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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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SPDX-License-Identifier: GPL-2.0-only/* * * 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/folio_batch.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 <linux/cacheinfo.h>#include <linux/pgalloc_tag.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))
/* Free the page without taking locks. Rely on trylock only. */#define FPI_TRYLOCK ((__force fpi_t)BIT(2))
/* free_pages_prepare() has already been called for page(s) being freed. */#define FPI_PREPARED ((__force fpi_t)BIT(3))
/* 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)
/* * 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
/* * A helper to lookup and trylock pcp with embedded spinlock. * The return value should be used with the unlock helper. * NULL return value means the trylock failed. */#ifdef CONFIG_SMP#define pcp_spin_trylock(ptr) \({ \ struct per_cpu_pages *_ret; \ pcpu_task_pin(); \ _ret = this_cpu_ptr(ptr); \ if (!spin_trylock(&_ret->lock)) { \ pcpu_task_unpin(); \ _ret = NULL; \ } \ _ret; \})
#define pcp_spin_unlock(ptr) \({ \ spin_unlock(&ptr->lock); \ pcpu_task_unpin(); \})
/* * On CONFIG_SMP=n the UP implementation of spin_trylock() never fails and thus * is not compatible with our locking scheme. However we do not need pcp for * scalability in the first place, so just make all the trylocks fail and take * the slow path unconditionally. */#else#define pcp_spin_trylock(ptr) \ NULL
#define pcp_spin_unlock(ptr) \ BUG_ON(1)#endif
/* * In some cases we do not need to pin the task to the CPU because we are * already given a specific cpu's pcp pointer. */#define pcp_spin_lock_nopin(ptr) \ spin_lock(&(ptr)->lock)#define pcp_spin_unlock_nopin(ptr) \ spin_unlock(&(ptr)->lock)
#ifdef CONFIG_USE_PERCPU_NUMA_NODE_IDDEFINE_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_ENTROPYvolatile 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;
#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLEunsigned int pageblock_order __read_mostly;#endif
static void __free_pages_ok(struct page *page, unsigned int order, fpi_t fpi_flags);static void reserve_highatomic_pageblock(struct page *page, int order, struct zone *zone);
/* * 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;int defrag_mode;
/* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */int movable_zone;EXPORT_SYMBOL(movable_zone);
#if MAX_NUMNODES > 1unsigned 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
/* * When page allocations stall for longer than a threshold, * ALLOC_STALL_WARN_MSECS, leave a warning in the kernel log. Only one warning * will be printed during this duration for the entire system. */#define ALLOC_STALL_WARN_MSECS (10 * 1000UL)static unsigned long alloc_stall_warn_jiffies = INITIAL_JIFFIES;
static bool page_contains_unaccepted(struct page *page, unsigned int order);static bool cond_accept_memory(struct zone *zone, unsigned int order, int alloc_flags);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);
/* * 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);}#elsestatic inline bool _deferred_grow_zone(struct zone *zone, unsigned int order){ return false;}#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
/* Return a pointer to the bitmap storing bits affecting a block of pages */static inline unsigned long *get_pageblock_bitmap(const struct page *page, unsigned long pfn){#ifdef CONFIG_SPARSEMEM return section_to_usemap(__pfn_to_section(pfn));#else return page_zone(page)->pageblock_flags;#endif /* CONFIG_SPARSEMEM */}
static inline int pfn_to_bitidx(const struct page *page, unsigned long pfn){#ifdef CONFIG_SPARSEMEM pfn &= (PAGES_PER_SECTION-1);#else pfn = pfn - pageblock_start_pfn(page_zone(page)->zone_start_pfn);#endif /* CONFIG_SPARSEMEM */ return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;}
static __always_inline bool is_standalone_pb_bit(enum pageblock_bits pb_bit){ return pb_bit >= PB_compact_skip && pb_bit < __NR_PAGEBLOCK_BITS;}
static __always_inline voidget_pfnblock_bitmap_bitidx(const struct page *page, unsigned long pfn, unsigned long **bitmap_word, unsigned long *bitidx){ unsigned long *bitmap; unsigned long word_bitidx;
#ifdef CONFIG_MEMORY_ISOLATION BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 8);#else BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4);#endif BUILD_BUG_ON(__MIGRATE_TYPE_END > PAGEBLOCK_MIGRATETYPE_MASK); VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);
bitmap = get_pageblock_bitmap(page, pfn); *bitidx = pfn_to_bitidx(page, pfn); word_bitidx = *bitidx / BITS_PER_LONG; *bitidx &= (BITS_PER_LONG - 1); *bitmap_word = &bitmap[word_bitidx];}
/** * __get_pfnblock_flags_mask - Return the requested group of flags for * a 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 */static unsigned long __get_pfnblock_flags_mask(const struct page *page, unsigned long pfn, unsigned long mask){ unsigned long *bitmap_word; unsigned long bitidx; unsigned long word;
get_pfnblock_bitmap_bitidx(page, pfn, &bitmap_word, &bitidx); /* * This races, without locks, with set_pfnblock_migratetype(). Ensure * a consistent read of the memory array, so that results, even though * racy, are not corrupted. */ word = READ_ONCE(*bitmap_word); return (word >> bitidx) & mask;}
/** * get_pfnblock_bit - Check if a standalone bit of a pageblock is set * @page: The page within the block of interest * @pfn: The target page frame number * @pb_bit: pageblock bit to check * * Return: true if the bit is set, otherwise false */bool get_pfnblock_bit(const struct page *page, unsigned long pfn, enum pageblock_bits pb_bit){ unsigned long *bitmap_word; unsigned long bitidx;
if (WARN_ON_ONCE(!is_standalone_pb_bit(pb_bit))) return false;
get_pfnblock_bitmap_bitidx(page, pfn, &bitmap_word, &bitidx);
return test_bit(bitidx + pb_bit, bitmap_word);}
/** * get_pfnblock_migratetype - Return the migratetype of a pageblock * @page: The page within the block of interest * @pfn: The target page frame number * * Return: The migratetype of the pageblock * * Use get_pfnblock_migratetype() if caller already has both @page and @pfn * to save a call to page_to_pfn(). */enum migratetypeget_pfnblock_migratetype(const struct page *page, unsigned long pfn){ unsigned long mask = PAGEBLOCK_MIGRATETYPE_MASK | PAGEBLOCK_ISO_MASK; unsigned long flags;
flags = __get_pfnblock_flags_mask(page, pfn, mask);
#ifdef CONFIG_MEMORY_ISOLATION if (flags & BIT(PB_migrate_isolate)) return MIGRATE_ISOLATE;#endif return flags & PAGEBLOCK_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 * @pfn: The target page frame number * @flags: The flags to set * @mask: mask of bits that the caller is interested in */static void __set_pfnblock_flags_mask(struct page *page, unsigned long pfn, unsigned long flags, unsigned long mask){ unsigned long *bitmap_word; unsigned long bitidx; unsigned long word;
get_pfnblock_bitmap_bitidx(page, pfn, &bitmap_word, &bitidx);
mask <<= bitidx; flags <<= bitidx;
word = READ_ONCE(*bitmap_word); do { } while (!try_cmpxchg(bitmap_word, &word, (word & ~mask) | flags));}
/** * set_pfnblock_bit - Set a standalone bit of a pageblock * @page: The page within the block of interest * @pfn: The target page frame number * @pb_bit: pageblock bit to set */void set_pfnblock_bit(const struct page *page, unsigned long pfn, enum pageblock_bits pb_bit){ unsigned long *bitmap_word; unsigned long bitidx;
if (WARN_ON_ONCE(!is_standalone_pb_bit(pb_bit))) return;
get_pfnblock_bitmap_bitidx(page, pfn, &bitmap_word, &bitidx);
set_bit(bitidx + pb_bit, bitmap_word);}
/** * clear_pfnblock_bit - Clear a standalone bit of a pageblock * @page: The page within the block of interest * @pfn: The target page frame number * @pb_bit: pageblock bit to clear */void clear_pfnblock_bit(const struct page *page, unsigned long pfn, enum pageblock_bits pb_bit){ unsigned long *bitmap_word; unsigned long bitidx;
if (WARN_ON_ONCE(!is_standalone_pb_bit(pb_bit))) return;
get_pfnblock_bitmap_bitidx(page, pfn, &bitmap_word, &bitidx);
clear_bit(bitidx + pb_bit, bitmap_word);}
/** * set_pageblock_migratetype - Set the migratetype of a pageblock * @page: The page within the block of interest * @migratetype: migratetype to set */static void set_pageblock_migratetype(struct page *page, enum migratetype migratetype){ if (unlikely(page_group_by_mobility_disabled && migratetype < MIGRATE_PCPTYPES)) migratetype = MIGRATE_UNMOVABLE;
#ifdef CONFIG_MEMORY_ISOLATION if (migratetype == MIGRATE_ISOLATE) { VM_WARN_ONCE(1, "Use set_pageblock_isolate() for pageblock isolation"); return; } VM_WARN_ONCE(get_pageblock_isolate(page), "Use clear_pageblock_isolate() to unisolate pageblock"); /* PAGEBLOCK_ISO_MASK clears PB_migrate_isolate if it is set */#endif __set_pfnblock_flags_mask(page, page_to_pfn(page), (unsigned long)migratetype, PAGEBLOCK_MIGRATETYPE_MASK | PAGEBLOCK_ISO_MASK);}
void __meminit init_pageblock_migratetype(struct page *page, enum migratetype migratetype, bool isolate){ unsigned long flags;
if (unlikely(page_group_by_mobility_disabled && migratetype < MIGRATE_PCPTYPES)) migratetype = MIGRATE_UNMOVABLE;
flags = migratetype;
#ifdef CONFIG_MEMORY_ISOLATION if (migratetype == MIGRATE_ISOLATE) { VM_WARN_ONCE( 1, "Set isolate=true to isolate pageblock with a migratetype"); return; } if (isolate) flags |= BIT(PB_migrate_isolate);#endif __set_pfnblock_flags_mask(page, page_to_pfn(page), flags, PAGEBLOCK_MIGRATETYPE_MASK | PAGEBLOCK_ISO_MASK);}
#ifdef CONFIG_DEBUG_VMstatic 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 bool __maybe_unused bad_range(struct zone *zone, struct page *page){ if (page_outside_zone_boundaries(zone, page)) return true; if (zone != page_zone(page)) return true;
return false;}#elsestatic inline bool __maybe_unused bad_range(struct zone *zone, struct page *page){ return false;}#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 */ if (PageBuddy(page)) __ClearPageBuddy(page); add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);}
static inline unsigned int order_to_pindex(int migratetype, int order){ if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) { bool movable = migratetype == MIGRATE_MOVABLE;
if (order > PAGE_ALLOC_COSTLY_ORDER) return NR_LOWORDER_PCP_LISTS + movable; }
return (MIGRATE_PCPTYPES * order) + migratetype;}
static inline int pindex_to_order(unsigned int pindex){ int order = pindex / MIGRATE_PCPTYPES;
if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) { if (pindex >= NR_LOWORDER_PCP_LISTS) order = HPAGE_PMD_ORDER; }
return order;}
static inline bool pcp_allowed_order(unsigned int order){ if (order <= PAGE_ALLOC_COSTLY_ORDER) return true;#ifdef CONFIG_TRANSPARENT_HUGEPAGE if (is_pmd_order(order)) return true;#endif return false;}
/* * 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_info. 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, page, order);
prep_compound_head(page, order);}
static inline void set_buddy_order(struct page *page, unsigned int order){ set_page_private(page, order); __SetPageBuddy(page);}
#ifdef CONFIG_COMPACTIONstatic 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 boolcompaction_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 * unless compaction is also requesting movable pages. * 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 && capc->cc->migratetype != MIGRATE_MOVABLE) return false;
if (migratetype != capc->cc->migratetype) trace_mm_page_alloc_extfrag(page, capc->cc->order, order, capc->cc->migratetype, migratetype);
capc->page = page; return true;}
#elsestatic inline struct capture_control *task_capc(struct zone *zone){ return NULL;}
static inline boolcompaction_capture(struct capture_control *capc, struct page *page, int order, int migratetype){ return false;}#endif /* CONFIG_COMPACTION */
static inline void account_freepages(struct zone *zone, int nr_pages, int migratetype){ lockdep_assert_held(&zone->lock);
if (is_migrate_isolate(migratetype)) return;
__mod_zone_page_state(zone, NR_FREE_PAGES, nr_pages);
if (is_migrate_cma(migratetype)) __mod_zone_page_state(zone, NR_FREE_CMA_PAGES, nr_pages); else if (migratetype == MIGRATE_HIGHATOMIC) WRITE_ONCE(zone->nr_free_highatomic, zone->nr_free_highatomic + nr_pages);}
/* 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, bool tail){ struct free_area *area = &zone->free_area[order]; int nr_pages = 1 << order;
VM_WARN_ONCE(get_pageblock_migratetype(page) != migratetype, "page type is %d, passed migratetype is %d (nr=%d)\n", get_pageblock_migratetype(page), migratetype, nr_pages);
if (tail) list_add_tail(&page->buddy_list, &area->free_list[migratetype]); else list_add(&page->buddy_list, &area->free_list[migratetype]); area->nr_free++;
if (order >= pageblock_order && !is_migrate_isolate(migratetype)) __mod_zone_page_state(zone, NR_FREE_PAGES_BLOCKS, nr_pages);}
/* * 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 old_mt, int new_mt){ struct free_area *area = &zone->free_area[order]; int nr_pages = 1 << order;
/* Free page moving can fail, so it happens before the type update */ VM_WARN_ONCE(get_pageblock_migratetype(page) != old_mt, "page type is %d, passed migratetype is %d (nr=%d)\n", get_pageblock_migratetype(page), old_mt, nr_pages);
list_move_tail(&page->buddy_list, &area->free_list[new_mt]);
account_freepages(zone, -nr_pages, old_mt); account_freepages(zone, nr_pages, new_mt);
if (order >= pageblock_order && is_migrate_isolate(old_mt) != is_migrate_isolate(new_mt)) { if (!is_migrate_isolate(old_mt)) nr_pages = -nr_pages; __mod_zone_page_state(zone, NR_FREE_PAGES_BLOCKS, nr_pages); }}
