISTS - 1;
unsigned int order;
bool isolated_pageblocks;
struct page *page;
/*
* Ensure proper count is passed which otherwise would stuck in the
* below while (list_empty(list)) loop.
*/
count = min(pcp->count, count);
/* Ensure requested pindex is drained first. */
pindex = pindex - 1;
spin_lock_irqsave(&zone->lock, flags);
isolated_pageblocks = has_isolate_pageblock(zone);
while (count > 0) {
struct list_head *list;
int nr_pages;
/* Remove pages from lists in a round-robin fashion. */
do {
if (++pindex > max_pindex)
pindex = min_pindex;
list = &pcp->lists[pindex];
if (!list_empty(list))
break;
if (pindex == max_pindex)
max_pindex--;
if (pindex == min_pindex)
min_pindex++;
} while (1);
order = pindex_to_order(pindex);
nr_pages = 1 << order;
do {
int mt;
page = list_last_entry(list, struct page, pcp_list);
mt = get_pcppage_migratetype(page);
/* must delete to avoid corrupting pcp list */
list_del(&page->pcp_list);
count -= nr_pages;
pcp->count -= nr_pages;
/* 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);
__free_one_page(page, page_to_pfn(page), zone, order, mt, FPI_NONE);
trace_mm_page_pcpu_drain(page, order, mt);
} while (count > 0 && !list_empty(list));
}
spin_unlock_irqrestore(&zone->lock, flags);
}
static void free_one_page(struct zone *zone,
struct page *page, unsigned long pfn,
unsigned int order,
int migratetype, fpi_t fpi_flags)
{
unsigned long flags;
spin_lock_irqsave(&zone->lock, flags);
if (unlikely(has_isolate_pageblock(zone) ||
is_migrate_isolate(migratetype))) {
migratetype = get_pfnblock_migratetype(page, pfn);
}
__free_one_page(page, pfn, zone, order, migratetype, fpi_flags);
spin_unlock_irqrestore(&zone->lock, flags);
}
static void __free_pages_ok(struct page *page, unsigned int order,
fpi_t fpi_flags)
{
unsigned long flags;
int migratetype;
unsigned long pfn = page_to_pfn(page);
struct zone *zone = page_zone(page);
if (!free_pages_prepare(page, order, fpi_flags))
return;
/*
* Calling get_pfnblock_migratetype() without spin_lock_irqsave() here
* is used to avoid calling get_pfnblock_migratetype() under the lock.
* This will reduce the lock holding time.
*/
migratetype = get_pfnblock_migratetype(page, pfn);
spin_lock_irqsave(&zone->lock, flags);
if (unlikely(has_isolate_pageblock(zone) ||
is_migrate_isolate(migratetype))) {
migratetype = get_pfnblock_migratetype(page, pfn);
}
__free_one_page(page, pfn, zone, order, migratetype, fpi_flags);
spin_unlock_irqrestore(&zone->lock, flags);
__count_vm_events(PGFREE, 1 << order);
}
void __free_pages_core(struct page *page, unsigned int order)
{
unsigned int nr_pages = 1 << order;
struct page *p = page;
unsigned int loop;
/*
* When initializing the memmap, __init_single_page() sets the refcount
* of all pages to 1 ("allocated"/"not free"). We have to set the
* refcount of all involved pages to 0.
*/
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);
atomic_long_add(nr_pages, &page_zone(page)->managed_pages);
/*
* Bypass PCP and place fresh pages right to the tail, primarily
* relevant for memory onlining.
*/
__free_pages_ok(page, order, FPI_TO_TAIL);
}
/*
* 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.
*
* 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.
*
* Note: the function may return non-NULL struct page even for a page block
* which contains a memory hole (i.e. there is no physical memory for a subset
* of the pfn range). For example, if the pageblock order is MAX_ORDER, which
* will fall into 2 sub-sections, and the end pfn of the pageblock may be hole
* even though the start pfn is online and valid. This should be safe most of
* the time because struct pages are still initialized via init_unavailable_range()
* and pfn walkers shouldn't touch any physical memory range for which they do
* not recognize any specific metadata in struct pages.
*/
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_online_page(start_pfn);
if (!start_page)
return NULL;
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 = pageblock_end_pfn(block_start_pfn);
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;
cond_resched();
}
/* We confirm that there is no hole */
zone->contiguous = true;
}
void clear_zone_contiguous(struct zone *zone)
{
zone->contiguous = false;
}
/*
* 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, int migratetype)
{
unsigned long size = 1 << high;
while (high > low) {
high--;
size >>= 1;
VM_BUG_ON_PAGE(bad_range(zone, &page[size]), &page[size]);
/*
* 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
*/
if (set_page_guard(zone, &page[size], high, migratetype))
continue;
add_to_free_list(&page[size], zone, high, migratetype);
set_buddy_order(&page[size], high);
}
}
static void check_new_page_bad(struct page *page)
{
if (unlikely(page->flags & __PG_HWPOISON)) {
/* Don't complain about hwpoisoned pages */
page_mapcount_reset(page); /* remove PageBuddy */
return;
}
bad_page(page,
page_bad_reason(page, PAGE_FLAGS_CHECK_AT_PREP));
}
/*
* This page is about to be returned from the page allocator
*/
static 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 check_new_pages(struct page *page, unsigned int order)
{
if (is_check_pages_enabled()) {
for (int i = 0; i < (1 << order); i++) {
struct page *p = page + i;
if (check_new_page(p))
return true;
}
}
return false;
}
static inline bool should_skip_kasan_unpoison(gfp_t flags)
{
/* Don't skip if a software KASAN mode is enabled. */
if (IS_ENABLED(CONFIG_KASAN_GENERIC) ||
IS_ENABLED(CONFIG_KASAN_SW_TAGS))
return false;
/* Skip, if hardware tag-based KASAN is not enabled. */
if (!kasan_hw_tags_enabled())
return true;
/*
* With hardware tag-based KASAN enabled, skip if this has been
* requested via __GFP_SKIP_KASAN.
*/
return flags & __GFP_SKIP_KASAN;
}
static inline bool should_skip_init(gfp_t flags)
{
/* Don't skip, if hardware tag-based KASAN is not enabled. */
if (!kasan_hw_tags_enabled())
return false;
/* For hardware tag-based KASAN, skip if requested. */
return (flags & __GFP_SKIP_ZERO);
}
inline void post_alloc_hook(struct page *page, unsigned int order,
gfp_t gfp_flags)
{
bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags) &&
!should_skip_init(gfp_flags);
bool zero_tags = init && (gfp_flags & __GFP_ZEROTAGS);
int i;
set_page_private(page, 0);
set_page_refcounted(page);
arch_alloc_page(page, order);
debug_pagealloc_map_pages(page, 1 << order);
/*
* Page unpoisoning must happen before memory initialization.
* Otherwise, the poison pattern will be overwritten for __GFP_ZERO
* allocations and the page unpoisoning code will complain.
*/
kernel_unpoison_pages(page, 1 << order);
/*
* As memory initialization might be integrated into KASAN,
* KASAN unpoisoning and memory initializion code must be
* kept together to avoid discrepancies in behavior.
*/
/*
* If memory tags should be zeroed
* (which happens only when memory should be initialized as well).
*/
if (zero_tags) {
/* Initialize both memory and memory tags. */
for (i = 0; i != 1 << order; ++i)
tag_clear_highpage(page + i);
/* Take note that memory was initialized by the loop above. */
init = false;
}
if (!should_skip_kasan_unpoison(gfp_flags) &&
kasan_unpoison_pages(page, order, init)) {
/* Take note that memory was initialized by KASAN. */
if (kasan_has_integrated_init())
init = false;
} else {
/*
* If memory tags have not been set by KASAN, reset the page
* tags to ensure page_address() dereferencing does not fault.
*/
for (i = 0; i != 1 << order; ++i)
page_kasan_tag_reset(page + i);
}
/* If memory is still not initialized, initialize it now. */
if (init)
kernel_init_pages(page, 1 << order);
set_page_owner(page, order, gfp_flags);
page_table_check_alloc(page, order);
}
static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
unsigned int alloc_flags)
{
post_alloc_hook(page, order, gfp_flags);
if (order && (gfp_flags & __GFP_COMP))
prep_compound_page(page, order);
/*
* 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 __always_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 = get_page_from_free_area(area, migratetype);
if (!page)
continue;
del_page_from_free_list(page, zone, current_order);
expand(zone, page, order, current_order, migratetype);
set_pcppage_migratetype(page, migratetype);
trace_mm_page_alloc_zone_locked(page, order, migratetype,
pcp_allowed_order(order) &&
migratetype < MIGRATE_PCPTYPES);
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
*
* The other migratetypes do not have fallbacks.
*/
static int fallbacks[MIGRATE_TYPES][MIGRATE_PCPTYPES - 1] = {
[MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE },
[MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE },
[MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE },
};
#ifdef CONFIG_CMA
static __always_inline 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 freelist tail 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()
*/
static int move_freepages(struct zone *zone,
unsigned long start_pfn, unsigned long end_pfn,
int migratetype, int *num_movable)
{
struct page *page;
unsigned long pfn;
unsigned int order;
int pages_moved = 0;
for (pfn = start_pfn; pfn <= end_pfn;) {
page = pfn_to_page(pfn);
if (!PageBuddy(page)) {
/*
* We assume that pages that could be isolated for
* migration are movable. But we don't actually try
* isolating, as that would be expensive.
*/
if (num_movable &&
(PageLRU(page) || __PageMovable(page)))
(*num_movable)++;
pfn++;
continue;
}
/* Make sure we are not inadvertently changing nodes */
VM_BUG_ON_PAGE(page_to_nid(page) != zone_to_nid(zone), page);
VM_BUG_ON_PAGE(page_zone(page) != zone, page);
order = buddy_order(page);
move_to_free_list(page, zone, order, migratetype);
pfn += 1 << order;
pages_moved += 1 << order;
}
return pages_moved;
}
int move_freepages_block(struct zone *zone, struct page *page,
int migratetype, int *num_movable)
{
unsigned long start_pfn, end_pfn, pfn;
if (num_movable)
*num_movable = 0;
pfn = page_to_pfn(page);
start_pfn = pageblock_start_pfn(pfn);
end_pfn = pageblock_end_pfn(pfn) - 1;
/* Do not cross zone boundaries */
if (!zone_spans_pfn(zone, start_pfn))
start_pfn = pfn;
if (!zone_spans_pfn(zone, end_pfn))
return 0;
return move_freepages(zone, start_pfn, end_pfn, migratetype,
num_movable);
}
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;
}
static inline bool boost_watermark(struct zone *zone)
{
unsigned long max_boost;
if (!watermark_boost_factor)
return false;
/*
* Don't bother in zones that are unlikely to produce results.
* On small machines, including kdump capture kernels running
* in a small area, boosting the watermark can cause an out of
* memory situation immediately.
*/
if ((pageblock_nr_pages * 4) > zone_managed_pages(zone))
return false;
max_boost = mult_frac(zone->_watermark[WMARK_HIGH],
watermark_boost_factor, 10000);
/*
* high watermark may be uninitialised if fragmentation occurs
* very early in boot so do not boost. We do not fall
* through and boost by pageblock_nr_pages as failing
* allocations that early means that reclaim is not going
* to help and it may even be impossible to reclaim the
* boosted watermark resulting in a hang.
*/
if (!max_boost)
return false;
max_boost = max(pageblock_nr_pages, max_boost);
zone->watermark_boost = min(zone->watermark_boost + pageblock_nr_pages,
max_boost);
return true;
}
/*
* 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 to our migratetype and determine how many already-allocated pages
* are there in the pageblock with a compatible migratetype. If at least half
* of pages are free or compatible, we can change migratetype of the pageblock
* itself, so pages freed in the future will be put on the correct free list.
*/
static void steal_suitable_fallback(struct zone *zone, struct page *page,
unsigned int alloc_flags, int start_type, bool whole_block)
{
unsigned int current_order = buddy_order(page);
int free_pages, movable_pages, alike_pages;
int old_block_type;
old_block_type = get_pageblock_migratetype(page);
/*
* This can happen due to races and we want to prevent broken
* highatomic accounting.
*/
if (is_migrate_highatomic(old_block_type))
goto single_page;
/* Take ownership for orders >= pageblock_order */
if (current_order >= pageblock_order) {
change_pageblock_range(page, current_order, start_type);
goto single_page;
}
/*
* Boost watermarks to increase reclaim pressure to reduce the
* likelihood of future fallbacks. Wake kswapd now as the node
* may be balanced overall and kswapd will not wake naturally.
*/
if (boost_watermark(zone) && (alloc_flags & ALLOC_KSWAPD))
set_bit(ZONE_BOOSTED_WATERMARK, &zone->flags);
/* We are not allowed to try stealing from the whole block */
if (!whole_block)
goto single_page;
free_pages = move_freepages_block(zone, page, start_type,
&movable_pages);
/*
* Determine how many pages are compatible with our allocation.
* For movable allocation, it's the number of movable pages which
* we just obtained. For other types it's a bit more tricky.
*/
if (start_type == MIGRATE_MOVABLE) {
alike_pages = movable_pages;
} else {
/*
* If we are falling back a RECLAIMABLE or UNMOVABLE allocation
* to MOVABLE pageblock, consider all non-movable pages as
* compatible. If it's UNMOVABLE falling back to RECLAIMABLE or
* vice versa, be conservative since we can't distinguish the
* exact migratetype of non-movable pages.
*/
if (old_block_type == MIGRATE_MOVABLE)
alike_pages = pageblock_nr_pages
- (free_pages + movable_pages);
else
alike_pages = 0;
}
/* moving whole block can fail due to zone boundary conditions */
if (!free_pages)
goto single_page;
/*
* If a sufficient number of pages in the block are either free or of
* comparable migratability as our allocation, claim the whole block.
*/
if (free_pages + alike_pages >= (1 << (pageblock_order-1)) ||
page_group_by_mobility_disabled)
set_pageblock_migratetype(page, start_type);
return;
single_page:
move_to_free_list(page, zone, current_order, 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 < MIGRATE_PCPTYPES - 1 ; i++) {
fallback_mt = fallbacks[migratetype][i];
if (free_area_empty(area, 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(zone) / 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);
/* Only reserve normal pageblocks (i.e., they can merge with others) */
if (migratetype_is_mergeable(mt)) {
zone->nr_reserved_highatomic += pageblock_nr_pages;
set_pageblock_migratetype(page, MIGRATE_HIGHATOMIC);
move_freepages_block(zone, page, MIGRATE_HIGHATOMIC, NULL);
}
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.
*
* If @force is true, try to unreserve a pageblock even though highatomic
* pageblock is exhausted.
*/
static bool unreserve_highatomic_pageblock(const struct alloc_context *ac,
bool force)
{
struct zonelist *zonelist = ac->zonelist;
unsigned long flags;
struct zoneref *z;
struct zone *zone;
struct page *page;
int order;
bool ret;
for_each_zone_zonelist_nodemask(zone, z, zonelist, ac->highest_zoneidx,
ac->nodemask) {
/*
* Preserve at least one pageblock unless memory pressure
* is really high.
*/
if (!force && 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 = get_page_from_free_area(area, MIGRATE_HIGHATOMIC);
if (!page)
continue;
/*
* In page freeing path, migratetype change is racy so
* we can counter several free pages in a pageblock
* in this loop although we changed the pageblock type
* from highatomic to ac->migratetype. So we should
* adjust the count once.
*/
if (is_migrate_highatomic_page(page)) {
/*
* 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);
ret = move_freepages_block(zone, page, ac->migratetype,
NULL);
if (ret) {
spin_unlock_irqrestore(&zone->lock, flags);
return ret;
}
}
spin_unlock_irqrestore(&zone->lock, flags);
}
return false;
}
/*
* Try finding a free buddy page on the fallback list and put it on the free
* list of requested migratetype, possibly along with other pages from the same
* block, depending on fragmentation avoidance heuristics. Returns true if
* fallback was found so that __rmqueue_smallest() can grab it.
*
* The use of signed ints for order and current_order is a deliberate
* deviation from the rest of this file, to make the for loop
* condition simpler.
*/
static __always_inline bool
__rmqueue_fallback(struct zone *zone, int order, int start_migratetype,
unsigned int alloc_flags)
{
struct free_area *area;
int current_order;
int min_order = order;
struct page *page;
int fallback_mt;
bool can_steal;
/*
* Do not steal pages from freelists belonging to other pageblocks
* i.e. orders < pageblock_order. If there are no local zones free,
* the zonelists will be reiterated without ALLOC_NOFRAGMENT.
*/
if (order < pageblock_order && alloc_flags & ALLOC_NOFRAGMENT)
min_order = pageblock_order;
/*
* Find the largest available free page in the other list. This roughly
* approximates finding the pageblock with the most free pages, which
* would be too costly to do exactly.
*/
for (current_order = MAX_ORDER; current_order >= min_order;
--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;
/*
* We cannot steal all free pages from the pageblock and the
* requested migratetype is movable. In that case it's better to
* steal and split the smallest available page instead of the
* largest available page, because even if the next movable
* allocation falls back into a different pageblock than this
* one, it won't cause permanent fragmentation.
*/
if (!can_steal && start_migratetype == MIGRATE_MOVABLE
&& current_order > order)
goto find_smallest;
goto do_steal;
}
return false;
find_smallest:
for (current_order = order; current_order <= MAX_ORDER;
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)
break;
}
/*
* This should not happen - we already found a suitable fallback
* when looking for the largest page.
*/
VM_BUG_ON(current_order > MAX_ORDER);
do_steal:
page = get_page_from_free_area(area, fallback_mt);
steal_suitable_fallback(zone, page, alloc_flags, start_migratetype,
can_steal);
trace_mm_page_alloc_extfrag(page, order, current_order,
start_migratetype, fallback_mt);
return true;
}
/*
* Do the hard work of removing an element from the buddy allocator.
* Call me with the zone->lock already held.
*/
static __always_inline struct page *
__rmqueue(struct zone *zone, unsigned int order, int migratetype,
unsigned int alloc_flags)
{
struct page *page;
if (IS_ENABLED(CONFIG_CMA)) {
/*
* Balance movable allocations between regular and CMA areas by
* allocating from CMA when over half of the zone's free memory
* is in the CMA area.
*/
if (alloc_flags & ALLOC_CMA &&
zone_page_state(zone, NR_FREE_CMA_PAGES) >
zone_page_state(zone, NR_FREE_PAGES) / 2) {
page = __rmqueue_cma_fallback(zone, order);
if (page)
return page;
}
}
retry:
page = __rmqueue_smallest(zone, order, migratetype);
if (unlikely(!page)) {
if (alloc_flags & ALLOC_CMA)
page = __rmqueue_cma_fallback(zone, order);
if (!page && __rmqueue_fallback(zone, order, migratetype,
alloc_flags))
goto retry;
}
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, unsigned int alloc_flags)
{
unsigned long flags;
int i;
spin_lock_irqsave(&zone->lock, flags);
for (i = 0; i < count; ++i) {
struct page *page = __rmqueue(zone, order, migratetype,
alloc_flags);
if (unlikely(page == NULL))
break;
/*
* Split buddy pages returned by expand() are received here in
* physical page order. The page is added to the tail of
* caller's list. From the callers perspective, the linked list
* is ordered by page number under some conditions. This is
* useful for IO devices that can forward direction from the
* head, thus also in the physical page order. This is useful
* for IO devices that can merge IO requests if the physical
* pages are ordered properly.
*/
list_add_tail(&page->pcp_list, list);
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_irqrestore(&zone->lock, flags);
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.
