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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /mm/page_alloc.c
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c6712
1 files changed, 6712 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
new file mode 100644
index 0000000000..afed33fd87
--- /dev/null
+++ b/mm/page_alloc.c
@@ -0,0 +1,6712 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/mm/page_alloc.c
+ *
+ * Manages the free list, the system allocates free pages here.
+ * Note that kmalloc() lives in slab.c
+ *
+ * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
+ * Swap reorganised 29.12.95, Stephen Tweedie
+ * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
+ * Reshaped it to be a zoned allocator, Ingo Molnar, Red Hat, 1999
+ * Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
+ * Zone balancing, Kanoj Sarcar, SGI, Jan 2000
+ * Per cpu hot/cold page lists, bulk allocation, Martin J. Bligh, Sept 2002
+ * (lots of bits borrowed from Ingo Molnar & Andrew Morton)
+ */
+
+#include <linux/stddef.h>
+#include <linux/mm.h>
+#include <linux/highmem.h>
+#include <linux/interrupt.h>
+#include <linux/jiffies.h>
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/kasan.h>
+#include <linux/kmsan.h>
+#include <linux/module.h>
+#include <linux/suspend.h>
+#include <linux/ratelimit.h>
+#include <linux/oom.h>
+#include <linux/topology.h>
+#include <linux/sysctl.h>
+#include <linux/cpu.h>
+#include <linux/cpuset.h>
+#include <linux/memory_hotplug.h>
+#include <linux/nodemask.h>
+#include <linux/vmstat.h>
+#include <linux/fault-inject.h>
+#include <linux/compaction.h>
+#include <trace/events/kmem.h>
+#include <trace/events/oom.h>
+#include <linux/prefetch.h>
+#include <linux/mm_inline.h>
+#include <linux/mmu_notifier.h>
+#include <linux/migrate.h>
+#include <linux/sched/mm.h>
+#include <linux/page_owner.h>
+#include <linux/page_table_check.h>
+#include <linux/memcontrol.h>
+#include <linux/ftrace.h>
+#include <linux/lockdep.h>
+#include <linux/psi.h>
+#include <linux/khugepaged.h>
+#include <linux/delayacct.h>
+#include <asm/div64.h>
+#include "internal.h"
+#include "shuffle.h"
+#include "page_reporting.h"
+
+/* Free Page Internal flags: for internal, non-pcp variants of free_pages(). */
+typedef int __bitwise fpi_t;
+
+/* No special request */
+#define FPI_NONE ((__force fpi_t)0)
+
+/*
+ * Skip free page reporting notification for the (possibly merged) page.
+ * This does not hinder free page reporting from grabbing the page,
+ * reporting it and marking it "reported" - it only skips notifying
+ * the free page reporting infrastructure about a newly freed page. For
+ * example, used when temporarily pulling a page from a freelist and
+ * putting it back unmodified.
+ */
+#define FPI_SKIP_REPORT_NOTIFY ((__force fpi_t)BIT(0))
+
+/*
+ * Place the (possibly merged) page to the tail of the freelist. Will ignore
+ * page shuffling (relevant code - e.g., memory onlining - is expected to
+ * shuffle the whole zone).
+ *
+ * Note: No code should rely on this flag for correctness - it's purely
+ * to allow for optimizations when handing back either fresh pages
+ * (memory onlining) or untouched pages (page isolation, free page
+ * reporting).
+ */
+#define FPI_TO_TAIL ((__force fpi_t)BIT(1))
+
+/* prevent >1 _updater_ of zone percpu pageset ->high and ->batch fields */
+static DEFINE_MUTEX(pcp_batch_high_lock);
+#define MIN_PERCPU_PAGELIST_HIGH_FRACTION (8)
+
+#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)
+/*
+ * On SMP, spin_trylock is sufficient protection.
+ * On PREEMPT_RT, spin_trylock is equivalent on both SMP and UP.
+ */
+#define pcp_trylock_prepare(flags) do { } while (0)
+#define pcp_trylock_finish(flag) do { } while (0)
+#else
+
+/* UP spin_trylock always succeeds so disable IRQs to prevent re-entrancy. */
+#define pcp_trylock_prepare(flags) local_irq_save(flags)
+#define pcp_trylock_finish(flags) local_irq_restore(flags)
+#endif
+
+/*
+ * Locking a pcp requires a PCP lookup followed by a spinlock. To avoid
+ * a migration causing the wrong PCP to be locked and remote memory being
+ * potentially allocated, pin the task to the CPU for the lookup+lock.
+ * preempt_disable is used on !RT because it is faster than migrate_disable.
+ * migrate_disable is used on RT because otherwise RT spinlock usage is
+ * interfered with and a high priority task cannot preempt the allocator.
+ */
+#ifndef CONFIG_PREEMPT_RT
+#define pcpu_task_pin() preempt_disable()
+#define pcpu_task_unpin() preempt_enable()
+#else
+#define pcpu_task_pin() migrate_disable()
+#define pcpu_task_unpin() migrate_enable()
+#endif
+
+/*
+ * Generic helper to lookup and a per-cpu variable with an embedded spinlock.
+ * Return value should be used with equivalent unlock helper.
+ */
+#define pcpu_spin_lock(type, member, ptr) \
+({ \
+ type *_ret; \
+ pcpu_task_pin(); \
+ _ret = this_cpu_ptr(ptr); \
+ spin_lock(&_ret->member); \
+ _ret; \
+})
+
+#define pcpu_spin_trylock(type, member, ptr) \
+({ \
+ type *_ret; \
+ pcpu_task_pin(); \
+ _ret = this_cpu_ptr(ptr); \
+ if (!spin_trylock(&_ret->member)) { \
+ pcpu_task_unpin(); \
+ _ret = NULL; \
+ } \
+ _ret; \
+})
+
+#define pcpu_spin_unlock(member, ptr) \
+({ \
+ spin_unlock(&ptr->member); \
+ pcpu_task_unpin(); \
+})
+
+/* struct per_cpu_pages specific helpers. */
+#define pcp_spin_lock(ptr) \
+ pcpu_spin_lock(struct per_cpu_pages, lock, ptr)
+
+#define pcp_spin_trylock(ptr) \
+ pcpu_spin_trylock(struct per_cpu_pages, lock, ptr)
+
+#define pcp_spin_unlock(ptr) \
+ pcpu_spin_unlock(lock, ptr)
+
+#ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID
+DEFINE_PER_CPU(int, numa_node);
+EXPORT_PER_CPU_SYMBOL(numa_node);
+#endif
+
+DEFINE_STATIC_KEY_TRUE(vm_numa_stat_key);
+
+#ifdef CONFIG_HAVE_MEMORYLESS_NODES
+/*
+ * N.B., Do NOT reference the '_numa_mem_' per cpu variable directly.
+ * It will not be defined when CONFIG_HAVE_MEMORYLESS_NODES is not defined.
+ * Use the accessor functions set_numa_mem(), numa_mem_id() and cpu_to_mem()
+ * defined in <linux/topology.h>.
+ */
+DEFINE_PER_CPU(int, _numa_mem_); /* Kernel "local memory" node */
+EXPORT_PER_CPU_SYMBOL(_numa_mem_);
+#endif
+
+static DEFINE_MUTEX(pcpu_drain_mutex);
+
+#ifdef CONFIG_GCC_PLUGIN_LATENT_ENTROPY
+volatile unsigned long latent_entropy __latent_entropy;
+EXPORT_SYMBOL(latent_entropy);
+#endif
+
+/*
+ * Array of node states.
+ */
+nodemask_t node_states[NR_NODE_STATES] __read_mostly = {
+ [N_POSSIBLE] = NODE_MASK_ALL,
+ [N_ONLINE] = { { [0] = 1UL } },
+#ifndef CONFIG_NUMA
+ [N_NORMAL_MEMORY] = { { [0] = 1UL } },
+#ifdef CONFIG_HIGHMEM
+ [N_HIGH_MEMORY] = { { [0] = 1UL } },
+#endif
+ [N_MEMORY] = { { [0] = 1UL } },
+ [N_CPU] = { { [0] = 1UL } },
+#endif /* NUMA */
+};
+EXPORT_SYMBOL(node_states);
+
+gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
+
+/*
+ * A cached value of the page's pageblock's migratetype, used when the page is
+ * put on a pcplist. Used to avoid the pageblock migratetype lookup when
+ * freeing from pcplists in most cases, at the cost of possibly becoming stale.
+ * Also the migratetype set in the page does not necessarily match the pcplist
+ * index, e.g. page might have MIGRATE_CMA set but be on a pcplist with any
+ * other index - this ensures that it will be put on the correct CMA freelist.
+ */
+static inline int get_pcppage_migratetype(struct page *page)
+{
+ return page->index;
+}
+
+static inline void set_pcppage_migratetype(struct page *page, int migratetype)
+{
+ page->index = migratetype;
+}
+
+#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
+unsigned int pageblock_order __read_mostly;
+#endif
+
+static void __free_pages_ok(struct page *page, unsigned int order,
+ fpi_t fpi_flags);
+
+/*
+ * results with 256, 32 in the lowmem_reserve sysctl:
+ * 1G machine -> (16M dma, 800M-16M normal, 1G-800M high)
+ * 1G machine -> (16M dma, 784M normal, 224M high)
+ * NORMAL allocation will leave 784M/256 of ram reserved in the ZONE_DMA
+ * HIGHMEM allocation will leave 224M/32 of ram reserved in ZONE_NORMAL
+ * HIGHMEM allocation will leave (224M+784M)/256 of ram reserved in ZONE_DMA
+ *
+ * TBD: should special case ZONE_DMA32 machines here - in those we normally
+ * don't need any ZONE_NORMAL reservation
+ */
+static int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES] = {
+#ifdef CONFIG_ZONE_DMA
+ [ZONE_DMA] = 256,
+#endif
+#ifdef CONFIG_ZONE_DMA32
+ [ZONE_DMA32] = 256,
+#endif
+ [ZONE_NORMAL] = 32,
+#ifdef CONFIG_HIGHMEM
+ [ZONE_HIGHMEM] = 0,
+#endif
+ [ZONE_MOVABLE] = 0,
+};
+
+char * const zone_names[MAX_NR_ZONES] = {
+#ifdef CONFIG_ZONE_DMA
+ "DMA",
+#endif
+#ifdef CONFIG_ZONE_DMA32
+ "DMA32",
+#endif
+ "Normal",
+#ifdef CONFIG_HIGHMEM
+ "HighMem",
+#endif
+ "Movable",
+#ifdef CONFIG_ZONE_DEVICE
+ "Device",
+#endif
+};
+
+const char * const migratetype_names[MIGRATE_TYPES] = {
+ "Unmovable",
+ "Movable",
+ "Reclaimable",
+ "HighAtomic",
+#ifdef CONFIG_CMA
+ "CMA",
+#endif
+#ifdef CONFIG_MEMORY_ISOLATION
+ "Isolate",
+#endif
+};
+
+int min_free_kbytes = 1024;
+int user_min_free_kbytes = -1;
+static int watermark_boost_factor __read_mostly = 15000;
+static int watermark_scale_factor = 10;
+
+/* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
+int movable_zone;
+EXPORT_SYMBOL(movable_zone);
+
+#if MAX_NUMNODES > 1
+unsigned int nr_node_ids __read_mostly = MAX_NUMNODES;
+unsigned int nr_online_nodes __read_mostly = 1;
+EXPORT_SYMBOL(nr_node_ids);
+EXPORT_SYMBOL(nr_online_nodes);
+#endif
+
+static bool page_contains_unaccepted(struct page *page, unsigned int order);
+static void accept_page(struct page *page, unsigned int order);
+static bool try_to_accept_memory(struct zone *zone, unsigned int order);
+static inline bool has_unaccepted_memory(void);
+static bool __free_unaccepted(struct page *page);
+
+int page_group_by_mobility_disabled __read_mostly;
+
+#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
+/*
+ * During boot we initialize deferred pages on-demand, as needed, but once
+ * page_alloc_init_late() has finished, the deferred pages are all initialized,
+ * and we can permanently disable that path.
+ */
+DEFINE_STATIC_KEY_TRUE(deferred_pages);
+
+static inline bool deferred_pages_enabled(void)
+{
+ return static_branch_unlikely(&deferred_pages);
+}
+
+/*
+ * deferred_grow_zone() is __init, but it is called from
+ * get_page_from_freelist() during early boot until deferred_pages permanently
+ * disables this call. This is why we have refdata wrapper to avoid warning,
+ * and to ensure that the function body gets unloaded.
+ */
+static bool __ref
+_deferred_grow_zone(struct zone *zone, unsigned int order)
+{
+ return deferred_grow_zone(zone, order);
+}
+#else
+static inline bool deferred_pages_enabled(void)
+{
+ return false;
+}
+#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
+
+/* Return a pointer to the bitmap storing bits affecting a block of pages */
+static inline unsigned long *get_pageblock_bitmap(const struct page *page,
+ unsigned long pfn)
+{
+#ifdef CONFIG_SPARSEMEM
+ return section_to_usemap(__pfn_to_section(pfn));
+#else
+ return page_zone(page)->pageblock_flags;
+#endif /* CONFIG_SPARSEMEM */
+}
+
+static inline int pfn_to_bitidx(const struct page *page, unsigned long pfn)
+{
+#ifdef CONFIG_SPARSEMEM
+ pfn &= (PAGES_PER_SECTION-1);
+#else
+ pfn = pfn - pageblock_start_pfn(page_zone(page)->zone_start_pfn);
+#endif /* CONFIG_SPARSEMEM */
+ return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
+}
+
+/**
+ * get_pfnblock_flags_mask - Return the requested group of flags for the pageblock_nr_pages block of pages
+ * @page: The page within the block of interest
+ * @pfn: The target page frame number
+ * @mask: mask of bits that the caller is interested in
+ *
+ * Return: pageblock_bits flags
+ */
+unsigned long get_pfnblock_flags_mask(const struct page *page,
+ unsigned long pfn, unsigned long mask)
+{
+ unsigned long *bitmap;
+ unsigned long bitidx, word_bitidx;
+ unsigned long word;
+
+ bitmap = get_pageblock_bitmap(page, pfn);
+ bitidx = pfn_to_bitidx(page, pfn);
+ word_bitidx = bitidx / BITS_PER_LONG;
+ bitidx &= (BITS_PER_LONG-1);
+ /*
+ * This races, without locks, with set_pfnblock_flags_mask(). Ensure
+ * a consistent read of the memory array, so that results, even though
+ * racy, are not corrupted.