static inline void __del_page_from_free_list(struct page *page, struct zone *zone, unsigned int order, int migratetype){ int nr_pages = 1 << order;
VM_WARN_ONCE(get_pageblock_migratetype(page) != migratetype, "page type is %d, passed migratetype is %d (nr=%d)\n", get_pageblock_migratetype(page), migratetype, nr_pages);
/* 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--;
if (order >= pageblock_order && !is_migrate_isolate(migratetype)) __mod_zone_page_state(zone, NR_FREE_PAGES_BLOCKS, -nr_pages);}
static inline void del_page_from_free_list(struct page *page, struct zone *zone, unsigned int order, int migratetype){ __del_page_from_free_list(page, zone, order, migratetype); account_freepages(zone, -(1 << order), migratetype);}
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 less than the 2nd largest possible page, check if the buddy * of the next-higher 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 2-level higher order page */static inline boolbuddy_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_PAGE_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;}
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; }}
/* * 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.f & PAGE_FLAGS_CHECK_AT_PREP, page);
VM_BUG_ON(migratetype == -1); VM_BUG_ON_PAGE(pfn & ((1 << order) - 1), page); VM_BUG_ON_PAGE(bad_range(zone, page), page);
account_freepages(zone, 1 << order, migratetype);
while (order < MAX_PAGE_ORDER) { int buddy_mt = migratetype;
if (compaction_capture(capc, page, order, migratetype)) { account_freepages(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. */ 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); else __del_page_from_free_list(buddy, zone, order, buddy_mt);
if (unlikely(buddy_mt != migratetype)) { /* * Match buddy type. This ensures that an * expand() down the line puts the sub-blocks * on the right freelists. */ change_pageblock_range(buddy, order, migratetype); }
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);
__add_to_free_list(page, zone, order, migratetype, to_tail);
/* Notify page reporting subsystem of freed page */ if (!(fpi_flags & FPI_SKIP_REPORT_NOTIFY)) page_reporting_notify_free(order);}
/* * 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_pool_page_is_pp(page) | (page->flags.f & 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.f & 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 if (unlikely(page_pool_page_is_pp(page))) bad_reason = "page_pool leak"; return bad_reason;}
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 */ bad_page(page, page_bad_reason(page, PAGE_FLAGS_CHECK_AT_FREE)); 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_large_mapcount(folio))) { bad_page(page, "nonzero large_mapcount"); goto out; } if (IS_ENABLED(CONFIG_PAGE_MAPCOUNT) && unlikely(atomic_read(&folio->_nr_pages_mapped))) { bad_page(page, "nonzero nr_pages_mapped"); goto out; } if (IS_ENABLED(CONFIG_MM_ID)) { if (unlikely(folio->_mm_id_mapcount[0] != -1)) { bad_page(page, "nonzero mm mapcount 0"); goto out; } if (unlikely(folio->_mm_id_mapcount[1] != -1)) { bad_page(page, "nonzero mm mapcount 1"); goto out; } } if (IS_ENABLED(CONFIG_64BIT)) { if (unlikely(atomic_read(&folio->_entire_mapcount) + 1)) { bad_page(page, "nonzero entire_mapcount"); goto out; } if (unlikely(atomic_read(&folio->_pincount))) { bad_page(page, "nonzero pincount"); goto out; } } break; case 2: /* the second tail page: deferred_list overlaps ->mapping */ if (unlikely(!list_empty(&folio->_deferred_list))) { bad_page(page, "on deferred list"); goto out; } if (!IS_ENABLED(CONFIG_64BIT)) { if (unlikely(atomic_read(&folio->_entire_mapcount) + 1)) { bad_page(page, "nonzero entire_mapcount"); goto out; } if (unlikely(atomic_read(&folio->_pincount))) { bad_page(page, "nonzero pincount"); goto out; } } break; case 3: /* the third tail page: hugetlb specifics overlap ->mappings */ if (IS_ENABLED(CONFIG_HUGETLB_PAGE)) break; fallthrough; 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){ if (IS_ENABLED(CONFIG_KASAN_GENERIC)) return deferred_pages_enabled();
return page_kasan_tag(page) == KASAN_TAG_KERNEL;}
static void clear_highpages_kasan_tagged(struct page *page, int numpages){ /* s390's use of memset() could override KASAN redzones. */ kasan_disable_current(); if (!IS_ENABLED(CONFIG_HIGHMEM)) { clear_pages(kasan_reset_tag(page_address(page)), numpages); } else { int i;
for (i = 0; i < numpages; i++) clear_highpage_kasan_tagged(page + i); } kasan_enable_current();}
#ifdef CONFIG_MEM_ALLOC_PROFILING
/* Should be called only if mem_alloc_profiling_enabled() */void __clear_page_tag_ref(struct page *page){ union pgtag_ref_handle handle; union codetag_ref ref;
if (get_page_tag_ref(page, &ref, &handle)) { set_codetag_empty(&ref); update_page_tag_ref(handle, &ref); put_page_tag_ref(handle); }}
/* Should be called only if mem_alloc_profiling_enabled() */static noinlinevoid __pgalloc_tag_add(struct page *page, struct task_struct *task, unsigned int nr, gfp_t gfp_flags){ union pgtag_ref_handle handle; union codetag_ref ref;
if (likely(get_page_tag_ref(page, &ref, &handle))) { alloc_tag_add(&ref, task->alloc_tag, PAGE_SIZE * nr); update_page_tag_ref(handle, &ref); put_page_tag_ref(handle); } else { /* * page_ext is not available yet, record the pfn so we can * clear the tag ref later when page_ext is initialized. */ alloc_tag_add_early_pfn(page_to_pfn(page), gfp_flags); if (task->alloc_tag) alloc_tag_set_inaccurate(task->alloc_tag); }}
static inline void pgalloc_tag_add(struct page *page, struct task_struct *task, unsigned int nr, gfp_t gfp_flags){ if (mem_alloc_profiling_enabled()) __pgalloc_tag_add(page, task, nr, gfp_flags);}
/* Should be called only if mem_alloc_profiling_enabled() */static noinlinevoid __pgalloc_tag_sub(struct page *page, unsigned int nr){ union pgtag_ref_handle handle; union codetag_ref ref;
if (get_page_tag_ref(page, &ref, &handle)) { alloc_tag_sub(&ref, PAGE_SIZE * nr); update_page_tag_ref(handle, &ref); put_page_tag_ref(handle); }}
static inline void pgalloc_tag_sub(struct page *page, unsigned int nr){ if (mem_alloc_profiling_enabled()) __pgalloc_tag_sub(page, nr);}
/* When tag is not NULL, assuming mem_alloc_profiling_enabled */static inline void pgalloc_tag_sub_pages(struct alloc_tag *tag, unsigned int nr){ if (tag) this_cpu_sub(tag->counters->bytes, PAGE_SIZE * nr);}
#else /* CONFIG_MEM_ALLOC_PROFILING */
static inline void pgalloc_tag_add(struct page *page, struct task_struct *task, unsigned int nr, gfp_t gfp_flags) {}static inline void pgalloc_tag_sub(struct page *page, unsigned int nr) {}static inline void pgalloc_tag_sub_pages(struct alloc_tag *tag, unsigned int nr) {}
#endif /* CONFIG_MEM_ALLOC_PROFILING */
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); bool init = want_init_on_free(); bool compound = PageCompound(page); struct folio *folio = page_folio(page);
if (fpi_flags & FPI_PREPARED) return true;
VM_BUG_ON_PAGE(PageTail(page), page);
trace_mm_page_free(page, order); kmsan_free_page(page, order);
if (memcg_kmem_online() && PageMemcgKmem(page)) __memcg_kmem_uncharge_page(page, order);
/* * In rare cases, when truncation or holepunching raced with * munlock after VM_LOCKED was cleared, Mlocked may still be * found set here. This does not indicate a problem, unless * "unevictable_pgs_cleared" appears worryingly large. */ if (unlikely(folio_test_mlocked(folio))) { long nr_pages = folio_nr_pages(folio);
__folio_clear_mlocked(folio); zone_stat_mod_folio(folio, NR_MLOCK, -nr_pages); count_vm_events(UNEVICTABLE_PGCLEARED, nr_pages); }
if (unlikely(PageHWPoison(page)) && !order) { /* Do not let hwpoison pages hit pcplists/buddy */ reset_page_owner(page, order); page_table_check_free(page, order); pgalloc_tag_sub(page, 1 << order);
/* * The page is isolated and accounted for. * Mark the codetag as empty to avoid accounting error * when the page is freed by unpoison_memory(). */ clear_page_tag_ref(page); return false; }
VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
/* * Check tail pages before head page information is cleared to * avoid checking PageCompound for order-0 pages. */ if (unlikely(order)) { int i;
if (compound) { page[1].flags.f &= ~PAGE_FLAGS_SECOND;#ifdef NR_PAGES_IN_LARGE_FOLIO folio->_nr_pages = 0;#endif } 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.f &= ~PAGE_FLAGS_CHECK_AT_PREP; } } if (folio_test_anon(folio)) { mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1); folio->mapping = NULL; } if (unlikely(page_has_type(page))) /* Reset the page_type (which overlays _mapcount) */ page->page_type = UINT_MAX;
if (is_check_pages_enabled()) { if (free_page_is_bad(page)) bad++; if (bad) return false; }
page_cpupid_reset_last(page); page->flags.f &= ~PAGE_FLAGS_CHECK_AT_PREP; page->private = 0; reset_page_owner(page, order); page_table_check_free(page, order); pgalloc_tag_sub(page, 1 << order);
if (!PageHighMem(page) && !(fpi_flags & FPI_TRYLOCK)) { 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) clear_highpages_kasan_tagged(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;}
bool free_pages_prepare(struct page *page, unsigned int order){ return __free_pages_prepare(page, order, FPI_NONE);}
/* * 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 int order; 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;
guard(spinlock_irqsave)(&zone->lock);
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 { unsigned long pfn; int mt;
page = list_last_entry(list, struct page, pcp_list); pfn = page_to_pfn(page); mt = get_pfnblock_migratetype(page, pfn);
/* must delete to avoid corrupting pcp list */ list_del(&page->pcp_list); count -= nr_pages; pcp->count -= nr_pages;
__free_one_page(page, pfn, zone, order, mt, FPI_NONE); trace_mm_page_pcpu_drain(page, order, mt); } while (count > 0 && !list_empty(list)); }}
/* Split a multi-block free page into its individual pageblocks. */static void split_large_buddy(struct zone *zone, struct page *page, unsigned long pfn, int order, fpi_t fpi){ unsigned long end = pfn + (1 << order);
VM_WARN_ON_ONCE(!IS_ALIGNED(pfn, 1 << order)); /* Caller removed page from freelist, buddy info cleared! */ VM_WARN_ON_ONCE(PageBuddy(page));
if (order > pageblock_order) order = pageblock_order;
do { int mt = get_pfnblock_migratetype(page, pfn);
__free_one_page(page, pfn, zone, order, mt, fpi); pfn += 1 << order; if (pfn == end) break; page = pfn_to_page(pfn); } while (1);}
static void add_page_to_zone_llist(struct zone *zone, struct page *page, unsigned int order){ /* Remember the order */ page->private = order; /* Add the page to the free list */ llist_add(&page->pcp_llist, &zone->trylock_free_pages);}
static void free_one_page(struct zone *zone, struct page *page, unsigned long pfn, unsigned int order, fpi_t fpi_flags){ struct llist_head *llhead; unsigned long flags;
if (unlikely(fpi_flags & FPI_TRYLOCK)) { if (!spin_trylock_irqsave(&zone->lock, flags)) { add_page_to_zone_llist(zone, page, order); return; } } else { spin_lock_irqsave(&zone->lock, flags); }
/* The lock succeeded. Process deferred pages. */ llhead = &zone->trylock_free_pages; if (unlikely(!llist_empty(llhead) && !(fpi_flags & FPI_TRYLOCK))) { struct llist_node *llnode; struct page *p, *tmp;
llnode = llist_del_all(llhead); llist_for_each_entry_safe(p, tmp, llnode, pcp_llist) { unsigned int p_order = p->private;
split_large_buddy(zone, p, page_to_pfn(p), p_order, fpi_flags); __count_vm_events(PGFREE, 1 << p_order); } } split_large_buddy(zone, page, pfn, order, fpi_flags); spin_unlock_irqrestore(&zone->lock, flags);
__count_vm_events(PGFREE, 1 << order);}
static void __free_pages_ok(struct page *page, unsigned int order, fpi_t fpi_flags){ unsigned long pfn = page_to_pfn(page); struct zone *zone = page_zone(page);
if (__free_pages_prepare(page, order, fpi_flags)) free_one_page(zone, page, pfn, order, fpi_flags);}
void __meminit __free_pages_core(struct page *page, unsigned int order, enum meminit_context context){ 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. * * Note that hotplugged memory pages are initialized to PageOffline(). * Pages freed from memblock might be marked as reserved. */ if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG) && unlikely(context == MEMINIT_HOTPLUG)) { for (loop = 0; loop < nr_pages; loop++, p++) { VM_WARN_ON_ONCE(PageReserved(p)); __ClearPageOffline(p); set_page_count(p, 0); }
adjust_managed_page_count(page, nr_pages); } else { for (loop = 0; loop < nr_pages; loop++, p++) { __ClearPageReserved(p); set_page_count(p, 0); }
/* memblock adjusts totalram_pages() manually. */ atomic_long_add(nr_pages, &page_zone(page)->managed_pages); }
if (page_contains_unaccepted(page, order)) { if (order == MAX_PAGE_ORDER && __free_unaccepted(page)) return;
accept_memory(page_to_phys(page), PAGE_SIZE << 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_PAGE_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 unsigned int expand(struct zone *zone, struct page *page, int low, int high, int migratetype){ unsigned int size = 1 << high; unsigned int nr_added = 0;
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)) continue;
__add_to_free_list(&page[size], zone, high, migratetype, false); set_buddy_order(&page[size], high); nr_added += size; }
return nr_added;}
static __always_inline void page_del_and_expand(struct zone *zone, struct page *page, int low, int high, int migratetype){ int nr_pages = 1 << high;