*/
void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
{
int to_drain, batch;
batch = READ_ONCE(pcp->batch);
to_drain = min(pcp->count, batch);
if (to_drain > 0) {
spin_lock(&pcp->lock);
free_pcppages_bulk(zone, to_drain, pcp, 0);
spin_unlock(&pcp->lock);
}
}
#endif
/*
* Drain pcplists of the indicated processor and zone.
*/
static void drain_pages_zone(unsigned int cpu, struct zone *zone)
{
struct per_cpu_pages *pcp;
pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
if (pcp->count) {
spin_lock(&pcp->lock);
free_pcppages_bulk(zone, pcp->count, pcp, 0);
spin_unlock(&pcp->lock);
}
}
/*
* Drain pcplists of all zones on the indicated processor.
*/
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.
*/
void drain_local_pages(struct zone *zone)
{
int cpu = smp_processor_id();
if (zone)
drain_pages_zone(cpu, zone);
else
drain_pages(cpu);
}
/*
* The implementation of drain_all_pages(), exposing an extra parameter to
* drain on all cpus.
*
* drain_all_pages() is optimized to only execute on cpus where pcplists are
* not empty. The check for non-emptiness can however race with a free to
* pcplist that has not yet increased the pcp->count from 0 to 1. Callers
* that need the guarantee that every CPU has drained can disable the
* optimizing racy check.
*/
static void __drain_all_pages(struct zone *zone, bool force_all_cpus)
{
int cpu;
/*
* Allocate in the BSS so we won't require allocation in
* direct reclaim path for CONFIG_CPUMASK_OFFSTACK=y
*/
static cpumask_t cpus_with_pcps;
/*
* Do not drain if one is already in progress unless it's specific to
* a zone. Such callers are primarily CMA and memory hotplug and need
* the drain to be complete when the call returns.
*/
if (unlikely(!mutex_trylock(&pcpu_drain_mutex))) {
if (!zone)
return;
mutex_lock(&pcpu_drain_mutex);
}
/*
* 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_pages *pcp;
struct zone *z;
bool has_pcps = false;
if (force_all_cpus) {
/*
* The pcp.count check is racy, some callers need a
* guarantee that no cpu is missed.
*/
has_pcps = true;
} else if (zone) {
pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
if (pcp->count)
has_pcps = true;
} else {
for_each_populated_zone(z) {
pcp = per_cpu_ptr(z->per_cpu_pageset, cpu);
if (pcp->count) {
has_pcps = true;
break;
}
}
}
if (has_pcps)
cpumask_set_cpu(cpu, &cpus_with_pcps);
else
cpumask_clear_cpu(cpu, &cpus_with_pcps);
}
for_each_cpu(cpu, &cpus_with_pcps) {
if (zone)
drain_pages_zone(cpu, zone);
else
drain_pages(cpu);
}
mutex_unlock(&pcpu_drain_mutex);
}
/*
* 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.
*/
void drain_all_pages(struct zone *zone)
{
__drain_all_pages(zone, false);
}
#ifdef CONFIG_HIBERNATION
/*
* Touch the watchdog for every WD_PAGE_COUNT pages.
*/
#define WD_PAGE_COUNT (128*1024)
void mark_free_pages(struct zone *zone)
{
unsigned long pfn, max_zone_pfn, page_count = WD_PAGE_COUNT;
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_count) {
touch_nmi_watchdog();
page_count = WD_PAGE_COUNT;
}
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], buddy_list) {
unsigned long i;
pfn = page_to_pfn(page);
for (i = 0; i < (1UL << order); i++) {
if (!--page_count) {
touch_nmi_watchdog();
page_count = WD_PAGE_COUNT;
}
swsusp_set_page_free(pfn_to_page(pfn + i));
}
}
}
spin_unlock_irqrestore(&zone->lock, flags);
}
#endif /* CONFIG_PM */
static bool free_unref_page_prepare(struct page *page, unsigned long pfn,
unsigned int order)
{
int migratetype;
if (!free_pages_prepare(page, order, FPI_NONE))
return false;
migratetype = get_pfnblock_migratetype(page, pfn);
set_pcppage_migratetype(page, migratetype);
return true;
}
static int nr_pcp_free(struct per_cpu_pages *pcp, int high, int batch,
bool free_high)
{
int min_nr_free, max_nr_free;
/* Free everything if batch freeing high-order pages. */
if (unlikely(free_high))
return pcp->count;
/* Check for PCP disabled or boot pageset */
if (unlikely(high < batch))
return 1;
/* Leave at least pcp->batch pages on the list */
min_nr_free = batch;
max_nr_free = high - batch;
/*
* Double the number of pages freed each time there is subsequent
* freeing of pages without any allocation.
*/
batch <<= pcp->free_factor;
if (batch < max_nr_free)
pcp->free_factor++;
batch = clamp(batch, min_nr_free, max_nr_free);
return batch;
}
static int nr_pcp_high(struct per_cpu_pages *pcp, struct zone *zone,
bool free_high)
{
int high = READ_ONCE(pcp->high);
if (unlikely(!high || free_high))
return 0;
if (!test_bit(ZONE_RECLAIM_ACTIVE, &zone->flags))
return high;
/*
* If reclaim is active, limit the number of pages that can be
* stored on pcp lists
*/
return min(READ_ONCE(pcp->batch) << 2, high);
}
static void free_unref_page_commit(struct zone *zone, struct per_cpu_pages *pcp,
struct page *page, int migratetype,
unsigned int order)
{
int high;
int pindex;
bool free_high;
__count_vm_events(PGFREE, 1 << order);
pindex = order_to_pindex(migratetype, order);
list_add(&page->pcp_list, &pcp->lists[pindex]);
pcp->count += 1 << order;
/*
* As high-order pages other than THP's stored on PCP can contribute
* to fragmentation, limit the number stored when PCP is heavily
* freeing without allocation. The remainder after bulk freeing
* stops will be drained from vmstat refresh context.
*/
free_high = (pcp->free_factor && order && order <= PAGE_ALLOC_COSTLY_ORDER);
high = nr_pcp_high(pcp, zone, free_high);
if (pcp->count >= high) {
int batch = READ_ONCE(pcp->batch);
free_pcppages_bulk(zone, nr_pcp_free(pcp, high, batch, free_high), pcp, pindex);
}
}
/*
* Free a pcp page
*/
void free_unref_page(struct page *page, unsigned int order)
{
unsigned long __maybe_unused UP_flags;
struct per_cpu_pages *pcp;
struct zone *zone;
unsigned long pfn = page_to_pfn(page);
int migratetype;
if (!free_unref_page_prepare(page, pfn, order))
return;
/*
* We only track unmovable, reclaimable and movable on pcp lists.
* Place ISOLATE pages on the isolated list because they are being
* offlined but treat HIGHATOMIC as movable pages so we can get those
* areas back if necessary. Otherwise, we may have to free
* excessively into the page allocator
*/
migratetype = get_pcppage_migratetype(page);
if (unlikely(migratetype >= MIGRATE_PCPTYPES)) {
if (unlikely(is_migrate_isolate(migratetype))) {
free_one_page(page_zone(page), page, pfn, order, migratetype, FPI_NONE);
return;
}
migratetype = MIGRATE_MOVABLE;
}
zone = page_zone(page);
pcp_trylock_prepare(UP_flags);
pcp = pcp_spin_trylock(zone->per_cpu_pageset);
if (pcp) {
free_unref_page_commit(zone, pcp, page, migratetype, order);
pcp_spin_unlock(pcp);
} else {
free_one_page(zone, page, pfn, order, migratetype, FPI_NONE);
}
pcp_trylock_finish(UP_flags);
}
/*
* Free a list of 0-order pages
*/
void free_unref_page_list(struct list_head *list)
{
unsigned long __maybe_unused UP_flags;
struct page *page, *next;
struct per_cpu_pages *pcp = NULL;
struct zone *locked_zone = NULL;
int batch_count = 0;
int migratetype;
/* Prepare pages for freeing */
list_for_each_entry_safe(page, next, list, lru) {
unsigned long pfn = page_to_pfn(page);
if (!free_unref_page_prepare(page, pfn, 0)) {
list_del(&page->lru);
continue;
}
/*
* Free isolated pages directly to the allocator, see
* comment in free_unref_page.
*/
migratetype = get_pcppage_migratetype(page);
if (unlikely(is_migrate_isolate(migratetype))) {
list_del(&page->lru);
free_one_page(page_zone(page), page, pfn, 0, migratetype, FPI_NONE);
continue;
}
}
list_for_each_entry_safe(page, next, list, lru) {
struct zone *zone = page_zone(page);
list_del(&page->lru);
migratetype = get_pcppage_migratetype(page);
/*
* Either different zone requiring a different pcp lock or
* excessive lock hold times when freeing a large list of
* pages.
*/
if (zone != locked_zone || batch_count == SWAP_CLUSTER_MAX) {
if (pcp) {
pcp_spin_unlock(pcp);
pcp_trylock_finish(UP_flags);
}
batch_count = 0;
/*
* trylock is necessary as pages may be getting freed
* from IRQ or SoftIRQ context after an IO completion.
*/
pcp_trylock_prepare(UP_flags);
pcp = pcp_spin_trylock(zone->per_cpu_pageset);
if (unlikely(!pcp)) {
pcp_trylock_finish(UP_flags);
free_one_page(zone, page, page_to_pfn(page),
0, migratetype, FPI_NONE);
locked_zone = NULL;
continue;
}
locked_zone = zone;
}
/*
* Non-isolated types over MIGRATE_PCPTYPES get added
* to the MIGRATE_MOVABLE pcp list.
*/
if (unlikely(migratetype >= MIGRATE_PCPTYPES))
migratetype = MIGRATE_MOVABLE;
trace_mm_page_free_batched(page);
free_unref_page_commit(zone, pcp, page, migratetype, 0);
batch_count++;
}
if (pcp) {
pcp_spin_unlock(pcp);
pcp_trylock_finish(UP_flags);
}
}
/*
* 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;
VM_BUG_ON_PAGE(PageCompound(page), page);
VM_BUG_ON_PAGE(!page_count(page), page);
for (i = 1; i < (1 << order); i++)
set_page_refcounted(page + i);
split_page_owner(page, 1 << order);
split_page_memcg(page, 1 << order);
}
EXPORT_SYMBOL_GPL(split_page);
int __isolate_free_page(struct page *page, unsigned int order)
{
struct zone *zone = page_zone(page);
int mt = get_pageblock_migratetype(page);
if (!is_migrate_isolate(mt)) {
unsigned long watermark;
/*
* Obey watermarks as if the page was being allocated. We can
* emulate a high-order watermark check with a raised order-0
* watermark, because we already know our high-order page
* exists.
*/
watermark = zone->_watermark[WMARK_MIN] + (1UL << order);
if (!zone_watermark_ok(zone, 0, watermark, 0, ALLOC_CMA))
return 0;
__mod_zone_freepage_state(zone, -(1UL << order), mt);
}
del_page_from_free_list(page, zone, order);
/*
* Set the pageblock if the isolated page is at least half of 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);
/*
* Only change normal pageblocks (i.e., they can merge
* with others)
*/
if (migratetype_is_mergeable(mt))
set_pageblock_migratetype(page,
MIGRATE_MOVABLE);
}
}
return 1UL << order;
}
/**
* __putback_isolated_page - Return a now-isolated page back where we got it
* @page: Page that was isolated
* @order: Order of the isolated page
* @mt: The page's pageblock's migratetype
*
* This function is meant to return a page pulled from the free lists via
* __isolate_free_page back to the free lists they were pulled from.
*/
void __putback_isolated_page(struct page *page, unsigned int order, int mt)
{
struct zone *zone = page_zone(page);
/* zone lock should be held when this function is called */
lockdep_assert_held(&zone->lock);
/* Return isolated page to tail of freelist. */
__free_one_page(page, page_to_pfn(page), zone, order, mt,
FPI_SKIP_REPORT_NOTIFY | FPI_TO_TAIL);
}
/*
* Update NUMA hit/miss statistics
*/
static inline void zone_statistics(struct zone *preferred_zone, struct zone *z,
long nr_account)
{
#ifdef CONFIG_NUMA
enum numa_stat_item local_stat = NUMA_LOCAL;
/* skip numa counters update if numa stats is disabled */
if (!static_branch_likely(&vm_numa_stat_key))
return;
if (zone_to_nid(z) != numa_node_id())
local_stat = NUMA_OTHER;
if (zone_to_nid(z) == zone_to_nid(preferred_zone))
__count_numa_events(z, NUMA_HIT, nr_account);
else {
__count_numa_events(z, NUMA_MISS, nr_account);
__count_numa_events(preferred_zone, NUMA_FOREIGN, nr_account);
}
__count_numa_events(z, local_stat, nr_account);
#endif
}
static __always_inline
struct page *rmqueue_buddy(struct zone *preferred_zone, struct zone *zone,
unsigned int order, unsigned int alloc_flags,
int migratetype)
{
struct page *page;
unsigned long flags;
do {
page = NULL;
spin_lock_irqsave(&zone->lock, flags);
/*
* order-0 request can reach here when the pcplist is skipped
* due to non-CMA allocation context. HIGHATOMIC area is
* reserved for high-order atomic allocation, so order-0
* request should skip it.
*/
if (alloc_flags & ALLOC_HIGHATOMIC)
page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
if (!page) {
page = __rmqueue(zone, order, migratetype, alloc_flags);
/*
* If the allocation fails, allow OOM handling access
* to HIGHATOMIC reserves as failing now is worse than
* failing a high-order atomic allocation in the
* future.
*/
if (!page && (alloc_flags & ALLOC_OOM))
page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
if (!page) {
spin_unlock_irqrestore(&zone->lock, flags);
return NULL;
}
}
__mod_zone_freepage_state(zone, -(1 << order),
get_pcppage_migratetype(page));
spin_unlock_irqrestore(&zone->lock, flags);
} while (check_new_pages(page, order));
__count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order);
zone_statistics(preferred_zone, zone, 1);
return page;
}
/* Remove page from the per-cpu list, caller must protect the list */
static inline
struct page *__rmqueue_pcplist(struct zone *zone, unsigned int order,
int migratetype,
unsigned int alloc_flags,
struct per_cpu_pages *pcp,
struct list_head *list)
{
struct page *page;
do {
if (list_empty(list)) {
int batch = READ_ONCE(pcp->batch);
int alloced;
/*
* Scale batch relative to order if batch implies
* free pages can be stored on the PCP. Batch can
* be 1 for small zones or for boot pagesets which
* should never store free pages as the pages may
* belong to arbitrary zones.
*/
if (batch > 1)
batch = max(batch >> order, 2);
alloced = rmqueue_bulk(zone, order,
batch, list,
migratetype, alloc_flags);
pcp->count += alloced << order;
if (unlikely(list_empty(list)))
return NULL;
}
page = list_first_entry(list, struct page, pcp_list);
list_del(&page->pcp_list);
pcp->count -= 1 << order;
} while (check_new_pages(page, order));
return page;
}
/* Lock and remove page from the per-cpu list */
static struct page *rmqueue_pcplist(struct zone *preferred_zone,
struct zone *zone, unsigned int order,
int migratetype, unsigned int alloc_flags)
{
struct per_cpu_pages *pcp;
struct list_head *list;
struct page *page;
unsigned long __maybe_unused UP_flags;
/* spin_trylock may fail due to a parallel drain or IRQ reentrancy. */
pcp_trylock_prepare(UP_flags);
pcp = pcp_spin_trylock(zone->per_cpu_pageset);
if (!pcp) {
pcp_trylock_finish(UP_flags);
return NULL;
}
/*
* On allocation, reduce the number of pages that are batch freed.
* See nr_pcp_free() where free_factor is increased for subsequent
* frees.
*/
pcp->free_factor >>= 1;
list = &pcp->lists[order_to_pindex(migratetype, order)];
page = __rmqueue_pcplist(zone, order, migratetype, alloc_flags, pcp, list);
pcp_spin_unlock(pcp);
pcp_trylock_finish(UP_flags);
if (page) {
__count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order);
zone_statistics(preferred_zone, zone, 1);
}
return page;
}
/*
* Allocate a page from the given zone.
* Use pcplists for THP or "cheap" high-order allocations.
*/
/*
* Do not instrument rmqueue() with KMSAN. This function may call
* __msan_poison_alloca() through a call to set_pfnblock_flags_mask().
* If __msan_poison_alloca() attempts to allocate pages for the stack depot, it
* may call rmqueue() again, which will result in a deadlock.
*/
__no_sanitize_memory
static inline
struct page *rmqueue(struct zone *preferred_zone,
struct zone *zone, unsigned int order,
gfp_t gfp_flags, unsigned int alloc_flags,
int migratetype)
{
struct page *page;
/*
* 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));
if (likely(pcp_allowed_order(order))) {
/*
* MIGRATE_MOVABLE pcplist could have the pages on CMA area and
* we need to skip it when CMA area isn't allowed.
*/
if (!IS_ENABLED(CONFIG_CMA) || alloc_flags & ALLOC_CMA ||
migratetype != MIGRATE_MOVABLE) {
page = rmqueue_pcplist(preferred_zone, zone, order,
migratetype, alloc_flags);
if (likely(page))
goto out;
}
}
page = rmqueue_buddy(preferred_zone, zone, order, alloc_flags,
migratetype);
out:
/* Separate test+clear to avoid unnecessary atomics */
if (unlikely(test_bit(ZONE_BOOSTED_WATERMARK, &zone->flags))) {
clear_bit(ZONE_BOOSTED_WATERMARK, &zone->flags);
wakeup_kswapd(zone, 0, 0, zone_idx(zone));
}
VM_BUG_ON_PAGE(page && bad_range(zone, page), page);
return page;
}
#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)
{
int flags = 0;
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;
/* See comment in __should_failslab() */
if (gfp_mask & __GFP_NOWARN)
flags |= FAULT_NOWARN;
return should_fail_ex(&fail_page_alloc.attr, 1 << order, flags);
}
#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
static int __init fail_page_alloc_debugfs(void)
{
umode_t mode = S_IFREG | 0600;
struct dentry *dir;
dir = fault_create_debugfs_attr("fail_page_alloc", NULL,
&fail_page_alloc.attr);
debugfs_create_bool("ignore-gfp-wait", mode, dir,
&fail_page_alloc.ignore_gfp_reclaim);
debugfs_create_bool("ignore-gfp-highmem", mode, dir,
&fail_page_alloc.ignore_gfp_highmem);
debugfs_create_u32("min-order", mode, dir, &fail_page_alloc.min_order);
return 0;
}
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 */
noinline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
{
return __should_fail_alloc_page(gfp_mask, order);
}
ALLOW_ERROR_INJECTION(should_fail_alloc_page, TRUE);
static inline long __zone_watermark_unusable_free(struct zone *z,
unsigned int order, unsigned int alloc_flags)
{
long unusable_free = (1 << order) - 1;
/*
* If the caller does not have rights to reserves below the min
* watermark then subtract the high-atomic reserves. This will
* over-estimate the size of the atomic reserve but it avoids a search.
*/
if (likely(!(alloc_flags & ALLOC_RESERVES)))
unusable_free += z->nr_reserved_highatomic;
#ifdef CONFIG_CMA
/* If allocation can't use CMA areas don't use free CMA pages */
if (!(alloc_flags & ALLOC_CMA))
unusable_free += zone_page_state(z, NR_FREE_CMA_PAGES);
#endif
return unusable_free;
}
/*
* 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 highest_zoneidx, unsigned int alloc_flags,
long free_pages)
{
long min = mark;
int o;
/* free_pages may go negative - that's OK */
free_pages -= __zone_watermark_unusable_free(z, order, alloc_flags);
if (unlikely(alloc_flags & ALLOC_RESERVES)) {
/*
* __GFP_HIGH allows access to 50% of the min reserve as well
* as OOM.