+ */
+ word = READ_ONCE(bitmap[word_bitidx]);
+ return (word >> bitidx) & mask;
+}
+
+static __always_inline int get_pfnblock_migratetype(const struct page *page,
+ unsigned long pfn)
+{
+ return get_pfnblock_flags_mask(page, pfn, MIGRATETYPE_MASK);
+}
+
+/**
+ * set_pfnblock_flags_mask - Set the requested group of flags for a pageblock_nr_pages block of pages
+ * @page: The page within the block of interest
+ * @flags: The flags to set
+ * @pfn: The target page frame number
+ * @mask: mask of bits that the caller is interested in
+ */
+void set_pfnblock_flags_mask(struct page *page, unsigned long flags,
+ unsigned long pfn,
+ unsigned long mask)
+{
+ unsigned long *bitmap;
+ unsigned long bitidx, word_bitidx;
+ unsigned long word;
+
+ BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4);
+ BUILD_BUG_ON(MIGRATE_TYPES > (1 << PB_migratetype_bits));
+
+ bitmap = get_pageblock_bitmap(page, pfn);
+ bitidx = pfn_to_bitidx(page, pfn);
+ word_bitidx = bitidx / BITS_PER_LONG;
+ bitidx &= (BITS_PER_LONG-1);
+
+ VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);
+
+ mask <<= bitidx;
+ flags <<= bitidx;
+
+ word = READ_ONCE(bitmap[word_bitidx]);
+ do {
+ } while (!try_cmpxchg(&bitmap[word_bitidx], &word, (word & ~mask) | flags));
+}
+
+void set_pageblock_migratetype(struct page *page, int migratetype)
+{
+ if (unlikely(page_group_by_mobility_disabled &&
+ migratetype < MIGRATE_PCPTYPES))
+ migratetype = MIGRATE_UNMOVABLE;
+
+ set_pfnblock_flags_mask(page, (unsigned long)migratetype,
+ page_to_pfn(page), MIGRATETYPE_MASK);
+}
+
+#ifdef CONFIG_DEBUG_VM
+static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
+{
+ int ret;
+ unsigned seq;
+ unsigned long pfn = page_to_pfn(page);
+ unsigned long sp, start_pfn;
+
+ do {
+ seq = zone_span_seqbegin(zone);
+ start_pfn = zone->zone_start_pfn;
+ sp = zone->spanned_pages;
+ ret = !zone_spans_pfn(zone, pfn);
+ } while (zone_span_seqretry(zone, seq));
+
+ if (ret)
+ pr_err("page 0x%lx outside node %d zone %s [ 0x%lx - 0x%lx ]\n",
+ pfn, zone_to_nid(zone), zone->name,
+ start_pfn, start_pfn + sp);
+
+ return ret;
+}
+
+/*
+ * Temporary debugging check for pages not lying within a given zone.
+ */
+static int __maybe_unused bad_range(struct zone *zone, struct page *page)
+{
+ if (page_outside_zone_boundaries(zone, page))
+ return 1;
+ if (zone != page_zone(page))
+ return 1;
+
+ return 0;
+}
+#else
+static inline int __maybe_unused bad_range(struct zone *zone, struct page *page)
+{
+ return 0;
+}
+#endif
+
+static void bad_page(struct page *page, const char *reason)
+{
+ static unsigned long resume;
+ static unsigned long nr_shown;
+ static unsigned long nr_unshown;
+
+ /*
+ * Allow a burst of 60 reports, then keep quiet for that minute;
+ * or allow a steady drip of one report per second.
+ */
+ if (nr_shown == 60) {
+ if (time_before(jiffies, resume)) {
+ nr_unshown++;
+ goto out;
+ }
+ if (nr_unshown) {
+ pr_alert(
+ "BUG: Bad page state: %lu messages suppressed\n",
+ nr_unshown);
+ nr_unshown = 0;
+ }
+ nr_shown = 0;
+ }
+ if (nr_shown++ == 0)
+ resume = jiffies + 60 * HZ;
+
+ pr_alert("BUG: Bad page state in process %s pfn:%05lx\n",
+ current->comm, page_to_pfn(page));
+ dump_page(page, reason);
+
+ print_modules();
+ dump_stack();
+out:
+ /* Leave bad fields for debug, except PageBuddy could make trouble */
+ page_mapcount_reset(page); /* remove PageBuddy */
+ add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
+}
+
+static inline unsigned int order_to_pindex(int migratetype, int order)
+{
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ if (order > PAGE_ALLOC_COSTLY_ORDER) {
+ VM_BUG_ON(order != pageblock_order);
+ return NR_LOWORDER_PCP_LISTS;
+ }
+#else
+ VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);
+#endif
+
+ return (MIGRATE_PCPTYPES * order) + migratetype;
+}
+
+static inline int pindex_to_order(unsigned int pindex)
+{
+ int order = pindex / MIGRATE_PCPTYPES;
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ if (pindex == NR_LOWORDER_PCP_LISTS)
+ order = pageblock_order;
+#else
+ VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);
+#endif
+
+ return order;
+}
+
+static inline bool pcp_allowed_order(unsigned int order)
+{
+ if (order <= PAGE_ALLOC_COSTLY_ORDER)
+ return true;
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ if (order == pageblock_order)
+ return true;
+#endif
+ return false;
+}
+
+static inline void free_the_page(struct page *page, unsigned int order)
+{
+ if (pcp_allowed_order(order)) /* Via pcp? */
+ free_unref_page(page, order);
+ else
+ __free_pages_ok(page, order, FPI_NONE);
+}
+
+/*
+ * Higher-order pages are called "compound pages". They are structured thusly:
+ *
+ * The first PAGE_SIZE page is called the "head page" and have PG_head set.
+ *
+ * The remaining PAGE_SIZE pages are called "tail pages". PageTail() is encoded
+ * in bit 0 of page->compound_head. The rest of bits is pointer to head page.
+ *
+ * The first tail page's ->compound_order holds the order of allocation.
+ * This usage means that zero-order pages may not be compound.
+ */
+
+void prep_compound_page(struct page *page, unsigned int order)
+{
+ int i;
+ int nr_pages = 1 << order;
+
+ __SetPageHead(page);
+ for (i = 1; i < nr_pages; i++)
+ prep_compound_tail(page, i);
+
+ prep_compound_head(page, order);
+}
+
+void destroy_large_folio(struct folio *folio)
+{
+ if (folio_test_hugetlb(folio)) {
+ free_huge_folio(folio);
+ return;
+ }
+
+ if (folio_test_large_rmappable(folio))
+ folio_undo_large_rmappable(folio);
+
+ mem_cgroup_uncharge(folio);
+ free_the_page(&folio->page, folio_order(folio));
+}
+
+static inline void set_buddy_order(struct page *page, unsigned int order)
+{
+ set_page_private(page, order);
+ __SetPageBuddy(page);
+}
+
+#ifdef CONFIG_COMPACTION
+static inline struct capture_control *task_capc(struct zone *zone)
+{
+ struct capture_control *capc = current->capture_control;
+
+ return unlikely(capc) &&
+ !(current->flags & PF_KTHREAD) &&
+ !capc->page &&
+ capc->cc->zone == zone ? capc : NULL;
+}
+
+static inline bool
+compaction_capture(struct capture_control *capc, struct page *page,
+ int order, int migratetype)
+{
+ if (!capc || order != capc->cc->order)
+ return false;
+
+ /* Do not accidentally pollute CMA or isolated regions*/
+ if (is_migrate_cma(migratetype) ||
+ is_migrate_isolate(migratetype))
+ return false;
+
+ /*
+ * Do not let lower order allocations pollute a movable pageblock.
+ * This might let an unmovable request use a reclaimable pageblock
+ * and vice-versa but no more than normal fallback logic which can
+ * have trouble finding a high-order free page.
+ */
+ if (order < pageblock_order && migratetype == MIGRATE_MOVABLE)
+ return false;
+
+ capc->page = page;
+ return true;
+}
+
+#else
+static inline struct capture_control *task_capc(struct zone *zone)
+{
+ return NULL;
+}
+
+static inline bool
+compaction_capture(struct capture_control *capc, struct page *page,
+ int order, int migratetype)
+{
+ return false;
+}
+#endif /* CONFIG_COMPACTION */
+
+/* Used for pages not on another list */
+static inline void add_to_free_list(struct page *page, struct zone *zone,
+ unsigned int order, int migratetype)
+{
+ struct free_area *area = &zone->free_area[order];
+
+ list_add(&page->buddy_list, &area->free_list[migratetype]);
+ area->nr_free++;
+}
+
+/* Used for pages not on another list */
+static inline void add_to_free_list_tail(struct page *page, struct zone *zone,
+ unsigned int order, int migratetype)
+{
+ struct free_area *area = &zone->free_area[order];
+
+ list_add_tail(&page->buddy_list, &area->free_list[migratetype]);
+ area->nr_free++;
+}
+
+/*
+ * Used for pages which are on another list. Move the pages to the tail
+ * of the list - so the moved pages won't immediately be considered for
+ * allocation again (e.g., optimization for memory onlining).
+ */
+static inline void move_to_free_list(struct page *page, struct zone *zone,
+ unsigned int order, int migratetype)
+{
+ struct free_area *area = &zone->free_area[order];
+
+ list_move_tail(&page->buddy_list, &area->free_list[migratetype]);
+}
+
+static inline void del_page_from_free_list(struct page *page, struct zone *zone,
+ unsigned int order)
+{
+ /* clear reported state and update reported page count */
+ if (page_reported(page))
+ __ClearPageReported(page);
+
+ list_del(&page->buddy_list);
+ __ClearPageBuddy(page);
+ set_page_private(page, 0);
+ zone->free_area[order].nr_free--;
+}
+
+static inline struct page *get_page_from_free_area(struct free_area *area,
+ int migratetype)
+{
+ return list_first_entry_or_null(&area->free_list[migratetype],
+ struct page, buddy_list);
+}
+
+/*
+ * If this is not the largest possible page, check if the buddy
+ * of the next-highest order is free. If it is, it's possible
+ * that pages are being freed that will coalesce soon. In case,
+ * that is happening, add the free page to the tail of the list
+ * so it's less likely to be used soon and more likely to be merged
+ * as a higher order page
+ */
+static inline bool
+buddy_merge_likely(unsigned long pfn, unsigned long buddy_pfn,
+ struct page *page, unsigned int order)
+{
+ unsigned long higher_page_pfn;
+ struct page *higher_page;
+
+ if (order >= MAX_ORDER - 1)
+ return false;
+
+ higher_page_pfn = buddy_pfn & pfn;
+ higher_page = page + (higher_page_pfn - pfn);
+
+ return find_buddy_page_pfn(higher_page, higher_page_pfn, order + 1,
+ NULL) != NULL;
+}
+
+/*
+ * Freeing function for a buddy system allocator.
+ *
+ * The concept of a buddy system is to maintain direct-mapped table
+ * (containing bit values) for memory blocks of various "orders".
+ * The bottom level table contains the map for the smallest allocatable
+ * units of memory (here, pages), and each level above it describes
+ * pairs of units from the levels below, hence, "buddies".
+ * At a high level, all that happens here is marking the table entry
+ * at the bottom level available, and propagating the changes upward
+ * as necessary, plus some accounting needed to play nicely with other
+ * parts of the VM system.
+ * At each level, we keep a list of pages, which are heads of continuous
+ * free pages of length of (1 << order) and marked with PageBuddy.
+ * Page's order is recorded in page_private(page) field.
+ * So when we are allocating or freeing one, we can derive the state of the
+ * other. That is, if we allocate a small block, and both were
+ * free, the remainder of the region must be split into blocks.
+ * If a block is freed, and its buddy is also free, then this
+ * triggers coalescing into a block of larger size.
+ *
+ * -- nyc
+ */
+
+static inline void __free_one_page(struct page *page,
+ unsigned long pfn,
+ struct zone *zone, unsigned int order,
+ int migratetype, fpi_t fpi_flags)
+{
+ struct capture_control *capc = task_capc(zone);
+ unsigned long buddy_pfn = 0;
+ unsigned long combined_pfn;
+ struct page *buddy;
+ bool to_tail;
+
+ VM_BUG_ON(!zone_is_initialized(zone));
+ VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP, page);
+
+ VM_BUG_ON(migratetype == -1);
+ if (likely(!is_migrate_isolate(migratetype)))
+ __mod_zone_freepage_state(zone, 1 << order, migratetype);
+
+ VM_BUG_ON_PAGE(pfn & ((1 << order) - 1), page);
+ VM_BUG_ON_PAGE(bad_range(zone, page), page);
+
+ while (order < MAX_ORDER) {
+ if (compaction_capture(capc, page, order, migratetype)) {
+ __mod_zone_freepage_state(zone, -(1 << order),
+ migratetype);
+ return;
+ }
+
+ buddy = find_buddy_page_pfn(page, pfn, order, &buddy_pfn);
+ if (!buddy)
+ goto done_merging;
+
+ if (unlikely(order >= pageblock_order)) {
+ /*
+ * We want to prevent merge between freepages on pageblock
+ * without fallbacks and normal pageblock. Without this,
+ * pageblock isolation could cause incorrect freepage or CMA
+ * accounting or HIGHATOMIC accounting.
+ */
+ int buddy_mt = get_pfnblock_migratetype(buddy, buddy_pfn);
+
+ if (migratetype != buddy_mt
+ && (!migratetype_is_mergeable(migratetype) ||
+ !migratetype_is_mergeable(buddy_mt)))
+ goto done_merging;
+ }
+
+ /*
+ * Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page,
+ * merge with it and move up one order.
+ */
+ if (page_is_guard(buddy))
+ clear_page_guard(zone, buddy, order, migratetype);
+ else
+ del_page_from_free_list(buddy, zone, order);
+ combined_pfn = buddy_pfn & pfn;
+ page = page + (combined_pfn - pfn);
+ pfn = combined_pfn;
+ order++;
+ }
+
+done_merging:
+ set_buddy_order(page, order);
+
+ if (fpi_flags & FPI_TO_TAIL)
+ to_tail = true;
+ else if (is_shuffle_order(order))
+ to_tail = shuffle_pick_tail();
+ else
+ to_tail = buddy_merge_likely(pfn, buddy_pfn, page, order);
+
+ if (to_tail)
+ add_to_free_list_tail(page, zone, order, migratetype);
+ else
+ add_to_free_list(page, zone, order, migratetype);
+
+ /* Notify page reporting subsystem of freed page */
+ if (!(fpi_flags & FPI_SKIP_REPORT_NOTIFY))
+ page_reporting_notify_free(order);
+}
+
+/**
+ * split_free_page() -- split a free page at split_pfn_offset
+ * @free_page: the original free page
+ * @order: the order of the page
+ * @split_pfn_offset: split offset within the page
+ *
+ * Return -ENOENT if the free page is changed, otherwise 0
+ *
+ * It is used when the free page crosses two pageblocks with different migratetypes
+ * at split_pfn_offset within the page. The split free page will be put into
+ * separate migratetype lists afterwards. Otherwise, the function achieves
+ * nothing.