__del_page_from_free_list(page, zone, high, migratetype); nr_pages -= expand(zone, page, low, high, migratetype); account_freepages(zone, -nr_pages, migratetype);}
static void check_new_page_bad(struct page *page){ if (unlikely(PageHWPoison(page))) { /* Don't complain about hwpoisoned pages */ if (PageBuddy(page)) __ClearPageBuddy(page); 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 bool check_new_page(struct page *page){ if (likely(page_expected_state(page, PAGE_FLAGS_CHECK_AT_PREP|__PG_HWPOISON))) return false;
check_new_page_bad(page); return true;}
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){ const bool zero_tags = gfp_flags & __GFP_ZEROTAGS; bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags) && !should_skip_init(gfp_flags); int i;
set_page_private(page, 0);
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 initialization code must be * kept together to avoid discrepancies in behavior. */
/* * Clearing tags can efficiently clear the memory for us as well, if * required. */ if (zero_tags) init = tag_clear_highpages(page, 1 << order, /* clear_pages= */init);
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) clear_highpages_kasan_tagged(page, 1 << order);
set_page_owner(page, order, gfp_flags); page_table_check_alloc(page, order); pgalloc_tag_add(page, current, 1 << order, gfp_flags);}
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_inlinestruct 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 < NR_PAGE_ORDERS; ++current_order) { area = &(zone->free_area[current_order]); page = get_page_from_free_area(area, migratetype); if (!page) continue;
page_del_and_expand(zone, page, order, current_order, 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_PCPTYPES][MIGRATE_PCPTYPES - 1] = { [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE }, [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE }, [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE },};
#ifdef CONFIG_CMAstatic __always_inline struct page *__rmqueue_cma_fallback(struct zone *zone, unsigned int order){ return __rmqueue_smallest(zone, order, MIGRATE_CMA);}#elsestatic inline struct page *__rmqueue_cma_fallback(struct zone *zone, unsigned int order) { return NULL; }#endif
/* * Move all free pages of a block to new type's freelist. Caller needs to * change the block type. */static int __move_freepages_block(struct zone *zone, unsigned long start_pfn, int old_mt, int new_mt){ struct page *page; unsigned long pfn, end_pfn; unsigned int order; int pages_moved = 0;
VM_WARN_ON(start_pfn & (pageblock_nr_pages - 1)); end_pfn = pageblock_end_pfn(start_pfn);
for (pfn = start_pfn; pfn < end_pfn;) { page = pfn_to_page(pfn); if (!PageBuddy(page)) { 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, old_mt, new_mt);
pfn += 1 << order; pages_moved += 1 << order; }
return pages_moved;}
static bool prep_move_freepages_block(struct zone *zone, struct page *page, unsigned long *start_pfn, int *num_free, int *num_movable){ unsigned long pfn, start, end;
pfn = page_to_pfn(page); start = pageblock_start_pfn(pfn); end = pageblock_end_pfn(pfn);
/* * The caller only has the lock for @zone, don't touch ranges * that straddle into other zones. While we could move part of * the range that's inside the zone, this call is usually * accompanied by other operations such as migratetype updates * which also should be locked. */ if (!zone_spans_pfn(zone, start)) return false; if (!zone_spans_pfn(zone, end - 1)) return false;
*start_pfn = start;
if (num_free) { *num_free = 0; *num_movable = 0; for (pfn = start; pfn < end;) { page = pfn_to_page(pfn); if (PageBuddy(page)) { int nr = 1 << buddy_order(page);
*num_free += nr; pfn += nr; continue; } /* * 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 (PageLRU(page) || page_has_movable_ops(page)) (*num_movable)++; pfn++; } }
return true;}
static int move_freepages_block(struct zone *zone, struct page *page, int old_mt, int new_mt){ unsigned long start_pfn; int res;
if (!prep_move_freepages_block(zone, page, &start_pfn, NULL, NULL)) return -1;
res = __move_freepages_block(zone, start_pfn, old_mt, new_mt); set_pageblock_migratetype(pfn_to_page(start_pfn), new_mt);
return res;
}
#ifdef CONFIG_MEMORY_ISOLATION/* Look for a buddy that straddles start_pfn */static unsigned long find_large_buddy(unsigned long start_pfn){ /* * If start_pfn is not an order-0 PageBuddy, next PageBuddy containing * start_pfn has minimal order of __ffs(start_pfn) + 1. Start checking * the order with __ffs(start_pfn). If start_pfn is order-0 PageBuddy, * the starting order does not matter. */ int order = start_pfn ? __ffs(start_pfn) : MAX_PAGE_ORDER; struct page *page; unsigned long pfn = start_pfn;
while (!PageBuddy(page = pfn_to_page(pfn))) { /* Nothing found */ if (++order > MAX_PAGE_ORDER) return start_pfn; pfn &= ~0UL << order; }
/* * Found a preceding buddy, but does it straddle? */ if (pfn + (1 << buddy_order(page)) > start_pfn) return pfn;
/* Nothing found */ return start_pfn;}
static inline void toggle_pageblock_isolate(struct page *page, bool isolate){ if (isolate) set_pageblock_isolate(page); else clear_pageblock_isolate(page);}
/** * __move_freepages_block_isolate - move free pages in block for page isolation * @zone: the zone * @page: the pageblock page * @isolate: to isolate the given pageblock or unisolate it * * This is similar to move_freepages_block(), but handles the special * case encountered in page isolation, where the block of interest * might be part of a larger buddy spanning multiple pageblocks. * * Unlike the regular page allocator path, which moves pages while * stealing buddies off the freelist, page isolation is interested in * arbitrary pfn ranges that may have overlapping buddies on both ends. * * This function handles that. Straddling buddies are split into * individual pageblocks. Only the block of interest is moved. * * Returns %true if pages could be moved, %false otherwise. */static bool __move_freepages_block_isolate(struct zone *zone, struct page *page, bool isolate){ unsigned long start_pfn, buddy_pfn; int from_mt; int to_mt; struct page *buddy;
if (isolate == get_pageblock_isolate(page)) { VM_WARN_ONCE(1, "%s a pageblock that is already in that state", isolate ? "Isolate" : "Unisolate"); return false; }
if (!prep_move_freepages_block(zone, page, &start_pfn, NULL, NULL)) return false;
/* No splits needed if buddies can't span multiple blocks */ if (pageblock_order == MAX_PAGE_ORDER) goto move;
buddy_pfn = find_large_buddy(start_pfn); buddy = pfn_to_page(buddy_pfn); /* We're a part of a larger buddy */ if (PageBuddy(buddy) && buddy_order(buddy) > pageblock_order) { int order = buddy_order(buddy);
del_page_from_free_list(buddy, zone, order, get_pfnblock_migratetype(buddy, buddy_pfn)); toggle_pageblock_isolate(page, isolate); split_large_buddy(zone, buddy, buddy_pfn, order, FPI_NONE); return true; }
move: /* Use PAGEBLOCK_MIGRATETYPE_MASK to get non-isolate migratetype */ if (isolate) { from_mt = __get_pfnblock_flags_mask(page, page_to_pfn(page), PAGEBLOCK_MIGRATETYPE_MASK); to_mt = MIGRATE_ISOLATE; } else { from_mt = MIGRATE_ISOLATE; to_mt = __get_pfnblock_flags_mask(page, page_to_pfn(page), PAGEBLOCK_MIGRATETYPE_MASK); }
__move_freepages_block(zone, start_pfn, from_mt, to_mt); toggle_pageblock_isolate(pfn_to_page(start_pfn), isolate);
return true;}
bool pageblock_isolate_and_move_free_pages(struct zone *zone, struct page *page){ return __move_freepages_block_isolate(zone, page, true);}
bool pageblock_unisolate_and_move_free_pages(struct zone *zone, struct page *page){ return __move_freepages_block_isolate(zone, page, false);}
#endif /* CONFIG_MEMORY_ISOLATION */
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;}
/* * When we are falling back to another migratetype during allocation, should we * try to claim an entire block to satisfy further allocations, instead of * polluting multiple pageblocks? */static bool should_try_claim_block(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 claim the 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;
/* * Above a certain threshold, always try to claim, as it's likely there * will be more free pages in the pageblock. */ if (order >= pageblock_order / 2) return true;
/* * Unmovable/reclaimable allocations would cause permanent * fragmentations if they fell back to allocating from a movable block * (polluting it), so we try to claim the whole block regardless of the * allocation size. Later movable allocations can always steal from this * block, which is less problematic. */ if (start_mt == MIGRATE_RECLAIMABLE || start_mt == MIGRATE_UNMOVABLE) return true;
if (page_group_by_mobility_disabled) return true;
/* * Movable pages won't cause permanent fragmentation, so when you alloc * small pages, we just need to temporarily steal unmovable or * reclaimable pages that are closest to the request size. After a * while, memory compaction may occur to form large contiguous pages, * and the next movable allocation may not need to steal. */ return false;}
/* * Check whether there is a suitable fallback freepage with requested order. * If claimable is true, this function returns fallback_mt only if * we would do this whole-block claiming. This would help to reduce * fragmentation due to mixed migratetype pages in one pageblock. */enum fallback_resultfind_suitable_fallback(struct free_area *area, unsigned int order, int migratetype, bool claimable, int *mt_out){ int i;
if (claimable && !should_try_claim_block(order, migratetype)) return FALLBACK_NOCLAIM;
if (area->nr_free == 0) return FALLBACK_EMPTY;
for (i = 0; i < MIGRATE_PCPTYPES - 1 ; i++) { int fallback_mt = fallbacks[migratetype][i];
if (!free_area_empty(area, fallback_mt)) { if (mt_out) *mt_out = fallback_mt; return FALLBACK_FOUND; } }
return FALLBACK_EMPTY;}
/* * This function implements actual block claiming behaviour. If order is large * enough, we can claim the whole pageblock for the requested migratetype. If * not, we check the pageblock for constituent pages; if at least half of the * pages are free or compatible, we can still claim the whole block, so pages * freed in the future will be put on the correct free list. */static struct page *try_to_claim_block(struct zone *zone, struct page *page, int current_order, int order, int start_type, int block_type, unsigned int alloc_flags){ int free_pages, movable_pages, alike_pages; unsigned long start_pfn;
/* Take ownership for orders >= pageblock_order */ if (current_order >= pageblock_order) { unsigned int nr_added;
del_page_from_free_list(page, zone, current_order, block_type); change_pageblock_range(page, current_order, start_type); nr_added = expand(zone, page, order, current_order, start_type); account_freepages(zone, nr_added, start_type); return 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);
/* moving whole block can fail due to zone boundary conditions */ if (!prep_move_freepages_block(zone, page, &start_pfn, &free_pages, &movable_pages)) return NULL;
/* * 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 (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) { __move_freepages_block(zone, start_pfn, block_type, start_type); set_pageblock_migratetype(pfn_to_page(start_pfn), start_type); return __rmqueue_smallest(zone, order, start_type); }
return NULL;}
/* * Try to allocate from some fallback migratetype by claiming the entire block, * i.e. converting it to the allocation's start migratetype. * * 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 struct page *__rmqueue_claim(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;
/* * 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_PAGE_ORDER; current_order >= min_order; --current_order) { enum fallback_result result;
area = &(zone->free_area[current_order]); result = find_suitable_fallback(area, current_order, start_migratetype, true, &fallback_mt);
if (result == FALLBACK_EMPTY) continue;
if (result == FALLBACK_NOCLAIM) break;
page = get_page_from_free_area(area, fallback_mt); page = try_to_claim_block(zone, page, current_order, order, start_migratetype, fallback_mt, alloc_flags); if (page) { trace_mm_page_alloc_extfrag(page, order, current_order, start_migratetype, fallback_mt); return page; } }
return NULL;}
/* * Try to steal a single page from some fallback migratetype. Leave the rest of * the block as its current migratetype, potentially causing fragmentation. */static __always_inline struct page *__rmqueue_steal(struct zone *zone, int order, int start_migratetype){ struct free_area *area; int current_order; struct page *page; int fallback_mt;
for (current_order = order; current_order < NR_PAGE_ORDERS; current_order++) { enum fallback_result result;
area = &(zone->free_area[current_order]); result = find_suitable_fallback(area, current_order, start_migratetype, false, &fallback_mt); if (result == FALLBACK_EMPTY) continue;
page = get_page_from_free_area(area, fallback_mt); page_del_and_expand(zone, page, order, current_order, fallback_mt); trace_mm_page_alloc_extfrag(page, order, current_order, start_migratetype, fallback_mt); return page; }
return NULL;}
enum rmqueue_mode { RMQUEUE_NORMAL, RMQUEUE_CMA, RMQUEUE_CLAIM, RMQUEUE_STEAL,};
/* * 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, enum rmqueue_mode *mode){ 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; } }