*/
if (alloc_flags & ALLOC_MIN_RESERVE) {
min -= min / 2;
/*
* Non-blocking allocations (e.g. GFP_ATOMIC) can
* access more reserves than just __GFP_HIGH. Other
* non-blocking allocations requests such as GFP_NOWAIT
* or (GFP_KERNEL & ~__GFP_DIRECT_RECLAIM) do not get
* access to the min reserve.
*/
if (alloc_flags & ALLOC_NON_BLOCK)
min -= min / 4;
}
/*
* OOM victims can try even harder than the normal reserve
* users on the grounds that it's definitely going to be in
* the exit path shortly and free memory. Any allocation it
* makes during the free path will be small and short-lived.
*/
if (alloc_flags & ALLOC_OOM)
min -= min / 2;
}
/*
* 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[highest_zoneidx])
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;
for (mt = 0; mt < MIGRATE_PCPTYPES; mt++) {
if (!free_area_empty(area, mt))
return true;
}
#ifdef CONFIG_CMA
if ((alloc_flags & ALLOC_CMA) &&
!free_area_empty(area, MIGRATE_CMA)) {
return true;
}
#endif
if ((alloc_flags & (ALLOC_HIGHATOMIC|ALLOC_OOM)) &&
!free_area_empty(area, MIGRATE_HIGHATOMIC)) {
return true;
}
}
return false;
}
bool zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
int highest_zoneidx, unsigned int alloc_flags)
{
return __zone_watermark_ok(z, order, mark, highest_zoneidx, 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 highest_zoneidx,
unsigned int alloc_flags, gfp_t gfp_mask)
{
long free_pages;
free_pages = zone_page_state(z, NR_FREE_PAGES);
/*
* Fast check for order-0 only. If this fails then the reserves
* need to be calculated.
*/
if (!order) {
long usable_free;
long reserved;
usable_free = free_pages;
reserved = __zone_watermark_unusable_free(z, 0, alloc_flags);
/* reserved may over estimate high-atomic reserves. */
usable_free -= min(usable_free, reserved);
if (usable_free > mark + z->lowmem_reserve[highest_zoneidx])
return true;
}
if (__zone_watermark_ok(z, order, mark, highest_zoneidx, alloc_flags,
free_pages))
return true;
/*
* Ignore watermark boosting for __GFP_HIGH order-0 allocations
* when checking the min watermark. The min watermark is the
* point where boosting is ignored so that kswapd is woken up
* when below the low watermark.
*/
if (unlikely(!order && (alloc_flags & ALLOC_MIN_RESERVE) && z->watermark_boost
&& ((alloc_flags & ALLOC_WMARK_MASK) == WMARK_MIN))) {
mark = z->_watermark[WMARK_MIN];
return __zone_watermark_ok(z, order, mark, highest_zoneidx,
alloc_flags, free_pages);
}
return false;
}
bool zone_watermark_ok_safe(struct zone *z, unsigned int order,
unsigned long mark, int highest_zoneidx)
{
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, highest_zoneidx, 0,
free_pages);
}
#ifdef CONFIG_NUMA
int __read_mostly node_reclaim_distance = RECLAIM_DISTANCE;
static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
{
return node_distance(zone_to_nid(local_zone), zone_to_nid(zone)) <=
node_reclaim_distance;
}
#else /* CONFIG_NUMA */
static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
{
return true;
}
#endif /* CONFIG_NUMA */
/*
* The restriction on ZONE_DMA32 as being a suitable zone to use to avoid
* fragmentation is subtle. If the preferred zone was HIGHMEM then
* premature use of a lower zone may cause lowmem pressure problems that
* are worse than fragmentation. If the next zone is ZONE_DMA then it is
* probably too small. It only makes sense to spread allocations to avoid
* fragmentation between the Normal and DMA32 zones.
*/
static inline unsigned int
alloc_flags_nofragment(struct zone *zone, gfp_t gfp_mask)
{
unsigned int alloc_flags;
/*
* __GFP_KSWAPD_RECLAIM is assumed to be the same as ALLOC_KSWAPD
* to save a branch.
*/
alloc_flags = (__force int) (gfp_mask & __GFP_KSWAPD_RECLAIM);
#ifdef CONFIG_ZONE_DMA32
if (!zone)
return alloc_flags;
if (zone_idx(zone) != ZONE_NORMAL)
return alloc_flags;
/*
* If ZONE_DMA32 exists, assume it is the one after ZONE_NORMAL and
* the pointer is within zone->zone_pgdat->node_zones[]. Also assume
* on UMA that if Normal is populated then so is DMA32.
*/
BUILD_BUG_ON(ZONE_NORMAL - ZONE_DMA32 != 1);
if (nr_online_nodes > 1 && !populated_zone(--zone))
return alloc_flags;
alloc_flags |= ALLOC_NOFRAGMENT;
#endif /* CONFIG_ZONE_DMA32 */
return alloc_flags;
}
/* Must be called after current_gfp_context() which can change gfp_mask */
static inline unsigned int gfp_to_alloc_flags_cma(gfp_t gfp_mask,
unsigned int alloc_flags)
{
#ifdef CONFIG_CMA
if (gfp_migratetype(gfp_mask) == MIGRATE_MOVABLE)
alloc_flags |= ALLOC_CMA;
#endif
return alloc_flags;
}
/*
* 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;
struct zone *zone;
struct pglist_data *last_pgdat = NULL;
bool last_pgdat_dirty_ok = false;
bool no_fallback;
retry:
/*
* Scan zonelist, looking for a zone with enough free.
* See also cpuset_node_allowed() comment in kernel/cgroup/cpuset.c.
*/
no_fallback = alloc_flags & ALLOC_NOFRAGMENT;
z = ac->preferred_zoneref;
for_next_zone_zonelist_nodemask(zone, z, ac->highest_zoneidx,
ac->nodemask) {
struct page *page;
unsigned long mark;
if (cpusets_enabled() &&
(alloc_flags & ALLOC_CPUSET) &&
!__cpuset_zone_allowed(zone, gfp_mask))
continue;
/*
* When allocating a page cache page for writing, we
* want to get it from a node that is within its dirty
* limit, such that no single node holds more than its
* proportional share of globally allowed dirty pages.
* The dirty limits take into account the node's
* lowmem reserves and high watermark so that kswapd
* should be able to balance it without having to
* write pages from its LRU list.
*
* XXX: For now, allow allocations to potentially
* exceed the per-node dirty limit in the slowpath
* (spread_dirty_pages unset) before going into reclaim,
* which is important when on a NUMA setup the allowed
* nodes are together not big enough to reach the
* global limit. The proper fix for these situations
* will require awareness of nodes in the
* dirty-throttling and the flusher threads.
*/
if (ac->spread_dirty_pages) {
if (last_pgdat != zone->zone_pgdat) {
last_pgdat = zone->zone_pgdat;
last_pgdat_dirty_ok = node_dirty_ok(zone->zone_pgdat);
}
if (!last_pgdat_dirty_ok)
continue;
}
if (no_fallback && nr_online_nodes > 1 &&
zone != ac->preferred_zoneref->zone) {
int local_nid;
/*
* If moving to a remote node, retry but allow
* fragmenting fallbacks. Locality is more important
* than fragmentation avoidance.
*/
local_nid = zone_to_nid(ac->preferred_zoneref->zone);
if (zone_to_nid(zone) != local_nid) {
alloc_flags &= ~ALLOC_NOFRAGMENT;
goto retry;
}
}
mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK);
if (!zone_watermark_fast(zone, order, mark,
ac->highest_zoneidx, alloc_flags,
gfp_mask)) {
int ret;
#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
/*
* Watermark failed for this zone, but see if we can
* grow this zone if it contains deferred pages.
*/
if (deferred_pages_enabled()) {
if (_deferred_grow_zone(zone, order))
goto try_this_zone;
}
#endif
/* 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 (!node_reclaim_enabled() ||
!zone_allows_reclaim(ac->preferred_zoneref->zone, zone))
continue;
ret = node_reclaim(zone->zone_pgdat, gfp_mask, order);
switch (ret) {
case NODE_RECLAIM_NOSCAN:
/* did not scan */
continue;
case NODE_RECLAIM_FULL:
/* scanned but unreclaimable */
continue;
default:
/* did we reclaim enough */
if (zone_watermark_ok(zone, order, mark,
ac->highest_zoneidx, alloc_flags))
goto try_this_zone;
continue;
}
}
try_this_zone:
page = 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(alloc_flags & ALLOC_HIGHATOMIC))
reserve_highatomic_pageblock(page, zone, order);
return page;
} else {
#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
/* Try again if zone has deferred pages */
if (deferred_pages_enabled()) {
if (_deferred_grow_zone(zone, order))
goto try_this_zone;
}
#endif
}
}
/*
* It's possible on a UMA machine to get through all zones that are
* fragmented. If avoiding fragmentation, reset and try again.
*/
if (no_fallback) {
alloc_flags &= ~ALLOC_NOFRAGMENT;
goto retry;
}
return NULL;
}
static void warn_alloc_show_mem(gfp_t gfp_mask, nodemask_t *nodemask)
{
unsigned int filter = SHOW_MEM_FILTER_NODES;
/*
* 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 (tsk_is_oom_victim(current) ||
(current->flags & (PF_MEMALLOC | PF_EXITING)))
filter &= ~SHOW_MEM_FILTER_NODES;
if (!in_task() || !(gfp_mask & __GFP_DIRECT_RECLAIM))
filter &= ~SHOW_MEM_FILTER_NODES;
__show_mem(filter, nodemask, gfp_zone(gfp_mask));
}
void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)
{
struct va_format vaf;
va_list args;
static DEFINE_RATELIMIT_STATE(nopage_rs, 10*HZ, 1);
if ((gfp_mask & __GFP_NOWARN) ||
!__ratelimit(&nopage_rs) ||
((gfp_mask & __GFP_DMA) && !has_managed_dma()))
return;
va_start(args, fmt);
vaf.fmt = fmt;
vaf.va = &args;
pr_warn("%s: %pV, mode:%#x(%pGg), nodemask=%*pbl",
current->comm, &vaf, gfp_mask, &gfp_mask,
nodemask_pr_args(nodemask));
va_end(args);
cpuset_print_current_mems_allowed();
pr_cont("\n");
dump_stack();
warn_alloc_show_mem(gfp_mask, nodemask);
}
static inline struct page *
__alloc_pages_cpuset_fallback(gfp_t gfp_mask, unsigned int order,
unsigned int alloc_flags,
const struct alloc_context *ac)
{
struct page *page;
page = get_page_from_freelist(gfp_mask, order,
alloc_flags|ALLOC_CPUSET, ac);
/*
* fallback to ignore cpuset restriction if our nodes
* are depleted
*/
if (!page)
page = get_page_from_freelist(gfp_mask, order,
alloc_flags, ac);
return page;
}
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,
.memcg = NULL,
.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. But make sure that this reclaim
* attempt shall not depend on __GFP_DIRECT_RECLAIM && !__GFP_NORETRY
* allocation which will never fail due to oom_lock already held.
*/
page = get_page_from_freelist((gfp_mask | __GFP_HARDWALL) &
~__GFP_DIRECT_RECLAIM, order,
ALLOC_WMARK_HIGH|ALLOC_CPUSET, ac);
if (page)
goto out;
/* 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;
/*
* We have already exhausted all our reclaim opportunities without any
* success so it is time to admit defeat. We will skip the OOM killer
* because it is very likely that the caller has a more reasonable
* fallback than shooting a random task.
*
* The OOM killer may not free memory on a specific node.
*/
if (gfp_mask & (__GFP_RETRY_MAYFAIL | __GFP_THISNODE))
goto out;
/* The OOM killer does not needlessly kill tasks for lowmem */
if (ac->highest_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.
*/
/* Exhausted what can be done so it's blame time */
if (out_of_memory(&oc) ||
WARN_ON_ONCE_GFP(gfp_mask & __GFP_NOFAIL, gfp_mask)) {
*did_some_progress = 1;
/*
* Help non-failing allocations by giving them access to memory
* reserves
*/
if (gfp_mask & __GFP_NOFAIL)
page = __alloc_pages_cpuset_fallback(gfp_mask, order,
ALLOC_NO_WATERMARKS, ac);
}
out:
mutex_unlock(&oom_lock);
return page;
}
/*
* Maximum number of compaction retries with 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 compact_priority prio, enum compact_result *compact_result)
{
struct page *page = NULL;
unsigned long pflags;
unsigned int noreclaim_flag;
if (!order)
return NULL;
psi_memstall_enter(&pflags);
delayacct_compact_start();
noreclaim_flag = memalloc_noreclaim_save();
*compact_result = try_to_compact_pages(gfp_mask, order, alloc_flags, ac,
prio, &page);
memalloc_noreclaim_restore(noreclaim_flag);
psi_memstall_leave(&pflags);
delayacct_compact_end();
if (*compact_result == COMPACT_SKIPPED)
return NULL;
/*
* At least in one zone compaction wasn't deferred or skipped, so let's
* count a compaction stall
*/
count_vm_event(COMPACTSTALL);
/* Prep a captured page if available */
if (page)
prep_new_page(page, order, gfp_mask, alloc_flags);
/* Try get a page from the freelist if available */
if (!page)
page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
if (page) {
struct zone *zone = page_zone(page);
zone->compact_blockskip_flush = false;
compaction_defer_reset(zone, order, true);
count_vm_event(COMPACTSUCCESS);
return page;
}
/*
* It's bad if compaction run occurs and fails. The most likely reason
* is that pages exist, but not enough to satisfy watermarks.
*/
count_vm_event(COMPACTFAIL);
cond_resched();
return NULL;
}
static inline bool
should_compact_retry(struct alloc_context *ac, int order, int alloc_flags,
enum compact_result compact_result,
enum compact_priority *compact_priority,
int *compaction_retries)
{
int max_retries = MAX_COMPACT_RETRIES;
int min_priority;
bool ret = false;
int retries = *compaction_retries;
enum compact_priority priority = *compact_priority;
if (!order)
return false;
if (fatal_signal_pending(current))
return false;
if (compaction_made_progress(compact_result))
(*compaction_retries)++;
/*
* compaction considers all the zone as desperately out of memory
* so it doesn't really make much sense to retry except when the
* failure could be caused by insufficient priority
*/
if (compaction_failed(compact_result))
goto check_priority;
/*
* compaction was skipped because there are not enough order-0 pages
* to work with, so we retry only if it looks like reclaim can help.
*/
if (compaction_needs_reclaim(compact_result)) {
ret = compaction_zonelist_suitable(ac, order, alloc_flags);
goto out;
}
/*
* make sure the compaction wasn't deferred or didn't bail out early
* due to locks contention before we declare that we should give up.
* But the next retry should use a higher priority if allowed, so
* we don't just keep bailing out endlessly.
*/
if (compaction_withdrawn(compact_result)) {
goto check_priority;
}
/*
* !costly requests are much more important than __GFP_RETRY_MAYFAIL
* costly ones because they are de facto nofail and invoke OOM
* killer to move on while costly can fail and users are ready
* to cope with that. 1/4 retries is rather arbitrary but we
* would need much more detailed feedback from compaction to
* make a better decision.
*/
if (order > PAGE_ALLOC_COSTLY_ORDER)
max_retries /= 4;
if (*compaction_retries <= max_retries) {
ret = true;
goto out;
}
/*
* Make sure there are attempts at the highest priority if we exhausted
* all retries or failed at the lower priorities.
*/
check_priority:
min_priority = (order > PAGE_ALLOC_COSTLY_ORDER) ?
MIN_COMPACT_COSTLY_PRIORITY : MIN_COMPACT_PRIORITY;
if (*compact_priority > min_priority) {
(*compact_priority)--;
*compaction_retries = 0;
ret = true;
}
out:
trace_compact_retry(order, priority, compact_result, retries, max_retries, ret);
return ret;
}
#else
static inline struct page *
__alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
unsigned int alloc_flags, const struct alloc_context *ac,
enum compact_priority prio, enum compact_result *compact_result)
{
*compact_result = COMPACT_SKIPPED;
return NULL;
}
static inline bool
should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_flags,
enum compact_result compact_result,
enum compact_priority *compact_priority,
int *compaction_retries)
{
struct zone *zone;
struct zoneref *z;
if (!order || order > PAGE_ALLOC_COSTLY_ORDER)
return false;
/*
* There are setups with compaction disabled which would prefer to loop
* inside the allocator rather than hit the oom killer prematurely.
* Let's give them a good hope and keep retrying while the order-0
* watermarks are OK.
*/
for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
ac->highest_zoneidx, ac->nodemask) {
if (zone_watermark_ok(zone, 0, min_wmark_pages(zone),
ac->highest_zoneidx, alloc_flags))
return true;
}
return false;
}
#endif /* CONFIG_COMPACTION */
#ifdef CONFIG_LOCKDEP
static struct lockdep_map __fs_reclaim_map =
STATIC_LOCKDEP_MAP_INIT("fs_reclaim", &__fs_reclaim_map);
static bool __need_reclaim(gfp_t gfp_mask)
{
/* no reclaim without waiting on it */
if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
return false;
/* this guy won't enter reclaim */
if (current->flags & PF_MEMALLOC)
return false;
if (gfp_mask & __GFP_NOLOCKDEP)
return false;
return true;
}
void __fs_reclaim_acquire(unsigned long ip)
{
lock_acquire_exclusive(&__fs_reclaim_map, 0, 0, NULL, ip);
}
void __fs_reclaim_release(unsigned long ip)
{
lock_release(&__fs_reclaim_map, ip);
}
void fs_reclaim_acquire(gfp_t gfp_mask)
{
gfp_mask = current_gfp_context(gfp_mask);
if (__need_reclaim(gfp_mask)) {
if (gfp_mask & __GFP_FS)
__fs_reclaim_acquire(_RET_IP_);
#ifdef CONFIG_MMU_NOTIFIER
lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
lock_map_release(&__mmu_notifier_invalidate_range_start_map);
#endif
}
}
EXPORT_SYMBOL_GPL(fs_reclaim_acquire);
void fs_reclaim_release(gfp_t gfp_mask)
{
gfp_mask = current_gfp_context(gfp_mask);
if (__need_reclaim(gfp_mask)) {
if (gfp_mask & __GFP_FS)
__fs_reclaim_release(_RET_IP_);
}
}
EXPORT_SYMBOL_GPL(fs_reclaim_release);
#endif
/*
* Zonelists may change due to hotplug during allocation. Detect when zonelists
* have been rebuilt so allocation retries. Reader side does not lock and
* retries the allocation if zonelist changes. Writer side is protected by the
* embedded spin_lock.