+ */
+int split_free_page(struct page *free_page,
+ unsigned int order, unsigned long split_pfn_offset)
+{
+ struct zone *zone = page_zone(free_page);
+ unsigned long free_page_pfn = page_to_pfn(free_page);
+ unsigned long pfn;
+ unsigned long flags;
+ int free_page_order;
+ int mt;
+ int ret = 0;
+
+ if (split_pfn_offset == 0)
+ return ret;
+
+ spin_lock_irqsave(&zone->lock, flags);
+
+ if (!PageBuddy(free_page) || buddy_order(free_page) != order) {
+ ret = -ENOENT;
+ goto out;
+ }
+
+ mt = get_pfnblock_migratetype(free_page, free_page_pfn);
+ if (likely(!is_migrate_isolate(mt)))
+ __mod_zone_freepage_state(zone, -(1UL << order), mt);
+
+ del_page_from_free_list(free_page, zone, order);
+ for (pfn = free_page_pfn;
+ pfn < free_page_pfn + (1UL << order);) {
+ int mt = get_pfnblock_migratetype(pfn_to_page(pfn), pfn);
+
+ free_page_order = min_t(unsigned int,
+ pfn ? __ffs(pfn) : order,
+ __fls(split_pfn_offset));
+ __free_one_page(pfn_to_page(pfn), pfn, zone, free_page_order,
+ mt, FPI_NONE);
+ pfn += 1UL << free_page_order;
+ split_pfn_offset -= (1UL << free_page_order);
+ /* we have done the first part, now switch to second part */
+ if (split_pfn_offset == 0)
+ split_pfn_offset = (1UL << order) - (pfn - free_page_pfn);
+ }
+out:
+ spin_unlock_irqrestore(&zone->lock, flags);
+ return ret;
+}
+/*
+ * A bad page could be due to a number of fields. Instead of multiple branches,
+ * try and check multiple fields with one check. The caller must do a detailed
+ * check if necessary.
+ */
+static inline bool page_expected_state(struct page *page,
+ unsigned long check_flags)
+{
+ if (unlikely(atomic_read(&page->_mapcount) != -1))
+ return false;
+
+ if (unlikely((unsigned long)page->mapping |
+ page_ref_count(page) |
+#ifdef CONFIG_MEMCG
+ page->memcg_data |
+#endif
+ (page->flags & check_flags)))
+ return false;
+
+ return true;
+}
+
+static const char *page_bad_reason(struct page *page, unsigned long flags)
+{
+ const char *bad_reason = NULL;
+
+ if (unlikely(atomic_read(&page->_mapcount) != -1))
+ bad_reason = "nonzero mapcount";
+ if (unlikely(page->mapping != NULL))
+ bad_reason = "non-NULL mapping";
+ if (unlikely(page_ref_count(page) != 0))
+ bad_reason = "nonzero _refcount";
+ if (unlikely(page->flags & flags)) {
+ if (flags == PAGE_FLAGS_CHECK_AT_PREP)
+ bad_reason = "PAGE_FLAGS_CHECK_AT_PREP flag(s) set";
+ else
+ bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
+ }
+#ifdef CONFIG_MEMCG
+ if (unlikely(page->memcg_data))
+ bad_reason = "page still charged to cgroup";
+#endif
+ return bad_reason;
+}
+
+static void free_page_is_bad_report(struct page *page)
+{
+ bad_page(page,
+ page_bad_reason(page, PAGE_FLAGS_CHECK_AT_FREE));
+}
+
+static inline bool free_page_is_bad(struct page *page)
+{
+ if (likely(page_expected_state(page, PAGE_FLAGS_CHECK_AT_FREE)))
+ return false;
+
+ /* Something has gone sideways, find it */
+ free_page_is_bad_report(page);
+ return true;
+}
+
+static inline bool is_check_pages_enabled(void)
+{
+ return static_branch_unlikely(&check_pages_enabled);
+}
+
+static int free_tail_page_prepare(struct page *head_page, struct page *page)
+{
+ struct folio *folio = (struct folio *)head_page;
+ int ret = 1;
+
+ /*
+ * We rely page->lru.next never has bit 0 set, unless the page
+ * is PageTail(). Let's make sure that's true even for poisoned ->lru.
+ */
+ BUILD_BUG_ON((unsigned long)LIST_POISON1 & 1);
+
+ if (!is_check_pages_enabled()) {
+ ret = 0;
+ goto out;
+ }
+ switch (page - head_page) {
+ case 1:
+ /* the first tail page: these may be in place of ->mapping */
+ if (unlikely(folio_entire_mapcount(folio))) {
+ bad_page(page, "nonzero entire_mapcount");
+ goto out;
+ }
+ if (unlikely(atomic_read(&folio->_nr_pages_mapped))) {
+ bad_page(page, "nonzero nr_pages_mapped");
+ goto out;
+ }
+ if (unlikely(atomic_read(&folio->_pincount))) {
+ bad_page(page, "nonzero pincount");
+ goto out;
+ }
+ break;
+ case 2:
+ /*
+ * the second tail page: ->mapping is
+ * deferred_list.next -- ignore value.
+ */
+ break;
+ default:
+ if (page->mapping != TAIL_MAPPING) {
+ bad_page(page, "corrupted mapping in tail page");
+ goto out;
+ }
+ break;
+ }
+ if (unlikely(!PageTail(page))) {
+ bad_page(page, "PageTail not set");
+ goto out;
+ }
+ if (unlikely(compound_head(page) != head_page)) {
+ bad_page(page, "compound_head not consistent");
+ goto out;
+ }
+ ret = 0;
+out:
+ page->mapping = NULL;
+ clear_compound_head(page);
+ return ret;
+}
+
+/*
+ * Skip KASAN memory poisoning when either:
+ *
+ * 1. For generic KASAN: deferred memory initialization has not yet completed.
+ * Tag-based KASAN modes skip pages freed via deferred memory initialization
+ * using page tags instead (see below).
+ * 2. For tag-based KASAN modes: the page has a match-all KASAN tag, indicating
+ * that error detection is disabled for accesses via the page address.
+ *
+ * Pages will have match-all tags in the following circumstances:
+ *
+ * 1. Pages are being initialized for the first time, including during deferred
+ * memory init; see the call to page_kasan_tag_reset in __init_single_page.
+ * 2. The allocation was not unpoisoned due to __GFP_SKIP_KASAN, with the
+ * exception of pages unpoisoned by kasan_unpoison_vmalloc.
+ * 3. The allocation was excluded from being checked due to sampling,
+ * see the call to kasan_unpoison_pages.
+ *
+ * Poisoning pages during deferred memory init will greatly lengthen the
+ * process and cause problem in large memory systems as the deferred pages
+ * initialization is done with interrupt disabled.
+ *
+ * Assuming that there will be no reference to those newly initialized
+ * pages before they are ever allocated, this should have no effect on
+ * KASAN memory tracking as the poison will be properly inserted at page
+ * allocation time. The only corner case is when pages are allocated by
+ * on-demand allocation and then freed again before the deferred pages
+ * initialization is done, but this is not likely to happen.
+ */
+static inline bool should_skip_kasan_poison(struct page *page, fpi_t fpi_flags)
+{
+ if (IS_ENABLED(CONFIG_KASAN_GENERIC))
+ return deferred_pages_enabled();
+
+ return page_kasan_tag(page) == 0xff;
+}
+
+static void kernel_init_pages(struct page *page, int numpages)
+{
+ int i;
+
+ /* s390's use of memset() could override KASAN redzones. */
+ kasan_disable_current();
+ for (i = 0; i < numpages; i++)
+ clear_highpage_kasan_tagged(page + i);
+ kasan_enable_current();
+}
+
+static __always_inline bool free_pages_prepare(struct page *page,
+ unsigned int order, fpi_t fpi_flags)
+{
+ int bad = 0;
+ bool skip_kasan_poison = should_skip_kasan_poison(page, fpi_flags);
+ bool init = want_init_on_free();
+
+ VM_BUG_ON_PAGE(PageTail(page), page);
+
+ trace_mm_page_free(page, order);
+ kmsan_free_page(page, order);
+
+ if (unlikely(PageHWPoison(page)) && !order) {
+ /*
+ * Do not let hwpoison pages hit pcplists/buddy
+ * Untie memcg state and reset page's owner
+ */
+ if (memcg_kmem_online() && PageMemcgKmem(page))
+ __memcg_kmem_uncharge_page(page, order);
+ reset_page_owner(page, order);
+ page_table_check_free(page, order);
+ return false;
+ }
+
+ /*
+ * Check tail pages before head page information is cleared to
+ * avoid checking PageCompound for order-0 pages.
+ */
+ if (unlikely(order)) {
+ bool compound = PageCompound(page);
+ int i;
+
+ VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
+
+ if (compound)
+ page[1].flags &= ~PAGE_FLAGS_SECOND;
+ for (i = 1; i < (1 << order); i++) {
+ if (compound)
+ bad += free_tail_page_prepare(page, page + i);
+ if (is_check_pages_enabled()) {
+ if (free_page_is_bad(page + i)) {
+ bad++;
+ continue;
+ }
+ }
+ (page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+ }
+ }
+ if (PageMappingFlags(page))
+ page->mapping = NULL;
+ if (memcg_kmem_online() && PageMemcgKmem(page))
+ __memcg_kmem_uncharge_page(page, order);
+ if (is_check_pages_enabled()) {
+ if (free_page_is_bad(page))
+ bad++;
+ if (bad)
+ return false;
+ }
+
+ page_cpupid_reset_last(page);
+ page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+ reset_page_owner(page, order);
+ page_table_check_free(page, order);
+
+ if (!PageHighMem(page)) {
+ debug_check_no_locks_freed(page_address(page),
+ PAGE_SIZE << order);
+ debug_check_no_obj_freed(page_address(page),
+ PAGE_SIZE << order);
+ }
+
+ kernel_poison_pages(page, 1 << order);
+
+ /*
+ * As memory initialization might be integrated into KASAN,
+ * KASAN poisoning and memory initialization code must be
+ * kept together to avoid discrepancies in behavior.
+ *
+ * With hardware tag-based KASAN, memory tags must be set before the
+ * page becomes unavailable via debug_pagealloc or arch_free_page.
+ */
+ if (!skip_kasan_poison) {
+ kasan_poison_pages(page, order, init);
+
+ /* Memory is already initialized if KASAN did it internally. */
+ if (kasan_has_integrated_init())
+ init = false;
+ }
+ if (init)
+ kernel_init_pages(page, 1 << order);
+
+ /*
+ * arch_free_page() can make the page's contents inaccessible. s390
+ * does this. So nothing which can access the page's contents should
+ * happen after this.
+ */
+ arch_free_page(page, order);
+
+ debug_pagealloc_unmap_pages(page, 1 << order);
+
+ return true;
+}
+
+/*
+ * Frees a number of pages from the PCP lists
+ * Assumes all pages on list are in same zone.
+ * count is the number of pages to free.
+ */
+static void free_pcppages_bulk(struct zone *zone, int count,
+ struct per_cpu_pages *pcp,
+ int pindex)
+{
+ unsigned long flags;
+ unsigned int order;
+ bool isolated_pageblocks;
+ struct page *page;
+
+ /*
+ * Ensure proper count is passed which otherwise would stuck in the
+ * below while (list_empty(list)) loop.
+ */
+ count = min(pcp->count, count);
+
+ /* Ensure requested pindex is drained first. */
+ pindex = pindex - 1;
+
+ spin_lock_irqsave(&zone->lock, flags);
+ isolated_pageblocks = has_isolate_pageblock(zone);
+
+ while (count > 0) {
+ struct list_head *list;
+ int nr_pages;
+
+ /* Remove pages from lists in a round-robin fashion. */
+ do {
+ if (++pindex > NR_PCP_LISTS - 1)
+ pindex = 0;
+ list = &pcp->lists[pindex];
+ } while (list_empty(list));
+
+ order = pindex_to_order(pindex);
+ nr_pages = 1 << order;
+ do {
+ int mt;
+
+ page = list_last_entry(list, struct page, pcp_list);
+ mt = get_pcppage_migratetype(page);
+
+ /* must delete to avoid corrupting pcp list */
+ list_del(&page->pcp_list);
+ count -= nr_pages;
+ pcp->count -= nr_pages;
+
+ /* MIGRATE_ISOLATE page should not go to pcplists */
+ VM_BUG_ON_PAGE(is_migrate_isolate(mt), page);
+ /* Pageblock could have been isolated meanwhile */
+ if (unlikely(isolated_pageblocks))
+ mt = get_pageblock_migratetype(page);
+
+ __free_one_page(page, page_to_pfn(page), zone, order, mt, FPI_NONE);
+ trace_mm_page_pcpu_drain(page, order, mt);
+ } while (count > 0 && !list_empty(list));
+ }
+
+ spin_unlock_irqrestore(&zone->lock, flags);
+}
+
+static void free_one_page(struct zone *zone,
+ struct page *page, unsigned long pfn,
+ unsigned int order,
+ int migratetype, fpi_t fpi_flags)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&zone->lock, flags);
+ if (unlikely(has_isolate_pageblock(zone) ||
+ is_migrate_isolate(migratetype))) {
+ migratetype = get_pfnblock_migratetype(page, pfn);
+ }
+ __free_one_page(page, pfn, zone, order, migratetype, fpi_flags);
+ spin_unlock_irqrestore(&zone->lock, flags);
+}
+
+static void __free_pages_ok(struct page *page, unsigned int order,
+ fpi_t fpi_flags)
+{
+ unsigned long flags;
+ int migratetype;
+ unsigned long pfn = page_to_pfn(page);
+ struct zone *zone = page_zone(page);
+
+ if (!free_pages_prepare(page, order, fpi_flags))
+ return;
+
+ /*
+ * Calling get_pfnblock_migratetype() without spin_lock_irqsave() here
+ * is used to avoid calling get_pfnblock_migratetype() under the lock.
+ * This will reduce the lock holding time.
+ */
+ migratetype = get_pfnblock_migratetype(page, pfn);
+
+ spin_lock_irqsave(&zone->lock, flags);
+ if (unlikely(has_isolate_pageblock(zone) ||
+ is_migrate_isolate(migratetype))) {
+ migratetype = get_pfnblock_migratetype(page, pfn);
+ }
+ __free_one_page(page, pfn, zone, order, migratetype, fpi_flags);
+ spin_unlock_irqrestore(&zone->lock, flags);
+
+ __count_vm_events(PGFREE, 1 << order);
+}
+
+void __free_pages_core(struct page *page, unsigned int order)
+{
+ unsigned int nr_pages = 1 << order;
+ struct page *p = page;
+ unsigned int loop;
+
+ /*
+ * When initializing the memmap, __init_single_page() sets the refcount
+ * of all pages to 1 ("allocated"/"not free"). We have to set the
+ * refcount of all involved pages to 0.
+ */
+ prefetchw(p);
+ for (loop = 0; loop < (nr_pages - 1); loop++, p++) {
+ prefetchw(p + 1);
+ __ClearPageReserved(p);
+ set_page_count(p, 0);
+ }
+ __ClearPageReserved(p);
+ set_page_count(p, 0);
+
+ atomic_long_add(nr_pages, &page_zone(page)->managed_pages);
+
+ if (page_contains_unaccepted(page, order)) {
+ if (order == MAX_ORDER && __free_unaccepted(page))
+ return;
+
+ accept_page(page, order);
+ }
+
+ /*
+ * Bypass PCP and place fresh pages right to the tail, primarily
+ * relevant for memory onlining.