/* * First try the freelists of the requested migratetype, then try * fallbacks modes with increasing levels of fragmentation risk. * * The fallback logic is expensive and rmqueue_bulk() calls in * a loop with the zone->lock held, meaning the freelists are * not subject to any outside changes. Remember in *mode where * we found pay dirt, to save us the search on the next call. */ switch (*mode) { case RMQUEUE_NORMAL: page = __rmqueue_smallest(zone, order, migratetype); if (page) return page; fallthrough; case RMQUEUE_CMA: if (alloc_flags & ALLOC_CMA) { page = __rmqueue_cma_fallback(zone, order); if (page) { *mode = RMQUEUE_CMA; return page; } } fallthrough; case RMQUEUE_CLAIM: page = __rmqueue_claim(zone, order, migratetype, alloc_flags); if (page) { /* Replenished preferred freelist, back to normal mode. */ *mode = RMQUEUE_NORMAL; return page; } fallthrough; case RMQUEUE_STEAL: if (!(alloc_flags & ALLOC_NOFRAGMENT)) { page = __rmqueue_steal(zone, order, migratetype); if (page) { *mode = RMQUEUE_STEAL; return page; } } } return NULL;}
/* * 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){ enum rmqueue_mode rmqm = RMQUEUE_NORMAL; unsigned long flags; int i;
if (unlikely(alloc_flags & ALLOC_TRYLOCK)) { if (!spin_trylock_irqsave(&zone->lock, flags)) return 0; } else { spin_lock_irqsave(&zone->lock, flags); } for (i = 0; i < count; ++i) { struct page *page = __rmqueue(zone, order, migratetype, alloc_flags, &rmqm); 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); } spin_unlock_irqrestore(&zone->lock, flags);
return i;}
/* * Called from the vmstat counter updater to decay the PCP high. * Return whether there are addition works to do. */bool decay_pcp_high(struct zone *zone, struct per_cpu_pages *pcp){ int high_min, to_drain, to_drain_batched, batch; bool todo = false;
high_min = READ_ONCE(pcp->high_min); batch = READ_ONCE(pcp->batch); /* * Decrease pcp->high periodically to try to free possible * idle PCP pages. And, avoid to free too many pages to * control latency. This caps pcp->high decrement too. */ if (pcp->high > high_min) { pcp->high = max3(pcp->count - (batch << CONFIG_PCP_BATCH_SCALE_MAX), pcp->high - (pcp->high >> 3), high_min); if (pcp->high > high_min) todo = true; }
to_drain = pcp->count - pcp->high; while (to_drain > 0) { to_drain_batched = min(to_drain, batch); pcp_spin_lock_nopin(pcp); free_pcppages_bulk(zone, to_drain_batched, pcp, 0); pcp_spin_unlock_nopin(pcp); todo = true;
to_drain -= to_drain_batched; }
return todo;}
#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) { pcp_spin_lock_nopin(pcp); free_pcppages_bulk(zone, to_drain, pcp, 0); pcp_spin_unlock_nopin(pcp); }}#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 = per_cpu_ptr(zone->per_cpu_pageset, cpu); int count;
do { pcp_spin_lock_nopin(pcp); count = pcp->count; if (count) { int to_drain = min(count, pcp->batch << CONFIG_PCP_BATCH_SCALE_MAX);
free_pcppages_bulk(zone, to_drain, pcp, 0); count -= to_drain; } pcp_spin_unlock_nopin(pcp); } while (count);}
/* * 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 int nr_pcp_free(struct per_cpu_pages *pcp, int batch, int high, bool free_high){ int min_nr_free, max_nr_free;
/* Free as much as possible if batch freeing high-order pages. */ if (unlikely(free_high)) return min(pcp->count, batch << CONFIG_PCP_BATCH_SCALE_MAX);
/* 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;
/* * Increase the batch number to the number of the consecutive * freed pages to reduce zone lock contention. */ batch = clamp_t(int, pcp->free_count, min_nr_free, max_nr_free);
return batch;}
static int nr_pcp_high(struct per_cpu_pages *pcp, struct zone *zone, int batch, bool free_high){ int high, high_min, high_max;
high_min = READ_ONCE(pcp->high_min); high_max = READ_ONCE(pcp->high_max); high = pcp->high = clamp(pcp->high, high_min, high_max);
if (unlikely(!high)) return 0;
if (unlikely(free_high)) { pcp->high = max(high - (batch << CONFIG_PCP_BATCH_SCALE_MAX), high_min); return 0; }
/* * If reclaim is active, limit the number of pages that can be * stored on pcp lists */ if (test_bit(ZONE_RECLAIM_ACTIVE, &zone->flags)) { int free_count = max_t(int, pcp->free_count, batch);
pcp->high = max(high - free_count, high_min); return min(batch << 2, pcp->high); }
if (high_min == high_max) return high;
if (test_bit(ZONE_BELOW_HIGH, &zone->flags)) { int free_count = max_t(int, pcp->free_count, batch);
pcp->high = max(high - free_count, high_min); high = max(pcp->count, high_min); } else if (pcp->count >= high) { int need_high = pcp->free_count + batch;
/* pcp->high should be large enough to hold batch freed pages */ if (pcp->high < need_high) pcp->high = clamp(need_high, high_min, high_max); }
return high;}
/* * Tune pcp alloc factor and adjust count & free_count. Free pages to bring the * pcp's watermarks below high. * * May return a freed pcp, if during page freeing the pcp spinlock cannot be * reacquired. Return true if pcp is locked, false otherwise. */static bool free_frozen_page_commit(struct zone *zone, struct per_cpu_pages *pcp, struct page *page, int migratetype, unsigned int order, fpi_t fpi_flags){ int high, batch; int to_free, to_free_batched; int pindex; int cpu = smp_processor_id(); int ret = true; bool free_high = false;
/* * On freeing, reduce the number of pages that are batch allocated. * See nr_pcp_alloc() where alloc_factor is increased for subsequent * allocations. */ pcp->alloc_factor >>= 1; __count_vm_events(PGFREE, 1 << order); pindex = order_to_pindex(migratetype, order); list_add(&page->pcp_list, &pcp->lists[pindex]); pcp->count += 1 << order;
batch = READ_ONCE(pcp->batch); /* * 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. */ if (order && order <= PAGE_ALLOC_COSTLY_ORDER) { free_high = (pcp->free_count >= (batch + pcp->high_min / 2) && (pcp->flags & PCPF_PREV_FREE_HIGH_ORDER) && (!(pcp->flags & PCPF_FREE_HIGH_BATCH) || pcp->count >= batch)); pcp->flags |= PCPF_PREV_FREE_HIGH_ORDER; } else if (pcp->flags & PCPF_PREV_FREE_HIGH_ORDER) { pcp->flags &= ~PCPF_PREV_FREE_HIGH_ORDER; } if (pcp->free_count < (batch << CONFIG_PCP_BATCH_SCALE_MAX)) pcp->free_count += (1 << order);
if (unlikely(fpi_flags & FPI_TRYLOCK)) { /* * Do not attempt to take a zone lock. Let pcp->count get * over high mark temporarily. */ return true; }
high = nr_pcp_high(pcp, zone, batch, free_high); if (pcp->count < high) return true;
to_free = nr_pcp_free(pcp, batch, high, free_high); while (to_free > 0 && pcp->count > 0) { to_free_batched = min(to_free, batch); free_pcppages_bulk(zone, to_free_batched, pcp, pindex); to_free -= to_free_batched;
if (to_free == 0 || pcp->count == 0) break;
pcp_spin_unlock(pcp);
pcp = pcp_spin_trylock(zone->per_cpu_pageset); if (!pcp) { ret = false; break; }
/* * Check if this thread has been migrated to a different CPU. * If that is the case, give up and indicate that the pcp is * returned in an unlocked state. */ if (smp_processor_id() != cpu) { pcp_spin_unlock(pcp); ret = false; break; } }
if (test_bit(ZONE_BELOW_HIGH, &zone->flags) && zone_watermark_ok(zone, 0, high_wmark_pages(zone), ZONE_MOVABLE, 0)) { struct pglist_data *pgdat = zone->zone_pgdat; clear_bit(ZONE_BELOW_HIGH, &zone->flags);
/* * Assume that memory pressure on this node is gone and may be * in a reclaimable state. If a memory fallback node exists, * direct reclaim may not have been triggered, causing a * 'hopeless node' to stay in that state for a while. Let * kswapd work again by resetting kswapd_failures. */ if (kswapd_test_hopeless(pgdat) && next_memory_node(pgdat->node_id) < MAX_NUMNODES) kswapd_clear_hopeless(pgdat, KSWAPD_CLEAR_HOPELESS_PCP); } return ret;}
/* * Free a pcp page */static void __free_frozen_pages(struct page *page, unsigned int order, fpi_t fpi_flags){ struct per_cpu_pages *pcp; struct zone *zone; unsigned long pfn = page_to_pfn(page); int migratetype;
if (!pcp_allowed_order(order)) { __free_pages_ok(page, order, fpi_flags); return; }
if (!__free_pages_prepare(page, order, fpi_flags)) 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 */ zone = page_zone(page); migratetype = get_pfnblock_migratetype(page, pfn); if (unlikely(migratetype >= MIGRATE_PCPTYPES)) { if (unlikely(is_migrate_isolate(migratetype))) { free_one_page(zone, page, pfn, order, fpi_flags); return; } migratetype = MIGRATE_MOVABLE; }
if (unlikely((fpi_flags & FPI_TRYLOCK) && IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq()))) { add_page_to_zone_llist(zone, page, order); return; } pcp = pcp_spin_trylock(zone->per_cpu_pageset); if (pcp) { if (!free_frozen_page_commit(zone, pcp, page, migratetype, order, fpi_flags)) return; pcp_spin_unlock(pcp); } else { free_one_page(zone, page, pfn, order, fpi_flags); }}
void free_frozen_pages(struct page *page, unsigned int order){ __free_frozen_pages(page, order, FPI_NONE);}
void free_frozen_pages_nolock(struct page *page, unsigned int order){ __free_frozen_pages(page, order, FPI_TRYLOCK);}
/* * Free a batch of folios */void free_unref_folios(struct folio_batch *folios){ struct per_cpu_pages *pcp = NULL; struct zone *locked_zone = NULL; int i, j;
/* Prepare folios for freeing */ for (i = 0, j = 0; i < folios->nr; i++) { struct folio *folio = folios->folios[i]; unsigned long pfn = folio_pfn(folio); unsigned int order = folio_order(folio);
if (!__free_pages_prepare(&folio->page, order, FPI_NONE)) continue; /* * Free orders not handled on the PCP directly to the * allocator. */ if (!pcp_allowed_order(order)) { free_one_page(folio_zone(folio), &folio->page, pfn, order, FPI_NONE); continue; } folio->private = (void *)(unsigned long)order; if (j != i) folios->folios[j] = folio; j++; } folios->nr = j;
for (i = 0; i < folios->nr; i++) { struct folio *folio = folios->folios[i]; struct zone *zone = folio_zone(folio); unsigned long pfn = folio_pfn(folio); unsigned int order = (unsigned long)folio->private; int migratetype;
folio->private = NULL; migratetype = get_pfnblock_migratetype(&folio->page, pfn);
/* Different zone requires a different pcp lock */ if (zone != locked_zone || is_migrate_isolate(migratetype)) { if (pcp) { pcp_spin_unlock(pcp); locked_zone = NULL; pcp = NULL; }
/* * Free isolated pages directly to the * allocator, see comment in free_frozen_pages. */ if (is_migrate_isolate(migratetype)) { free_one_page(zone, &folio->page, pfn, order, FPI_NONE); continue; }
/* * trylock is necessary as folios may be getting freed * from IRQ or SoftIRQ context after an IO completion. */ pcp = pcp_spin_trylock(zone->per_cpu_pageset); if (unlikely(!pcp)) { free_one_page(zone, &folio->page, pfn, order, FPI_NONE); 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(&folio->page); if (!free_frozen_page_commit(zone, pcp, &folio->page, migratetype, order, FPI_NONE)) { pcp = NULL; locked_zone = NULL; } }
if (pcp) pcp_spin_unlock(pcp); folio_batch_reinit(folios);}
static void __split_page(struct page *page, unsigned int order){ VM_WARN_ON_PAGE(PageCompound(page), page);
split_page_owner(page, order, 0); pgalloc_tag_split(page_folio(page), order, 0); split_page_memcg(page, order);}
/* * 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_WARN_ON_PAGE(!page_count(page), page);
for (i = 1; i < (1 << order); i++) set_page_refcounted(page + i);
__split_page(page, 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; }
del_page_from_free_list(page, zone, order, mt);
/* * 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)) move_freepages_block(zone, page, mt, 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_inlinestruct 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; if (unlikely(alloc_flags & ALLOC_TRYLOCK)) { if (!spin_trylock_irqsave(&zone->lock, flags)) return NULL; } else { spin_lock_irqsave(&zone->lock, flags); } if (alloc_flags & ALLOC_HIGHATOMIC) page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC); if (!page) { enum rmqueue_mode rmqm = RMQUEUE_NORMAL;
page = __rmqueue(zone, order, migratetype, alloc_flags, &rmqm);
/* * If the allocation fails, allow OOM handling and * order-0 (atomic) allocs 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|ALLOC_NON_BLOCK))) page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
if (!page) { spin_unlock_irqrestore(&zone->lock, flags); return NULL; } } spin_unlock_irqrestore(&zone->lock, flags); } while (check_new_pages(page, order));
/* * 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, order, zone);
__count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order); zone_statistics(preferred_zone, zone, 1);
return page;}
static int nr_pcp_alloc(struct per_cpu_pages *pcp, struct zone *zone, int order){ int high, base_batch, batch, max_nr_alloc; int high_max, high_min;
base_batch = READ_ONCE(pcp->batch); high_min = READ_ONCE(pcp->high_min); high_max = READ_ONCE(pcp->high_max); high = pcp->high = clamp(pcp->high, high_min, high_max);
/* Check for PCP disabled or boot pageset */ if (unlikely(high < base_batch)) return 1;
if (order) batch = base_batch; else batch = (base_batch << pcp->alloc_factor);
/* * If we had larger pcp->high, we could avoid to allocate from * zone. */ if (high_min != high_max && !test_bit(ZONE_BELOW_HIGH, &zone->flags)) high = pcp->high = min(high + batch, high_max);
if (!order) { max_nr_alloc = max(high - pcp->count - base_batch, base_batch); /* * Double the number of pages allocated each time there is * subsequent allocation of order-0 pages without any freeing. */ if (batch <= max_nr_alloc && pcp->alloc_factor < CONFIG_PCP_BATCH_SCALE_MAX) pcp->alloc_factor++; batch = min(batch, max_nr_alloc); }
/* * 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);
return batch;}
/* Remove page from the per-cpu list, caller must protect the list */static inlinestruct 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 = nr_pcp_alloc(pcp, zone, order); int alloced;