*/
static DEFINE_SEQLOCK(zonelist_update_seq);
static unsigned int zonelist_iter_begin(void)
{
if (IS_ENABLED(CONFIG_MEMORY_HOTREMOVE))
return read_seqbegin(&zonelist_update_seq);
return 0;
}
static unsigned int check_retry_zonelist(unsigned int seq)
{
if (IS_ENABLED(CONFIG_MEMORY_HOTREMOVE))
return read_seqretry(&zonelist_update_seq, seq);
return seq;
}
/* Perform direct synchronous page reclaim */
static unsigned long
__perform_reclaim(gfp_t gfp_mask, unsigned int order,
const struct alloc_context *ac)
{
unsigned int noreclaim_flag;
unsigned long progress;
cond_resched();
/* We now go into synchronous reclaim */
cpuset_memory_pressure_bump();
fs_reclaim_acquire(gfp_mask);
noreclaim_flag = memalloc_noreclaim_save();
progress = try_to_free_pages(ac->zonelist, order, gfp_mask,
ac->nodemask);
memalloc_noreclaim_restore(noreclaim_flag);
fs_reclaim_release(gfp_mask);
cond_resched();
return progress;
}
/* The really slow allocator path where we enter direct reclaim */
static inline struct page *
__alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order,
unsigned int alloc_flags, const struct alloc_context *ac,
unsigned long *did_some_progress)
{
struct page *page = NULL;
unsigned long pflags;
bool drained = false;
psi_memstall_enter(&pflags);
*did_some_progress = __perform_reclaim(gfp_mask, order, ac);
if (unlikely(!(*did_some_progress)))
goto out;
retry:
page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
/*
* If an allocation failed after direct reclaim, it could be because
* pages are pinned on the per-cpu lists or in high alloc reserves.
* Shrink them and try again
*/
if (!page && !drained) {
unreserve_highatomic_pageblock(ac, false);
drain_all_pages(NULL);
drained = true;
goto retry;
}
out:
psi_memstall_leave(&pflags);
return page;
}
static void wake_all_kswapds(unsigned int order, gfp_t gfp_mask,
const struct alloc_context *ac)
{
struct zoneref *z;
struct zone *zone;
pg_data_t *last_pgdat = NULL;
enum zone_type highest_zoneidx = ac->highest_zoneidx;
for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, highest_zoneidx,
ac->nodemask) {
if (!managed_zone(zone))
continue;
if (last_pgdat != zone->zone_pgdat) {
wakeup_kswapd(zone, gfp_mask, order, highest_zoneidx);
last_pgdat = zone->zone_pgdat;
}
}
}
static inline unsigned int
gfp_to_alloc_flags(gfp_t gfp_mask, unsigned int order)
{
unsigned int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET;
/*
* __GFP_HIGH is assumed to be the same as ALLOC_MIN_RESERVE
* and __GFP_KSWAPD_RECLAIM is assumed to be the same as ALLOC_KSWAPD
* to save two branches.
*/
BUILD_BUG_ON(__GFP_HIGH != (__force gfp_t) ALLOC_MIN_RESERVE);
BUILD_BUG_ON(__GFP_KSWAPD_RECLAIM != (__force gfp_t) ALLOC_KSWAPD);
/*
* The caller may dip into page reserves a bit more if the caller
* cannot run direct reclaim, or if the caller has realtime scheduling
* policy or is asking for __GFP_HIGH memory. GFP_ATOMIC requests will
* set both ALLOC_NON_BLOCK and ALLOC_MIN_RESERVE(__GFP_HIGH).
*/
alloc_flags |= (__force int)
(gfp_mask & (__GFP_HIGH | __GFP_KSWAPD_RECLAIM));
if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) {
/*
* Not worth trying to allocate harder for __GFP_NOMEMALLOC even
* if it can't schedule.
*/
if (!(gfp_mask & __GFP_NOMEMALLOC)) {
alloc_flags |= ALLOC_NON_BLOCK;
if (order > 0)
alloc_flags |= ALLOC_HIGHATOMIC;
}
/*
* Ignore cpuset mems for non-blocking __GFP_HIGH (probably
* GFP_ATOMIC) rather than fail, see the comment for
* cpuset_node_allowed().
*/
if (alloc_flags & ALLOC_MIN_RESERVE)
alloc_flags &= ~ALLOC_CPUSET;
} else if (unlikely(rt_task(current)) && in_task())
alloc_flags |= ALLOC_MIN_RESERVE;
alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, alloc_flags);
return alloc_flags;
}
static bool oom_reserves_allowed(struct task_struct *tsk)
{
if (!tsk_is_oom_victim(tsk))
return false;
/*
* !MMU doesn't have oom reaper so give access to memory reserves
* only to the thread with TIF_MEMDIE set
*/
if (!IS_ENABLED(CONFIG_MMU) && !test_thread_flag(TIF_MEMDIE))
return false;
return true;
}
/*
* Distinguish requests which really need access to full memory
* reserves from oom victims which can live with a portion of it
*/
static inline int __gfp_pfmemalloc_flags(gfp_t gfp_mask)
{
if (unlikely(gfp_mask & __GFP_NOMEMALLOC))
return 0;
if (gfp_mask & __GFP_MEMALLOC)
return ALLOC_NO_WATERMARKS;
if (in_serving_softirq() && (current->flags & PF_MEMALLOC))
return ALLOC_NO_WATERMARKS;
if (!in_interrupt()) {
if (current->flags & PF_MEMALLOC)
return ALLOC_NO_WATERMARKS;
else if (oom_reserves_allowed(current))
return ALLOC_OOM;
}
return 0;
}
bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
{
return !!__gfp_pfmemalloc_flags(gfp_mask);
}
/*
* Checks whether it makes sense to retry the reclaim to make a forward progress
* for the given allocation request.
*
* We give up when we either have tried MAX_RECLAIM_RETRIES in a row
* without success, or when we couldn't even meet the watermark if we
* reclaimed all remaining pages on the LRU lists.
*
* Returns true if a retry is viable or false to enter the oom path.
*/
static inline bool
should_reclaim_retry(gfp_t gfp_mask, unsigned order,
struct alloc_context *ac, int alloc_flags,
bool did_some_progress, int *no_progress_loops)
{
struct zone *zone;
struct zoneref *z;
bool ret = false;
/*
* Costly allocations might have made a progress but this doesn't mean
* their order will become available due to high fragmentation so
* always increment the no progress counter for them
*/
if (did_some_progress && order <= PAGE_ALLOC_COSTLY_ORDER)
*no_progress_loops = 0;
else
(*no_progress_loops)++;
/*
* Make sure we converge to OOM if we cannot make any progress
* several times in the row.
*/
if (*no_progress_loops > MAX_RECLAIM_RETRIES) {
/* Before OOM, exhaust highatomic_reserve */
return unreserve_highatomic_pageblock(ac, true);
}
/*
* Keep reclaiming pages while there is a chance this will lead
* somewhere. If none of the target zones can satisfy our allocation
* request even if all reclaimable pages are considered then we are
* screwed and have to go OOM.
*/
for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
ac->highest_zoneidx, ac->nodemask) {
unsigned long available;
unsigned long reclaimable;
unsigned long min_wmark = min_wmark_pages(zone);
bool wmark;
available = reclaimable = zone_reclaimable_pages(zone);
available += zone_page_state_snapshot(zone, NR_FREE_PAGES);
/*
* Would the allocation succeed if we reclaimed all
* reclaimable pages?
*/
wmark = __zone_watermark_ok(zone, order, min_wmark,
ac->highest_zoneidx, alloc_flags, available);
trace_reclaim_retry_zone(z, order, reclaimable,
available, min_wmark, *no_progress_loops, wmark);
if (wmark) {
ret = true;
break;
}
}
/*
* Memory allocation/reclaim might be called from a WQ context and the
* current implementation of the WQ concurrency control doesn't
* recognize that a particular WQ is congested if the worker thread is
* looping without ever sleeping. Therefore we have to do a short sleep
* here rather than calling cond_resched().
*/
if (current->flags & PF_WQ_WORKER)
schedule_timeout_uninterruptible(1);
else
cond_resched();
return ret;
}
static inline bool
check_retry_cpuset(int cpuset_mems_cookie, struct alloc_context *ac)
{
/*
* It's possible that cpuset's mems_allowed and the nodemask from
* mempolicy don't intersect. This should be normally dealt with by
* policy_nodemask(), but it's possible to race with cpuset update in
* such a way the check therein was true, and then it became false
* before we got our cpuset_mems_cookie here.
* This assumes that for all allocations, ac->nodemask can come only
* from MPOL_BIND mempolicy (whose documented semantics is to be ignored
* when it does not intersect with the cpuset restrictions) or the
* caller can deal with a violated nodemask.
*/
if (cpusets_enabled() && ac->nodemask &&
!cpuset_nodemask_valid_mems_allowed(ac->nodemask)) {
ac->nodemask = NULL;
return true;
}
/*
* When updating a task's mems_allowed or mempolicy nodemask, it is
* possible to race with parallel threads in such a way that our
* allocation can fail while the mask is being updated. If we are about
* to fail, check if the cpuset changed during allocation and if so,
* retry.
*/
if (read_mems_allowed_retry(cpuset_mems_cookie))
return true;
return false;
}
static inline struct page *
__alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
struct alloc_context *ac)
{
bool can_direct_reclaim = gfp_mask & __GFP_DIRECT_RECLAIM;
const bool costly_order = order > PAGE_ALLOC_COSTLY_ORDER;
struct page *page = NULL;
unsigned int alloc_flags;
unsigned long did_some_progress;
enum compact_priority compact_priority;
enum compact_result compact_result;
int compaction_retries;
int no_progress_loops;
unsigned int cpuset_mems_cookie;
unsigned int zonelist_iter_cookie;
int reserve_flags;
restart:
compaction_retries = 0;
no_progress_loops = 0;
compact_priority = DEF_COMPACT_PRIORITY;
cpuset_mems_cookie = read_mems_allowed_begin();
zonelist_iter_cookie = zonelist_iter_begin();
/*
* The fast path uses conservative alloc_flags to succeed only until
* kswapd needs to be woken up, and to avoid the cost of setting up
* alloc_flags precisely. So we do that now.
*/
alloc_flags = gfp_to_alloc_flags(gfp_mask, order);
/*
* We need to recalculate the starting point for the zonelist iterator
* because we might have used different nodemask in the fast path, or
* there was a cpuset modification and we are retrying - otherwise we
* could end up iterating over non-eligible zones endlessly.
*/
ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
ac->highest_zoneidx, ac->nodemask);
if (!ac->preferred_zoneref->zone)
goto nopage;
/*
* Check for insane configurations where the cpuset doesn't contain
* any suitable zone to satisfy the request - e.g. non-movable
* GFP_HIGHUSER allocations from MOVABLE nodes only.
*/
if (cpusets_insane_config() && (gfp_mask & __GFP_HARDWALL)) {
struct zoneref *z = first_zones_zonelist(ac->zonelist,
ac->highest_zoneidx,
&cpuset_current_mems_allowed);
if (!z->zone)
goto nopage;
}
if (alloc_flags & ALLOC_KSWAPD)
wake_all_kswapds(order, gfp_mask, ac);
/*
* The adjusted alloc_flags might result in immediate success, so try
* that first
*/
page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
if (page)
goto got_pg;
/*
* For costly allocations, try direct compaction first, as it's likely
* that we have enough base pages and don't need to reclaim. For non-
* movable high-order allocations, do that as well, as compaction will
* try prevent permanent fragmentation by migrating from blocks of the
* same migratetype.
* Don't try this for allocations that are allowed to ignore
* watermarks, as the ALLOC_NO_WATERMARKS attempt didn't yet happen.
*/
if (can_direct_reclaim &&
(costly_order ||
(order > 0 && ac->migratetype != MIGRATE_MOVABLE))
&& !gfp_pfmemalloc_allowed(gfp_mask)) {
page = __alloc_pages_direct_compact(gfp_mask, order,
alloc_flags, ac,
INIT_COMPACT_PRIORITY,
&compact_result);
if (page)
goto got_pg;
/*
* Checks for costly allocations with __GFP_NORETRY, which
* includes some THP page fault allocations
*/
if (costly_order && (gfp_mask & __GFP_NORETRY)) {
/*
* If allocating entire pageblock(s) and compaction
* failed because all zones are below low watermarks
* or is prohibited because it recently failed at this
* order, fail immediately unless the allocator has
* requested compaction and reclaim retry.
*
* Reclaim is
* - potentially very expensive because zones are far
* below their low watermarks or this is part of very
* bursty high order allocations,
* - not guaranteed to help because isolate_freepages()
* may not iterate over freed pages as part of its
* linear scan, and
* - unlikely to make entire pageblocks free on its
* own.
*/
if (compact_result == COMPACT_SKIPPED ||
compact_result == COMPACT_DEFERRED)
goto nopage;
/*
* Looks like reclaim/compaction is worth trying, but
* sync compaction could be very expensive, so keep
* using async compaction.
*/
compact_priority = INIT_COMPACT_PRIORITY;
}
}
retry:
/* Ensure kswapd doesn't accidentally go to sleep as long as we loop */
if (alloc_flags & ALLOC_KSWAPD)
wake_all_kswapds(order, gfp_mask, ac);
reserve_flags = __gfp_pfmemalloc_flags(gfp_mask);
if (reserve_flags)
alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, reserve_flags) |
(alloc_flags & ALLOC_KSWAPD);
/*
* Reset the nodemask and zonelist iterators if memory policies can be
* ignored. These allocations are high priority and system rather than
* user oriented.
*/
if (!(alloc_flags & ALLOC_CPUSET) || reserve_flags) {
ac->nodemask = NULL;
ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
ac->highest_zoneidx, ac->nodemask);
}
/* Attempt with potentially adjusted zonelist and alloc_flags */
page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
if (page)
goto got_pg;
/* Caller is not willing to reclaim, we can't balance anything */
if (!can_direct_reclaim)
goto nopage;
/* Avoid recursion of direct reclaim */
if (current->flags & PF_MEMALLOC)
goto nopage;
/* Try direct reclaim and then allocating */
page = __alloc_pages_direct_reclaim(gfp_mask, order, alloc_flags, ac,
&did_some_progress);
if (page)
goto got_pg;
/* Try direct compaction and then allocating */
page = __alloc_pages_direct_compact(gfp_mask, order, alloc_flags, ac,
compact_priority, &compact_result);
if (page)
goto got_pg;
/* Do not loop if specifically requested */
if (gfp_mask & __GFP_NORETRY)
goto nopage;
/*
* Do not retry costly high order allocations unless they are
* __GFP_RETRY_MAYFAIL
*/
if (costly_order && !(gfp_mask & __GFP_RETRY_MAYFAIL))
goto nopage;
if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags,
did_some_progress > 0, &no_progress_loops))
goto retry;
/*
* It doesn't make any sense to retry for the compaction if the order-0
* reclaim is not able to make any progress because the current
* implementation of the compaction depends on the sufficient amount
* of free memory (see __compaction_suitable)
*/
if (did_some_progress > 0 &&
should_compact_retry(ac, order, alloc_flags,
compact_result, &compact_priority,
&compaction_retries))
goto retry;
/*
* Deal with possible cpuset update races or zonelist updates to avoid
* a unnecessary OOM kill.
*/
if (check_retry_cpuset(cpuset_mems_cookie, ac) ||
check_retry_zonelist(zonelist_iter_cookie))
goto restart;
/* Reclaim has failed us, start killing things */
page = __alloc_pages_may_oom(gfp_mask, order, ac, &did_some_progress);
if (page)
goto got_pg;
/* Avoid allocations with no watermarks from looping endlessly */
if (tsk_is_oom_victim(current) &&
(alloc_flags & ALLOC_OOM ||
(gfp_mask & __GFP_NOMEMALLOC)))
goto nopage;
/* Retry as long as the OOM killer is making progress */
if (did_some_progress) {
no_progress_loops = 0;
goto retry;
}
nopage:
/*
* Deal with possible cpuset update races or zonelist updates to avoid
* a unnecessary OOM kill.
*/
if (check_retry_cpuset(cpuset_mems_cookie, ac) ||
check_retry_zonelist(zonelist_iter_cookie))
goto restart;
/*
* Make sure that __GFP_NOFAIL request doesn't leak out and make sure
* we always retry
*/
if (gfp_mask & __GFP_NOFAIL) {
/*
* All existing users of the __GFP_NOFAIL are blockable, so warn
* of any new users that actually require GFP_NOWAIT
*/
if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
goto fail;
/*
* PF_MEMALLOC request from this context is rather bizarre
* because we cannot reclaim anything and only can loop waiting
* for somebody to do a work for us
*/
WARN_ON_ONCE_GFP(current->flags & PF_MEMALLOC, gfp_mask);
/*
* non failing costly orders are a hard requirement which we
* are not prepared for much so let's warn about these users
* so that we can identify them and convert them to something
* else.
*/
WARN_ON_ONCE_GFP(costly_order, gfp_mask);
/*
* Help non-failing allocations by giving some access to memory
* reserves normally used for high priority non-blocking
* allocations but do not use ALLOC_NO_WATERMARKS because this
* could deplete whole memory reserves which would just make
* the situation worse.
*/
page = __alloc_pages_cpuset_fallback(gfp_mask, order, ALLOC_MIN_RESERVE, ac);
if (page)
goto got_pg;
cond_resched();
goto retry;
}
fail:
warn_alloc(gfp_mask, ac->nodemask,
"page allocation failure: order:%u", order);
got_pg:
return page;
}
static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
int preferred_nid, nodemask_t *nodemask,
struct alloc_context *ac, gfp_t *alloc_gfp,
unsigned int *alloc_flags)
{
ac->highest_zoneidx = gfp_zone(gfp_mask);
ac->zonelist = node_zonelist(preferred_nid, gfp_mask);
ac->nodemask = nodemask;
ac->migratetype = gfp_migratetype(gfp_mask);
if (cpusets_enabled()) {
*alloc_gfp |= __GFP_HARDWALL;
/*
* When we are in the interrupt context, it is irrelevant
* to the current task context. It means that any node ok.
*/
if (in_task() && !ac->nodemask)
ac->nodemask = &cpuset_current_mems_allowed;
else
*alloc_flags |= ALLOC_CPUSET;
}
might_alloc(gfp_mask);
if (should_fail_alloc_page(gfp_mask, order))
return false;
*alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, *alloc_flags);
/* Dirty zone balancing only done in the fast path */
ac->spread_dirty_pages = (gfp_mask & __GFP_WRITE);
/*
* The preferred zone is used for statistics but crucially it is
* also used as the starting point for the zonelist iterator. It
* may get reset for allocations that ignore memory policies.
*/
ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
ac->highest_zoneidx, ac->nodemask);
return true;
}
/*
* __alloc_pages_bulk - Allocate a number of order-0 pages to a list or array
* @gfp: GFP flags for the allocation
* @preferred_nid: The preferred NUMA node ID to allocate from
* @nodemask: Set of nodes to allocate from, may be NULL
* @nr_pages: The number of pages desired on the list or array
* @page_list: Optional list to store the allocated pages
* @page_array: Optional array to store the pages
*
* This is a batched version of the page allocator that attempts to
* allocate nr_pages quickly. Pages are added to page_list if page_list
* is not NULL, otherwise it is assumed that the page_array is valid.
*
* For lists, nr_pages is the number of pages that should be allocated.
*
* For arrays, only NULL elements are populated with pages and nr_pages
* is the maximum number of pages that will be stored in the array.
*
* Returns the number of pages on the list or array.
*/
unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid,
nodemask_t *nodemask, int nr_pages,
struct list_head *page_list,
struct page **page_array)
{
struct page *page;
unsigned long __maybe_unused UP_flags;
struct zone *zone;
struct zoneref *z;
struct per_cpu_pages *pcp;
struct list_head *pcp_list;
struct alloc_context ac;
gfp_t alloc_gfp;
unsigned int alloc_flags = ALLOC_WMARK_LOW;
int nr_populated = 0, nr_account = 0;
/*
* Skip populated array elements to determine if any pages need
* to be allocated before disabling IRQs.
