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linux/mm/page_alloc.c
Johannes Weiner 7b086755fb mm: page_alloc: fix CMA and HIGHATOMIC landing on the wrong buddy list 
Commit 4b23a68f95 ("mm/page_alloc: protect PCP lists with a spinlock")
bypasses the pcplist on lock contention and returns the page directly to
the buddy list of the page's migratetype.

For pages that don't have their own pcplist, such as CMA and HIGHATOMIC,
the migratetype is temporarily updated such that the page can hitch a ride
on the MOVABLE pcplist.  Their true type is later reassessed when flushing
in free_pcppages_bulk().  However, when lock contention is detected after
the type was already overridden, the bypass will then put the page on the
wrong buddy list.

Once on the MOVABLE buddy list, the page becomes eligible for fallbacks
and even stealing.  In the case of HIGHATOMIC, otherwise ineligible
allocations can dip into the highatomic reserves.  In the case of CMA, the
page can be lost from the CMA region permanently.

Use a separate pcpmigratetype variable for the pcplist override.  Use the
original migratetype when going directly to the buddy.  This fixes the bug
and should make the intentions more obvious in the code.

Originally sent here to address the HIGHATOMIC case:
https://lore.kernel.org/lkml/20230821183733.106619-4-hannes@cmpxchg.org/

Changelog updated in response to the CMA-specific bug report.

[mgorman@techsingularity.net: updated changelog]
Link: https://lkml.kernel.org/r/20230911181108.GA104295@cmpxchg.org
Fixes: 4b23a68f95 ("mm/page_alloc: protect PCP lists with a spinlock")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Joe Liu <joe.liu@mediatek.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-09-19 13:21:32 -07:00