+ */
+ __free_pages_ok(page, order, FPI_TO_TAIL);
+}
+
+/*
+ * Check that the whole (or subset of) a pageblock given by the interval of
+ * [start_pfn, end_pfn) is valid and within the same zone, before scanning it
+ * with the migration of free compaction scanner.
+ *
+ * Return struct page pointer of start_pfn, or NULL if checks were not passed.
+ *
+ * It's possible on some configurations to have a setup like node0 node1 node0
+ * i.e. it's possible that all pages within a zones range of pages do not
+ * belong to a single zone. We assume that a border between node0 and node1
+ * can occur within a single pageblock, but not a node0 node1 node0
+ * interleaving within a single pageblock. It is therefore sufficient to check
+ * the first and last page of a pageblock and avoid checking each individual
+ * page in a pageblock.
+ *
+ * Note: the function may return non-NULL struct page even for a page block
+ * which contains a memory hole (i.e. there is no physical memory for a subset
+ * of the pfn range). For example, if the pageblock order is MAX_ORDER, which
+ * will fall into 2 sub-sections, and the end pfn of the pageblock may be hole
+ * even though the start pfn is online and valid. This should be safe most of
+ * the time because struct pages are still initialized via init_unavailable_range()
+ * and pfn walkers shouldn't touch any physical memory range for which they do
+ * not recognize any specific metadata in struct pages.
+ */
+struct page *__pageblock_pfn_to_page(unsigned long start_pfn,
+ unsigned long end_pfn, struct zone *zone)
+{
+ struct page *start_page;
+ struct page *end_page;
+
+ /* end_pfn is one past the range we are checking */
+ end_pfn--;
+
+ if (!pfn_valid(end_pfn))
+ return NULL;
+
+ start_page = pfn_to_online_page(start_pfn);
+ if (!start_page)
+ return NULL;
+
+ if (page_zone(start_page) != zone)
+ return NULL;
+
+ end_page = pfn_to_page(end_pfn);
+
+ /* This gives a shorter code than deriving page_zone(end_page) */
+ if (page_zone_id(start_page) != page_zone_id(end_page))
+ return NULL;
+
+ return start_page;
+}
+
+/*
+ * The order of subdivision here is critical for the IO subsystem.
+ * Please do not alter this order without good reasons and regression
+ * testing. Specifically, as large blocks of memory are subdivided,
+ * the order in which smaller blocks are delivered depends on the order
+ * they're subdivided in this function. This is the primary factor
+ * influencing the order in which pages are delivered to the IO
+ * subsystem according to empirical testing, and this is also justified
+ * by considering the behavior of a buddy system containing a single
+ * large block of memory acted on by a series of small allocations.
+ * This behavior is a critical factor in sglist merging's success.
+ *
+ * -- nyc
+ */
+static inline void expand(struct zone *zone, struct page *page,
+ int low, int high, int migratetype)
+{
+ unsigned long size = 1 << high;
+
+ while (high > low) {
+ high--;
+ size >>= 1;
+ VM_BUG_ON_PAGE(bad_range(zone, &page[size]), &page[size]);
+
+ /*
+ * Mark as guard pages (or page), that will allow to
+ * merge back to allocator when buddy will be freed.
+ * Corresponding page table entries will not be touched,
+ * pages will stay not present in virtual address space
+ */
+ if (set_page_guard(zone, &page[size], high, migratetype))
+ continue;
+
+ add_to_free_list(&page[size], zone, high, migratetype);
+ set_buddy_order(&page[size], high);
+ }
+}
+
+static void check_new_page_bad(struct page *page)
+{
+ if (unlikely(page->flags & __PG_HWPOISON)) {
+ /* Don't complain about hwpoisoned pages */
+ page_mapcount_reset(page); /* remove PageBuddy */
+ return;
+ }
+
+ bad_page(page,
+ page_bad_reason(page, PAGE_FLAGS_CHECK_AT_PREP));
+}
+
+/*
+ * This page is about to be returned from the page allocator
+ */
+static int check_new_page(struct page *page)
+{
+ if (likely(page_expected_state(page,
+ PAGE_FLAGS_CHECK_AT_PREP|__PG_HWPOISON)))
+ return 0;
+
+ check_new_page_bad(page);
+ return 1;
+}
+
+static inline bool check_new_pages(struct page *page, unsigned int order)
+{
+ if (is_check_pages_enabled()) {
+ for (int i = 0; i < (1 << order); i++) {
+ struct page *p = page + i;
+
+ if (check_new_page(p))
+ return true;
+ }
+ }
+
+ return false;
+}
+
+static inline bool should_skip_kasan_unpoison(gfp_t flags)
+{
+ /* Don't skip if a software KASAN mode is enabled. */
+ if (IS_ENABLED(CONFIG_KASAN_GENERIC) ||
+ IS_ENABLED(CONFIG_KASAN_SW_TAGS))
+ return false;
+
+ /* Skip, if hardware tag-based KASAN is not enabled. */
+ if (!kasan_hw_tags_enabled())
+ return true;
+
+ /*
+ * With hardware tag-based KASAN enabled, skip if this has been
+ * requested via __GFP_SKIP_KASAN.
+ */
+ return flags & __GFP_SKIP_KASAN;
+}
+
+static inline bool should_skip_init(gfp_t flags)
+{
+ /* Don't skip, if hardware tag-based KASAN is not enabled. */
+ if (!kasan_hw_tags_enabled())
+ return false;
+
+ /* For hardware tag-based KASAN, skip if requested. */
+ return (flags & __GFP_SKIP_ZERO);
+}
+
+inline void post_alloc_hook(struct page *page, unsigned int order,
+ gfp_t gfp_flags)
+{
+ bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags) &&
+ !should_skip_init(gfp_flags);
+ bool zero_tags = init && (gfp_flags & __GFP_ZEROTAGS);
+ int i;
+
+ set_page_private(page, 0);
+ set_page_refcounted(page);
+
+ arch_alloc_page(page, order);
+ debug_pagealloc_map_pages(page, 1 << order);
+
+ /*
+ * Page unpoisoning must happen before memory initialization.
+ * Otherwise, the poison pattern will be overwritten for __GFP_ZERO
+ * allocations and the page unpoisoning code will complain.
+ */
+ kernel_unpoison_pages(page, 1 << order);
+
+ /*
+ * As memory initialization might be integrated into KASAN,
+ * KASAN unpoisoning and memory initializion code must be
+ * kept together to avoid discrepancies in behavior.
+ */
+
+ /*
+ * If memory tags should be zeroed
+ * (which happens only when memory should be initialized as well).
+ */
+ if (zero_tags) {
+ /* Initialize both memory and memory tags. */
+ for (i = 0; i != 1 << order; ++i)
+ tag_clear_highpage(page + i);
+
+ /* Take note that memory was initialized by the loop above. */
+ init = false;
+ }
+ if (!should_skip_kasan_unpoison(gfp_flags) &&
+ kasan_unpoison_pages(page, order, init)) {
+ /* Take note that memory was initialized by KASAN. */
+ if (kasan_has_integrated_init())
+ init = false;
+ } else {
+ /*
+ * If memory tags have not been set by KASAN, reset the page
+ * tags to ensure page_address() dereferencing does not fault.
+ */
+ for (i = 0; i != 1 << order; ++i)
+ page_kasan_tag_reset(page + i);
+ }
+ /* If memory is still not initialized, initialize it now. */
+ if (init)
+ kernel_init_pages(page, 1 << order);
+
+ set_page_owner(page, order, gfp_flags);
+ page_table_check_alloc(page, order);
+}
+
+static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
+ unsigned int alloc_flags)
+{
+ post_alloc_hook(page, order, gfp_flags);
+
+ if (order && (gfp_flags & __GFP_COMP))
+ prep_compound_page(page, order);
+
+ /*
+ * page is set pfmemalloc when ALLOC_NO_WATERMARKS was necessary to
+ * allocate the page. The expectation is that the caller is taking
+ * steps that will free more memory. The caller should avoid the page
+ * being used for !PFMEMALLOC purposes.
+ */
+ if (alloc_flags & ALLOC_NO_WATERMARKS)
+ set_page_pfmemalloc(page);
+ else
+ clear_page_pfmemalloc(page);
+}
+
+/*
+ * Go through the free lists for the given migratetype and remove
+ * the smallest available page from the freelists
+ */
+static __always_inline
+struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
+ int migratetype)
+{
+ unsigned int current_order;
+ struct free_area *area;
+ struct page *page;
+
+ /* Find a page of the appropriate size in the preferred list */
+ for (current_order = order; current_order <= MAX_ORDER; ++current_order) {
+ area = &(zone->free_area[current_order]);
+ page = get_page_from_free_area(area, migratetype);
+ if (!page)
+ continue;
+ del_page_from_free_list(page, zone, current_order);
+ expand(zone, page, order, current_order, migratetype);
+ set_pcppage_migratetype(page, migratetype);
+ trace_mm_page_alloc_zone_locked(page, order, migratetype,
+ pcp_allowed_order(order) &&
+ migratetype < MIGRATE_PCPTYPES);
+ return page;
+ }
+
+ return NULL;
+}
+
+
+/*
+ * This array describes the order lists are fallen back to when
+ * the free lists for the desirable migrate type are depleted
+ *
+ * The other migratetypes do not have fallbacks.
+ */
+static int fallbacks[MIGRATE_TYPES][MIGRATE_PCPTYPES - 1] = {
+ [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE },
+ [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE },
+ [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE },
+};
+
+#ifdef CONFIG_CMA
+static __always_inline struct page *__rmqueue_cma_fallback(struct zone *zone,
+ unsigned int order)
+{
+ return __rmqueue_smallest(zone, order, MIGRATE_CMA);
+}
+#else
+static inline struct page *__rmqueue_cma_fallback(struct zone *zone,
+ unsigned int order) { return NULL; }
+#endif
+
+/*
+ * Move the free pages in a range to the freelist tail of the requested type.
+ * Note that start_page and end_pages are not aligned on a pageblock
+ * boundary. If alignment is required, use move_freepages_block()
+ */
+static int move_freepages(struct zone *zone,
+ unsigned long start_pfn, unsigned long end_pfn,
+ int migratetype, int *num_movable)
+{
+ struct page *page;
+ unsigned long pfn;
+ unsigned int order;
+ int pages_moved = 0;
+
+ for (pfn = start_pfn; pfn <= end_pfn;) {
+ page = pfn_to_page(pfn);
+ if (!PageBuddy(page)) {
+ /*
+ * We assume that pages that could be isolated for
+ * migration are movable. But we don't actually try
+ * isolating, as that would be expensive.
+ */
+ if (num_movable &&
+ (PageLRU(page) || __PageMovable(page)))
+ (*num_movable)++;
+ pfn++;
+ continue;
+ }
+
+ /* Make sure we are not inadvertently changing nodes */
+ VM_BUG_ON_PAGE(page_to_nid(page) != zone_to_nid(zone), page);
+ VM_BUG_ON_PAGE(page_zone(page) != zone, page);
+
+ order = buddy_order(page);
+ move_to_free_list(page, zone, order, migratetype);
+ pfn += 1 << order;
+ pages_moved += 1 << order;
+ }
+
+ return pages_moved;
+}
+
+int move_freepages_block(struct zone *zone, struct page *page,
+ int migratetype, int *num_movable)
+{
+ unsigned long start_pfn, end_pfn, pfn;
+
+ if (num_movable)
+ *num_movable = 0;
+
+ pfn = page_to_pfn(page);
+ start_pfn = pageblock_start_pfn(pfn);
+ end_pfn = pageblock_end_pfn(pfn) - 1;
+
+ /* Do not cross zone boundaries */
+ if (!zone_spans_pfn(zone, start_pfn))
+ start_pfn = pfn;
+ if (!zone_spans_pfn(zone, end_pfn))
+ return 0;
+
+ return move_freepages(zone, start_pfn, end_pfn, migratetype,
+ num_movable);
+}
+
+static void change_pageblock_range(struct page *pageblock_page,
+ int start_order, int migratetype)
+{
+ int nr_pageblocks = 1 << (start_order - pageblock_order);
+
+ while (nr_pageblocks--) {
+ set_pageblock_migratetype(pageblock_page, migratetype);
+ pageblock_page += pageblock_nr_pages;
+ }
+}
+
+/*
+ * When we are falling back to another migratetype during allocation, try to
+ * steal extra free pages from the same pageblocks to satisfy further
+ * allocations, instead of polluting multiple pageblocks.
+ *
+ * If we are stealing a relatively large buddy page, it is likely there will
+ * be more free pages in the pageblock, so try to steal them all. For
+ * reclaimable and unmovable allocations, we steal regardless of page size,
+ * as fragmentation caused by those allocations polluting movable pageblocks
+ * is worse than movable allocations stealing from unmovable and reclaimable
+ * pageblocks.
+ */
+static bool can_steal_fallback(unsigned int order, int start_mt)
+{
+ /*
+ * Leaving this order check is intended, although there is
+ * relaxed order check in next check. The reason is that
+ * we can actually steal whole pageblock if this condition met,
+ * but, below check doesn't guarantee it and that is just heuristic
+ * so could be changed anytime.
+ */
+ if (order >= pageblock_order)
+ return true;
+
+ if (order >= pageblock_order / 2 ||
+ start_mt == MIGRATE_RECLAIMABLE ||
+ start_mt == MIGRATE_UNMOVABLE ||
+ page_group_by_mobility_disabled)
+ return true;
+
+ return false;
+}
+
+static inline bool boost_watermark(struct zone *zone)
+{
+ unsigned long max_boost;
+
+ if (!watermark_boost_factor)
+ return false;
+ /*
+ * Don't bother in zones that are unlikely to produce results.
+ * On small machines, including kdump capture kernels running
+ * in a small area, boosting the watermark can cause an out of
+ * memory situation immediately.
+ */
+ if ((pageblock_nr_pages * 4) > zone_managed_pages(zone))
+ return false;
+
+ max_boost = mult_frac(zone->_watermark[WMARK_HIGH],
+ watermark_boost_factor, 10000);
+
+ /*
+ * high watermark may be uninitialised if fragmentation occurs
+ * very early in boot so do not boost. We do not fall
+ * through and boost by pageblock_nr_pages as failing
+ * allocations that early means that reclaim is not going
+ * to help and it may even be impossible to reclaim the
+ * boosted watermark resulting in a hang.
+ */
+ if (!max_boost)
+ return false;
+
+ max_boost = max(pageblock_nr_pages, max_boost);
+
+ zone->watermark_boost = min(zone->watermark_boost + pageblock_nr_pages,
+ max_boost);
+
+ return true;
+}
+
+/*
+ * This function implements actual steal behaviour. If order is large enough,
+ * we can steal whole pageblock. If not, we first move freepages in this
+ * pageblock to our migratetype and determine how many already-allocated pages
+ * are there in the pageblock with a compatible migratetype. If at least half
+ * of pages are free or compatible, we can change migratetype of the pageblock
+ * itself, so pages freed in the future will be put on the correct free list.