*/
while (page_array && nr_populated < nr_pages && page_array[nr_populated])
nr_populated++;
/* No pages requested? */
if (unlikely(nr_pages <= 0))
goto out;
/* Already populated array? */
if (unlikely(page_array && nr_pages - nr_populated == 0))
goto out;
/* Bulk allocator does not support memcg accounting. */
if (memcg_kmem_online() && (gfp & __GFP_ACCOUNT))
goto failed;
/* Use the single page allocator for one page. */
if (nr_pages - nr_populated == 1)
goto failed;
#ifdef CONFIG_PAGE_OWNER
/*
* PAGE_OWNER may recurse into the allocator to allocate space to
* save the stack with pagesets.lock held. Releasing/reacquiring
* removes much of the performance benefit of bulk allocation so
* force the caller to allocate one page at a time as it'll have
* similar performance to added complexity to the bulk allocator.
*/
if (static_branch_unlikely(&page_owner_inited))
goto failed;
#endif
/* May set ALLOC_NOFRAGMENT, fragmentation will return 1 page. */
gfp &= gfp_allowed_mask;
alloc_gfp = gfp;
if (!prepare_alloc_pages(gfp, 0, preferred_nid, nodemask, &ac, &alloc_gfp, &alloc_flags))
goto out;
gfp = alloc_gfp;
/* Find an allowed local zone that meets the low watermark. */
for_each_zone_zonelist_nodemask(zone, z, ac.zonelist, ac.highest_zoneidx, ac.nodemask) {
unsigned long mark;
if (cpusets_enabled() && (alloc_flags & ALLOC_CPUSET) &&
!__cpuset_zone_allowed(zone, gfp)) {
continue;
}
if (nr_online_nodes > 1 && zone != ac.preferred_zoneref->zone &&
zone_to_nid(zone) != zone_to_nid(ac.preferred_zoneref->zone)) {
goto failed;
}
mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK) + nr_pages;
if (zone_watermark_fast(zone, 0, mark,
zonelist_zone_idx(ac.preferred_zoneref),
alloc_flags, gfp)) {
break;
}
}
/*
* If there are no allowed local zones that meets the watermarks then
* try to allocate a single page and reclaim if necessary.
*/
if (unlikely(!zone))
goto failed;
/* spin_trylock may fail due to a parallel drain or IRQ reentrancy. */
pcp_trylock_prepare(UP_flags);
pcp = pcp_spin_trylock(zone->per_cpu_pageset);
if (!pcp)
goto failed_irq;
/* Attempt the batch allocation */
pcp_list = &pcp->lists[order_to_pindex(ac.migratetype, 0)];
while (nr_populated < nr_pages) {
/* Skip existing pages */
if (page_array && page_array[nr_populated]) {
nr_populated++;
continue;
}
page = __rmqueue_pcplist(zone, 0, ac.migratetype, alloc_flags,
pcp, pcp_list);
if (unlikely(!page)) {
/* Try and allocate at least one page */
if (!nr_account) {
pcp_spin_unlock(pcp);
goto failed_irq;
}
break;
}
nr_account++;
prep_new_page(page, 0, gfp, 0);
if (page_list)
list_add(&page->lru, page_list);
else
page_array[nr_populated] = page;
nr_populated++;
}
pcp_spin_unlock(pcp);
pcp_trylock_finish(UP_flags);
__count_zid_vm_events(PGALLOC, zone_idx(zone), nr_account);
zone_statistics(ac.preferred_zoneref->zone, zone, nr_account);
out:
return nr_populated;
failed_irq:
pcp_trylock_finish(UP_flags);
failed:
page = __alloc_pages(gfp, 0, preferred_nid, nodemask);
if (page) {
if (page_list)
list_add(&page->lru, page_list);
else
page_array[nr_populated] = page;
nr_populated++;
}
goto out;
}
EXPORT_SYMBOL_GPL(__alloc_pages_bulk);
/*
* This is the 'heart' of the zoned buddy allocator.
*/
struct page *__alloc_pages(gfp_t gfp, unsigned int order, int preferred_nid,
nodemask_t *nodemask)
{
struct page *page;
unsigned int alloc_flags = ALLOC_WMARK_LOW;
gfp_t alloc_gfp; /* The gfp_t that was actually used for allocation */
struct alloc_context ac = { };
/*
* There are several places where we assume that the order value is sane
* so bail out early if the request is out of bound.
*/
if (WARN_ON_ONCE_GFP(order > MAX_ORDER, gfp))
return NULL;
gfp &= gfp_allowed_mask;
/*
* Apply scoped allocation constraints. This is mainly about GFP_NOFS
* resp. GFP_NOIO which has to be inherited for all allocation requests
* from a particular context which has been marked by
* memalloc_no{fs,io}_{save,restore}. And PF_MEMALLOC_PIN which ensures
* movable zones are not used during allocation.
*/
gfp = current_gfp_context(gfp);
alloc_gfp = gfp;
if (!prepare_alloc_pages(gfp, order, preferred_nid, nodemask, &ac,
&alloc_gfp, &alloc_flags))
return NULL;
/*
* Forbid the first pass from falling back to types that fragment
* memory until all local zones are considered.
*/
alloc_flags |= alloc_flags_nofragment(ac.preferred_zoneref->zone, gfp);
/* First allocation attempt */
page = get_page_from_freelist(alloc_gfp, order, alloc_flags, &ac);
if (likely(page))
goto out;
alloc_gfp = gfp;
ac.spread_dirty_pages = false;
/*
* Restore the original nodemask if it was potentially replaced with
* &cpuset_current_mems_allowed to optimize the fast-path attempt.
*/
ac.nodemask = nodemask;
page = __alloc_pages_slowpath(alloc_gfp, order, &ac);
out:
if (memcg_kmem_online() && (gfp & __GFP_ACCOUNT) && page &&
unlikely(__memcg_kmem_charge_page(page, gfp, order) != 0)) {
__free_pages(page, order);
page = NULL;
}
trace_mm_page_alloc(page, order, alloc_gfp, ac.migratetype);
kmsan_alloc_page(page, order, alloc_gfp);
return page;
}
EXPORT_SYMBOL(__alloc_pages);
struct folio *__folio_alloc(gfp_t gfp, unsigned int order, int preferred_nid,
nodemask_t *nodemask)
{
struct page *page = __alloc_pages(gfp | __GFP_COMP, order,
preferred_nid, nodemask);
if (page && order > 1)
prep_transhuge_page(page);
return (struct folio *)page;
}
EXPORT_SYMBOL(__folio_alloc);
/*
* Common helper functions. Never use with __GFP_HIGHMEM because the returned
* address cannot represent highmem pages. Use alloc_pages and then kmap if
* you need to access high mem.
*/
unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order)
{
struct page *page;
page = alloc_pages(gfp_mask & ~__GFP_HIGHMEM, order);
if (!page)
return 0;
return (unsigned long) page_address(page);
}
EXPORT_SYMBOL(__get_free_pages);
unsigned long get_zeroed_page(gfp_t gfp_mask)
{
return __get_free_page(gfp_mask | __GFP_ZERO);
}
EXPORT_SYMBOL(get_zeroed_page);
/**
* __free_pages - Free pages allocated with alloc_pages().
* @page: The page pointer returned from alloc_pages().
* @order: The order of the allocation.
*
* This function can free multi-page allocations that are not compound
* pages. It does not check that the @order passed in matches that of
* the allocation, so it is easy to leak memory. Freeing more memory
* than was allocated will probably emit a warning.
*
* If the last reference to this page is speculative, it will be released
* by put_page() which only frees the first page of a non-compound
* allocation. To prevent the remaining pages from being leaked, we free
* the subsequent pages here. If you want to use the page's reference
* count to decide when to free the allocation, you should allocate a
* compound page, and use put_page() instead of __free_pages().
*
* Context: May be called in interrupt context or while holding a normal
* spinlock, but not in NMI context or while holding a raw spinlock.
*/
void __free_pages(struct page *page, unsigned int order)
{
/* get PageHead before we drop reference */
int head = PageHead(page);
if (put_page_testzero(page))
free_the_page(page, order);
else if (!head)
while (order-- > 0)
free_the_page(page + (1 << order), order);
}
EXPORT_SYMBOL(__free_pages);
void free_pages(unsigned long addr, unsigned int order)
{
if (addr != 0) {
VM_BUG_ON(!virt_addr_valid((void *)addr));
__free_pages(virt_to_page((void *)addr), order);
}
}
EXPORT_SYMBOL(free_pages);
/*
* Page Fragment:
* An arbitrary-length arbitrary-offset area of memory which resides
* within a 0 or higher order page. Multiple fragments within that page
* are individually refcounted, in the page's reference counter.
*
* The page_frag functions below provide a simple allocation framework for
* page fragments. This is used by the network stack and network device
* drivers to provide a backing region of memory for use as either an
* sk_buff->head, or to be used in the "frags" portion of skb_shared_info.
*/
static struct page *__page_frag_cache_refill(struct page_frag_cache *nc,
gfp_t gfp_mask)
{
struct page *page = NULL;
gfp_t gfp = gfp_mask;
#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
gfp_mask |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY |
__GFP_NOMEMALLOC;
page = alloc_pages_node(NUMA_NO_NODE, gfp_mask,
PAGE_FRAG_CACHE_MAX_ORDER);
nc->size = page ? PAGE_FRAG_CACHE_MAX_SIZE : PAGE_SIZE;
#endif
if (unlikely(!page))
page = alloc_pages_node(NUMA_NO_NODE, gfp, 0);
nc->va = page ? page_address(page) : NULL;
return page;
}
void __page_frag_cache_drain(struct page *page, unsigned int count)
{
VM_BUG_ON_PAGE(page_ref_count(page) == 0, page);
if (page_ref_sub_and_test(page, count))
free_the_page(page, compound_order(page));
}
EXPORT_SYMBOL(__page_frag_cache_drain);
void *page_frag_alloc_align(struct page_frag_cache *nc,
unsigned int fragsz, gfp_t gfp_mask,
unsigned int align_mask)
{
unsigned int size = PAGE_SIZE;
struct page *page;
int offset;
if (unlikely(!nc->va)) {
refill:
page = __page_frag_cache_refill(nc, gfp_mask);
if (!page)
return NULL;
#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
/* if size can vary use size else just use PAGE_SIZE */
size = nc->size;
#endif
/* Even if we own the page, we do not use atomic_set().
* This would break get_page_unless_zero() users.
*/
page_ref_add(page, PAGE_FRAG_CACHE_MAX_SIZE);
/* reset page count bias and offset to start of new frag */
nc->pfmemalloc = page_is_pfmemalloc(page);
nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1;
nc->offset = size;
}
offset = nc->offset - fragsz;
if (unlikely(offset < 0)) {
page = virt_to_page(nc->va);
if (!page_ref_sub_and_test(page, nc->pagecnt_bias))
goto refill;
if (unlikely(nc->pfmemalloc)) {
free_the_page(page, compound_order(page));
goto refill;
}
#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
/* if size can vary use size else just use PAGE_SIZE */
size = nc->size;
#endif
/* OK, page count is 0, we can safely set it */
set_page_count(page, PAGE_FRAG_CACHE_MAX_SIZE + 1);
/* reset page count bias and offset to start of new frag */
nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1;
offset = size - fragsz;
if (unlikely(offset < 0)) {
/*
* The caller is trying to allocate a fragment
* with fragsz > PAGE_SIZE but the cache isn't big
* enough to satisfy the request, this may
* happen in low memory conditions.
* We don't release the cache page because
* it could make memory pressure worse
* so we simply return NULL here.
*/
return NULL;
}
}
nc->pagecnt_bias--;
offset &= align_mask;
nc->offset = offset;
return nc->va + offset;
}
EXPORT_SYMBOL(page_frag_alloc_align);
/*
* Frees a page fragment allocated out of either a compound or order 0 page.
*/
void page_frag_free(void *addr)
{
struct page *page = virt_to_head_page(addr);
if (unlikely(put_page_testzero(page)))
free_the_page(page, compound_order(page));
}
EXPORT_SYMBOL(page_frag_free);
static void *make_alloc_exact(unsigned long addr, unsigned int order,
size_t size)
{
if (addr) {
unsigned long nr = DIV_ROUND_UP(size, PAGE_SIZE);
struct page *page = virt_to_page((void *)addr);
struct page *last = page + nr;
split_page_owner(page, 1 << order);
split_page_memcg(page, 1 << order);
while (page < --last)
set_page_refcounted(last);
last = page + (1UL << order);
for (page += nr; page < last; page++)
__free_pages_ok(page, 0, FPI_TO_TAIL);
}
return (void *)addr;
}
/**
* alloc_pages_exact - allocate an exact number physically-contiguous pages.
* @size: the number of bytes to allocate
* @gfp_mask: GFP flags for the allocation, must not contain __GFP_COMP
*
* This function is similar to alloc_pages(), except that it allocates the
* minimum number of pages to satisfy the request. alloc_pages() can only
* allocate memory in power-of-two pages.
*
* This function is also limited by MAX_ORDER.
*
* Memory allocated by this function must be released by free_pages_exact().
*
* Return: pointer to the allocated area or %NULL in case of error.
*/
void *alloc_pages_exact(size_t size, gfp_t gfp_mask)
{
unsigned int order = get_order(size);
unsigned long addr;
if (WARN_ON_ONCE(gfp_mask & (__GFP_COMP | __GFP_HIGHMEM)))
gfp_mask &= ~(__GFP_COMP | __GFP_HIGHMEM);
addr = __get_free_pages(gfp_mask, order);
return make_alloc_exact(addr, order, size);
}
EXPORT_SYMBOL(alloc_pages_exact);
/**
* alloc_pages_exact_nid - allocate an exact number of physically-contiguous
* pages on a node.
* @nid: the preferred node ID where memory should be allocated
* @size: the number of bytes to allocate
* @gfp_mask: GFP flags for the allocation, must not contain __GFP_COMP
*
* Like alloc_pages_exact(), but try to allocate on node nid first before falling
* back.
*
* Return: pointer to the allocated area or %NULL in case of error.
*/
void * __meminit alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask)
{
unsigned int order = get_order(size);
struct page *p;
if (WARN_ON_ONCE(gfp_mask & (__GFP_COMP | __GFP_HIGHMEM)))
gfp_mask &= ~(__GFP_COMP | __GFP_HIGHMEM);
p = alloc_pages_node(nid, gfp_mask, order);
if (!p)
return NULL;
return make_alloc_exact((unsigned long)page_address(p), order, size);
}
/**
* free_pages_exact - release memory allocated via alloc_pages_exact()
* @virt: the value returned by alloc_pages_exact.
* @size: size of allocation, same value as passed to alloc_pages_exact().
*
* Release the memory allocated by a previous call to alloc_pages_exact.
*/
void free_pages_exact(void *virt, size_t size)
{
unsigned long addr = (unsigned long)virt;
unsigned long end = addr + PAGE_ALIGN(size);
while (addr < end) {
free_page(addr);
addr += PAGE_SIZE;
}
}
EXPORT_SYMBOL(free_pages_exact);
/**
* nr_free_zone_pages - count number of pages beyond high watermark
* @offset: The zone index of the highest zone
*
* nr_free_zone_pages() counts the number of pages which are beyond the
* high watermark within all zones at or below a given zone index. For each
* zone, the number of pages is calculated as:
*
* nr_free_zone_pages = managed_pages - high_pages
*
* Return: number of pages beyond high watermark.
*/
static unsigned long nr_free_zone_pages(int offset)
{
struct zoneref *z;
struct zone *zone;
/* Just pick one node, since fallback list is circular */
unsigned long sum = 0;
struct zonelist *zonelist = node_zonelist(numa_node_id(), GFP_KERNEL);
for_each_zone_zonelist(zone, z, zonelist, offset) {
unsigned long size = zone_managed_pages(zone);
unsigned long high = high_wmark_pages(zone);
if (size > high)
sum += size - high;
}
return sum;
}
/**
* nr_free_buffer_pages - count number of pages beyond high watermark
*
* nr_free_buffer_pages() counts the number of pages which are beyond the high
* watermark within ZONE_DMA and ZONE_NORMAL.
*
* Return: number of pages beyond high watermark within ZONE_DMA and
* ZONE_NORMAL.
*/
unsigned long nr_free_buffer_pages(void)
{
return nr_free_zone_pages(gfp_zone(GFP_USER));
}
EXPORT_SYMBOL_GPL(nr_free_buffer_pages);
static inline void show_node(struct zone *zone)
{
if (IS_ENABLED(CONFIG_NUMA))
printk("Node %d ", zone_to_nid(zone));
}
long si_mem_available(void)
{
long available;
unsigned long pagecache;
unsigned long wmark_low = 0;
unsigned long pages[NR_LRU_LISTS];
unsigned long reclaimable;
struct zone *zone;
int lru;
for (lru = LRU_BASE; lru < NR_LRU_LISTS; lru++)
pages[lru] = global_node_page_state(NR_LRU_BASE + lru);
for_each_zone(zone)
wmark_low += low_wmark_pages(zone);
/*
* Estimate the amount of memory available for userspace allocations,
* without causing swapping or OOM.
*/
available = global_zone_page_state(NR_FREE_PAGES) - totalreserve_pages;
/*
* Not all the page cache can be freed, otherwise the system will
* start swapping or thrashing. Assume at least half of the page
* cache, or the low watermark worth of cache, needs to stay.
*/
pagecache = pages[LRU_ACTIVE_FILE] + pages[LRU_INACTIVE_FILE];
pagecache -= min(pagecache / 2, wmark_low);
available += pagecache;
/*
* Part of the reclaimable slab and other kernel memory consists of
* items that are in use, and cannot be freed. Cap this estimate at the
* low watermark.
*/
reclaimable = global_node_page_state_pages(NR_SLAB_RECLAIMABLE_B) +
global_node_page_state(NR_KERNEL_MISC_RECLAIMABLE);
available += reclaimable - min(reclaimable / 2, wmark_low);
if (available < 0)
available = 0;
return available;
}
EXPORT_SYMBOL_GPL(si_mem_available);
void si_meminfo(struct sysinfo *val)
{
val->totalram = totalram_pages();
val->sharedram = global_node_page_state(NR_SHMEM);
val->freeram = global_zone_page_state(NR_FREE_PAGES);
val->bufferram = nr_blockdev_pages();
val->totalhigh = totalhigh_pages();
val->freehigh = nr_free_highpages();
val->mem_unit = PAGE_SIZE;
}
EXPORT_SYMBOL(si_meminfo);
#ifdef CONFIG_NUMA
void si_meminfo_node(struct sysinfo *val, int nid)
{
int zone_type; /* needs to be signed */
unsigned long managed_pages = 0;
unsigned long managed_highpages = 0;
unsigned long free_highpages = 0;
pg_data_t *pgdat = NODE_DATA(nid);
for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++)
managed_pages += zone_managed_pages(&pgdat->node_zones[zone_type]);
val->totalram = managed_pages;
val->sharedram = node_page_state(pgdat, NR_SHMEM);
val->freeram = sum_zone_node_page_state(nid, NR_FREE_PAGES);
#ifdef CONFIG_HIGHMEM
for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++) {
struct zone *zone = &pgdat->node_zones[zone_type];
if (is_highmem(zone)) {
managed_highpages += zone_managed_pages(zone);
free_highpages += zone_page_state(zone, NR_FREE_PAGES);
}
}
val->totalhigh = managed_highpages;
val->freehigh = free_highpages;
#else
val->totalhigh = managed_highpages;
val->freehigh = free_highpages;
#endif
val->mem_unit = PAGE_SIZE;
}
#endif
/*
* Determine whether the node should be displayed or not, depending on whether
* SHOW_MEM_FILTER_NODES was passed to show_free_areas().