/* * Don't refill the list for a higher order atomic * allocation under memory pressure, as this would * not build up any HIGHATOMIC reserves, which * might be needed soon. * * Instead, direct it towards the reserves by * returning NULL, which will make the caller fall * back to rmqueue_buddy. This will try to use the * reserves first and grow them if needed. */ if (alloc_flags & ALLOC_HIGHATOMIC) return NULL;
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;
/* spin_trylock may fail due to a parallel drain or IRQ reentrancy. */ pcp = pcp_spin_trylock(zone->per_cpu_pageset); if (!pcp) 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_count >>= 1; list = &pcp->lists[order_to_pindex(migratetype, order)]; page = __rmqueue_pcplist(zone, order, migratetype, alloc_flags, pcp, list); pcp_spin_unlock(pcp); 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_migratetype(). * 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_memorystatic inlinestruct 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;
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;}
/* * Reserve the pageblock(s) surrounding an allocation request 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, int order, struct zone *zone){ int mt; unsigned long max_managed;
/* * The number reserved as: minimum is 1 pageblock, maximum is * roughly 1% of a zone. But if 1% of a zone falls below a * pageblock size, then don't reserve any pageblocks. * Check is race-prone but harmless. */ if ((zone_managed_pages(zone) / 100) < pageblock_nr_pages) return; max_managed = ALIGN((zone_managed_pages(zone) / 100), pageblock_nr_pages); if (zone->nr_reserved_highatomic >= max_managed) return;
guard(spinlock_irqsave)(&zone->lock);
/* Recheck the nr_reserved_highatomic limit under the lock */ if (zone->nr_reserved_highatomic >= max_managed) return;
/* Yoink! */ mt = get_pageblock_migratetype(page); /* Only reserve normal pageblocks (i.e., they can merge with others) */ if (!migratetype_is_mergeable(mt)) return;
if (order < pageblock_order) { if (move_freepages_block(zone, page, mt, MIGRATE_HIGHATOMIC) == -1) return; zone->nr_reserved_highatomic += pageblock_nr_pages; } else { change_pageblock_range(page, order, MIGRATE_HIGHATOMIC); zone->nr_reserved_highatomic += 1 << order; }}
/* * 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 pageblocks even though highatomic * pageblock is exhausted. */static bool unreserve_highatomic_pageblock(const struct alloc_context *ac, bool force){ struct zonelist *zonelist = ac->zonelist; struct zoneref *z; struct zone *zone; struct page *page; int order; int 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;
guard(spinlock_irqsave)(&zone->lock); for (order = 0; order < NR_PAGE_ORDERS; order++) { struct free_area *area = &(zone->free_area[order]); unsigned long size;
page = get_page_from_free_area(area, MIGRATE_HIGHATOMIC); if (!page) continue;
size = max(pageblock_nr_pages, 1UL << order); /* * 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. */ if (WARN_ON_ONCE(size > zone->nr_reserved_highatomic)) size = zone->nr_reserved_highatomic; zone->nr_reserved_highatomic -= size;
/* * 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. */ if (order < pageblock_order) ret = move_freepages_block(zone, page, MIGRATE_HIGHATOMIC, ac->migratetype); else { move_to_free_list(page, zone, order, MIGRATE_HIGHATOMIC, ac->migratetype); change_pageblock_range(page, order, ac->migratetype); ret = 1; } /* * Reserving the block(s) already succeeded, * so this should not fail on zone boundaries. */ WARN_ON_ONCE(ret == -1); if (ret > 0) return ret; } }
return false;}
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 free pages reserved for highatomic. */ if (likely(!(alloc_flags & ALLOC_RESERVES))) unusable_free += READ_ONCE(z->nr_free_highatomic);
#ifdef CONFIG_CMA /* If allocation can't use CMA areas don't use free CMA pages */ if (!(alloc_flags & ALLOC_CMA)) unusable_free += zone_page_state(z, NR_FREE_CMA_PAGES);#endif
return unusable_free;}
/* * Return true if free base pages are above 'mark'. For high-order checks it * will return true of the order-0 watermark is reached and there is at least * one free page of a suitable size. Checking now avoids taking the zone lock * to check in the allocation paths if no pages are free. */bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark, int highest_zoneidx, unsigned int alloc_flags, long free_pages){ long min = mark; int o;
/* free_pages may go negative - that's OK */ free_pages -= __zone_watermark_unusable_free(z, order, alloc_flags);
if (unlikely(alloc_flags & ALLOC_RESERVES)) { /* * __GFP_HIGH allows access to 50% of the min reserve as well * as OOM. */ if (alloc_flags & ALLOC_MIN_RESERVE) { min -= min / 2;
/* * Non-blocking allocations (e.g. GFP_ATOMIC) can * access more reserves than just __GFP_HIGH. Other * non-blocking allocations requests such as GFP_NOWAIT * or (GFP_KERNEL & ~__GFP_DIRECT_RECLAIM) do not get * access to the min reserve. */ if (alloc_flags & ALLOC_NON_BLOCK) min -= min / 4; }
/* * OOM victims can try even harder than the normal reserve * users on the grounds that it's definitely going to be in * the exit path shortly and free memory. Any allocation it * makes during the free path will be small and short-lived. */ if (alloc_flags & ALLOC_OOM) min -= min / 2; }
/* * Check watermarks for an order-0 allocation request. If these * are not met, then a high-order request also cannot go ahead * even if a suitable page happened to be free. */ if (free_pages <= min + z->lowmem_reserve[highest_zoneidx]) return false;
/* If this is an order-0 request then the watermark is fine */ if (!order) return true;
/* For a high-order request, check at least one suitable page is free */ for (o = order; o < NR_PAGE_ORDERS; 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;}
#ifdef CONFIG_NUMAint __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 intalloc_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);
if (defrag_mode) { alloc_flags |= ALLOC_NOFRAGMENT; return alloc_flags; }
#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; bool skip_kswapd_nodes = nr_online_nodes > 1; bool skipped_kswapd_nodes = false;
retry: /* * Scan zonelist, looking for a zone with enough free. * See also cpuset_current_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 && !defrag_mode && nr_online_nodes > 1 && zone != zonelist_zone(ac->preferred_zoneref)) { int local_nid;
/* * If moving to a remote node, retry but allow * fragmenting fallbacks. Locality is more important * than fragmentation avoidance. */ local_nid = zonelist_node_idx(ac->preferred_zoneref); if (zone_to_nid(zone) != local_nid) { alloc_flags &= ~ALLOC_NOFRAGMENT; goto retry; } }
/* * If kswapd is already active on a node, keep looking * for other nodes that might be idle. This can happen * if another process has NUMA bindings and is causing * kswapd wakeups on only some nodes. Avoid accidental * "node_reclaim_mode"-like behavior in this case. */ if (skip_kswapd_nodes && !waitqueue_active(&zone->zone_pgdat->kswapd_wait)) { skipped_kswapd_nodes = true; continue; }
cond_accept_memory(zone, order, alloc_flags);
/* * Detect whether the number of free pages is below high * watermark. If so, we will decrease pcp->high and free * PCP pages in free path to reduce the possibility of * premature page reclaiming. Detection is done here to * avoid to do that in hotter free path. */ if (test_bit(ZONE_BELOW_HIGH, &zone->flags)) goto check_alloc_wmark;
mark = high_wmark_pages(zone); if (zone_watermark_fast(zone, order, mark, ac->highest_zoneidx, alloc_flags, gfp_mask)) goto try_this_zone; else set_bit(ZONE_BELOW_HIGH, &zone->flags);
check_alloc_wmark: 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 (cond_accept_memory(zone, order, alloc_flags)) goto try_this_zone;
/* * 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; } /* 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(zonelist_zone(ac->preferred_zoneref), 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(zonelist_zone(ac->preferred_zoneref), zone, order, gfp_mask, alloc_flags, ac->migratetype); if (page) { prep_new_page(page, order, gfp_mask, alloc_flags);
return page; } else { if (cond_accept_memory(zone, order, alloc_flags)) goto try_this_zone;
/* Try again if zone has deferred pages */ if (deferred_pages_enabled()) { if (_deferred_grow_zone(zone, order)) goto try_this_zone; } } }
/* * If we skipped over nodes with active kswapds and found no * idle nodes, retry and place anywhere the watermarks permit. */ if (skip_kswapd_nodes && skipped_kswapd_nodes) { skip_kswapd_nodes = false; goto retry; }
/* * 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 && !defrag_mode) { 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)); mem_cgroup_show_protected_memory(NULL);}
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 || *compact_result == COMPACT_DEFERRED) 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 boolshould_compact_retry(gfp_t gfp_mask, 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, gfp_mask); 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;}#elsestatic 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 boolshould_compact_retry(gfp_t gfp_mask, struct alloc_context *ac, 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_LOCKDEPstatic 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; unsigned int reclaim_order;
if (defrag_mode) reclaim_order = max(order, pageblock_order); else reclaim_order = order;
for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, highest_zoneidx, ac->nodemask) { if (!managed_zone(zone)) continue; if (last_pgdat == zone->zone_pgdat) continue; wakeup_kswapd(zone, gfp_mask, reclaim_order, highest_zoneidx); last_pgdat = zone->zone_pgdat; }}
static inline unsigned intgfp_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_MIN_RESERVE)) alloc_flags |= ALLOC_HIGHATOMIC; }
/* * Ignore cpuset mems for non-blocking __GFP_HIGH (probably * GFP_ATOMIC) rather than fail, see the comment for * cpuset_current_node_allowed(). */ if (alloc_flags & ALLOC_MIN_RESERVE) alloc_flags &= ~ALLOC_CPUSET; } else if (unlikely(rt_or_dl_task(current)) && in_task()) alloc_flags |= ALLOC_MIN_RESERVE;
alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, alloc_flags);
if (defrag_mode) alloc_flags |= ALLOC_NOFRAGMENT;
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 boolshould_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)++;
if (*no_progress_loops > MAX_RECLAIM_RETRIES) goto out;
/* * 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;
if (cpusets_enabled() && (alloc_flags & ALLOC_CPUSET) && !__cpuset_zone_allowed(zone, gfp_mask)) continue;
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();out: /* Before OOM, exhaust highatomic_reserve */ if (!ret) return unreserve_highatomic_pageblock(ac, true);
return ret;}
static inline boolcheck_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 void check_alloc_stall_warn(gfp_t gfp_mask, nodemask_t *nodemask, unsigned int order, unsigned long alloc_start_time){ static DEFINE_SPINLOCK(alloc_stall_lock); unsigned long stall_msecs = jiffies_to_msecs(jiffies - alloc_start_time);
if (likely(stall_msecs < ALLOC_STALL_WARN_MSECS)) return; if (time_is_after_jiffies(READ_ONCE(alloc_stall_warn_jiffies))) return; if (gfp_mask & __GFP_NOWARN) return;
if (!spin_trylock(&alloc_stall_lock)) return;
/* Check again, this time under the lock */ if (time_is_after_jiffies(alloc_stall_warn_jiffies)) { spin_unlock(&alloc_stall_lock); return; }
WRITE_ONCE(alloc_stall_warn_jiffies, jiffies + msecs_to_jiffies(ALLOC_STALL_WARN_MSECS)); spin_unlock(&alloc_stall_lock);
pr_warn("%s: page allocation stall for %lu secs: order:%d, mode:%#x(%pGg) nodemask=%*pbl", current->comm, stall_msecs / MSEC_PER_SEC, order, gfp_mask, &gfp_mask, nodemask_pr_args(nodemask)); cpuset_print_current_mems_allowed(); pr_cont("\n"); dump_stack(); warn_alloc_show_mem(gfp_mask, nodemask);}
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; bool can_compact = can_direct_reclaim && gfp_compaction_allowed(gfp_mask); bool nofail = gfp_mask & __GFP_NOFAIL; 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; bool compact_first = false; bool can_retry_reserves = true; unsigned long alloc_start_time = jiffies;
if (unlikely(nofail)) { /* * Also we don't support __GFP_NOFAIL without __GFP_DIRECT_RECLAIM, * otherwise, we may result in lockup. */ WARN_ON_ONCE(!can_direct_reclaim); /* * 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(current->flags & PF_MEMALLOC); }
restart: compaction_retries = 0; no_progress_loops = 0; compact_result = COMPACT_SKIPPED; compact_priority = DEF_COMPACT_PRIORITY; cpuset_mems_cookie = read_mems_allowed_begin(); zonelist_iter_cookie = zonelist_iter_begin();
/* * 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. */ if (can_compact && (costly_order || (order > 0 && ac->migratetype != MIGRATE_MOVABLE))) { compact_first = true; compact_priority = INIT_COMPACT_PRIORITY; }
/* * 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 (!zonelist_zone(ac->preferred_zoneref)) 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 (!zonelist_zone(z)) goto nopage; }
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);
/* * 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;
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);
/* * The first time we adjust anything due to being allowed to * ignore memory policies or watermarks, retry immediately. This * allows us to keep the first allocation attempt optimistic so * it can succeed in a zone that is still above watermarks. */ if (can_retry_reserves) { can_retry_reserves = false; goto retry; } }