+ */
+static void steal_suitable_fallback(struct zone *zone, struct page *page,
+ unsigned int alloc_flags, int start_type, bool whole_block)
+{
+ unsigned int current_order = buddy_order(page);
+ int free_pages, movable_pages, alike_pages;
+ int old_block_type;
+
+ old_block_type = get_pageblock_migratetype(page);
+
+ /*
+ * This can happen due to races and we want to prevent broken
+ * highatomic accounting.
+ */
+ if (is_migrate_highatomic(old_block_type))
+ goto single_page;
+
+ /* Take ownership for orders >= pageblock_order */
+ if (current_order >= pageblock_order) {
+ change_pageblock_range(page, current_order, start_type);
+ goto single_page;
+ }
+
+ /*
+ * Boost watermarks to increase reclaim pressure to reduce the
+ * likelihood of future fallbacks. Wake kswapd now as the node
+ * may be balanced overall and kswapd will not wake naturally.
+ */
+ if (boost_watermark(zone) && (alloc_flags & ALLOC_KSWAPD))
+ set_bit(ZONE_BOOSTED_WATERMARK, &zone->flags);
+
+ /* We are not allowed to try stealing from the whole block */
+ if (!whole_block)
+ goto single_page;
+
+ free_pages = move_freepages_block(zone, page, start_type,
+ &movable_pages);
+ /* moving whole block can fail due to zone boundary conditions */
+ if (!free_pages)
+ goto single_page;
+
+ /*
+ * Determine how many pages are compatible with our allocation.
+ * For movable allocation, it's the number of movable pages which
+ * we just obtained. For other types it's a bit more tricky.
+ */
+ if (start_type == MIGRATE_MOVABLE) {
+ alike_pages = movable_pages;
+ } else {
+ /*
+ * If we are falling back a RECLAIMABLE or UNMOVABLE allocation
+ * to MOVABLE pageblock, consider all non-movable pages as
+ * compatible. If it's UNMOVABLE falling back to RECLAIMABLE or
+ * vice versa, be conservative since we can't distinguish the
+ * exact migratetype of non-movable pages.
+ */
+ if (old_block_type == MIGRATE_MOVABLE)
+ alike_pages = pageblock_nr_pages
+ - (free_pages + movable_pages);
+ else
+ alike_pages = 0;
+ }
+ /*
+ * If a sufficient number of pages in the block are either free or of
+ * compatible migratability as our allocation, claim the whole block.
+ */
+ if (free_pages + alike_pages >= (1 << (pageblock_order-1)) ||
+ page_group_by_mobility_disabled)
+ set_pageblock_migratetype(page, start_type);
+
+ return;
+
+single_page:
+ move_to_free_list(page, zone, current_order, start_type);
+}
+
+/*
+ * Check whether there is a suitable fallback freepage with requested order.
+ * If only_stealable is true, this function returns fallback_mt only if
+ * we can steal other freepages all together. This would help to reduce
+ * fragmentation due to mixed migratetype pages in one pageblock.
+ */
+int find_suitable_fallback(struct free_area *area, unsigned int order,
+ int migratetype, bool only_stealable, bool *can_steal)
+{
+ int i;
+ int fallback_mt;
+
+ if (area->nr_free == 0)
+ return -1;
+
+ *can_steal = false;
+ for (i = 0; i < MIGRATE_PCPTYPES - 1 ; i++) {
+ fallback_mt = fallbacks[migratetype][i];
+ if (free_area_empty(area, fallback_mt))
+ continue;
+
+ if (can_steal_fallback(order, migratetype))
+ *can_steal = true;
+
+ if (!only_stealable)
+ return fallback_mt;
+
+ if (*can_steal)
+ return fallback_mt;
+ }
+
+ return -1;
+}
+
+/*
+ * Reserve a pageblock for exclusive use of high-order atomic allocations if
+ * there are no empty page blocks that contain a page with a suitable order
+ */
+static void reserve_highatomic_pageblock(struct page *page, struct zone *zone)
+{
+ int mt;
+ unsigned long max_managed, flags;
+
+ /*
+ * Limit the number reserved to 1 pageblock or roughly 1% of a zone.
+ * Check is race-prone but harmless.
+ */
+ max_managed = (zone_managed_pages(zone) / 100) + pageblock_nr_pages;
+ if (zone->nr_reserved_highatomic >= max_managed)
+ return;
+
+ spin_lock_irqsave(&zone->lock, flags);
+
+ /* Recheck the nr_reserved_highatomic limit under the lock */
+ if (zone->nr_reserved_highatomic >= max_managed)
+ goto out_unlock;
+
+ /* Yoink! */
+ mt = get_pageblock_migratetype(page);
+ /* Only reserve normal pageblocks (i.e., they can merge with others) */
+ if (migratetype_is_mergeable(mt)) {
+ zone->nr_reserved_highatomic += pageblock_nr_pages;
+ set_pageblock_migratetype(page, MIGRATE_HIGHATOMIC);
+ move_freepages_block(zone, page, MIGRATE_HIGHATOMIC, NULL);
+ }
+
+out_unlock:
+ spin_unlock_irqrestore(&zone->lock, flags);
+}
+
+/*
+ * Used when an allocation is about to fail under memory pressure. This
+ * potentially hurts the reliability of high-order allocations when under
+ * intense memory pressure but failed atomic allocations should be easier
+ * to recover from than an OOM.
+ *
+ * If @force is true, try to unreserve a pageblock even though highatomic
+ * pageblock is exhausted.
+ */
+static bool unreserve_highatomic_pageblock(const struct alloc_context *ac,
+ bool force)
+{
+ struct zonelist *zonelist = ac->zonelist;
+ unsigned long flags;
+ struct zoneref *z;
+ struct zone *zone;
+ struct page *page;
+ int order;
+ bool ret;
+
+ for_each_zone_zonelist_nodemask(zone, z, zonelist, ac->highest_zoneidx,
+ ac->nodemask) {
+ /*
+ * Preserve at least one pageblock unless memory pressure
+ * is really high.
+ */
+ if (!force && zone->nr_reserved_highatomic <=
+ pageblock_nr_pages)
+ continue;
+
+ spin_lock_irqsave(&zone->lock, flags);
+ for (order = 0; order <= MAX_ORDER; order++) {
+ struct free_area *area = &(zone->free_area[order]);
+
+ page = get_page_from_free_area(area, MIGRATE_HIGHATOMIC);
+ if (!page)
+ continue;
+
+ /*
+ * In page freeing path, migratetype change is racy so
+ * we can counter several free pages in a pageblock
+ * in this loop although we changed the pageblock type
+ * from highatomic to ac->migratetype. So we should
+ * adjust the count once.
+ */
+ if (is_migrate_highatomic_page(page)) {
+ /*
+ * It should never happen but changes to
+ * locking could inadvertently allow a per-cpu
+ * drain to add pages to MIGRATE_HIGHATOMIC
+ * while unreserving so be safe and watch for
+ * underflows.
+ */
+ zone->nr_reserved_highatomic -= min(
+ pageblock_nr_pages,
+ zone->nr_reserved_highatomic);
+ }
+
+ /*
+ * Convert to ac->migratetype and avoid the normal
+ * pageblock stealing heuristics. Minimally, the caller
+ * is doing the work and needs the pages. More
+ * importantly, if the block was always converted to
+ * MIGRATE_UNMOVABLE or another type then the number
+ * of pageblocks that cannot be completely freed
+ * may increase.
+ */
+ set_pageblock_migratetype(page, ac->migratetype);
+ ret = move_freepages_block(zone, page, ac->migratetype,
+ NULL);
+ if (ret) {
+ spin_unlock_irqrestore(&zone->lock, flags);
+ return ret;
+ }
+ }
+ spin_unlock_irqrestore(&zone->lock, flags);
+ }
+
+ return false;
+}
+
+/*
+ * Try finding a free buddy page on the fallback list and put it on the free
+ * list of requested migratetype, possibly along with other pages from the same
+ * block, depending on fragmentation avoidance heuristics. Returns true if
+ * fallback was found so that __rmqueue_smallest() can grab it.
+ *
+ * The use of signed ints for order and current_order is a deliberate
+ * deviation from the rest of this file, to make the for loop
+ * condition simpler.
+ */
+static __always_inline bool
+__rmqueue_fallback(struct zone *zone, int order, int start_migratetype,
+ unsigned int alloc_flags)
+{
+ struct free_area *area;
+ int current_order;
+ int min_order = order;
+ struct page *page;
+ int fallback_mt;
+ bool can_steal;
+
+ /*
+ * Do not steal pages from freelists belonging to other pageblocks
+ * i.e. orders < pageblock_order. If there are no local zones free,
+ * the zonelists will be reiterated without ALLOC_NOFRAGMENT.
+ */
+ if (order < pageblock_order && alloc_flags & ALLOC_NOFRAGMENT)
+ min_order = pageblock_order;
+
+ /*
+ * Find the largest available free page in the other list. This roughly
+ * approximates finding the pageblock with the most free pages, which
+ * would be too costly to do exactly.
+ */
+ for (current_order = MAX_ORDER; current_order >= min_order;
+ --current_order) {
+ area = &(zone->free_area[current_order]);
+ fallback_mt = find_suitable_fallback(area, current_order,
+ start_migratetype, false, &can_steal);
+ if (fallback_mt == -1)
+ continue;
+
+ /*
+ * We cannot steal all free pages from the pageblock and the
+ * requested migratetype is movable. In that case it's better to
+ * steal and split the smallest available page instead of the
+ * largest available page, because even if the next movable
+ * allocation falls back into a different pageblock than this
+ * one, it won't cause permanent fragmentation.
+ */
+ if (!can_steal && start_migratetype == MIGRATE_MOVABLE
+ && current_order > order)
+ goto find_smallest;
+
+ goto do_steal;
+ }
+
+ return false;
+
+find_smallest:
+ for (current_order = order; current_order <= MAX_ORDER;
+ current_order++) {
+ area = &(zone->free_area[current_order]);
+ fallback_mt = find_suitable_fallback(area, current_order,
+ start_migratetype, false, &can_steal);
+ if (fallback_mt != -1)
+ break;
+ }
+
+ /*
+ * This should not happen - we already found a suitable fallback
+ * when looking for the largest page.
+ */
+ VM_BUG_ON(current_order > MAX_ORDER);
+
+do_steal:
+ page = get_page_from_free_area(area, fallback_mt);
+
+ steal_suitable_fallback(zone, page, alloc_flags, start_migratetype,
+ can_steal);
+
+ trace_mm_page_alloc_extfrag(page, order, current_order,
+ start_migratetype, fallback_mt);
+
+ return true;
+
+}
+
+/*
+ * Do the hard work of removing an element from the buddy allocator.
+ * Call me with the zone->lock already held.
+ */
+static __always_inline struct page *
+__rmqueue(struct zone *zone, unsigned int order, int migratetype,
+ unsigned int alloc_flags)
+{
+ struct page *page;
+
+ if (IS_ENABLED(CONFIG_CMA)) {
+ /*
+ * Balance movable allocations between regular and CMA areas by
+ * allocating from CMA when over half of the zone's free memory
+ * is in the CMA area.
+ */
+ if (alloc_flags & ALLOC_CMA &&
+ zone_page_state(zone, NR_FREE_CMA_PAGES) >
+ zone_page_state(zone, NR_FREE_PAGES) / 2) {
+ page = __rmqueue_cma_fallback(zone, order);
+ if (page)
+ return page;
+ }
+ }
+retry:
+ page = __rmqueue_smallest(zone, order, migratetype);
+ if (unlikely(!page)) {
+ if (alloc_flags & ALLOC_CMA)
+ page = __rmqueue_cma_fallback(zone, order);
+
+ if (!page && __rmqueue_fallback(zone, order, migratetype,
+ alloc_flags))
+ goto retry;
+ }
+ return page;
+}
+
+/*
+ * Obtain a specified number of elements from the buddy allocator, all under
+ * a single hold of the lock, for efficiency. Add them to the supplied list.
+ * Returns the number of new pages which were placed at *list.
+ */
+static int rmqueue_bulk(struct zone *zone, unsigned int order,
+ unsigned long count, struct list_head *list,
+ int migratetype, unsigned int alloc_flags)
+{
+ unsigned long flags;
+ int i;
+
+ spin_lock_irqsave(&zone->lock, flags);
+ for (i = 0; i < count; ++i) {
+ struct page *page = __rmqueue(zone, order, migratetype,
+ alloc_flags);
+ if (unlikely(page == NULL))
+ break;
+
+ /*
+ * Split buddy pages returned by expand() are received here in
+ * physical page order. The page is added to the tail of
+ * caller's list. From the callers perspective, the linked list
+ * is ordered by page number under some conditions. This is
+ * useful for IO devices that can forward direction from the
+ * head, thus also in the physical page order. This is useful
+ * for IO devices that can merge IO requests if the physical
+ * pages are ordered properly.
+ */
+ list_add_tail(&page->pcp_list, list);
+ if (is_migrate_cma(get_pcppage_migratetype(page)))
+ __mod_zone_page_state(zone, NR_FREE_CMA_PAGES,
+ -(1 << order));
+ }
+
+ __mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order));
+ spin_unlock_irqrestore(&zone->lock, flags);
+
+ return i;
+}
+
+#ifdef CONFIG_NUMA
+/*
+ * Called from the vmstat counter updater to drain pagesets of this
+ * currently executing processor on remote nodes after they have
+ * expired.
+ */
+void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
+{
+ int to_drain, batch;
+
+ batch = READ_ONCE(pcp->batch);
+ to_drain = min(pcp->count, batch);
+ if (to_drain > 0) {
+ spin_lock(&pcp->lock);
+ free_pcppages_bulk(zone, to_drain, pcp, 0);
+ spin_unlock(&pcp->lock);
+ }
+}
+#endif
+
+/*
+ * Drain pcplists of the indicated processor and zone.
+ */
+static void drain_pages_zone(unsigned int cpu, struct zone *zone)
+{
+ struct per_cpu_pages *pcp;
+
+ pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
+ if (pcp->count) {
+ spin_lock(&pcp->lock);
+ free_pcppages_bulk(zone, pcp->count, pcp, 0);
+ spin_unlock(&pcp->lock);
+ }
+}
+
+/*
+ * Drain pcplists of all zones on the indicated processor.
+ */
+static void drain_pages(unsigned int cpu)
+{
+ struct zone *zone;
+
+ for_each_populated_zone(zone) {
+ drain_pages_zone(cpu, zone);
+ }
+}
+
+/*
+ * Spill all of this CPU's per-cpu pages back into the buddy allocator.