*/
static bool show_mem_node_skip(unsigned int flags, int nid, nodemask_t *nodemask)
{
if (!(flags & SHOW_MEM_FILTER_NODES))
return false;
/*
* no node mask - aka implicit memory numa policy. Do not bother with
* the synchronization - read_mems_allowed_begin - because we do not
* have to be precise here.
*/
if (!nodemask)
nodemask = &cpuset_current_mems_allowed;
return !node_isset(nid, *nodemask);
}
static void show_migration_types(unsigned char type)
{
static const char types[MIGRATE_TYPES] = {
[MIGRATE_UNMOVABLE] = 'U',
[MIGRATE_MOVABLE] = 'M',
[MIGRATE_RECLAIMABLE] = 'E',
[MIGRATE_HIGHATOMIC] = 'H',
#ifdef CONFIG_CMA
[MIGRATE_CMA] = 'C',
#endif
#ifdef CONFIG_MEMORY_ISOLATION
[MIGRATE_ISOLATE] = 'I',
#endif
};
char tmp[MIGRATE_TYPES + 1];
char *p = tmp;
int i;
for (i = 0; i < MIGRATE_TYPES; i++) {
if (type & (1 << i))
*p++ = types[i];
}
*p = '\0';
printk(KERN_CONT "(%s) ", tmp);
}
static bool node_has_managed_zones(pg_data_t *pgdat, int max_zone_idx)
{
int zone_idx;
for (zone_idx = 0; zone_idx <= max_zone_idx; zone_idx++)
if (zone_managed_pages(pgdat->node_zones + zone_idx))
return true;
return false;
}
/*
* Show free area list (used inside shift_scroll-lock stuff)
* We also calculate the percentage fragmentation. We do this by counting the
* memory on each free list with the exception of the first item on the list.
*
* Bits in @filter:
* SHOW_MEM_FILTER_NODES: suppress nodes that are not allowed by current's
* cpuset.
*/
void __show_free_areas(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
{
unsigned long free_pcp = 0;
int cpu, nid;
struct zone *zone;
pg_data_t *pgdat;
for_each_populated_zone(zone) {
if (zone_idx(zone) > max_zone_idx)
continue;
if (show_mem_node_skip(filter, zone_to_nid(zone), nodemask))
continue;
for_each_online_cpu(cpu)
free_pcp += per_cpu_ptr(zone->per_cpu_pageset, cpu)->count;
}
printk("active_anon:%lu inactive_anon:%lu isolated_anon:%lu\n"
" active_file:%lu inactive_file:%lu isolated_file:%lu\n"
" unevictable:%lu dirty:%lu writeback:%lu\n"
" slab_reclaimable:%lu slab_unreclaimable:%lu\n"
" mapped:%lu shmem:%lu pagetables:%lu\n"
" sec_pagetables:%lu bounce:%lu\n"
" kernel_misc_reclaimable:%lu\n"
" free:%lu free_pcp:%lu free_cma:%lu\n",
global_node_page_state(NR_ACTIVE_ANON),
global_node_page_state(NR_INACTIVE_ANON),
global_node_page_state(NR_ISOLATED_ANON),
global_node_page_state(NR_ACTIVE_FILE),
global_node_page_state(NR_INACTIVE_FILE),
global_node_page_state(NR_ISOLATED_FILE),
global_node_page_state(NR_UNEVICTABLE),
global_node_page_state(NR_FILE_DIRTY),
global_node_page_state(NR_WRITEBACK),
global_node_page_state_pages(NR_SLAB_RECLAIMABLE_B),
global_node_page_state_pages(NR_SLAB_UNRECLAIMABLE_B),
global_node_page_state(NR_FILE_MAPPED),
global_node_page_state(NR_SHMEM),
global_node_page_state(NR_PAGETABLE),
global_node_page_state(NR_SECONDARY_PAGETABLE),
global_zone_page_state(NR_BOUNCE),
global_node_page_state(NR_KERNEL_MISC_RECLAIMABLE),
global_zone_page_state(NR_FREE_PAGES),
free_pcp,
global_zone_page_state(NR_FREE_CMA_PAGES));
for_each_online_pgdat(pgdat) {
if (show_mem_node_skip(filter, pgdat->node_id, nodemask))
continue;
if (!node_has_managed_zones(pgdat, max_zone_idx))
continue;
printk("Node %d"
" active_anon:%lukB"
" inactive_anon:%lukB"
" active_file:%lukB"
" inactive_file:%lukB"
" unevictable:%lukB"
" isolated(anon):%lukB"
" isolated(file):%lukB"
" mapped:%lukB"
" dirty:%lukB"
" writeback:%lukB"
" shmem:%lukB"
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
" shmem_thp: %lukB"
" shmem_pmdmapped: %lukB"
" anon_thp: %lukB"
#endif
" writeback_tmp:%lukB"
" kernel_stack:%lukB"
#ifdef CONFIG_SHADOW_CALL_STACK
" shadow_call_stack:%lukB"
#endif
" pagetables:%lukB"
" sec_pagetables:%lukB"
" all_unreclaimable? %s"
"\n",
pgdat->node_id,
K(node_page_state(pgdat, NR_ACTIVE_ANON)),
K(node_page_state(pgdat, NR_INACTIVE_ANON)),
K(node_page_state(pgdat, NR_ACTIVE_FILE)),
K(node_page_state(pgdat, NR_INACTIVE_FILE)),
K(node_page_state(pgdat, NR_UNEVICTABLE)),
K(node_page_state(pgdat, NR_ISOLATED_ANON)),
K(node_page_state(pgdat, NR_ISOLATED_FILE)),
K(node_page_state(pgdat, NR_FILE_MAPPED)),
K(node_page_state(pgdat, NR_FILE_DIRTY)),
K(node_page_state(pgdat, NR_WRITEBACK)),
K(node_page_state(pgdat, NR_SHMEM)),
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
K(node_page_state(pgdat, NR_SHMEM_THPS)),
K(node_page_state(pgdat, NR_SHMEM_PMDMAPPED)),
K(node_page_state(pgdat, NR_ANON_THPS)),
#endif
K(node_page_state(pgdat, NR_WRITEBACK_TEMP)),
node_page_state(pgdat, NR_KERNEL_STACK_KB),
#ifdef CONFIG_SHADOW_CALL_STACK
node_page_state(pgdat, NR_KERNEL_SCS_KB),
#endif
K(node_page_state(pgdat, NR_PAGETABLE)),
K(node_page_state(pgdat, NR_SECONDARY_PAGETABLE)),
pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES ?
"yes" : "no");
}
for_each_populated_zone(zone) {
int i;
if (zone_idx(zone) > max_zone_idx)
continue;
if (show_mem_node_skip(filter, zone_to_nid(zone), nodemask))
continue;
free_pcp = 0;
for_each_online_cpu(cpu)
free_pcp += per_cpu_ptr(zone->per_cpu_pageset, cpu)->count;
show_node(zone);
printk(KERN_CONT
"%s"
" free:%lukB"
" boost:%lukB"
" min:%lukB"
" low:%lukB"
" high:%lukB"
" reserved_highatomic:%luKB"
" active_anon:%lukB"
" inactive_anon:%lukB"
" active_file:%lukB"
" inactive_file:%lukB"
" unevictable:%lukB"
" writepending:%lukB"
" present:%lukB"
" managed:%lukB"
" mlocked:%lukB"
" bounce:%lukB"
" free_pcp:%lukB"
" local_pcp:%ukB"
" free_cma:%lukB"
"\n",
zone->name,
K(zone_page_state(zone, NR_FREE_PAGES)),
K(zone->watermark_boost),
K(min_wmark_pages(zone)),
K(low_wmark_pages(zone)),
K(high_wmark_pages(zone)),
K(zone->nr_reserved_highatomic),
K(zone_page_state(zone, NR_ZONE_ACTIVE_ANON)),
K(zone_page_state(zone, NR_ZONE_INACTIVE_ANON)),
K(zone_page_state(zone, NR_ZONE_ACTIVE_FILE)),
K(zone_page_state(zone, NR_ZONE_INACTIVE_FILE)),
K(zone_page_state(zone, NR_ZONE_UNEVICTABLE)),
K(zone_page_state(zone, NR_ZONE_WRITE_PENDING)),
K(zone->present_pages),
K(zone_managed_pages(zone)),
K(zone_page_state(zone, NR_MLOCK)),
K(zone_page_state(zone, NR_BOUNCE)),
K(free_pcp),
K(this_cpu_read(zone->per_cpu_pageset->count)),
K(zone_page_state(zone, NR_FREE_CMA_PAGES)));
printk("lowmem_reserve[]:");
for (i = 0; i < MAX_NR_ZONES; i++)
printk(KERN_CONT " %ld", zone->lowmem_reserve[i]);
printk(KERN_CONT "\n");
}
for_each_populated_zone(zone) {
unsigned int order;
unsigned long nr[MAX_ORDER + 1], flags, total = 0;
unsigned char types[MAX_ORDER + 1];
if (zone_idx(zone) > max_zone_idx)
continue;
if (show_mem_node_skip(filter, zone_to_nid(zone), nodemask))
continue;
show_node(zone);
printk(KERN_CONT "%s: ", zone->name);
spin_lock_irqsave(&zone->lock, flags);
for (order = 0; order <= MAX_ORDER; order++) {
struct free_area *area = &zone->free_area[order];
int type;
nr[order] = area->nr_free;
total += nr[order] << order;
types[order] = 0;
for (type = 0; type < MIGRATE_TYPES; type++) {
if (!free_area_empty(area, type))
types[order] |= 1 << type;
}
}
spin_unlock_irqrestore(&zone->lock, flags);
for (order = 0; order <= MAX_ORDER; order++) {
printk(KERN_CONT "%lu*%lukB ",
nr[order], K(1UL) << order);
if (nr[order])
show_migration_types(types[order]);
}
printk(KERN_CONT "= %lukB\n", K(total));
}
for_each_online_node(nid) {
if (show_mem_node_skip(filter, nid, nodemask))
continue;
hugetlb_show_meminfo_node(nid);
}
printk("%ld total pagecache pages\n", global_node_page_state(NR_FILE_PAGES));
show_swap_cache_info();
}
static void zoneref_set_zone(struct zone *zone, struct zoneref *zoneref)
{
zoneref->zone = zone;
zoneref->zone_idx = zone_idx(zone);
}
/*
* Builds allocation fallback zone lists.
*
* Add all populated zones of a node to the zonelist.
*/
static int build_zonerefs_node(pg_data_t *pgdat, struct zoneref *zonerefs)
{
struct zone *zone;
enum zone_type zone_type = MAX_NR_ZONES;
int nr_zones = 0;
do {
zone_type--;
zone = pgdat->node_zones + zone_type;
if (populated_zone(zone)) {
zoneref_set_zone(zone, &zonerefs[nr_zones++]);
check_highest_zone(zone_type);
}
} while (zone_type);
return nr_zones;
}
#ifdef CONFIG_NUMA
static int __parse_numa_zonelist_order(char *s)
{
/*
* We used to support different zonelists modes but they turned
* out to be just not useful. Let's keep the warning in place
* if somebody still use the cmd line parameter so that we do
* not fail it silently
*/
if (!(*s == 'd' || *s == 'D' || *s == 'n' || *s == 'N')) {
pr_warn("Ignoring unsupported numa_zonelist_order value: %s\n", s);
return -EINVAL;
}
return 0;
}
char numa_zonelist_order[] = "Node";
/*
* sysctl handler for numa_zonelist_order
*/
int numa_zonelist_order_handler(struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
{
if (write)
return __parse_numa_zonelist_order(buffer);
return proc_dostring(table, write, buffer, length, ppos);
}
static int node_load[MAX_NUMNODES];
/**
* find_next_best_node - find the next node that should appear in a given node's fallback list
* @node: node whose fallback list we're appending
* @used_node_mask: nodemask_t of already used nodes
*
* We use a number of factors to determine which is the next node that should
* appear on a given node's fallback list. The node should not have appeared
* already in @node's fallback list, and it should be the next closest node
* according to the distance array (which contains arbitrary distance values
* from each node to each node in the system), and should also prefer nodes
* with no CPUs, since presumably they'll have very little allocation pressure
* on them otherwise.
*
* Return: node id of the found node or %NUMA_NO_NODE if no node is found.
*/
int find_next_best_node(int node, nodemask_t *used_node_mask)
{
int n, val;
int min_val = INT_MAX;
int best_node = NUMA_NO_NODE;
/* Use the local node if we haven't already */
if (!node_isset(node, *used_node_mask)) {
node_set(node, *used_node_mask);
return node;
}
for_each_node_state(n, N_MEMORY) {
/* Don't want a node to appear more than once */
if (node_isset(n, *used_node_mask))
continue;
/* Use the distance array to find the distance */
val = node_distance(node, n);
/* Penalize nodes under us ("prefer the next node") */
val += (n < node);
/* Give preference to headless and unused nodes */
if (!cpumask_empty(cpumask_of_node(n)))
val += PENALTY_FOR_NODE_WITH_CPUS;
/* Slight preference for less loaded node */
val *= MAX_NUMNODES;
val += node_load[n];
if (val < min_val) {
min_val = val;
best_node = n;
}
}
if (best_node >= 0)
node_set(best_node, *used_node_mask);
return best_node;
}
/*
* Build zonelists ordered by node and zones within node.
* This results in maximum locality--normal zone overflows into local
* DMA zone, if any--but risks exhausting DMA zone.
*/
static void build_zonelists_in_node_order(pg_data_t *pgdat, int *node_order,
unsigned nr_nodes)
{
struct zoneref *zonerefs;
int i;
zonerefs = pgdat->node_zonelists[ZONELIST_FALLBACK]._zonerefs;
for (i = 0; i < nr_nodes; i++) {
int nr_zones;
pg_data_t *node = NODE_DATA(node_order[i]);
nr_zones = build_zonerefs_node(node, zonerefs);
zonerefs += nr_zones;
}
zonerefs->zone = NULL;
zonerefs->zone_idx = 0;
}
/*
* Build gfp_thisnode zonelists
*/
static void build_thisnode_zonelists(pg_data_t *pgdat)
{
struct zoneref *zonerefs;
int nr_zones;
zonerefs = pgdat->node_zonelists[ZONELIST_NOFALLBACK]._zonerefs;
nr_zones = build_zonerefs_node(pgdat, zonerefs);
zonerefs += nr_zones;
zonerefs->zone = NULL;
zonerefs->zone_idx = 0;
}
/*
* Build zonelists ordered by zone and nodes within zones.
* This results in conserving DMA zone[s] until all Normal memory is
* exhausted, but results in overflowing to remote node while memory
* may still exist in local DMA zone.
*/
static void build_zonelists(pg_data_t *pgdat)
{
static int node_order[MAX_NUMNODES];
int node, nr_nodes = 0;
nodemask_t used_mask = NODE_MASK_NONE;
int local_node, prev_node;
/* NUMA-aware ordering of nodes */
local_node = pgdat->node_id;
prev_node = local_node;
memset(node_order, 0, sizeof(node_order));
while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
/*
* We don't want to pressure a particular node.
* So adding penalty to the first node in same
* distance group to make it round-robin.
*/
if (node_distance(local_node, node) !=
node_distance(local_node, prev_node))
node_load[node] += 1;
node_order[nr_nodes++] = node;
prev_node = node;
}
build_zonelists_in_node_order(pgdat, node_order, nr_nodes);
build_thisnode_zonelists(pgdat);
pr_info("Fallback order for Node %d: ", local_node);
for (node = 0; node < nr_nodes; node++)
pr_cont("%d ", node_order[node]);
pr_cont("\n");
}
#ifdef CONFIG_HAVE_MEMORYLESS_NODES
/*
* Return node id of node used for "local" allocations.
* I.e., first node id of first zone in arg node's generic zonelist.
* Used for initializing percpu 'numa_mem', which is used primarily
* for kernel allocations, so use GFP_KERNEL flags to locate zonelist.
*/
int local_memory_node(int node)
{
struct zoneref *z;
z = first_zones_zonelist(node_zonelist(node, GFP_KERNEL),
gfp_zone(GFP_KERNEL),
NULL);
return zone_to_nid(z->zone);
}
#endif
static void setup_min_unmapped_ratio(void);
static void setup_min_slab_ratio(void);
#else /* CONFIG_NUMA */
static void build_zonelists(pg_data_t *pgdat)
{
int node, local_node;
struct zoneref *zonerefs;
int nr_zones;
local_node = pgdat->node_id;
zonerefs = pgdat->node_zonelists[ZONELIST_FALLBACK]._zonerefs;
nr_zones = build_zonerefs_node(pgdat, zonerefs);
zonerefs += nr_zones;
/*
* Now we build the zonelist so that it contains the zones
* of all the other nodes.
* We don't want to pressure a particular node, so when
* building the zones for node N, we make sure that the
* zones coming right after the local ones are those from
* node N+1 (modulo N)
*/
for (node = local_node + 1; node < MAX_NUMNODES; node++) {
if (!node_online(node))
continue;
nr_zones = build_zonerefs_node(NODE_DATA(node), zonerefs);
zonerefs += nr_zones;
}
for (node = 0; node < local_node; node++) {
if (!node_online(node))
continue;
nr_zones = build_zonerefs_node(NODE_DATA(node), zonerefs);
zonerefs += nr_zones;
}
zonerefs->zone = NULL;
zonerefs->zone_idx = 0;
}
#endif /* CONFIG_NUMA */
/*
* Boot pageset table. One per cpu which is going to be used for all
* zones and all nodes. The parameters will be set in such a way
* that an item put on a list will immediately be handed over to
* the buddy list. This is safe since pageset manipulation is done
* with interrupts disabled.
*
* The boot_pagesets must be kept even after bootup is complete for
* unused processors and/or zones. They do play a role for bootstrapping
* hotplugged processors.
*
* zoneinfo_show() and maybe other functions do
* not check if the processor is online before following the pageset pointer.
* Other parts of the kernel may not check if the zone is available.
*/
static void per_cpu_pages_init(struct per_cpu_pages *pcp, struct per_cpu_zonestat *pzstats);
/* These effectively disable the pcplists in the boot pageset completely */
#define BOOT_PAGESET_HIGH 0
#define BOOT_PAGESET_BATCH 1
static DEFINE_PER_CPU(struct per_cpu_pages, boot_pageset);
static DEFINE_PER_CPU(struct per_cpu_zonestat, boot_zonestats);
static void __build_all_zonelists(void *data)
{
int nid;
int __maybe_unused cpu;
pg_data_t *self = data;
unsigned long flags;
/*
* Explicitly disable this CPU's interrupts before taking seqlock
* to prevent any IRQ handler from calling into the page allocator
* (e.g. GFP_ATOMIC) that could hit zonelist_iter_begin and livelock.
*/
local_irq_save(flags);
/*
* Explicitly disable this CPU's synchronous printk() before taking
* seqlock to prevent any printk() from trying to hold port->lock, for
* tty_insert_flip_string_and_push_buffer() on other CPU might be
* calling kmalloc(GFP_ATOMIC | __GFP_NOWARN) with port->lock held.
*/
printk_deferred_enter();
write_seqlock(&zonelist_update_seq);
#ifdef CONFIG_NUMA
memset(node_load, 0, sizeof(node_load));
#endif
/*
* This node is hotadded and no memory is yet present. So just
* building zonelists is fine - no need to touch other nodes.
*/
if (self && !node_online(self->node_id)) {
build_zonelists(self);
} else {
/*
* All possible nodes have pgdat preallocated
* in free_area_init
*/
for_each_node(nid) {
pg_data_t *pgdat = NODE_DATA(nid);
build_zonelists(pgdat);
}
#ifdef CONFIG_HAVE_MEMORYLESS_NODES
/*
* We now know the "local memory node" for each node--
* i.e., the node of the first zone in the generic zonelist.