/* Caller is not willing to reclaim, we can't balance anything */ if (!can_direct_reclaim) { /* * Reclaim/compaction cannot run, so defrag_mode's strategy * of enforcing ALLOC_NOFRAGMENT cannot be fulfilled. Allow * fallbacks rather than failing the allocation outright. */ if (defrag_mode && (alloc_flags & ALLOC_NOFRAGMENT) && (gfp_mask & __GFP_KSWAPD_RECLAIM)) { alloc_flags &= ~ALLOC_NOFRAGMENT; goto retry; } goto nopage; }
/* Avoid recursion of direct reclaim */ if (current->flags & PF_MEMALLOC) goto nopage;
/* If allocation has taken excessively long, warn about it */ check_alloc_stall_warn(gfp_mask, ac->nodemask, order, alloc_start_time);
/* Try direct reclaim and then allocating */ if (!compact_first) { 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;
if (compact_first) { /* * THP page faults may attempt local node only first, but are * then allowed to only compact, not reclaim, see * alloc_pages_mpol(). * * Compaction has failed above and we don't want such THP * allocations to put reclaim pressure on a single node in a * situation where other nodes might have plenty of available * memory. */ if (gfp_has_flags(gfp_mask, __GFP_NORETRY | __GFP_THISNODE)) goto nopage;
/* * For the initial compaction attempt we have lowered its * priority. Restore it for further retries, if those are * allowed. With __GFP_NORETRY there will be a single round of * reclaim and compaction with the lowered priority. */ if (!(gfp_mask & __GFP_NORETRY)) compact_priority = DEF_COMPACT_PRIORITY;
compact_first = false; goto retry; }
/* 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 and we can compact */ if (costly_order && (!can_compact || !(gfp_mask & __GFP_RETRY_MAYFAIL))) goto nopage;
/* * Deal with possible cpuset update races or zonelist updates to avoid * infinite retries. No "goto retry;" can be placed above this check * unless it can execute just once. */ if (check_retry_cpuset(cpuset_mems_cookie, ac) || check_retry_zonelist(zonelist_iter_cookie)) goto restart;
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 && can_compact && should_compact_retry(gfp_mask, ac, order, alloc_flags, compact_result, &compact_priority, &compaction_retries)) goto retry;
/* Reclaim/compaction failed to prevent the fallback */ if (defrag_mode && (alloc_flags & ALLOC_NOFRAGMENT)) { alloc_flags &= ~ALLOC_NOFRAGMENT; 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 (unlikely(nofail)) { /* * Lacking direct_reclaim we can't do anything to reclaim memory, * we disregard these unreasonable nofail requests and still * return NULL */ if (!can_direct_reclaim) goto fail;
/* * 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);
/* * Don't invoke should_fail logic, since it may call * get_random_u32() and printk() which need to spin_lock. */ if (!(*alloc_flags & ALLOC_TRYLOCK) && 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 an 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 in the array * @page_array: 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_array. * * Note that only the elements in @page_array that were cleared to %NULL on * entry are populated with newly allocated pages. @nr_pages is the maximum * number of pages that will be stored in the array. * * Returns the number of pages in @page_array, including ones already * allocated on entry. This can be less than the number requested in @nr_pages, * but all empty slots are filled from the beginning. I.e., if all slots in * @page_array were set to %NULL on entry, the slots from 0 to the return value * - 1 will be filled. */unsigned long alloc_pages_bulk_noprof(gfp_t gfp, int preferred_nid, nodemask_t *nodemask, int nr_pages, struct page **page_array){ struct page *page; struct zone *zone; struct zoneref *z; struct per_cpu_pages *pcp; struct list_head *pcp_list; struct alloc_context ac; 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 (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(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; if (!prepare_alloc_pages(gfp, 0, preferred_nid, nodemask, &ac, &gfp, &alloc_flags)) goto out;
/* Find an allowed local zone that meets the low watermark. */ z = ac.preferred_zoneref; for_next_zone_zonelist_nodemask(zone, z, 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 != zonelist_zone(ac.preferred_zoneref) && zone_to_nid(zone) != zonelist_node_idx(ac.preferred_zoneref)) { goto failed; }
cond_accept_memory(zone, 0, alloc_flags);retry_this_zone: mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK) + nr_pages - nr_populated; if (zone_watermark_fast(zone, 0, mark, zonelist_zone_idx(ac.preferred_zoneref), alloc_flags, gfp)) { break; }
if (cond_accept_memory(zone, 0, alloc_flags)) goto retry_this_zone;
/* Try again if zone has deferred pages */ if (deferred_pages_enabled()) { if (_deferred_grow_zone(zone, 0)) goto retry_this_zone; } }
/* * 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 = pcp_spin_trylock(zone->per_cpu_pageset); if (!pcp) goto failed;
/* 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[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; } break; } nr_account++;
prep_new_page(page, 0, gfp, 0); set_page_refcounted(page); page_array[nr_populated++] = page; }
pcp_spin_unlock(pcp);
__count_zid_vm_events(PGALLOC, zone_idx(zone), nr_account); zone_statistics(zonelist_zone(ac.preferred_zoneref), zone, nr_account);
out: return nr_populated;
failed: page = __alloc_pages_noprof(gfp, 0, preferred_nid, nodemask); if (page) page_array[nr_populated++] = page; goto out;}EXPORT_SYMBOL_GPL(alloc_pages_bulk_noprof);
/* * free_pages_bulk - Free an array of order-0 pages * @page_array: Array of pages to free * @nr_pages: The number of pages in the array * * Free the order-0 pages. Adjacent entries whose PFNs form a contiguous * run are released with a single __free_contig_range() call. * * This assumes page_array is sorted in ascending PFN order. Without that, * the function still frees all pages, but contiguous runs may not be * detected and the freeing pattern can degrade to freeing one page at a * time. * * Context: Sleepable process context only; calls cond_resched() */void free_pages_bulk(struct page **page_array, unsigned long nr_pages){ while (nr_pages) { unsigned long nr_contig = num_pages_contiguous(page_array, nr_pages);
__free_contig_range(page_to_pfn(*page_array), nr_contig);
nr_pages -= nr_contig; page_array += nr_contig; cond_resched(); }}
/* * This is the 'heart' of the zoned buddy allocator. */struct page *__alloc_frozen_pages_noprof(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_PAGE_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(zonelist_zone(ac.preferred_zoneref), 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_frozen_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_frozen_pages_noprof);
struct page *__alloc_pages_noprof(gfp_t gfp, unsigned int order, int preferred_nid, nodemask_t *nodemask){ struct page *page;
page = __alloc_frozen_pages_noprof(gfp, order, preferred_nid, nodemask); if (page) set_page_refcounted(page); return page;}EXPORT_SYMBOL(__alloc_pages_noprof);
struct folio *__folio_alloc_noprof(gfp_t gfp, unsigned int order, int preferred_nid, nodemask_t *nodemask){ struct page *page = __alloc_pages_noprof(gfp | __GFP_COMP, order, preferred_nid, nodemask); return page_rmappable_folio(page);}EXPORT_SYMBOL(__folio_alloc_noprof);
/* * 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_noprof(gfp_t gfp_mask, unsigned int order){ struct page *page;
page = alloc_pages_noprof(gfp_mask & ~__GFP_HIGHMEM, order); if (!page) return 0; return (unsigned long) page_address(page);}EXPORT_SYMBOL(get_free_pages_noprof);
unsigned long get_zeroed_page_noprof(gfp_t gfp_mask){ return get_free_pages_noprof(gfp_mask | __GFP_ZERO, 0);}EXPORT_SYMBOL(get_zeroed_page_noprof);
static void ___free_pages(struct page *page, unsigned int order, fpi_t fpi_flags){ /* get PageHead before we drop reference */ int head = PageHead(page); /* get alloc tag in case the page is released by others */ struct alloc_tag *tag = pgalloc_tag_get(page);
if (put_page_testzero(page)) __free_frozen_pages(page, order, fpi_flags); else if (!head) { pgalloc_tag_sub_pages(tag, (1 << order) - 1); while (order-- > 0) { /* * The "tail" pages of this non-compound high-order * page will have no code tags, so to avoid warnings * mark them as empty. */ clear_page_tag_ref(page + (1 << order)); __free_frozen_pages(page + (1 << order), order, fpi_flags); } }}
/** * __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){ ___free_pages(page, order, FPI_NONE);}EXPORT_SYMBOL(__free_pages);
/* * Can be called while holding raw_spin_lock or from IRQ and NMI for any * page type (not only those that came from alloc_pages_nolock) */void free_pages_nolock(struct page *page, unsigned int order){ ___free_pages(page, order, FPI_TRYLOCK);}
/** * free_pages - Free pages allocated with __get_free_pages(). * @addr: The virtual address tied to a page returned from __get_free_pages(). * @order: The order of the allocation. * * This function behaves the same as __free_pages(). Use this function * to free pages when you only have a valid virtual address. If you have * the page, call __free_pages() instead. */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);
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(page, 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_PAGE_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_noprof(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_noprof(gfp_mask, order); return make_alloc_exact(addr, order, size);}EXPORT_SYMBOL(alloc_pages_exact_noprof);
/** * 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_noprof(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_noprof(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(const 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, but for memoryless local * node, we should skip it and fall back to other nodes. */ if (!node_isset(node, *used_node_mask) && node_state(node, N_MEMORY)) { 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;}
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 zonelist_node_idx(z);}#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){ struct zoneref *zonerefs; int nr_zones;
zonerefs = pgdat->node_zonelists[ZONELIST_FALLBACK]._zonerefs; nr_zones = build_zonerefs_node(pgdat, 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 1static 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 __initbuild_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, str_off_on(page_group_by_mobility_disabled), 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 ~0.025% * of the zone or 256KB, whichever is smaller. The batch * size is striking a balance between allocation latency * and zone lock contention. */ batch = min(zone_managed_pages(zone) >> 12, SZ_256K / PAGE_SIZE); if (batch <= 1) return 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 1;#endif}
static int percpu_pagelist_high_fraction;static int zone_highsize(struct zone *zone, int batch, int cpu_online, int high_fraction){#ifdef CONFIG_MMU int high; int nr_split_cpus; unsigned long total_pages;
if (!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) / 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 the high value * 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, pcp->high_min and pcp->high_max * 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_min, unsigned long high_max, unsigned long batch){ WRITE_ONCE(pcp->batch, batch); WRITE_ONCE(pcp->high_min, high_min); WRITE_ONCE(pcp->high_max, high_max);}
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_min = BOOT_PAGESET_HIGH; pcp->high_max = BOOT_PAGESET_HIGH; pcp->batch = BOOT_PAGESET_BATCH;}
static void __zone_set_pageset_high_and_batch(struct zone *zone, unsigned long high_min, unsigned long high_max, 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_min, high_max, 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_min, new_high_max, new_batch;
new_batch = zone_batchsize(zone); if (percpu_pagelist_high_fraction) { new_high_min = zone_highsize(zone, new_batch, cpu_online, percpu_pagelist_high_fraction); /* * PCP high is tuned manually, disable auto-tuning via * setting high_min and high_max to the manual value. */ new_high_max = new_high_min; } else { new_high_min = zone_highsize(zone, new_batch, cpu_online, 0); new_high_max = zone_highsize(zone, new_batch, cpu_online, MIN_PERCPU_PAGELIST_HIGH_FRACTION); }
if (zone->pageset_high_min == new_high_min && zone->pageset_high_max == new_high_max && zone->pageset_batch == new_batch) return;
zone->pageset_high_min = new_high_min; zone->pageset_high_max = new_high_max; zone->pageset_batch = new_batch;
__zone_set_pageset_high_and_batch(zone, new_high_min, new_high_max, 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);}
static void zone_pcp_update_cacheinfo(struct zone *zone, unsigned int cpu){ struct per_cpu_pages *pcp; struct cpu_cacheinfo *cci;
pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu); cci = get_cpu_cacheinfo(cpu); /* * If data cache slice of CPU is large enough, "pcp->batch" * pages can be preserved in PCP before draining PCP for * consecutive high-order pages freeing without allocation. * This can reduce zone lock contention without hurting * cache-hot pages sharing. */ pcp_spin_lock_nopin(pcp); if ((cci->per_cpu_data_slice_size >> PAGE_SHIFT) > 3 * pcp->batch) pcp->flags |= PCPF_FREE_HIGH_BATCH; else pcp->flags &= ~PCPF_FREE_HIGH_BATCH; pcp_spin_unlock_nopin(pcp);}