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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/interrupt.h>
#include <linux/jiffies.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/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/vmstat.h>
#include <linux/fault-inject.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/sched/mm.h>
#include <linux/page_owner.h>
#include <linux/page_table_check.h>
#include <linux/memcontrol.h>
#include <linux/ftrace.h>
#include <linux/lockdep.h>
#include <linux/psi.h>
#include <linux/khugepaged.h>
#include <linux/delayacct.h>
#include <asm/div64.h>
#include "internal.h"
#include "shuffle.h"
#include "page_reporting.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);
gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
/*
* A cached value of the page's pageblock's migratetype, used when the page is
* put on a pcplist. Used to avoid the pageblock migratetype lookup when
* freeing from pcplists in most cases, at the cost of possibly becoming stale.
* Also the migratetype set in the page does not necessarily match the pcplist
* index, e.g. page might have MIGRATE_CMA set but be on a pcplist with any
* other index - this ensures that it will be put on the correct CMA freelist.
*/
static inline int get_pcppage_migratetype(struct page *page)
{
return page->index;
}
static inline void set_pcppage_migratetype(struct page *page, int migratetype)
{
page->index = migratetype;
}
#ifdef CONFIG_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
*/
static 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
};
int min_free_kbytes = 1024;
int user_min_free_kbytes = -1;
static int watermark_boost_factor __read_mostly = 15000;
static int watermark_scale_factor = 10;
/* 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
static bool page_contains_unaccepted(struct page *page, unsigned int order);
static void accept_page(struct page *page, unsigned int order);
static bool try_to_accept_memory(struct zone *zone, unsigned int order);
static inline bool has_unaccepted_memory(void);
static bool __free_unaccepted(struct page *page);
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;
}
/**
* 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)
{
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;
}
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;
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;
ret = !zone_spans_pfn(zone, pfn);
} 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;
}
/*
* 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 (zone != page_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)
{
#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 * order) + 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_order holds the order of allocation.
* This usage means that zero-order pages may not be compound.
*/
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)
{
if (folio_test_hugetlb(folio)) {
free_huge_folio(folio);
return;
}
if (folio_test_large_rmappable(folio))
folio_undo_large_rmappable(folio);
mem_cgroup_uncharge(folio);
free_the_page(&folio->page, folio_order(folio));
}
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, buddy_list);
}
/*
* 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_pfnblock_migratetype(buddy, buddy_pfn);
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_pfnblock_migratetype(free_page, free_page_pfn);
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 inline bool is_check_pages_enabled(void)
{
return static_branch_unlikely(&check_pages_enabled);
}
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 (!is_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)
page[1].flags &= ~PAGE_FLAGS_SECOND;
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;
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 > NR_PCP_LISTS - 1)
pindex = 0;
list = &pcp->lists[pindex];
} while (list_empty(list));
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);
if (page_contains_unaccepted(page, order)) {
if (order == MAX_ORDER && __free_unaccepted(page))
return;
accept_page(page, order);
}
/*
* 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(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;
}
/*
* 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);
/* moving whole block can fail due to zone boundary conditions */
if (!free_pages)
goto single_page;
/*
* 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;
}
/*
* If a sufficient number of pages in the block are either free or of
* compatible 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)
{
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);
}
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, bool free_high)
{
int min_nr_free, max_nr_free;
int batch = READ_ONCE(pcp->batch);
/* 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) {
free_pcppages_bulk(zone, nr_pcp_free(pcp, high, 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, pcpmigratetype;
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 and CMA as movable pages so we can
* get those areas back if necessary. Otherwise, we may have to free
* excessively into the page allocator
*/
migratetype = pcpmigratetype = 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;
}
pcpmigratetype = 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, pcpmigratetype, 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);
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))) {
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 ((alloc_flags & ALLOC_KSWAPD) &&
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;
}
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
#ifdef CONFIG_UNACCEPTED_MEMORY
unusable_free += zone_page_state(z, NR_UNACCEPTED);
#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;
if (has_unaccepted_memory()) {
if (try_to_accept_memory(zone, order))
goto try_this_zone;
}
#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);
return page;
} else {
if (has_unaccepted_memory()) {
if (try_to_accept_memory(zone, order))
goto try_this_zone;
}
#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;
/*
* Compaction was skipped due to a lack of free order-0
* migration targets. Continue if reclaim can help.
*/
if (compact_result == COMPACT_SKIPPED) {
ret = compaction_zonelist_suitable(ac, order, alloc_flags);
goto out;
}
/*
* Compaction managed to coalesce some page blocks, but the
* allocation failed presumably due to a race. Retry some.
*/
if (compact_result == COMPACT_SUCCESS) {
/*
* !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;
}
}
/*
* Compaction failed. Retry with increasing 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);
struct folio *folio = (struct folio *)page;
if (folio && order > 1)
folio_prep_large_rmappable(folio);
return folio;
}