* Set up numa_mem percpu variable for on-line cpus. During
* boot, only the boot cpu should be on-line; we'll init the
* secondary cpus' numa_mem as they come on-line. During
* node/memory hotplug, we'll fixup all on-line cpus.
*/
for_each_online_cpu(cpu)
set_cpu_numa_mem(cpu, local_memory_node(cpu_to_node(cpu)));
#endif
}
write_sequnlock(&zonelist_update_seq);
printk_deferred_exit();
local_irq_restore(flags);
}
static noinline void __init
build_all_zonelists_init(void)
{
int cpu;
__build_all_zonelists(NULL);
/*
* Initialize the boot_pagesets that are going to be used
* for bootstrapping processors. The real pagesets for
* each zone will be allocated later when the per cpu
* allocator is available.
*
* boot_pagesets are used also for bootstrapping offline
* cpus if the system is already booted because the pagesets
* are needed to initialize allocators on a specific cpu too.
* F.e. the percpu allocator needs the page allocator which
* needs the percpu allocator in order to allocate its pagesets
* (a chicken-egg dilemma).
*/
for_each_possible_cpu(cpu)
per_cpu_pages_init(&per_cpu(boot_pageset, cpu), &per_cpu(boot_zonestats, cpu));
mminit_verify_zonelist();
cpuset_init_current_mems_allowed();
}
/*
* unless system_state == SYSTEM_BOOTING.
*
* __ref due to call of __init annotated helper build_all_zonelists_init
* [protected by SYSTEM_BOOTING].
*/
void __ref build_all_zonelists(pg_data_t *pgdat)
{
unsigned long vm_total_pages;
if (system_state == SYSTEM_BOOTING) {
build_all_zonelists_init();
} else {
__build_all_zonelists(pgdat);
/* cpuset refresh routine should be here */
}
/* Get the number of free pages beyond high watermark in all zones. */
vm_total_pages = nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
/*
* Disable grouping by mobility if the number of pages in the
* system is too low to allow the mechanism to work. It would be
* more accurate, but expensive to check per-zone. This check is
* made on memory-hotadd so a system can start with mobility
* disabled and enable it later
*/
if (vm_total_pages < (pageblock_nr_pages * MIGRATE_TYPES))
page_group_by_mobility_disabled = 1;
else
page_group_by_mobility_disabled = 0;
pr_info("Built %u zonelists, mobility grouping %s. Total pages: %ld\n",
nr_online_nodes,
page_group_by_mobility_disabled ? "off" : "on",
vm_total_pages);
#ifdef CONFIG_NUMA
pr_info("Policy zone: %s\n", zone_names[policy_zone]);
#endif
}
static int zone_batchsize(struct zone *zone)
{
#ifdef CONFIG_MMU
int batch;
/*
* The number of pages to batch allocate is either ~0.1%
* of the zone or 1MB, whichever is smaller. The batch
* size is striking a balance between allocation latency
* and zone lock contention.
*/
batch = min(zone_managed_pages(zone) >> 10, SZ_1M / PAGE_SIZE);
batch /= 4; /* We effectively *= 4 below */
if (batch < 1)
batch = 1;
/*
* Clamp the batch to a 2^n - 1 value. Having a power
* of 2 value was found to be more likely to have
* suboptimal cache aliasing properties in some cases.
*
* For example if 2 tasks are alternately allocating
* batches of pages, one task can end up with a lot
* of pages of one half of the possible page colors
* and the other with pages of the other colors.
*/
batch = rounddown_pow_of_two(batch + batch/2) - 1;
return batch;
#else
/* The deferral and batching of frees should be suppressed under NOMMU
* conditions.
*
* The problem is that NOMMU needs to be able to allocate large chunks
* of contiguous memory as there's no hardware page translation to
* assemble apparent contiguous memory from discontiguous pages.
*
* Queueing large contiguous runs of pages for batching, however,
* causes the pages to actually be freed in smaller chunks. As there
* can be a significant delay between the individual batches being
* recycled, this leads to the once large chunks of space being
* fragmented and becoming unavailable for high-order allocations.
*/
return 0;
#endif
}
static int zone_highsize(struct zone *zone, int batch, int cpu_online)
{
#ifdef CONFIG_MMU
int high;
int nr_split_cpus;
unsigned long total_pages;
if (!percpu_pagelist_high_fraction) {
/*
* By default, the high value of the pcp is based on the zone
* low watermark so that if they are full then background
* reclaim will not be started prematurely.
*/
total_pages = low_wmark_pages(zone);
} else {
/*
* If percpu_pagelist_high_fraction is configured, the high
* value is based on a fraction of the managed pages in the
* zone.
*/
total_pages = zone_managed_pages(zone) / percpu_pagelist_high_fraction;
}
/*
* Split the high value across all online CPUs local to the zone. Note
* that early in boot that CPUs may not be online yet and that during
* CPU hotplug that the cpumask is not yet updated when a CPU is being
* onlined. For memory nodes that have no CPUs, split pcp->high across
* all online CPUs to mitigate the risk that reclaim is triggered
* prematurely due to pages stored on pcp lists.
*/
nr_split_cpus = cpumask_weight(cpumask_of_node(zone_to_nid(zone))) + cpu_online;
if (!nr_split_cpus)
nr_split_cpus = num_online_cpus();
high = total_pages / nr_split_cpus;
/*
* Ensure high is at least batch*4. The multiple is based on the
* historical relationship between high and batch.
*/
high = max(high, batch << 2);
return high;
#else
return 0;
#endif
}
/*
* pcp->high and pcp->batch values are related and generally batch is lower
* than high. They are also related to pcp->count such that count is lower
* than high, and as soon as it reaches high, the pcplist is flushed.
*
* However, guaranteeing these relations at all times would require e.g. write
* barriers here but also careful usage of read barriers at the read side, and
* thus be prone to error and bad for performance. Thus the update only prevents
* store tearing. Any new users of pcp->batch and pcp->high should ensure they
* can cope with those fields changing asynchronously, and fully trust only the
* pcp->count field on the local CPU with interrupts disabled.
*
* mutex_is_locked(&pcp_batch_high_lock) required when calling this function
* outside of boot time (or some other assurance that no concurrent updaters
* exist).
*/
static void pageset_update(struct per_cpu_pages *pcp, unsigned long high,
unsigned long batch)
{
WRITE_ONCE(pcp->batch, batch);
WRITE_ONCE(pcp->high, high);
}
static void per_cpu_pages_init(struct per_cpu_pages *pcp, struct per_cpu_zonestat *pzstats)
{
int pindex;
memset(pcp, 0, sizeof(*pcp));
memset(pzstats, 0, sizeof(*pzstats));
spin_lock_init(&pcp->lock);
for (pindex = 0; pindex < NR_PCP_LISTS; pindex++)
INIT_LIST_HEAD(&pcp->lists[pindex]);
/*
* Set batch and high values safe for a boot pageset. A true percpu
* pageset's initialization will update them subsequently. Here we don't
* need to be as careful as pageset_update() as nobody can access the
* pageset yet.
*/
pcp->high = BOOT_PAGESET_HIGH;
pcp->batch = BOOT_PAGESET_BATCH;
pcp->free_factor = 0;
}
static void __zone_set_pageset_high_and_batch(struct zone *zone, unsigned long high,
unsigned long batch)
{
struct per_cpu_pages *pcp;
int cpu;
for_each_possible_cpu(cpu) {
pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
pageset_update(pcp, high, batch);
}
}
/*
* Calculate and set new high and batch values for all per-cpu pagesets of a
* zone based on the zone's size.
*/
static void zone_set_pageset_high_and_batch(struct zone *zone, int cpu_online)
{
int new_high, new_batch;
new_batch = max(1, zone_batchsize(zone));
new_high = zone_highsize(zone, new_batch, cpu_online);
if (zone->pageset_high == new_high &&
zone->pageset_batch == new_batch)
return;
zone->pageset_high = new_high;
zone->pageset_batch = new_batch;
__zone_set_pageset_high_and_batch(zone, new_high, new_batch);
}
void __meminit setup_zone_pageset(struct zone *zone)
{
int cpu;
/* Size may be 0 on !SMP && !NUMA */
if (sizeof(struct per_cpu_zonestat) > 0)
zone->per_cpu_zonestats = alloc_percpu(struct per_cpu_zonestat);
zone->per_cpu_pageset = alloc_percpu(struct per_cpu_pages);
for_each_possible_cpu(cpu) {
struct per_cpu_pages *pcp;
struct per_cpu_zonestat *pzstats;
pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu);
per_cpu_pages_init(pcp, pzstats);
}
zone_set_pageset_high_and_batch(zone, 0);
}
/*
* The zone indicated has a new number of managed_pages; batch sizes and percpu
* page high values need to be recalculated.
*/
static void zone_pcp_update(struct zone *zone, int cpu_online)
{
mutex_lock(&pcp_batch_high_lock);
zone_set_pageset_high_and_batch(zone, cpu_online);
mutex_unlock(&pcp_batch_high_lock);
}
/*
* Allocate per cpu pagesets and initialize them.
* Before this call only boot pagesets were available.
*/
void __init setup_per_cpu_pageset(void)
{
struct pglist_data *pgdat;
struct zone *zone;
int __maybe_unused cpu;
for_each_populated_zone(zone)
setup_zone_pageset(zone);
#ifdef CONFIG_NUMA
/*
* Unpopulated zones continue using the boot pagesets.
* The numa stats for these pagesets need to be reset.
* Otherwise, they will end up skewing the stats of
* the nodes these zones are associated with.
*/
for_each_possible_cpu(cpu) {
struct per_cpu_zonestat *pzstats = &per_cpu(boot_zonestats, cpu);
memset(pzstats->vm_numa_event, 0,
sizeof(pzstats->vm_numa_event));
}
#endif
for_each_online_pgdat(pgdat)
pgdat->per_cpu_nodestats =
alloc_percpu(struct per_cpu_nodestat);
}
__meminit void zone_pcp_init(struct zone *zone)
{
/*
* per cpu subsystem is not up at this point. The following code
* relies on the ability of the linker to provide the
* offset of a (static) per cpu variable into the per cpu area.
*/
zone->per_cpu_pageset = &boot_pageset;
zone->per_cpu_zonestats = &boot_zonestats;
zone->pageset_high = BOOT_PAGESET_HIGH;
zone->pageset_batch = BOOT_PAGESET_BATCH;
if (populated_zone(zone))
pr_debug(" %s zone: %lu pages, LIFO batch:%u\n", zone->name,
zone->present_pages, zone_batchsize(zone));
}
void adjust_managed_page_count(struct page *page, long count)
{
atomic_long_add(count, &page_zone(page)->managed_pages);
totalram_pages_add(count);
#ifdef CONFIG_HIGHMEM
if (PageHighMem(page))
totalhigh_pages_add(count);
#endif
}
EXPORT_SYMBOL(adjust_managed_page_count);
unsigned long free_reserved_area(void *start, void *end, int poison, const char *s)
{
void *pos;
unsigned long pages = 0;
start = (void *)PAGE_ALIGN((unsigned long)start);
end = (void *)((unsigned long)end & PAGE_MASK);
for (pos = start; pos < end; pos += PAGE_SIZE, pages++) {
struct page *page = virt_to_page(pos);
void *direct_map_addr;
/*
* 'direct_map_addr' might be different from 'pos'
* because some architectures' virt_to_page()
* work with aliases. Getting the direct map
* address ensures that we get a _writeable_
* alias for the memset().
*/
direct_map_addr = page_address(page);
/*
* Perform a kasan-unchecked memset() since this memory
* has not been initialized.
*/
direct_map_addr = kasan_reset_tag(direct_map_addr);
if ((unsigned int)poison <= 0xFF)
memset(direct_map_addr, poison, PAGE_SIZE);
free_reserved_page(page);
}
if (pages && s)
pr_info("Freeing %s memory: %ldK\n", s, K(pages));
return pages;
}
static int page_alloc_cpu_dead(unsigned int cpu)
{
struct zone *zone;
lru_add_drain_cpu(cpu);
mlock_drain_remote(cpu);
drain_pages(cpu);
/*
* Spill the event counters of the dead processor
* into the current processors event counters.
* This artificially elevates the count of the current
* processor.
*/
vm_events_fold_cpu(cpu);
/*
* Zero the differential counters of the dead processor
* so that the vm statistics are consistent.
*
* This is only okay since the processor is dead and cannot
* race with what we are doing.
*/
cpu_vm_stats_fold(cpu);
for_each_populated_zone(zone)
zone_pcp_update(zone, 0);
return 0;
}
static int page_alloc_cpu_online(unsigned int cpu)
{
struct zone *zone;
for_each_populated_zone(zone)
zone_pcp_update(zone, 1);
return 0;
}
void __init page_alloc_init_cpuhp(void)
{
int ret;
ret = cpuhp_setup_state_nocalls(CPUHP_PAGE_ALLOC,
"mm/page_alloc:pcp",
page_alloc_cpu_online,
page_alloc_cpu_dead);
WARN_ON(ret < 0);
}
/*
* calculate_totalreserve_pages - called when sysctl_lowmem_reserve_ratio
* or min_free_kbytes changes.
*/
static void calculate_totalreserve_pages(void)
{
struct pglist_data *pgdat;
unsigned long reserve_pages = 0;
enum zone_type i, j;
for_each_online_pgdat(pgdat) {
pgdat->totalreserve_pages = 0;
for (i = 0; i < MAX_NR_ZONES; i++) {
struct zone *zone = pgdat->node_zones + i;
long max = 0;
unsigned long managed_pages = zone_managed_pages(zone);
/* Find valid and maximum lowmem_reserve in the zone */
for (j = i; j < MAX_NR_ZONES; j++) {
if (zone->lowmem_reserve[j] > max)
max = zone->lowmem_reserve[j];
}
/* we treat the high watermark as reserved pages. */
max += high_wmark_pages(zone);
if (max > managed_pages)
max = managed_pages;
pgdat->totalreserve_pages += max;
reserve_pages += max;
}
}
totalreserve_pages = reserve_pages;
}
/*
* setup_per_zone_lowmem_reserve - called whenever
* sysctl_lowmem_reserve_ratio changes. Ensures that each zone
* has a correct pages reserved value, so an adequate number of
* pages are left in the zone after a successful __alloc_pages().
*/
static void setup_per_zone_lowmem_reserve(void)
{
struct pglist_data *pgdat;
enum zone_type i, j;
for_each_online_pgdat(pgdat) {
for (i = 0; i < MAX_NR_ZONES - 1; i++) {
struct zone *zone = &pgdat->node_zones[i];
int ratio = sysctl_lowmem_reserve_ratio[i];
bool clear = !ratio || !zone_managed_pages(zone);
unsigned long managed_pages = 0;
for (j = i + 1; j < MAX_NR_ZONES; j++) {
struct zone *upper_zone = &pgdat->node_zones[j];
managed_pages += zone_managed_pages(upper_zone);
if (clear)
zone->lowmem_reserve[j] = 0;
else
zone->lowmem_reserve[j] = managed_pages / ratio;
}
}
}
/* update totalreserve_pages */
calculate_totalreserve_pages();
}
static void __setup_per_zone_wmarks(void)
{
unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10);
unsigned long lowmem_pages = 0;
struct zone *zone;
unsigned long flags;
/* Calculate total number of !ZONE_HIGHMEM pages */
for_each_zone(zone) {
if (!is_highmem(zone))
lowmem_pages += zone_managed_pages(zone);
}
for_each_zone(zone) {
u64 tmp;
spin_lock_irqsave(&zone->lock, flags);
tmp = (u64)pages_min * zone_managed_pages(zone);
do_div(tmp, lowmem_pages);
if (is_highmem(zone)) {
/*
* __GFP_HIGH and PF_MEMALLOC allocations usually don't
* need highmem pages, so cap pages_min to a small
* value here.
*
* The WMARK_HIGH-WMARK_LOW and (WMARK_LOW-WMARK_MIN)
* deltas control async page reclaim, and so should
* not be capped for highmem.
*/
unsigned long min_pages;
min_pages = zone_managed_pages(zone) / 1024;
min_pages = clamp(min_pages, SWAP_CLUSTER_MAX, 128UL);
zone->_watermark[WMARK_MIN] = min_pages;
} else {
/*
* If it's a lowmem zone, reserve a number of pages
* proportionate to the zone's size.
*/
zone->_watermark[WMARK_MIN] = tmp;
}
/*
* Set the kswapd watermarks distance according to the
* scale factor in proportion to available memory, but
* ensure a minimum size on small systems.
*/
tmp = max_t(u64, tmp >> 2,
mult_frac(zone_managed_pages(zone),
watermark_scale_factor, 10000));
zone->watermark_boost = 0;
zone->_watermark[WMARK_LOW] = min_wmark_pages(zone) + tmp;
zone->_watermark[WMARK_HIGH] = low_wmark_pages(zone) + tmp;
zone->_watermark[WMARK_PROMO] = high_wmark_pages(zone) + tmp;
spin_unlock_irqrestore(&zone->lock, flags);
}
/* update totalreserve_pages */
calculate_totalreserve_pages();
}
/**
* setup_per_zone_wmarks - called when min_free_kbytes changes
* or when memory is hot-{added|removed}
*
* Ensures that the watermark[min,low,high] values for each zone are set
* correctly with respect to min_free_kbytes.
*/
void setup_per_zone_wmarks(void)
{
struct zone *zone;
static DEFINE_SPINLOCK(lock);
spin_lock(&lock);
__setup_per_zone_wmarks();
spin_unlock(&lock);
/*
* The watermark size have changed so update the pcpu batch
* and high limits or the limits may be inappropriate.
*/
for_each_zone(zone)
zone_pcp_update(zone, 0);
}
/*
* Initialise min_free_kbytes.
*
* For small machines we want it small (128k min). For large machines
* we want it large (256MB max). But it is not linear, because network
* bandwidth does not increase linearly with machine size. We use
*
* min_free_kbytes = 4 * sqrt(lowmem_kbytes), for better accuracy:
* min_free_kbytes = sqrt(lowmem_kbytes * 16)
*
* which yields
*
* 16MB: 512k
* 32MB: 724k
* 64MB: 1024k
* 128MB: 1448k
* 256MB: 2048k
* 512MB: 2896k
* 1024MB: 4096k
* 2048MB: 5792k
* 4096MB: 8192k
* 8192MB: 11584k
* 16384MB: 16384k
*/
void calculate_min_free_kbytes(void)
{
unsigned long lowmem_kbytes;
int new_min_free_kbytes;
lowmem_kbytes = nr_free_buffer_pages() * (PAGE_SIZE >> 10);
new_min_free_kbytes = int_sqrt(lowmem_kbytes * 16);
if (new_min_free_kbytes > user_min_free_kbytes)
min_free_kbytes = clamp(new_min_free_kbytes, 128, 262144);
else
pr_warn("min_free_kbytes is not updated to %d because user defined value %d is preferred\n",
new_min_free_kbytes, user_min_free_kbytes);
}
int __meminit init_per_zone_wmark_min(void)
{
calculate_min_free_kbytes();
setup_per_zone_wmarks();
refresh_zone_stat_thresholds();
setup_per_zone_lowmem_reserve();
#ifdef CONFIG_NUMA
setup_min_unmapped_ratio();
setup_min_slab_ratio();
#endif
khugepaged_min_free_kbytes_update();
return 0;
}
postcore_initcall(init_per_zone_wmark_min)
/*
* min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so
* that we can call two helper functions whenever min_free_kbytes
* changes.