void setup_pcp_cacheinfo(unsigned int cpu){ struct zone *zone;
for_each_populated_zone(zone) zone_pcp_update_cacheinfo(zone, cpu);}
/* * 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_min = BOOT_PAGESET_HIGH; zone->pageset_high_max = 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));}
static void setup_per_zone_lowmem_reserve(void);
void adjust_managed_page_count(struct page *page, long count){ atomic_long_add(count, &page_zone(page)->managed_pages); totalram_pages_add(count); setup_per_zone_lowmem_reserve();}EXPORT_SYMBOL(adjust_managed_page_count);
void free_reserved_page(struct page *page){ clear_page_tag_ref(page); ClearPageReserved(page); init_page_count(page); __free_page(page); adjust_managed_page_count(page, 1);}EXPORT_SYMBOL(free_reserved_page);
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);
/* * lowmem_reserve[j] is monotonically non-decreasing * in j for a given zone (see * setup_per_zone_lowmem_reserve()). The maximum * valid reserve lives at the highest index with a * non-zero value, so scan backwards and stop at the * first hit. */ for (j = MAX_NR_ZONES - 1; j > i; j--) { if (!zone->lowmem_reserve[j]) continue;
max = zone->lowmem_reserve[j]; break; } /* we treat the high watermark as reserved pages. */ max += high_wmark_pages(zone);
max = min_t(unsigned long, max, managed_pages);
pgdat->totalreserve_pages += max;
reserve_pages += max; } } totalreserve_pages = reserve_pages; trace_mm_calculate_totalreserve_pages(totalreserve_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 a given zone node_zones[i], lowmem_reserve[j] (j > i) * represents how many pages in zone i must effectively be kept * in reserve when deciding whether an allocation class that is * allowed to allocate from zones up to j may fall back into * zone i. * * As j increases, the allocation class can use a strictly larger * set of fallback zones and therefore must not be allowed to * deplete low zones more aggressively than a less flexible one. * As a result, lowmem_reserve[j] is required to be monotonically * non-decreasing in j for each zone i. Callers such as * calculate_totalreserve_pages() rely on this monotonicity when * selecting the maximum reserve entry. */ 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; trace_mm_setup_per_zone_lowmem_reserve(zone, upper_zone, zone->lowmem_reserve[j]); } } }
/* 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); tmp = div64_ul(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; trace_mm_setup_per_zone_wmarks(zone);
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_ratelimited("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(const 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(const 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_NUMAstatic 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(const 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_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(const 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_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(const 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(const 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;
/* * Avoid using pcp_batch_high_lock for reads as the value is read * atomically and a race with offlining is harmless. */
if (!write) return proc_dointvec_minmax(table, write, buffer, length, ppos);
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 (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 const 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 = "defrag_mode", .data = &defrag_mode, .maxlen = sizeof(defrag_mode), .mode = 0644, .proc_handler = proc_dointvec_minmax, .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_ONE, }, { .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);}
static void free_prepared_contig_range(struct page *page, unsigned long nr_pages){ unsigned long pfn = page_to_pfn(page);
while (nr_pages) { unsigned int order;
/* We are limited by the largest buddy order. */ order = pfn ? __ffs(pfn) : MAX_PAGE_ORDER; /* Don't exceed the number of pages to free. */ order = min_t(unsigned int, order, ilog2(nr_pages)); order = min_t(unsigned int, order, MAX_PAGE_ORDER);
/* * Free the chunk as a single block. Our caller has already * called free_pages_prepare() for each order-0 page. */ __free_frozen_pages(page, order, FPI_PREPARED);
pfn += 1UL << order; page += 1UL << order; nr_pages -= 1UL << order; }}
static void __free_contig_range_common(unsigned long pfn, unsigned long nr_pages, bool is_frozen){ struct page *page, *start = NULL; unsigned long nr_start = 0; unsigned long start_sec; unsigned long i;
for (i = 0; i < nr_pages; i++) { bool can_free = true;
/* * Contiguous PFNs might not have contiguous "struct pages" * in some kernel configs: page++ across a section boundary * is undefined. Use pfn_to_page() for each PFN. */ page = pfn_to_page(pfn + i);
VM_WARN_ON_ONCE(PageHead(page)); VM_WARN_ON_ONCE(PageTail(page));
if (!is_frozen) can_free = put_page_testzero(page);
if (can_free) can_free = free_pages_prepare(page, 0);
if (!can_free) { if (start) { free_prepared_contig_range(start, i - nr_start); start = NULL; } continue; }
if (start && memdesc_section(page->flags) != start_sec) { free_prepared_contig_range(start, i - nr_start); start = page; nr_start = i; start_sec = memdesc_section(page->flags); } else if (!start) { start = page; nr_start = i; start_sec = memdesc_section(page->flags); } }
if (start) free_prepared_contig_range(start, nr_pages - nr_start);}
/** * __free_contig_range - Free contiguous range of order-0 pages. * @pfn: Page frame number of the first page in the range. * @nr_pages: Number of pages to free. * * For each order-0 struct page in the physically contiguous range, put a * reference. Free any page who's reference count falls to zero. The * implementation is functionally equivalent to, but significantly faster than * calling __free_page() for each struct page in a loop. * * Memory allocated with alloc_pages(order>=1) then subsequently split to * order-0 with split_page() is an example of appropriate contiguous pages that * can be freed with this API. * * 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_contig_range(unsigned long pfn, unsigned long nr_pages){ __free_contig_range_common(pfn, nr_pages, /* is_frozen= */ false);}
#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. */static 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 = cc->gfp_mask, .reason = MR_CONTIG_RANGE, };
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 < 0) ? ret : 0;}
static void split_free_frozen_pages(struct list_head *list, gfp_t gfp_mask){ int order;
for (order = 0; order < NR_PAGE_ORDERS; order++) { struct page *page, *next; int nr_pages = 1 << order;
list_for_each_entry_safe(page, next, &list[order], lru) { int i;
post_alloc_hook(page, order, gfp_mask); if (!order) continue;
__split_page(page, order);
/* Add all subpages to the order-0 head, in sequence. */ list_del(&page->lru); for (i = 0; i < nr_pages; i++) list_add_tail(&page[i].lru, &list[0]); } }}
static int __alloc_contig_verify_gfp_mask(gfp_t gfp_mask, gfp_t *gfp_cc_mask){ const gfp_t reclaim_mask = __GFP_IO | __GFP_FS | __GFP_RECLAIM; const gfp_t action_mask = __GFP_COMP | __GFP_RETRY_MAYFAIL | __GFP_NOWARN | __GFP_ZERO | __GFP_ZEROTAGS | __GFP_SKIP_ZERO | __GFP_SKIP_KASAN; const gfp_t cc_action_mask = __GFP_RETRY_MAYFAIL | __GFP_NOWARN;
/* * We are given the range to allocate; node, mobility and placement * hints are irrelevant at this point. We'll simply ignore them. */ gfp_mask &= ~(GFP_ZONEMASK | __GFP_RECLAIMABLE | __GFP_WRITE | __GFP_HARDWALL | __GFP_THISNODE | __GFP_MOVABLE);
/* * We only support most reclaim flags (but not NOFAIL/NORETRY), and * selected action flags. */ if (gfp_mask & ~(reclaim_mask | action_mask)) return -EINVAL;
/* * Flags to control page compaction/migration/reclaim, to free up our * page range. Migratable pages are movable, __GFP_MOVABLE is implied * for them. * * Traditionally we always had __GFP_RETRY_MAYFAIL set, keep doing that * to not degrade callers. */ *gfp_cc_mask = (gfp_mask & (reclaim_mask | cc_action_mask)) | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL; return 0;}
static void __free_contig_frozen_range(unsigned long pfn, unsigned long nr_pages){ __free_contig_range_common(pfn, nr_pages, /* is_frozen= */ true);}
/** * alloc_contig_frozen_range() -- tries to allocate given range of frozen pages * @start: start PFN to allocate * @end: one-past-the-last PFN to allocate * @alloc_flags: allocation information * @gfp_mask: GFP mask. Node/zone/placement hints are ignored; only some * action and reclaim modifiers are supported. Reclaim modifiers * control allocation behavior during compaction/migration/reclaim. * * 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. * * All frozen pages which PFN is in [start, end) are allocated for the * caller, and they could be freed with free_contig_frozen_range(), * free_frozen_pages() also could be used to free compound frozen pages * directly. * * Return: zero on success or negative error code. */int alloc_contig_frozen_range_noprof(unsigned long start, unsigned long end, acr_flags_t alloc_flags, gfp_t gfp_mask){ const unsigned int order = ilog2(end - start); unsigned long outer_start, outer_end; 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, .alloc_contig = true, }; INIT_LIST_HEAD(&cc.migratepages); enum pb_isolate_mode mode = (alloc_flags & ACR_FLAGS_CMA) ? PB_ISOLATE_MODE_CMA_ALLOC : PB_ISOLATE_MODE_OTHER;
/* * In contrast to the buddy, we allow for orders here that exceed * MAX_PAGE_ORDER, so we must manually make sure that we are not * exceeding the maximum folio order. */ if (WARN_ON_ONCE((gfp_mask & __GFP_COMP) && order > MAX_FOLIO_ORDER)) return -EINVAL;
gfp_mask = current_gfp_context(gfp_mask); if (__alloc_contig_verify_gfp_mask(gfp_mask, (gfp_t *)&cc.gfp_mask)) return -EINVAL;
/* * 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, mode); 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;
/* * When in-use hugetlb pages are migrated, they may simply be released * back into the free hugepage pool instead of being returned to the * buddy system. After the migration of in-use huge pages is completed, * we will invoke replace_free_hugepage_folios() to ensure that these * hugepages are properly released to the buddy system. */ ret = replace_free_hugepage_folios(start, end); if (ret) goto done;
/* * 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. */ outer_start = find_large_buddy(start);
/* Make sure the range is really isolated. */ if (test_pages_isolated(outer_start, end, mode)) { 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; }
if (!(gfp_mask & __GFP_COMP)) { split_free_frozen_pages(cc.freepages, gfp_mask);
/* Free head and tail (if any) */ if (start != outer_start) __free_contig_frozen_range(outer_start, start - outer_start); if (end != outer_end) __free_contig_frozen_range(end, outer_end - end); } else if (start == outer_start && end == outer_end && is_power_of_2(end - start)) { struct page *head = pfn_to_page(start);
check_new_pages(head, order); prep_new_page(head, order, gfp_mask, 0); } else { ret = -EINVAL; WARN(true, "PFN range: requested [%lu, %lu), allocated [%lu, %lu)\n", start, end, outer_start, outer_end); }done: undo_isolate_page_range(start, end); return ret;}EXPORT_SYMBOL(alloc_contig_frozen_range_noprof);
/** * alloc_contig_range() -- tries to allocate given range of pages * @start: start PFN to allocate * @end: one-past-the-last PFN to allocate * @alloc_flags: allocation information * @gfp_mask: GFP mask. * * This routine is a wrapper around alloc_contig_frozen_range(), it can't * be used to allocate compound pages, the refcount of each allocated page * will be set to one. * * All pages which PFN is in [start, end) are allocated for the caller, * and should be freed with free_contig_range() or by manually calling * __free_page() on each allocated page. * * Return: zero on success or negative error code. */int alloc_contig_range_noprof(unsigned long start, unsigned long end, acr_flags_t alloc_flags, gfp_t gfp_mask){ int ret;
if (WARN_ON(gfp_mask & __GFP_COMP)) return -EINVAL;
ret = alloc_contig_frozen_range_noprof(start, end, alloc_flags, gfp_mask); if (!ret) set_pages_refcounted(pfn_to_page(start), end - start);
return ret;}EXPORT_SYMBOL(alloc_contig_range_noprof);
static bool pfn_range_valid_contig(struct zone *z, unsigned long start_pfn, unsigned long nr_pages, bool skip_hugetlb, bool *skipped_hugetlb){ unsigned long end_pfn = start_pfn + nr_pages; struct page *page;
while (start_pfn < end_pfn) { unsigned long step = 1;
page = pfn_to_online_page(start_pfn); if (!page) return false;
if (page_zone(page) != z) return false;
if (page_is_unmovable(z, page, PB_ISOLATE_MODE_OTHER, &step)) return false;
/* * Only consider ranges containing hugepages if those pages are * smaller than the requested contiguous region. e.g.: * Move 2MB pages to free up a 1GB range. * Don't move 1GB pages to free up a 2MB range. * * This makes contiguous allocation more reliable if multiple * hugepage sizes are used without causing needless movement. */ if (PageHuge(page)) { unsigned int order;
if (skip_hugetlb) { *skipped_hugetlb = true; return false; }
page = compound_head(page); order = compound_order(page); if ((order >= MAX_FOLIO_ORDER) || (nr_pages <= (1 << order))) return false; }