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 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;
}
static char numa_zonelist_order[] = "Node";
#define NUMA_ZONELIST_ORDER_LEN 16
/*
* sysctl handler for numa_zonelist_order
*/
static 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;
/*
* The zonelist_update_seq must be acquired with irqsave because the
* reader can be invoked from IRQ with GFP_ATOMIC.
*/
write_seqlock_irqsave(&zonelist_update_seq, flags);
/*
* Also disable synchronous printk() 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();
#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
}
printk_deferred_exit();
write_sequnlock_irqrestore(&zonelist_update_seq, 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 percpu_pagelist_high_fraction;
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 and !ZONE_MOVABLE pages */
for_each_zone(zone) {
if (!is_highmem(zone) && zone_idx(zone) != ZONE_MOVABLE)
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) || zone_idx(zone) == ZONE_MOVABLE) {
/*
* __GFP_HIGH and PF_MEMALLOC allocations usually don't
* need highmem and movable zones 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 and movable zones.
*/
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.
*/
static 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;
}
static 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;
}
static 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;
}
static 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.
*/
static 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.
*/
static 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;
}
static struct ctl_table page_alloc_sysctl_table[] = {
{
.procname = "min_free_kbytes",
.data = &min_free_kbytes,
.maxlen = sizeof(min_free_kbytes),
.mode = 0644,
.proc_handler = min_free_kbytes_sysctl_handler,
.extra1 = SYSCTL_ZERO,
},
{
.procname = "watermark_boost_factor",
.data = &watermark_boost_factor,
.maxlen = sizeof(watermark_boost_factor),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
},
{
.procname = "watermark_scale_factor",
.data = &watermark_scale_factor,
.maxlen = sizeof(watermark_scale_factor),
.mode = 0644,
.proc_handler = watermark_scale_factor_sysctl_handler,
.extra1 = SYSCTL_ONE,
.extra2 = SYSCTL_THREE_THOUSAND,
},
{
.procname = "percpu_pagelist_high_fraction",
.data = &percpu_pagelist_high_fraction,
.maxlen = sizeof(percpu_pagelist_high_fraction),
.mode = 0644,
.proc_handler = percpu_pagelist_high_fraction_sysctl_handler,
.extra1 = SYSCTL_ZERO,
},
{
.procname = "lowmem_reserve_ratio",
.data = &sysctl_lowmem_reserve_ratio,
.maxlen = sizeof(sysctl_lowmem_reserve_ratio),
.mode = 0644,
.proc_handler = lowmem_reserve_ratio_sysctl_handler,
},
#ifdef CONFIG_NUMA
{
.procname = "numa_zonelist_order",
.data = &numa_zonelist_order,
.maxlen = NUMA_ZONELIST_ORDER_LEN,
.mode = 0644,
.proc_handler = numa_zonelist_order_handler,
},
{
.procname = "min_unmapped_ratio",
.data = &sysctl_min_unmapped_ratio,
.maxlen = sizeof(sysctl_min_unmapped_ratio),
.mode = 0644,
.proc_handler = sysctl_min_unmapped_ratio_sysctl_handler,
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE_HUNDRED,
},
{
.procname = "min_slab_ratio",
.data = &sysctl_min_slab_ratio,
.maxlen = sizeof(sysctl_min_slab_ratio),
.mode = 0644,
.proc_handler = sysctl_min_slab_ratio_sysctl_handler,
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE_HUNDRED,
},
#endif
{}
};
void __init page_alloc_sysctl_init(void)
{
register_sysctl_init("vm", page_alloc_sysctl_table);
}
#ifdef CONFIG_CONTIG_ALLOC
/* 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");
}
}
/* [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 */
#ifdef CONFIG_UNACCEPTED_MEMORY
/* Counts number of zones with unaccepted pages. */
static DEFINE_STATIC_KEY_FALSE(zones_with_unaccepted_pages);
static bool lazy_accept = true;
static int __init accept_memory_parse(char *p)
{
if (!strcmp(p, "lazy")) {
lazy_accept = true;
return 0;
} else if (!strcmp(p, "eager")) {
lazy_accept = false;
return 0;
} else {
return -EINVAL;
}
}
early_param("accept_memory", accept_memory_parse);
static bool page_contains_unaccepted(struct page *page, unsigned int order)
{
phys_addr_t start = page_to_phys(page);
phys_addr_t end = start + (PAGE_SIZE << order);
return range_contains_unaccepted_memory(start, end);
}
static void accept_page(struct page *page, unsigned int order)
{
phys_addr_t start = page_to_phys(page);
accept_memory(start, start + (PAGE_SIZE << order));
}
static bool try_to_accept_memory_one(struct zone *zone)
{
unsigned long flags;
struct page *page;
bool last;
if (list_empty(&zone->unaccepted_pages))
return false;
spin_lock_irqsave(&zone->lock, flags);
page = list_first_entry_or_null(&zone->unaccepted_pages,
struct page, lru);
if (!page) {
spin_unlock_irqrestore(&zone->lock, flags);
return false;
}
list_del(&page->lru);
last = list_empty(&zone->unaccepted_pages);
__mod_zone_freepage_state(zone, -MAX_ORDER_NR_PAGES, MIGRATE_MOVABLE);
__mod_zone_page_state(zone, NR_UNACCEPTED, -MAX_ORDER_NR_PAGES);
spin_unlock_irqrestore(&zone->lock, flags);
accept_page(page, MAX_ORDER);
__free_pages_ok(page, MAX_ORDER, FPI_TO_TAIL);
if (last)
static_branch_dec(&zones_with_unaccepted_pages);
return true;
}
static bool try_to_accept_memory(struct zone *zone, unsigned int order)
{
long to_accept;
int ret = false;
/* How much to accept to get to high watermark? */
to_accept = high_wmark_pages(zone) -
(zone_page_state(zone, NR_FREE_PAGES) -
__zone_watermark_unusable_free(zone, order, 0));
/* Accept at least one page */
do {
if (!try_to_accept_memory_one(zone))
break;
ret = true;
to_accept -= MAX_ORDER_NR_PAGES;
} while (to_accept > 0);
return ret;
}
static inline bool has_unaccepted_memory(void)
{
return static_branch_unlikely(&zones_with_unaccepted_pages);
}
static bool __free_unaccepted(struct page *page)
{
struct zone *zone = page_zone(page);
unsigned long flags;
bool first = false;
if (!lazy_accept)
return false;
spin_lock_irqsave(&zone->lock, flags);
first = list_empty(&zone->unaccepted_pages);
list_add_tail(&page->lru, &zone->unaccepted_pages);
__mod_zone_freepage_state(zone, MAX_ORDER_NR_PAGES, MIGRATE_MOVABLE);
__mod_zone_page_state(zone, NR_UNACCEPTED, MAX_ORDER_NR_PAGES);
spin_unlock_irqrestore(&zone->lock, flags);
if (first)
static_branch_inc(&zones_with_unaccepted_pages);
return true;
}
#else
static bool page_contains_unaccepted(struct page *page, unsigned int order)
{
return false;
}
static void accept_page(struct page *page, unsigned int order)
{
}
static bool try_to_accept_memory(struct zone *zone, unsigned int order)
{
return false;
}
static inline bool has_unaccepted_memory(void)
{
return false;
}
static bool __free_unaccepted(struct page *page)
{
BUILD_BUG();
return false;
}
#endif /* CONFIG_UNACCEPTED_MEMORY */
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