*/
int min_free_kbytes_sysctl_handler(struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
{
int rc;
rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
if (rc)
return rc;
if (write) {
user_min_free_kbytes = min_free_kbytes;
setup_per_zone_wmarks();
}
return 0;
}
int watermark_scale_factor_sysctl_handler(struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
{
int rc;
rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
if (rc)
return rc;
if (write)
setup_per_zone_wmarks();
return 0;
}
#ifdef CONFIG_NUMA
static void setup_min_unmapped_ratio(void)
{
pg_data_t *pgdat;
struct zone *zone;
for_each_online_pgdat(pgdat)
pgdat->min_unmapped_pages = 0;
for_each_zone(zone)
zone->zone_pgdat->min_unmapped_pages += (zone_managed_pages(zone) *
sysctl_min_unmapped_ratio) / 100;
}
int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
{
int rc;
rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
if (rc)
return rc;
setup_min_unmapped_ratio();
return 0;
}
static void setup_min_slab_ratio(void)
{
pg_data_t *pgdat;
struct zone *zone;
for_each_online_pgdat(pgdat)
pgdat->min_slab_pages = 0;
for_each_zone(zone)
zone->zone_pgdat->min_slab_pages += (zone_managed_pages(zone) *
sysctl_min_slab_ratio) / 100;
}
int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
{
int rc;
rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
if (rc)
return rc;
setup_min_slab_ratio();
return 0;
}
#endif
/*
* lowmem_reserve_ratio_sysctl_handler - just a wrapper around
* proc_dointvec() so that we can call setup_per_zone_lowmem_reserve()
* whenever sysctl_lowmem_reserve_ratio changes.
*
* The reserve ratio obviously has absolutely no relation with the
* minimum watermarks. The lowmem reserve ratio can only make sense
* if in function of the boot time zone sizes.
*/
int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
{
int i;
proc_dointvec_minmax(table, write, buffer, length, ppos);
for (i = 0; i < MAX_NR_ZONES; i++) {
if (sysctl_lowmem_reserve_ratio[i] < 1)
sysctl_lowmem_reserve_ratio[i] = 0;
}
setup_per_zone_lowmem_reserve();
return 0;
}
/*
* percpu_pagelist_high_fraction - changes the pcp->high for each zone on each
* cpu. It is the fraction of total pages in each zone that a hot per cpu
* pagelist can have before it gets flushed back to buddy allocator.
*/
int percpu_pagelist_high_fraction_sysctl_handler(struct ctl_table *table,
int write, void *buffer, size_t *length, loff_t *ppos)
{
struct zone *zone;
int old_percpu_pagelist_high_fraction;
int ret;
mutex_lock(&pcp_batch_high_lock);
old_percpu_pagelist_high_fraction = percpu_pagelist_high_fraction;
ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
if (!write || ret < 0)
goto out;
/* Sanity checking to avoid pcp imbalance */
if (percpu_pagelist_high_fraction &&
percpu_pagelist_high_fraction < MIN_PERCPU_PAGELIST_HIGH_FRACTION) {
percpu_pagelist_high_fraction = old_percpu_pagelist_high_fraction;
ret = -EINVAL;
goto out;
}
/* No change? */
if (percpu_pagelist_high_fraction == old_percpu_pagelist_high_fraction)
goto out;
for_each_populated_zone(zone)
zone_set_pageset_high_and_batch(zone, 0);
out:
mutex_unlock(&pcp_batch_high_lock);
return ret;
}
#ifdef CONFIG_CONTIG_ALLOC
#if defined(CONFIG_DYNAMIC_DEBUG) || \
(defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))
/* Usage: See admin-guide/dynamic-debug-howto.rst */
static void alloc_contig_dump_pages(struct list_head *page_list)
{
DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, "migrate failure");
if (DYNAMIC_DEBUG_BRANCH(descriptor)) {
struct page *page;
dump_stack();
list_for_each_entry(page, page_list, lru)
dump_page(page, "migration failure");
}
}
#else
static inline void alloc_contig_dump_pages(struct list_head *page_list)
{
}
#endif
/* [start, end) must belong to a single zone. */
int __alloc_contig_migrate_range(struct compact_control *cc,
unsigned long start, unsigned long end)
{
/* This function is based on compact_zone() from compaction.c. */
unsigned int nr_reclaimed;
unsigned long pfn = start;
unsigned int tries = 0;
int ret = 0;
struct migration_target_control mtc = {
.nid = zone_to_nid(cc->zone),
.gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
};
lru_cache_disable();
while (pfn < end || !list_empty(&cc->migratepages)) {
if (fatal_signal_pending(current)) {
ret = -EINTR;
break;
}
if (list_empty(&cc->migratepages)) {
cc->nr_migratepages = 0;
ret = isolate_migratepages_range(cc, pfn, end);
if (ret && ret != -EAGAIN)
break;
pfn = cc->migrate_pfn;
tries = 0;
} else if (++tries == 5) {
ret = -EBUSY;
break;
}
nr_reclaimed = reclaim_clean_pages_from_list(cc->zone,
&cc->migratepages);
cc->nr_migratepages -= nr_reclaimed;
ret = migrate_pages(&cc->migratepages, alloc_migration_target,
NULL, (unsigned long)&mtc, cc->mode, MR_CONTIG_RANGE, NULL);
/*
* On -ENOMEM, migrate_pages() bails out right away. It is pointless
* to retry again over this error, so do the same here.
*/
if (ret == -ENOMEM)
break;
}
lru_cache_enable();
if (ret < 0) {
if (!(cc->gfp_mask & __GFP_NOWARN) && ret == -EBUSY)
alloc_contig_dump_pages(&cc->migratepages);
putback_movable_pages(&cc->migratepages);
return ret;
}
return 0;
}
/**
* alloc_contig_range() -- tries to allocate given range of pages
* @start: start PFN to allocate
* @end: one-past-the-last PFN to allocate
* @migratetype: migratetype of the underlying pageblocks (either
* #MIGRATE_MOVABLE or #MIGRATE_CMA). All pageblocks
* in range must have the same migratetype and it must
* be either of the two.
* @gfp_mask: GFP mask to use during compaction
*
* The PFN range does not have to be pageblock aligned. The PFN range must
* belong to a single zone.
*
* The first thing this routine does is attempt to MIGRATE_ISOLATE all
* pageblocks in the range. Once isolated, the pageblocks should not
* be modified by others.
*
* Return: zero on success or negative error code. On success all
* pages which PFN is in [start, end) are allocated for the caller and
* need to be freed with free_contig_range().
*/
int alloc_contig_range(unsigned long start, unsigned long end,
unsigned migratetype, gfp_t gfp_mask)
{
unsigned long outer_start, outer_end;
int order;
int ret = 0;
struct compact_control cc = {
.nr_migratepages = 0,
.order = -1,
.zone = page_zone(pfn_to_page(start)),
.mode = MIGRATE_SYNC,
.ignore_skip_hint = true,
.no_set_skip_hint = true,
.gfp_mask = current_gfp_context(gfp_mask),
.alloc_contig = true,
};
INIT_LIST_HEAD(&cc.migratepages);
/*
* What we do here is we mark all pageblocks in range as
* MIGRATE_ISOLATE. Because pageblock and max order pages may
* have different sizes, and due to the way page allocator
* work, start_isolate_page_range() has special handlings for this.
*
* Once the pageblocks are marked as MIGRATE_ISOLATE, we
* migrate the pages from an unaligned range (ie. pages that
* we are interested in). This will put all the pages in
* range back to page allocator as MIGRATE_ISOLATE.
*
* When this is done, we take the pages in range from page
* allocator removing them from the buddy system. This way
* page allocator will never consider using them.
*
* This lets us mark the pageblocks back as
* MIGRATE_CMA/MIGRATE_MOVABLE so that free pages in the
* aligned range but not in the unaligned, original range are
* put back to page allocator so that buddy can use them.
*/
ret = start_isolate_page_range(start, end, migratetype, 0, gfp_mask);
if (ret)
goto done;
drain_all_pages(cc.zone);
/*
* In case of -EBUSY, we'd like to know which page causes problem.
* So, just fall through. test_pages_isolated() has a tracepoint
* which will report the busy page.
*
* It is possible that busy pages could become available before
* the call to test_pages_isolated, and the range will actually be
* allocated. So, if we fall through be sure to clear ret so that
* -EBUSY is not accidentally used or returned to caller.
*/
ret = __alloc_contig_migrate_range(&cc, start, end);
if (ret && ret != -EBUSY)
goto done;
ret = 0;
/*
* Pages from [start, end) are within a pageblock_nr_pages
* aligned blocks that are marked as MIGRATE_ISOLATE. What's
* more, all pages in [start, end) are free in page allocator.
* What we are going to do is to allocate all pages from
* [start, end) (that is remove them from page allocator).
*
* The only problem is that pages at the beginning and at the
* end of interesting range may be not aligned with pages that
* page allocator holds, ie. they can be part of higher order
* pages. Because of this, we reserve the bigger range and
* once this is done free the pages we are not interested in.
*
* We don't have to hold zone->lock here because the pages are
* isolated thus they won't get removed from buddy.
*/
order = 0;
outer_start = start;
while (!PageBuddy(pfn_to_page(outer_start))) {
if (++order > MAX_ORDER) {
outer_start = start;
break;
}
outer_start &= ~0UL << order;
}
if (outer_start != start) {
order = buddy_order(pfn_to_page(outer_start));
/*
* outer_start page could be small order buddy page and
* it doesn't include start page. Adjust outer_start
* in this case to report failed page properly
* on tracepoint in test_pages_isolated()
*/
if (outer_start + (1UL << order) <= start)
outer_start = start;
}
/* Make sure the range is really isolated. */
if (test_pages_isolated(outer_start, end, 0)) {
ret = -EBUSY;
goto done;
}
/* Grab isolated pages from freelists. */
outer_end = isolate_freepages_range(&cc, outer_start, end);
if (!outer_end) {
ret = -EBUSY;
goto done;
}
/* Free head and tail (if any) */
if (start != outer_start)
free_contig_range(outer_start, start - outer_start);
if (end != outer_end)
free_contig_range(end, outer_end - end);
done:
undo_isolate_page_range(start, end, migratetype);
return ret;
}
EXPORT_SYMBOL(alloc_contig_range);
static int __alloc_contig_pages(unsigned long start_pfn,
unsigned long nr_pages, gfp_t gfp_mask)
{
unsigned long end_pfn = start_pfn + nr_pages;
return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE,
gfp_mask);
}
static bool pfn_range_valid_contig(struct zone *z, unsigned long start_pfn,
unsigned long nr_pages)
{
unsigned long i, end_pfn = start_pfn + nr_pages;
struct page *page;
for (i = start_pfn; i < end_pfn; i++) {
page = pfn_to_online_page(i);
if (!page)
return false;
if (page_zone(page) != z)
return false;
if (PageReserved(page))
return false;
if (PageHuge(page))
return false;
}
return true;
}
static bool zone_spans_last_pfn(const struct zone *zone,
unsigned long start_pfn, unsigned long nr_pages)
{
unsigned long last_pfn = start_pfn + nr_pages - 1;
return zone_spans_pfn(zone, last_pfn);
}
/**
* alloc_contig_pages() -- tries to find and allocate contiguous range of pages
* @nr_pages: Number of contiguous pages to allocate
* @gfp_mask: GFP mask to limit search and used during compaction
* @nid: Target node
* @nodemask: Mask for other possible nodes
*
* This routine is a wrapper around alloc_contig_range(). It scans over zones
* on an applicable zonelist to find a contiguous pfn range which can then be
* tried for allocation with alloc_contig_range(). This routine is intended
* for allocation requests which can not be fulfilled with the buddy allocator.
*
* The allocated memory is always aligned to a page boundary. If nr_pages is a
* power of two, then allocated range is also guaranteed to be aligned to same
* nr_pages (e.g. 1GB request would be aligned to 1GB).
*
* Allocated pages can be freed with free_contig_range() or by manually calling
* __free_page() on each allocated page.
*
* Return: pointer to contiguous pages on success, or NULL if not successful.
*/
struct page *alloc_contig_pages(unsigned long nr_pages, gfp_t gfp_mask,
int nid, nodemask_t *nodemask)
{
unsigned long ret, pfn, flags;
struct zonelist *zonelist;
struct zone *zone;
struct zoneref *z;
zonelist = node_zonelist(nid, gfp_mask);
for_each_zone_zonelist_nodemask(zone, z, zonelist,
gfp_zone(gfp_mask), nodemask) {
spin_lock_irqsave(&zone->lock, flags);
pfn = ALIGN(zone->zone_start_pfn, nr_pages);
while (zone_spans_last_pfn(zone, pfn, nr_pages)) {
if (pfn_range_valid_contig(zone, pfn, nr_pages)) {
/*
* We release the zone lock here because
* alloc_contig_range() will also lock the zone
* at some point. If there's an allocation
* spinning on this lock, it may win the race
* and cause alloc_contig_range() to fail...
*/
spin_unlock_irqrestore(&zone->lock, flags);
ret = __alloc_contig_pages(pfn, nr_pages,
gfp_mask);
if (!ret)
return pfn_to_page(pfn);
spin_lock_irqsave(&zone->lock, flags);
}
pfn += nr_pages;
}
spin_unlock_irqrestore(&zone->lock, flags);
}
return NULL;
}
#endif /* CONFIG_CONTIG_ALLOC */
void free_contig_range(unsigned long pfn, unsigned long nr_pages)
{
unsigned long count = 0;
for (; nr_pages--; pfn++) {
struct page *page = pfn_to_page(pfn);
count += page_count(page) != 1;
__free_page(page);
}
WARN(count != 0, "%lu pages are still in use!\n", count);
}
EXPORT_SYMBOL(free_contig_range);
/*
* Effectively disable pcplists for the zone by setting the high limit to 0
* and draining all cpus. A concurrent page freeing on another CPU that's about
* to put the page on pcplist will either finish before the drain and the page
* will be drained, or observe the new high limit and skip the pcplist.
*
* Must be paired with a call to zone_pcp_enable().
*/
void zone_pcp_disable(struct zone *zone)
{
mutex_lock(&pcp_batch_high_lock);
__zone_set_pageset_high_and_batch(zone, 0, 1);
__drain_all_pages(zone, true);
}
void zone_pcp_enable(struct zone *zone)
{
__zone_set_pageset_high_and_batch(zone, zone->pageset_high, zone->pageset_batch);
mutex_unlock(&pcp_batch_high_lock);
}
void zone_pcp_reset(struct zone *zone)
{
int cpu;
struct per_cpu_zonestat *pzstats;
if (zone->per_cpu_pageset != &boot_pageset) {
for_each_online_cpu(cpu) {
pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu);
drain_zonestat(zone, pzstats);
}
free_percpu(zone->per_cpu_pageset);
zone->per_cpu_pageset = &boot_pageset;
if (zone->per_cpu_zonestats != &boot_zonestats) {
free_percpu(zone->per_cpu_zonestats);
zone->per_cpu_zonestats = &boot_zonestats;
}
}
}
#ifdef CONFIG_MEMORY_HOTREMOVE
/*
* All pages in the range must be in a single zone, must not contain holes,
* must span full sections, and must be isolated before calling this function.
*/
void __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
{
unsigned long pfn = start_pfn;
struct page *page;
struct zone *zone;
unsigned int order;
unsigned long flags;
offline_mem_sections(pfn, end_pfn);
zone = page_zone(pfn_to_page(pfn));
spin_lock_irqsave(&zone->lock, flags);
while (pfn < end_pfn) {
page = pfn_to_page(pfn);
/*
* The HWPoisoned page may be not in buddy system, and
* page_count() is not 0.
*/
if (unlikely(!PageBuddy(page) && PageHWPoison(page))) {
pfn++;
continue;
}
/*
* At this point all remaining PageOffline() pages have a
* reference count of 0 and can simply be skipped.
*/
if (PageOffline(page)) {
BUG_ON(page_count(page));
BUG_ON(PageBuddy(page));
pfn++;
continue;
}
BUG_ON(page_count(page));
BUG_ON(!PageBuddy(page));
order = buddy_order(page);
del_page_from_free_list(page, zone, order);
pfn += (1 << order);
}
spin_unlock_irqrestore(&zone->lock, flags);
}
#endif
/*
* This function returns a stable result only if called under zone lock.
*/
bool is_free_buddy_page(struct page *page)
{
unsigned long pfn = page_to_pfn(page);
unsigned int order;
for (order = 0; order <= MAX_ORDER; order++) {
struct page *page_head = page - (pfn & ((1 << order) - 1));
if (PageBuddy(page_head) &&
buddy_order_unsafe(page_head) >= order)
break;
}
return order <= MAX_ORDER;
}
EXPORT_SYMBOL(is_free_buddy_page);
#ifdef CONFIG_MEMORY_FAILURE
/*
* Break down a higher-order page in sub-pages, and keep our target out of
* buddy allocator.
*/
static void break_down_buddy_pages(struct zone *zone, struct page *page,
struct page *target, int low, int high,
int migratetype)
{
unsigned long size = 1 << high;
struct page *current_buddy, *next_page;
while (high > low) {
high--;
size >>= 1;
if (target >= &page[size]) {
next_page = page + size;
current_buddy = page;
} else {
next_page = page;
current_buddy = page + size;
}
if (set_page_guard(zone, current_buddy, high, migratetype))
continue;
if (current_buddy != target) {
add_to_free_list(current_buddy, zone, high, migratetype);
set_buddy_order(current_buddy, high);
page = next_page;
}
}
}
/*
* Take a page that will be marked as poisoned off the buddy allocator.
*/
bool take_page_off_buddy(struct page *page)
{
struct zone *zone = page_zone(page);
unsigned long pfn = page_to_pfn(page);
unsigned long flags;
unsigned int order;
bool ret = false;
spin_lock_irqsave(&zone->lock, flags);
for (order = 0; order <= MAX_ORDER; order++) {
struct page *page_head = page - (pfn & ((1 << order) - 1));
int page_order = buddy_order(page_head);
if (PageBuddy(page_head) && page_order >= order) {
unsigned long pfn_head = page_to_pfn(page_head);
int migratetype = get_pfnblock_migratetype(page_head,
pfn_head);
del_page_from_free_list(page_head, zone, page_order);
break_down_buddy_pages(zone, page_head, page, 0,
page_order, migratetype);
SetPageHWPoisonTakenOff(page);
if (!is_migrate_isolate(migratetype))
__mod_zone_freepage_state(zone, -1, migratetype);
ret = true;
break;
}
if (page_count(page_head) > 0)
break;
}
spin_unlock_irqrestore(&zone->lock, flags);
return ret;
}
/*
* Cancel takeoff done by take_page_off_buddy().
*/
bool put_page_back_buddy(struct page *page)
{
struct zone *zone = page_zone(page);
unsigned long pfn = page_to_pfn(page);
unsigned long flags;
int migratetype = get_pfnblock_migratetype(page, pfn);
bool ret = false;
spin_lock_irqsave(&zone->lock, flags);
if (put_page_testzero(page)) {
ClearPageHWPoisonTakenOff(page);
__free_one_page(page, pfn, zone, 0, migratetype, FPI_NONE);
if (TestClearPageHWPoison(page)) {
ret = true;
}
}
spin_unlock_irqrestore(&zone->lock, flags);
return ret;
}
#endif
#ifdef CONFIG_ZONE_DMA
bool has_managed_dma(void)
{
struct pglist_data *pgdat;
for_each_online_pgdat(pgdat) {
struct zone *zone = &pgdat->node_zones[ZONE_DMA];
if (managed_zone(zone))
return true;
}
return false;
}
#endif /* CONFIG_ZONE_DMA */
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