start_pfn += step; } 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_frozen_pages() -- tries to find and allocate contiguous range of frozen pages * @nr_pages: Number of contiguous pages to allocate * @gfp_mask: GFP mask. Node/zone/placement hints limit the search; only some * action and reclaim modifiers are supported. Reclaim modifiers * control allocation behavior during compaction/migration/reclaim. * @nid: Target node * @nodemask: Mask for other possible nodes * * This routine is a wrapper around alloc_contig_frozen_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_frozen_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 frozen pages need be freed with free_contig_frozen_range(), * or by manually calling free_frozen_pages() on each allocated frozen * non-compound page, for compound frozen pages could be freed with * free_frozen_pages() directly. * * Return: pointer to contiguous frozen pages on success, or NULL if not successful. */struct page *alloc_contig_frozen_pages_noprof(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; bool skip_hugetlb = true; bool skipped_hugetlb = false;
retry: 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, skip_hugetlb, &skipped_hugetlb)) { /* * We release the zone lock here because * alloc_contig_frozen_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 allocation to fail. */ spin_unlock_irqrestore(&zone->lock, flags); ret = alloc_contig_frozen_range_noprof(pfn, pfn + nr_pages, ACR_FLAGS_NONE, gfp_mask); if (!ret) return pfn_to_page(pfn); spin_lock_irqsave(&zone->lock, flags); } pfn += nr_pages; } spin_unlock_irqrestore(&zone->lock, flags); } /* * If we failed, retry the search, but treat regions with HugeTLB pages * as valid targets. This retains fast-allocations on first pass * without trying to migrate HugeTLB pages (which may fail). On the * second pass, we will try moving HugeTLB pages when those pages are * smaller than the requested contiguous region size. */ if (skip_hugetlb && skipped_hugetlb) { skip_hugetlb = false; goto retry; } return NULL;}EXPORT_SYMBOL(alloc_contig_frozen_pages_noprof);
/** * alloc_contig_pages() -- tries to find and allocate contiguous range of pages * @nr_pages: Number of contiguous pages to allocate * @gfp_mask: GFP mask. * @nid: Target node * @nodemask: Mask for other possible nodes * * This routine is a wrapper around alloc_contig_frozen_pages(), it can't * be used to allocate compound pages, the refcount of each allocated page * will be set to one. * * 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_noprof(unsigned long nr_pages, gfp_t gfp_mask, int nid, nodemask_t *nodemask){ struct page *page;
if (WARN_ON(gfp_mask & __GFP_COMP)) return NULL;
page = alloc_contig_frozen_pages_noprof(nr_pages, gfp_mask, nid, nodemask); if (page) set_pages_refcounted(page, nr_pages);
return page;}EXPORT_SYMBOL(alloc_contig_pages_noprof);
/** * free_contig_frozen_range() -- free the contiguous range of frozen pages * @pfn: start PFN to free * @nr_pages: Number of contiguous frozen pages to free * * This can be used to free the allocated compound/non-compound frozen pages. */void free_contig_frozen_range(unsigned long pfn, unsigned long nr_pages){ struct page *first_page = pfn_to_page(pfn); const unsigned int order = ilog2(nr_pages);
if (WARN_ON_ONCE(first_page != compound_head(first_page))) return;
if (PageHead(first_page)) { WARN_ON_ONCE(order != compound_order(first_page)); free_frozen_pages(first_page, order); return; }
__free_contig_frozen_range(pfn, nr_pages);}EXPORT_SYMBOL(free_contig_frozen_range);
/** * free_contig_range() -- free the contiguous range of pages * @pfn: start PFN to free * @nr_pages: Number of contiguous pages to free * * This can be only used to free the allocated non-compound pages. */void free_contig_range(unsigned long pfn, unsigned long nr_pages){ if (WARN_ON_ONCE(PageHead(pfn_to_page(pfn)))) return;
__free_contig_range(pfn, nr_pages);}EXPORT_SYMBOL(free_contig_range);#endif /* CONFIG_CONTIG_ALLOC */
/* * 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, 0, 1); __drain_all_pages(zone, true);}
void zone_pcp_enable(struct zone *zone){ __zone_set_pageset_high_and_batch(zone, zone->pageset_high_min, zone->pageset_high_max, 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. * * Returns the number of managed (non-PageOffline()) pages in the range: the * number of pages for which memory offlining code must adjust managed page * counters using adjust_managed_page_count(). */unsigned long __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn){ unsigned long already_offline = 0; unsigned long pfn = start_pfn; struct page *page; struct zone *zone; unsigned int order;
offline_mem_sections(pfn, end_pfn); zone = page_zone(pfn_to_page(pfn)); guard(spinlock_irqsave)(&zone->lock); 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)); already_offline++; pfn++; continue; }
BUG_ON(page_count(page)); BUG_ON(!PageBuddy(page)); VM_WARN_ON(get_pageblock_migratetype(page) != MIGRATE_ISOLATE); order = buddy_order(page); del_page_from_free_list(page, zone, order, MIGRATE_ISOLATE); pfn += (1 << order); }
return end_pfn - start_pfn - already_offline;}#endif
/* * This function returns a stable result only if called under zone lock. */bool is_free_buddy_page(const struct page *page){ unsigned long pfn = page_to_pfn(page); unsigned int order;
for (order = 0; order < NR_PAGE_ORDERS; order++) { const struct page *head = page - (pfn & ((1 << order) - 1));
if (PageBuddy(head) && buddy_order_unsafe(head) >= order) break; }
return order <= MAX_PAGE_ORDER;}EXPORT_SYMBOL(is_free_buddy_page);
#ifdef CONFIG_MEMORY_FAILUREstatic inline void add_to_free_list(struct page *page, struct zone *zone, unsigned int order, int migratetype, bool tail){ __add_to_free_list(page, zone, order, migratetype, tail); account_freepages(zone, 1 << order, migratetype);}
/* * 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;
while (high > low) { high--; size >>= 1;
if (target >= &page[size]) { current_buddy = page; page = page + size; } else { current_buddy = page + size; }
if (set_page_guard(zone, current_buddy, high)) continue;
add_to_free_list(current_buddy, zone, high, migratetype, false); set_buddy_order(current_buddy, high); }}
/* * 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 int order;
guard(spinlock_irqsave)(&zone->lock); for (order = 0; order < NR_PAGE_ORDERS; 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, migratetype); break_down_buddy_pages(zone, page_head, page, 0, page_order, migratetype); SetPageHWPoisonTakenOff(page); return true; } if (page_count(page_head) > 0) break; } return false;}
/* * Cancel takeoff done by take_page_off_buddy(). */bool put_page_back_buddy(struct page *page){ struct zone *zone = page_zone(page);
guard(spinlock_irqsave)(&zone->lock); if (put_page_testzero(page)) { unsigned long pfn = page_to_pfn(page); int migratetype = get_pfnblock_migratetype(page, pfn);
ClearPageHWPoisonTakenOff(page); __free_one_page(page, pfn, zone, 0, migratetype, FPI_NONE); if (TestClearPageHWPoison(page)) return true; }
return false;}#endif
bool has_managed_zone(enum zone_type zone){ struct pglist_data *pgdat;
for_each_online_pgdat(pgdat) { if (managed_zone(&pgdat->node_zones[zone])) return true; } return false;}
#ifdef CONFIG_UNACCEPTED_MEMORY
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);
return range_contains_unaccepted_memory(start, PAGE_SIZE << order);}
static void __accept_page(struct zone *zone, unsigned long *flags, struct page *page){ list_del(&page->lru); account_freepages(zone, -MAX_ORDER_NR_PAGES, MIGRATE_MOVABLE); __mod_zone_page_state(zone, NR_UNACCEPTED, -MAX_ORDER_NR_PAGES); __ClearPageUnaccepted(page); spin_unlock_irqrestore(&zone->lock, *flags);
accept_memory(page_to_phys(page), PAGE_SIZE << MAX_PAGE_ORDER);
__free_pages_ok(page, MAX_PAGE_ORDER, FPI_TO_TAIL);}
void accept_page(struct page *page){ struct zone *zone = page_zone(page); unsigned long flags;
spin_lock_irqsave(&zone->lock, flags); if (!PageUnaccepted(page)) { spin_unlock_irqrestore(&zone->lock, flags); return; }
/* Unlocks zone->lock */ __accept_page(zone, &flags, page);}
static bool try_to_accept_memory_one(struct zone *zone){ unsigned long flags; struct page *page;
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; }
/* Unlocks zone->lock */ __accept_page(zone, &flags, page);
return true;}
static bool cond_accept_memory(struct zone *zone, unsigned int order, int alloc_flags){ long to_accept, wmark; bool ret = false;
if (list_empty(&zone->unaccepted_pages)) return false;
/* Bailout, since try_to_accept_memory_one() needs to take a lock */ if (alloc_flags & ALLOC_TRYLOCK) return false;
wmark = promo_wmark_pages(zone);
/* * Watermarks have not been initialized yet. * * Accepting one MAX_ORDER page to ensure progress. */ if (!wmark) return try_to_accept_memory_one(zone);
/* How much to accept to get to promo watermark? */ to_accept = wmark - (zone_page_state(zone, NR_FREE_PAGES) - __zone_watermark_unusable_free(zone, order, 0) - zone_page_state(zone, NR_UNACCEPTED));
while (to_accept > 0) { if (!try_to_accept_memory_one(zone)) break; ret = true; to_accept -= MAX_ORDER_NR_PAGES; }
return ret;}
static bool __free_unaccepted(struct page *page){ struct zone *zone = page_zone(page); unsigned long flags;
if (!lazy_accept) return false;
spin_lock_irqsave(&zone->lock, flags); list_add_tail(&page->lru, &zone->unaccepted_pages); account_freepages(zone, MAX_ORDER_NR_PAGES, MIGRATE_MOVABLE); __mod_zone_page_state(zone, NR_UNACCEPTED, MAX_ORDER_NR_PAGES); __SetPageUnaccepted(page); spin_unlock_irqrestore(&zone->lock, flags);
return true;}
#else
static bool page_contains_unaccepted(struct page *page, unsigned int order){ return false;}
static bool cond_accept_memory(struct zone *zone, unsigned int order, int alloc_flags){ return false;}
static bool __free_unaccepted(struct page *page){ BUILD_BUG(); return false;}
#endif /* CONFIG_UNACCEPTED_MEMORY */
struct page *alloc_frozen_pages_nolock_noprof(gfp_t gfp_flags, int nid, unsigned int order){ /* * Do not specify __GFP_DIRECT_RECLAIM, since direct claim is not allowed. * Do not specify __GFP_KSWAPD_RECLAIM either, since wake up of kswapd * is not safe in arbitrary context. * * These two are the conditions for gfpflags_allow_spinning() being true. * * Specify __GFP_NOWARN since failing alloc_pages_nolock() is not a reason * to warn. Also warn would trigger printk() which is unsafe from * various contexts. We cannot use printk_deferred_enter() to mitigate, * since the running context is unknown. * * Specify __GFP_ZERO to make sure that call to kmsan_alloc_page() below * is safe in any context. Also zeroing the page is mandatory for * BPF use cases. * * Though __GFP_NOMEMALLOC is not checked in the code path below, * specify it here to highlight that alloc_pages_nolock() * doesn't want to deplete reserves. */ gfp_t alloc_gfp = __GFP_NOWARN | __GFP_ZERO | __GFP_NOMEMALLOC | __GFP_COMP | gfp_flags; unsigned int alloc_flags = ALLOC_TRYLOCK; struct alloc_context ac = { }; struct page *page;
VM_WARN_ON_ONCE(gfp_flags & ~__GFP_ACCOUNT); /* * In PREEMPT_RT spin_trylock() will call raw_spin_lock() which is * unsafe in NMI. If spin_trylock() is called from hard IRQ the current * task may be waiting for one rt_spin_lock, but rt_spin_trylock() will * mark the task as the owner of another rt_spin_lock which will * confuse PI logic, so return immediately if called from hard IRQ or * NMI. * * Note, irqs_disabled() case is ok. This function can be called * from raw_spin_lock_irqsave region. */ if (IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq())) return NULL;
/* On UP, spin_trylock() always succeeds even when it is locked */ if (!IS_ENABLED(CONFIG_SMP) && in_nmi()) return NULL;
if (!pcp_allowed_order(order)) return NULL;
/* Bailout, since _deferred_grow_zone() needs to take a lock */ if (deferred_pages_enabled()) return NULL;
if (nid == NUMA_NO_NODE) nid = numa_node_id();
prepare_alloc_pages(alloc_gfp, order, nid, NULL, &ac, &alloc_gfp, &alloc_flags);
/* * Best effort allocation from percpu free list. * If it's empty attempt to spin_trylock zone->lock. */ page = get_page_from_freelist(alloc_gfp, order, alloc_flags, &ac);
/* Unlike regular alloc_pages() there is no __alloc_pages_slowpath(). */
if (memcg_kmem_online() && page && (gfp_flags & __GFP_ACCOUNT) && unlikely(__memcg_kmem_charge_page(page, alloc_gfp, order) != 0)) { __free_frozen_pages(page, order, FPI_TRYLOCK); page = NULL; } trace_mm_page_alloc(page, order, alloc_gfp, ac.migratetype); kmsan_alloc_page(page, order, alloc_gfp); return page;}/** * alloc_pages_nolock - opportunistic reentrant allocation from any context * @gfp_flags: GFP flags. Only __GFP_ACCOUNT allowed. * @nid: node to allocate from * @order: allocation order size * * Allocates pages of a given order from the given node. This is safe to * call from any context where RCU is watching (from atomic, NMI, and also * reentrant allocator -> tracepoint -> alloc_pages_nolock_noprof). * Allocation is best effort and to be expected to fail easily so nobody should * rely on the success. Failures are not reported via warn_alloc(). * See always fail conditions below. * * Return: allocated page or NULL on failure. NULL does not mean EBUSY or EAGAIN. * It means ENOMEM. There is no reason to call it again and expect !NULL. */struct page *alloc_pages_nolock_noprof(gfp_t gfp_flags, int nid, unsigned int order){ struct page *page;
page = alloc_frozen_pages_nolock_noprof(gfp_flags, nid, order); if (page) set_page_refcounted(page); return page;}EXPORT_SYMBOL_GPL(alloc_pages_nolock_noprof);