+ */
+void drain_local_pages(struct zone *zone)
+{
+ int cpu = smp_processor_id();
+
+ if (zone)
+ drain_pages_zone(cpu, zone);
+ else
+ drain_pages(cpu);
+}
+
+/*
+ * The implementation of drain_all_pages(), exposing an extra parameter to
+ * drain on all cpus.
+ *
+ * drain_all_pages() is optimized to only execute on cpus where pcplists are
+ * not empty. The check for non-emptiness can however race with a free to
+ * pcplist that has not yet increased the pcp->count from 0 to 1. Callers
+ * that need the guarantee that every CPU has drained can disable the
+ * optimizing racy check.
+ */
+static void __drain_all_pages(struct zone *zone, bool force_all_cpus)
+{
+ int cpu;
+
+ /*
+ * Allocate in the BSS so we won't require allocation in
+ * direct reclaim path for CONFIG_CPUMASK_OFFSTACK=y
+ */
+ static cpumask_t cpus_with_pcps;
+
+ /*
+ * Do not drain if one is already in progress unless it's specific to
+ * a zone. Such callers are primarily CMA and memory hotplug and need
+ * the drain to be complete when the call returns.
+ */
+ if (unlikely(!mutex_trylock(&pcpu_drain_mutex))) {
+ if (!zone)
+ return;
+ mutex_lock(&pcpu_drain_mutex);
+ }
+
+ /*
+ * We don't care about racing with CPU hotplug event
+ * as offline notification will cause the notified
+ * cpu to drain that CPU pcps and on_each_cpu_mask
+ * disables preemption as part of its processing
+ */
+ for_each_online_cpu(cpu) {
+ struct per_cpu_pages *pcp;
+ struct zone *z;
+ bool has_pcps = false;
+
+ if (force_all_cpus) {
+ /*
+ * The pcp.count check is racy, some callers need a
+ * guarantee that no cpu is missed.
+ */
+ has_pcps = true;
+ } else if (zone) {
+ pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
+ if (pcp->count)
+ has_pcps = true;
+ } else {
+ for_each_populated_zone(z) {
+ pcp = per_cpu_ptr(z->per_cpu_pageset, cpu);
+ if (pcp->count) {
+ has_pcps = true;
+ break;
+ }
+ }
+ }
+
+ if (has_pcps)
+ cpumask_set_cpu(cpu, &cpus_with_pcps);
+ else
+ cpumask_clear_cpu(cpu, &cpus_with_pcps);
+ }
+
+ for_each_cpu(cpu, &cpus_with_pcps) {
+ if (zone)
+ drain_pages_zone(cpu, zone);
+ else
+ drain_pages(cpu);
+ }
+
+ mutex_unlock(&pcpu_drain_mutex);
+}
+
+/*
+ * Spill all the per-cpu pages from all CPUs back into the buddy allocator.
+ *
+ * When zone parameter is non-NULL, spill just the single zone's pages.
+ */
+void drain_all_pages(struct zone *zone)
+{
+ __drain_all_pages(zone, false);
+}
+
+static bool free_unref_page_prepare(struct page *page, unsigned long pfn,
+ unsigned int order)
+{
+ int migratetype;
+
+ if (!free_pages_prepare(page, order, FPI_NONE))
+ return false;
+
+ migratetype = get_pfnblock_migratetype(page, pfn);
+ set_pcppage_migratetype(page, migratetype);
+ return true;
+}
+
+static int nr_pcp_free(struct per_cpu_pages *pcp, int high, bool free_high)
+{
+ int min_nr_free, max_nr_free;
+ int batch = READ_ONCE(pcp->batch);
+
+ /* Free everything if batch freeing high-order pages. */
+ if (unlikely(free_high))
+ return pcp->count;
+
+ /* Check for PCP disabled or boot pageset */
+ if (unlikely(high < batch))
+ return 1;
+
+ /* Leave at least pcp->batch pages on the list */
+ min_nr_free = batch;
+ max_nr_free = high - batch;
+
+ /*
+ * Double the number of pages freed each time there is subsequent
+ * freeing of pages without any allocation.
+ */
+ batch <<= pcp->free_factor;
+ if (batch < max_nr_free)
+ pcp->free_factor++;
+ batch = clamp(batch, min_nr_free, max_nr_free);
+
+ return batch;
+}
+
+static int nr_pcp_high(struct per_cpu_pages *pcp, struct zone *zone,
+ bool free_high)
+{
+ int high = READ_ONCE(pcp->high);
+
+ if (unlikely(!high || free_high))
+ return 0;
+
+ if (!test_bit(ZONE_RECLAIM_ACTIVE, &zone->flags))
+ return high;
+
+ /*
+ * If reclaim is active, limit the number of pages that can be
+ * stored on pcp lists
+ */
+ return min(READ_ONCE(pcp->batch) << 2, high);
+}
+
+static void free_unref_page_commit(struct zone *zone, struct per_cpu_pages *pcp,
+ struct page *page, int migratetype,
+ unsigned int order)
+{
+ int high;
+ int pindex;
+ bool free_high;
+
+ __count_vm_events(PGFREE, 1 << order);
+ pindex = order_to_pindex(migratetype, order);
+ list_add(&page->pcp_list, &pcp->lists[pindex]);
+ pcp->count += 1 << order;
+
+ /*
+ * As high-order pages other than THP's stored on PCP can contribute
+ * to fragmentation, limit the number stored when PCP is heavily
+ * freeing without allocation. The remainder after bulk freeing
+ * stops will be drained from vmstat refresh context.
+ */
+ free_high = (pcp->free_factor && order && order <= PAGE_ALLOC_COSTLY_ORDER);
+
+ high = nr_pcp_high(pcp, zone, free_high);
+ if (pcp->count >= high) {
+ free_pcppages_bulk(zone, nr_pcp_free(pcp, high, free_high), pcp, pindex);
+ }
+}
+
+/*
+ * Free a pcp page
+ */
+void free_unref_page(struct page *page, unsigned int order)
+{
+ unsigned long __maybe_unused UP_flags;
+ struct per_cpu_pages *pcp;
+ struct zone *zone;
+ unsigned long pfn = page_to_pfn(page);
+ int migratetype, pcpmigratetype;
+
+ if (!free_unref_page_prepare(page, pfn, order))
+ return;
+
+ /*
+ * We only track unmovable, reclaimable and movable on pcp lists.
+ * Place ISOLATE pages on the isolated list because they are being
+ * offlined but treat HIGHATOMIC and CMA as movable pages so we can
+ * get those areas back if necessary. Otherwise, we may have to free
+ * excessively into the page allocator
+ */
+ migratetype = pcpmigratetype = get_pcppage_migratetype(page);
+ if (unlikely(migratetype >= MIGRATE_PCPTYPES)) {
+ if (unlikely(is_migrate_isolate(migratetype))) {
+ free_one_page(page_zone(page), page, pfn, order, migratetype, FPI_NONE);
+ return;
+ }
+ pcpmigratetype = MIGRATE_MOVABLE;
+ }
+
+ zone = page_zone(page);
+ pcp_trylock_prepare(UP_flags);
+ pcp = pcp_spin_trylock(zone->per_cpu_pageset);
+ if (pcp) {
+ free_unref_page_commit(zone, pcp, page, pcpmigratetype, order);
+ pcp_spin_unlock(pcp);
+ } else {
+ free_one_page(zone, page, pfn, order, migratetype, FPI_NONE);
+ }
+ pcp_trylock_finish(UP_flags);
+}
+
+/*
+ * Free a list of 0-order pages
+ */
+void free_unref_page_list(struct list_head *list)
+{
+ unsigned long __maybe_unused UP_flags;
+ struct page *page, *next;
+ struct per_cpu_pages *pcp = NULL;
+ struct zone *locked_zone = NULL;
+ int batch_count = 0;
+ int migratetype;
+
+ /* Prepare pages for freeing */
+ list_for_each_entry_safe(page, next, list, lru) {
+ unsigned long pfn = page_to_pfn(page);
+ if (!free_unref_page_prepare(page, pfn, 0)) {
+ list_del(&page->lru);
+ continue;
+ }
+
+ /*
+ * Free isolated pages directly to the allocator, see
+ * comment in free_unref_page.
+ */
+ migratetype = get_pcppage_migratetype(page);
+ if (unlikely(is_migrate_isolate(migratetype))) {
+ list_del(&page->lru);
+ free_one_page(page_zone(page), page, pfn, 0, migratetype, FPI_NONE);
+ continue;
+ }
+ }
+
+ list_for_each_entry_safe(page, next, list, lru) {
+ struct zone *zone = page_zone(page);
+
+ list_del(&page->lru);
+ migratetype = get_pcppage_migratetype(page);
+
+ /*
+ * Either different zone requiring a different pcp lock or
+ * excessive lock hold times when freeing a large list of
+ * pages.
+ */
+ if (zone != locked_zone || batch_count == SWAP_CLUSTER_MAX) {
+ if (pcp) {
+ pcp_spin_unlock(pcp);
+ pcp_trylock_finish(UP_flags);
+ }
+
+ batch_count = 0;
+
+ /*
+ * trylock is necessary as pages may be getting freed
+ * from IRQ or SoftIRQ context after an IO completion.
+ */
+ pcp_trylock_prepare(UP_flags);
+ pcp = pcp_spin_trylock(zone->per_cpu_pageset);
+ if (unlikely(!pcp)) {
+ pcp_trylock_finish(UP_flags);
+ free_one_page(zone, page, page_to_pfn(page),
+ 0, migratetype, FPI_NONE);
+ locked_zone = NULL;
+ continue;
+ }
+ locked_zone = zone;
+ }
+
+ /*
+ * Non-isolated types over MIGRATE_PCPTYPES get added
+ * to the MIGRATE_MOVABLE pcp list.
+ */
+ if (unlikely(migratetype >= MIGRATE_PCPTYPES))
+ migratetype = MIGRATE_MOVABLE;
+
+ trace_mm_page_free_batched(page);
+ free_unref_page_commit(zone, pcp, page, migratetype, 0);
+ batch_count++;
+ }
+
+ if (pcp) {
+ pcp_spin_unlock(pcp);
+ pcp_trylock_finish(UP_flags);
+ }
+}
+
+/*
+ * split_page takes a non-compound higher-order page, and splits it into
+ * n (1<<order) sub-pages: page[0..n]
+ * Each sub-page must be freed individually.
+ *
+ * Note: this is probably too low level an operation for use in drivers.
+ * Please consult with lkml before using this in your driver.
+ */
+void split_page(struct page *page, unsigned int order)
+{
+ int i;
+
+ VM_BUG_ON_PAGE(PageCompound(page), page);
+ VM_BUG_ON_PAGE(!page_count(page), page);
+
+ for (i = 1; i < (1 << order); i++)
+ set_page_refcounted(page + i);
+ split_page_owner(page, 1 << order);
+ split_page_memcg(page, 1 << order);
+}
+EXPORT_SYMBOL_GPL(split_page);
+
+int __isolate_free_page(struct page *page, unsigned int order)
+{
+ struct zone *zone = page_zone(page);
+ int mt = get_pageblock_migratetype(page);
+
+ if (!is_migrate_isolate(mt)) {
+ unsigned long watermark;
+ /*
+ * Obey watermarks as if the page was being allocated. We can
+ * emulate a high-order watermark check with a raised order-0
+ * watermark, because we already know our high-order page
+ * exists.
+ */
+ watermark = zone->_watermark[WMARK_MIN] + (1UL << order);
+ if (!zone_watermark_ok(zone, 0, watermark, 0, ALLOC_CMA))
+ return 0;
+
+ __mod_zone_freepage_state(zone, -(1UL << order), mt);
+ }
+
+ del_page_from_free_list(page, zone, order);
+
+ /*
+ * Set the pageblock if the isolated page is at least half of a
+ * pageblock
+ */
+ if (order >= pageblock_order - 1) {
+ struct page *endpage = page + (1 << order) - 1;
+ for (; page < endpage; page += pageblock_nr_pages) {
+ int mt = get_pageblock_migratetype(page);
+ /*
+ * Only change normal pageblocks (i.e., they can merge
+ * with others)
+ */
+ if (migratetype_is_mergeable(mt))
+ set_pageblock_migratetype(page,
+ MIGRATE_MOVABLE);
+ }
+ }
+
+ return 1UL << order;
+}
+
+/**
+ * __putback_isolated_page - Return a now-isolated page back where we got it
+ * @page: Page that was isolated
+ * @order: Order of the isolated page
+ * @mt: The page's pageblock's migratetype
+ *
+ * This function is meant to return a page pulled from the free lists via
+ * __isolate_free_page back to the free lists they were pulled from.
+ */
+void __putback_isolated_page(struct page *page, unsigned int order, int mt)
+{
+ struct zone *zone = page_zone(page);
+
+ /* zone lock should be held when this function is called */
+ lockdep_assert_held(&zone->lock);
+
+ /* Return isolated page to tail of freelist. */
+ __free_one_page(page, page_to_pfn(page), zone, order, mt,
+ FPI_SKIP_REPORT_NOTIFY | FPI_TO_TAIL);
+}
+
+/*
+ * Update NUMA hit/miss statistics
+ */
+static inline void zone_statistics(struct zone *preferred_zone, struct zone *z,
+ long nr_account)
+{
+#ifdef CONFIG_NUMA
+ enum numa_stat_item local_stat = NUMA_LOCAL;
+
+ /* skip numa counters update if numa stats is disabled */
+ if (!static_branch_likely(&vm_numa_stat_key))
+ return;
+
+ if (zone_to_nid(z) != numa_node_id())
+ local_stat = NUMA_OTHER;
+
+ if (zone_to_nid(z) == zone_to_nid(preferred_zone))
+ __count_numa_events(z, NUMA_HIT, nr_account);
+ else {
+ __count_numa_events(z, NUMA_MISS, nr_account);
+ __count_numa_events(preferred_zone, NUMA_FOREIGN, nr_account);
+ }
+ __count_numa_events(z, local_stat, nr_account);
+#endif
+}
+
+static __always_inline
+struct page *rmqueue_buddy(struct zone *preferred_zone, struct zone *zone,
+ unsigned int order, unsigned int alloc_flags,
+ int migratetype)
+{
+ struct page *page;
+ unsigned long flags;
+
+ do {
+ page = NULL;
+ spin_lock_irqsave(&zone->lock, flags);
+ if (alloc_flags & ALLOC_HIGHATOMIC)
+ page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
+ if (!page) {
+ page = __rmqueue(zone, order, migratetype, alloc_flags);
+
+ /*
+ * If the allocation fails, allow OOM handling access
+ * to HIGHATOMIC reserves as failing now is worse than
+ * failing a high-order atomic allocation in the
+ * future.
+ */
+ if (!page && (alloc_flags & ALLOC_OOM))
+ page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
+
+ if (!page) {
+ spin_unlock_irqrestore(&zone->lock, flags);
+ return NULL;
+ }
+ }
+ __mod_zone_freepage_state(zone, -(1 << order),
+ get_pcppage_migratetype(page));
+ spin_unlock_irqrestore(&zone->lock, flags);
+ } while (check_new_pages(page, order));
+
+ __count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order);
+ zone_statistics(preferred_zone, zone, 1);
+
+ return page;
+}
+
+/* Remove page from the per-cpu list, caller must protect the list */
+static inline
+struct page *__rmqueue_pcplist(struct zone *zone, unsigned int order,
+ int migratetype,
+ unsigned int alloc_flags,
+ struct per_cpu_pages *pcp,
+ struct list_head *list)
+{
+ struct page *page;
+
+ do {
+ if (list_empty(list)) {
+ int batch = READ_ONCE(pcp->batch);
+ int alloced;
+
+ /*
+ * Scale batch relative to order if batch implies
+ * free pages can be stored on the PCP. Batch can
+ * be 1 for small zones or for boot pagesets which
+ * should never store free pages as the pages may
+ * belong to arbitrary zones.
+ */
+ if (batch > 1)
+ batch = max(batch >> order, 2);
+ alloced = rmqueue_bulk(zone, order,
+ batch, list,
+ migratetype, alloc_flags);
+
+ pcp->count += alloced << order;
+ if (unlikely(list_empty(list)))
+ return NULL;
+ }
+
+ page = list_first_entry(list, struct page, pcp_list);
+ list_del(&page->pcp_list);
+ pcp->count -= 1 << order;
+ } while (check_new_pages(page, order));
+
+ return page;
+}
+
+/* Lock and remove page from the per-cpu list */
+static struct page *rmqueue_pcplist(struct zone *preferred_zone,
+ struct zone *zone, unsigned int order,
+ int migratetype, unsigned int alloc_flags)
+{
+ struct per_cpu_pages *pcp;
+ struct list_head *list;
+ struct page *page;
+ unsigned long __maybe_unused UP_flags;
+
+ /* spin_trylock may fail due to a parallel drain or IRQ reentrancy. */
+ pcp_trylock_prepare(UP_flags);
+ pcp = pcp_spin_trylock(zone->per_cpu_pageset);
+ if (!pcp) {
+ pcp_trylock_finish(UP_flags);
+ return NULL;
+ }
+
+ /*
+ * On allocation, reduce the number of pages that are batch freed.
+ * See nr_pcp_free() where free_factor is increased for subsequent
+ * frees.
+ */
+ pcp->free_factor >>= 1;
+ list = &pcp->lists[order_to_pindex(migratetype, order)];
+ page = __rmqueue_pcplist(zone, order, migratetype, alloc_flags, pcp, list);
+ pcp_spin_unlock(pcp);
+ pcp_trylock_finish(UP_flags);
+ if (page) {
+ __count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order);
+ zone_statistics(preferred_zone, zone, 1);
+ }
+ return page;
+}
+
+/*
+ * Allocate a page from the given zone.
+ * Use pcplists for THP or "cheap" high-order allocations.
+ */
+
+/*
+ * Do not instrument rmqueue() with KMSAN. This function may call
+ * __msan_poison_alloca() through a call to set_pfnblock_flags_mask().
+ * If __msan_poison_alloca() attempts to allocate pages for the stack depot, it
+ * may call rmqueue() again, which will result in a deadlock.
+ */
+__no_sanitize_memory
+static inline
+struct page *rmqueue(struct zone *preferred_zone,
+ struct zone *zone, unsigned int order,
+ gfp_t gfp_flags, unsigned int alloc_flags,
+ int migratetype)
+{
+ struct page *page;
+
+ /*
+ * We most definitely don't want callers attempting to
+ * allocate greater than order-1 page units with __GFP_NOFAIL.
+ */
+ WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1));
+
+ if (likely(pcp_allowed_order(order))) {
+ page = rmqueue_pcplist(preferred_zone, zone, order,
+ migratetype, alloc_flags);
+ if (likely(page))
+ goto out;
+ }
+
+ page = rmqueue_buddy(preferred_zone, zone, order, alloc_flags,
+ migratetype);
+
+out:
+ /* Separate test+clear to avoid unnecessary atomics */
+ if ((alloc_flags & ALLOC_KSWAPD) &&
+ unlikely(test_bit(ZONE_BOOSTED_WATERMARK, &zone->flags))) {
+ clear_bit(ZONE_BOOSTED_WATERMARK, &zone->flags);
+ wakeup_kswapd(zone, 0, 0, zone_idx(zone));
+ }
+
+ VM_BUG_ON_PAGE(page && bad_range(zone, page), page);
+ return page;
+}
+
+noinline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
+{
+ return __should_fail_alloc_page(gfp_mask, order);
+}
+ALLOW_ERROR_INJECTION(should_fail_alloc_page, TRUE);
+
+static inline long __zone_watermark_unusable_free(struct zone *z,
+ unsigned int order, unsigned int alloc_flags)
+{
+ long unusable_free = (1 << order) - 1;
+
+ /*
+ * If the caller does not have rights to reserves below the min
+ * watermark then subtract the high-atomic reserves. This will
+ * over-estimate the size of the atomic reserve but it avoids a search.
+ */
+ if (likely(!(alloc_flags & ALLOC_RESERVES)))
+ unusable_free += z->nr_reserved_highatomic;
+
+#ifdef CONFIG_CMA
+ /* If allocation can't use CMA areas don't use free CMA pages */
+ if (!(alloc_flags & ALLOC_CMA))
+ unusable_free += zone_page_state(z, NR_FREE_CMA_PAGES);
+#endif
+#ifdef CONFIG_UNACCEPTED_MEMORY
+ unusable_free += zone_page_state(z, NR_UNACCEPTED);
+#endif
+
+ return unusable_free;
+}
+
+/*
+ * Return true if free base pages are above 'mark'. For high-order checks it
+ * will return true of the order-0 watermark is reached and there is at least
+ * one free page of a suitable size. Checking now avoids taking the zone lock
+ * to check in the allocation paths if no pages are free.
+ */
+bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
+ int highest_zoneidx, unsigned int alloc_flags,
+ long free_pages)
+{
+ long min = mark;
+ int o;
+
+ /* free_pages may go negative - that's OK */
+ free_pages -= __zone_watermark_unusable_free(z, order, alloc_flags);
+
+ if (unlikely(alloc_flags & ALLOC_RESERVES)) {
+ /*
+ * __GFP_HIGH allows access to 50% of the min reserve as well
+ * as OOM.
+ */
+ if (alloc_flags & ALLOC_MIN_RESERVE) {
+ min -= min / 2;
+
+ /*
+ * Non-blocking allocations (e.g. GFP_ATOMIC) can
+ * access more reserves than just __GFP_HIGH. Other
+ * non-blocking allocations requests such as GFP_NOWAIT
+ * or (GFP_KERNEL & ~__GFP_DIRECT_RECLAIM) do not get
+ * access to the min reserve.
+ */
+ if (alloc_flags & ALLOC_NON_BLOCK)
+ min -= min / 4;
+ }
+
+ /*
+ * OOM victims can try even harder than the normal reserve
+ * users on the grounds that it's definitely going to be in
+ * the exit path shortly and free memory. Any allocation it
+ * makes during the free path will be small and short-lived.
+ */
+ if (alloc_flags & ALLOC_OOM)
+ min -= min / 2;
+ }
+
+ /*
+ * Check watermarks for an order-0 allocation request. If these
+ * are not met, then a high-order request also cannot go ahead
+ * even if a suitable page happened to be free.
+ */
+ if (free_pages <= min + z->lowmem_reserve[highest_zoneidx])
+ return false;
+
+ /* If this is an order-0 request then the watermark is fine */
+ if (!order)
+ return true;
+
+ /* For a high-order request, check at least one suitable page is free */
+ for (o = order; o <= MAX_ORDER; o++) {
+ struct free_area *area = &z->free_area[o];
+ int mt;
+
+ if (!area->nr_free)
+ continue;
+
+ for (mt = 0; mt < MIGRATE_PCPTYPES; mt++) {
+ if (!free_area_empty(area, mt))
+ return true;
+ }
+
+#ifdef CONFIG_CMA
+ if ((alloc_flags & ALLOC_CMA) &&
+ !free_area_empty(area, MIGRATE_CMA)) {
+ return true;
+ }
+#endif
+ if ((alloc_flags & (ALLOC_HIGHATOMIC|ALLOC_OOM)) &&
+ !free_area_empty(area, MIGRATE_HIGHATOMIC)) {
+ return true;
+ }
+ }
+ return false;
+}
+
+bool zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
+ int highest_zoneidx, unsigned int alloc_flags)
+{
+ return __zone_watermark_ok(z, order, mark, highest_zoneidx, alloc_flags,
+ zone_page_state(z, NR_FREE_PAGES));
+}
+
+static inline bool zone_watermark_fast(struct zone *z, unsigned int order,
+ unsigned long mark, int highest_zoneidx,
+ unsigned int alloc_flags, gfp_t gfp_mask)
+{
+ long free_pages;
+
+ free_pages = zone_page_state(z, NR_FREE_PAGES);
+
+ /*
+ * Fast check for order-0 only. If this fails then the reserves
+ * need to be calculated.
+ */
+ if (!order) {
+ long usable_free;
+ long reserved;
+
+ usable_free = free_pages;
+ reserved = __zone_watermark_unusable_free(z, 0, alloc_flags);
+
+ /* reserved may over estimate high-atomic reserves. */
+ usable_free -= min(usable_free, reserved);
+ if (usable_free > mark + z->lowmem_reserve[highest_zoneidx])
+ return true;
+ }
+
+ if (__zone_watermark_ok(z, order, mark, highest_zoneidx, alloc_flags,
+ free_pages))
+ return true;
+
+ /*
+ * Ignore watermark boosting for __GFP_HIGH order-0 allocations
+ * when checking the min watermark. The min watermark is the
+ * point where boosting is ignored so that kswapd is woken up
+ * when below the low watermark.
+ */
+ if (unlikely(!order && (alloc_flags & ALLOC_MIN_RESERVE) && z->watermark_boost
+ && ((alloc_flags & ALLOC_WMARK_MASK) == WMARK_MIN))) {
+ mark = z->_watermark[WMARK_MIN];
+ return __zone_watermark_ok(z, order, mark, highest_zoneidx,
+ alloc_flags, free_pages);
+ }
+
+ return false;
+}
+
+bool zone_watermark_ok_safe(struct zone *z, unsigned int order,
+ unsigned long mark, int highest_zoneidx)
+{
+ long free_pages = zone_page_state(z, NR_FREE_PAGES);
+
+ if (z->percpu_drift_mark && free_pages < z->percpu_drift_mark)
+ free_pages = zone_page_state_snapshot(z, NR_FREE_PAGES);
+
+ return __zone_watermark_ok(z, order, mark, highest_zoneidx, 0,
+ free_pages);
+}
+
+#ifdef CONFIG_NUMA
+int __read_mostly node_reclaim_distance = RECLAIM_DISTANCE;
+
+static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
+{
+ return node_distance(zone_to_nid(local_zone), zone_to_nid(zone)) <=
+ node_reclaim_distance;
+}
+#else /* CONFIG_NUMA */
+static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
+{
+ return true;
+}
+#endif /* CONFIG_NUMA */
+
+/*
+ * The restriction on ZONE_DMA32 as being a suitable zone to use to avoid
+ * fragmentation is subtle. If the preferred zone was HIGHMEM then
+ * premature use of a lower zone may cause lowmem pressure problems that
+ * are worse than fragmentation. If the next zone is ZONE_DMA then it is
+ * probably too small. It only makes sense to spread allocations to avoid
+ * fragmentation between the Normal and DMA32 zones.
+ */
+static inline unsigned int
+alloc_flags_nofragment(struct zone *zone, gfp_t gfp_mask)
+{
+ unsigned int alloc_flags;
+
+ /*
+ * __GFP_KSWAPD_RECLAIM is assumed to be the same as ALLOC_KSWAPD
+ * to save a branch.
+ */
+ alloc_flags = (__force int) (gfp_mask & __GFP_KSWAPD_RECLAIM);
+
+#ifdef CONFIG_ZONE_DMA32
+ if (!zone)
+ return alloc_flags;
+
+ if (zone_idx(zone) != ZONE_NORMAL)
+ return alloc_flags;
+
+ /*
+ * If ZONE_DMA32 exists, assume it is the one after ZONE_NORMAL and
+ * the pointer is within zone->zone_pgdat->node_zones[]. Also assume
+ * on UMA that if Normal is populated then so is DMA32.
+ */
+ BUILD_BUG_ON(ZONE_NORMAL - ZONE_DMA32 != 1);
+ if (nr_online_nodes > 1 && !populated_zone(--zone))
+ return alloc_flags;
+
+ alloc_flags |= ALLOC_NOFRAGMENT;
+#endif /* CONFIG_ZONE_DMA32 */
+ return alloc_flags;
+}
+
+/* Must be called after current_gfp_context() which can change gfp_mask */
+static inline unsigned int gfp_to_alloc_flags_cma(gfp_t gfp_mask,
+ unsigned int alloc_flags)
+{
+#ifdef CONFIG_CMA
+ if (gfp_migratetype(gfp_mask) == MIGRATE_MOVABLE)
+ alloc_flags |= ALLOC_CMA;
+#endif
+ return alloc_flags;
+}
+
+/*
+ * get_page_from_freelist goes through the zonelist trying to allocate
+ * a page.
+ */
+static struct page *
+get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
+ const struct alloc_context *ac)
+{
+ struct zoneref *z;
+ struct zone *zone;
+ struct pglist_data *last_pgdat = NULL;
+ bool last_pgdat_dirty_ok = false;
+ bool no_fallback;
+
+retry:
+ /*
+ * Scan zonelist, looking for a zone with enough free.
+ * See also cpuset_node_allowed() comment in kernel/cgroup/cpuset.c.
+ */
+ no_fallback = alloc_flags & ALLOC_NOFRAGMENT;
+ z = ac->preferred_zoneref;
+ for_next_zone_zonelist_nodemask(zone, z, ac->highest_zoneidx,
+ ac->nodemask) {
+ struct page *page;
+ unsigned long mark;
+
+ if (cpusets_enabled() &&
+ (alloc_flags & ALLOC_CPUSET) &&
+ !__cpuset_zone_allowed(zone, gfp_mask))
+ continue;
+ /*
+ * When allocating a page cache page for writing, we
+ * want to get it from a node that is within its dirty
+ * limit, such that no single node holds more than its
+ * proportional share of globally allowed dirty pages.
+ * The dirty limits take into account the node's
+ * lowmem reserves and high watermark so that kswapd
+ * should be able to balance it without having to
+ * write pages from its LRU list.
+ *
+ * XXX: For now, allow allocations to potentially
+ * exceed the per-node dirty limit in the slowpath
+ * (spread_dirty_pages unset) before going into reclaim,
+ * which is important when on a NUMA setup the allowed
+ * nodes are together not big enough to reach the
+ * global limit. The proper fix for these situations
+ * will require awareness of nodes in the
+ * dirty-throttling and the flusher threads.
+ */
+ if (ac->spread_dirty_pages) {
+ if (last_pgdat != zone->zone_pgdat) {
+ last_pgdat = zone->zone_pgdat;
+ last_pgdat_dirty_ok = node_dirty_ok(zone->zone_pgdat);
+ }
+
+ if (!last_pgdat_dirty_ok)
+ continue;
+ }
+
+ if (no_fallback && nr_online_nodes > 1 &&
+ zone != ac->preferred_zoneref->zone) {
+ int local_nid;
+
+ /*
+ * If moving to a remote node, retry but allow
+ * fragmenting fallbacks. Locality is more important
+ * than fragmentation avoidance.
+ */
+ local_nid = zone_to_nid(ac->preferred_zoneref->zone);
+ if (zone_to_nid(zone) != local_nid) {
+ alloc_flags &= ~ALLOC_NOFRAGMENT;
+ goto retry;
+ }
+ }
+
+ mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK);
+ if (!zone_watermark_fast(zone, order, mark,
+ ac->highest_zoneidx, alloc_flags,
+ gfp_mask)) {
+ int ret;
+
+ if (has_unaccepted_memory()) {
+ if (try_to_accept_memory(zone, order))
+ goto try_this_zone;
+ }
+
+#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
+ /*
+ * Watermark failed for this zone, but see if we can
+ * grow this zone if it contains deferred pages.
+ */
+ if (deferred_pages_enabled()) {
+ if (_deferred_grow_zone(zone, order))
+ goto try_this_zone;
+ }
+#endif
+ /* Checked here to keep the fast path fast */
+ BUILD_BUG_ON(ALLOC_NO_WATERMARKS < NR_WMARK);
+ if (alloc_flags & ALLOC_NO_WATERMARKS)
+ goto try_this_zone;
+
+ if (!node_reclaim_enabled() ||
+ !zone_allows_reclaim(ac->preferred_zoneref->zone, zone))
+ continue;
+
+ ret = node_reclaim(zone->zone_pgdat, gfp_mask, order);
+ switch (ret) {
+ case NODE_RECLAIM_NOSCAN:
+ /* did not scan */
+ continue;
+ case NODE_RECLAIM_FULL:
+ /* scanned but unreclaimable */
+ continue;
+ default:
+ /* did we reclaim enough */
+ if (zone_watermark_ok(zone, order, mark,
+ ac->highest_zoneidx, alloc_flags))
+ goto try_this_zone;
+
+ continue;
+ }
+ }
+
+try_this_zone:
+ page = rmqueue(ac->preferred_zoneref->zone, zone, order,
+ gfp_mask, alloc_flags, ac->migratetype);
+ if (page) {
+ prep_new_page(page, order, gfp_mask, alloc_flags);
+
+ /*
+ * If this is a high-order atomic allocation then check
+ * if the pageblock should be reserved for the future
+ */
+ if (unlikely(alloc_flags & ALLOC_HIGHATOMIC))
+ reserve_highatomic_pageblock(page, zone);
+
+ return page;
+ } else {
+ if (has_unaccepted_memory()) {
+ if (try_to_accept_memory(zone, order))
+ goto try_this_zone;
+ }
+
+#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
+ /* Try again if zone has deferred pages */
+ if (deferred_pages_enabled()) {
+ if (_deferred_grow_zone(zone, order))
+ goto try_this_zone;
+ }
+#endif
+ }
+ }
+
+ /*
+ * It's possible on a UMA machine to get through all zones that are
+ * fragmented. If avoiding fragmentation, reset and try again.
+ */
+ if (no_fallback) {
+ alloc_flags &= ~ALLOC_NOFRAGMENT;
+ goto retry;
+ }
+
+ return NULL;
+}
+
+static void warn_alloc_show_mem(gfp_t gfp_mask, nodemask_t *nodemask)
+{
+ unsigned int filter = SHOW_MEM_FILTER_NODES;
+
+ /*
+ * This documents exceptions given to allocations in certain
+ * contexts that are allowed to allocate outside current's set
+ * of allowed nodes.
+ */
+ if (!(gfp_mask & __GFP_NOMEMALLOC))
+ if (tsk_is_oom_victim(current) ||
+ (current->flags & (PF_MEMALLOC | PF_EXITING)))
+ filter &= ~SHOW_MEM_FILTER_NODES;
+ if (!in_task() || !(gfp_mask & __GFP_DIRECT_RECLAIM))
+ filter &= ~SHOW_MEM_FILTER_NODES;
+
+ __show_mem(filter, nodemask, gfp_zone(gfp_mask));
+}
+
+void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)
+{
+ struct va_format vaf;
+ va_list args;
+ static DEFINE_RATELIMIT_STATE(nopage_rs, 10*HZ, 1);
+
+ if ((gfp_mask & __GFP_NOWARN) ||
+ !__ratelimit(&nopage_rs) ||
+ ((gfp_mask & __GFP_DMA) && !has_managed_dma()))
+ return;
+
+ va_start(args, fmt);
+ vaf.fmt = fmt;
+ vaf.va = &args;
+ pr_warn("%s: %pV, mode:%#x(%pGg), nodemask=%*pbl",
+ current->comm, &vaf, gfp_mask, &gfp_mask,
+ nodemask_pr_args(nodemask));
+ va_end(args);
+
+ cpuset_print_current_mems_allowed();
+ pr_cont("\n");
+ dump_stack();
+ warn_alloc_show_mem(gfp_mask, nodemask);
+}
+
+static inline struct page *
+__alloc_pages_cpuset_fallback(gfp_t gfp_mask, unsigned int order,
+ unsigned int alloc_flags,
+ const struct alloc_context *ac)
+{
+ struct page *page;
+
+ page = get_page_from_freelist(gfp_mask, order,
+ alloc_flags|ALLOC_CPUSET, ac);
+ /*
+ * fallback to ignore cpuset restriction if our nodes
+ * are depleted
+ */
+ if (!page)
+ page = get_page_from_freelist(gfp_mask, order,
+ alloc_flags, ac);
+
+ return page;
+}
+
+static inline struct page *
+__alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
+ const struct alloc_context *ac, unsigned long *did_some_progress)
+{
+ struct oom_control oc = {
+ .zonelist = ac->zonelist,
+ .nodemask = ac->nodemask,
+ .memcg = NULL,
+ .gfp_mask = gfp_mask,
+ .order = order,
+ };
+ struct page *page;
+
+ *did_some_progress = 0;
+
+ /*
+ * Acquire the oom lock. If that fails, somebody else is
+ * making progress for us.
+ */
+ if (!mutex_trylock(&oom_lock)) {
+ *did_some_progress = 1;
+ schedule_timeout_uninterruptible(1);
+ return NULL;
+ }
+
+ /*
+ * Go through the zonelist yet one more time, keep very high watermark
+ * here, this is only to catch a parallel oom killing, we must fail if
+ * we're still under heavy pressure. But make sure that this reclaim
+ * attempt shall not depend on __GFP_DIRECT_RECLAIM && !__GFP_NORETRY
+ * allocation which will never fail due to oom_lock already held.
+ */
+ page = get_page_from_freelist((gfp_mask | __GFP_HARDWALL) &
+ ~__GFP_DIRECT_RECLAIM, order,
+ ALLOC_WMARK_HIGH|ALLOC_CPUSET, ac);
+ if (page)
+ goto out;
+
+ /* Coredumps can quickly deplete all memory reserves */
+ if (current->flags & PF_DUMPCORE)
+ goto out;
+ /* The OOM killer will not help higher order allocs */
+ if (order > PAGE_ALLOC_COSTLY_ORDER)
+ goto out;
+ /*
+ * We have already exhausted all our reclaim opportunities without any
+ * success so it is time to admit defeat. We will skip the OOM killer
+ * because it is very likely that the caller has a more reasonable
+ * fallback than shooting a random task.
+ *
+ * The OOM killer may not free memory on a specific node.
+ */
+ if (gfp_mask & (__GFP_RETRY_MAYFAIL | __GFP_THISNODE))
+ goto out;
+ /* The OOM killer does not needlessly kill tasks for lowmem */
+ if (ac->highest_zoneidx < ZONE_NORMAL)
+ goto out;
+ if (pm_suspended_storage())
+ goto out;
+ /*
+ * XXX: GFP_NOFS allocations should rather fail than rely on
+ * other request to make a forward progress.
+ * We are in an unfortunate situation where out_of_memory cannot
+ * do much for this context but let's try it to at least get
+ * access to memory reserved if the current task is killed (see
+ * out_of_memory). Once filesystems are ready to handle allocation
+ * failures more gracefully we should just bail out here.
+ */
+
+ /* Exhausted what can be done so it's blame time */
+ if (out_of_memory(&oc) ||
+ WARN_ON_ONCE_GFP(gfp_mask & __GFP_NOFAIL, gfp_mask)) {
+ *did_some_progress = 1;
+
+ /*
+ * Help non-failing allocations by giving them access to memory
+ * reserves
+ */
+ if (gfp_mask & __GFP_NOFAIL)
+ page = __alloc_pages_cpuset_fallback(gfp_mask, order,
+ ALLOC_NO_WATERMARKS, ac);
+ }
+out:
+ mutex_unlock(&oom_lock);
+ return page;
+}
+
+/*
+ * Maximum number of compaction retries with a progress before OOM
+ * killer is consider as the only way to move forward.
+ */
+#define MAX_COMPACT_RETRIES 16
+
+#ifdef CONFIG_COMPACTION
+/* Try memory compaction for high-order allocations before reclaim */
+static struct page *
+__alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
+ unsigned int alloc_flags, const struct alloc_context *ac,
+ enum compact_priority prio, enum compact_result *compact_result)
+{
+ struct page *page = NULL;
+ unsigned long pflags;
+ unsigned int noreclaim_flag;
+
+ if (!order)
+ return NULL;
+
+ psi_memstall_enter(&pflags);
+ delayacct_compact_start();
+ noreclaim_flag = memalloc_noreclaim_save();
+
+ *compact_result = try_to_compact_pages(gfp_mask, order, alloc_flags, ac,
+ prio, &page);
+
+ memalloc_noreclaim_restore(noreclaim_flag);
+ psi_memstall_leave(&pflags);
+ delayacct_compact_end();
+
+ if (*compact_result == COMPACT_SKIPPED)
+ return NULL;
+ /*
+ * At least in one zone compaction wasn't deferred or skipped, so let's
+ * count a compaction stall
+ */
+ count_vm_event(COMPACTSTALL);
+
+ /* Prep a captured page if available */
+ if (page)
+ prep_new_page(page, order, gfp_mask, alloc_flags);
+
+ /* Try get a page from the freelist if available */
+ if (!page)
+ page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
+
+ if (page) {
+ struct zone *zone = page_zone(page);
+
+ zone->compact_blockskip_flush = false;
+ compaction_defer_reset(zone, order, true);
+ count_vm_event(COMPACTSUCCESS);
+ return page;
+ }
+
+ /*
+ * It's bad if compaction run occurs and fails. The most likely reason
+ * is that pages exist, but not enough to satisfy watermarks.
+ */
+ count_vm_event(COMPACTFAIL);
+
+ cond_resched();
+
+ return NULL;
+}
+
+static inline bool
+should_compact_retry(struct alloc_context *ac, int order, int alloc_flags,
+ enum compact_result compact_result,
+ enum compact_priority *compact_priority,
+ int *compaction_retries)
+{
+ int max_retries = MAX_COMPACT_RETRIES;
+ int min_priority;
+ bool ret = false;
+ int retries = *compaction_retries;
+ enum compact_priority priority = *compact_priority;
+
+ if (!order)
+ return false;
+
+ if (fatal_signal_pending(current))
+ return false;
+
+ /*
+ * Compaction was skipped due to a lack of free order-0
+ * migration targets. Continue if reclaim can help.
+ */
+ if (compact_result == COMPACT_SKIPPED) {
+ ret = compaction_zonelist_suitable(ac, order, alloc_flags);
+ goto out;
+ }
+
+ /*
+ * Compaction managed to coalesce some page blocks, but the
+ * allocation failed presumably due to a race. Retry some.
+ */
+ if (compact_result == COMPACT_SUCCESS) {
+ /*
+ * !costly requests are much more important than
+ * __GFP_RETRY_MAYFAIL costly ones because they are de
+ * facto nofail and invoke OOM killer to move on while
+ * costly can fail and users are ready to cope with
+ * that. 1/4 retries is rather arbitrary but we would
+ * need much more detailed feedback from compaction to
+ * make a better decision.
+ */
+ if (order > PAGE_ALLOC_COSTLY_ORDER)
+ max_retries /= 4;
+
+ if (++(*compaction_retries) <= max_retries) {
+ ret = true;
+ goto out;
+ }
+ }
+
+ /*
+ * Compaction failed. Retry with increasing priority.
+ */
+ min_priority = (order > PAGE_ALLOC_COSTLY_ORDER) ?
+ MIN_COMPACT_COSTLY_PRIORITY : MIN_COMPACT_PRIORITY;
+
+ if (*compact_priority > min_priority) {
+ (*compact_priority)--;
+ *compaction_retries = 0;
+ ret = true;
+ }
+out:
+ trace_compact_retry(order, priority, compact_result, retries, max_retries, ret);
+ return ret;
+}
+#else
+static inline struct page *
+__alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
+ unsigned int alloc_flags, const struct alloc_context *ac,
+ enum compact_priority prio, enum compact_result *compact_result)
+{
+ *compact_result = COMPACT_SKIPPED;
+ return NULL;
+}
+
+static inline bool
+should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_flags,
+ enum compact_result compact_result,
+ enum compact_priority *compact_priority,
+ int *compaction_retries)
+{
+ struct zone *zone;
+ struct zoneref *z;
+
+ if (!order || order > PAGE_ALLOC_COSTLY_ORDER)
+ return false;
+
+ /*
+ * There are setups with compaction disabled which would prefer to loop
+ * inside the allocator rather than hit the oom killer prematurely.
+ * Let's give them a good hope and keep retrying while the order-0
+ * watermarks are OK.
+ */
+ for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
+ ac->highest_zoneidx, ac->nodemask) {
+ if (zone_watermark_ok(zone, 0, min_wmark_pages(zone),
+ ac->highest_zoneidx, alloc_flags))
+ return true;
+ }
+ return false;
+}
+#endif /* CONFIG_COMPACTION */
+
+#ifdef CONFIG_LOCKDEP
+static struct lockdep_map __fs_reclaim_map =
+ STATIC_LOCKDEP_MAP_INIT("fs_reclaim", &__fs_reclaim_map);
+
+static bool __need_reclaim(gfp_t gfp_mask)
+{
+ /* no reclaim without waiting on it */
+ if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
+ return false;
+
+ /* this guy won't enter reclaim */
+ if (current->flags & PF_MEMALLOC)
+ return false;
+
+ if (gfp_mask & __GFP_NOLOCKDEP)
+ return false;
+
+ return true;
+}
+
+void __fs_reclaim_acquire(unsigned long ip)
+{
+ lock_acquire_exclusive(&__fs_reclaim_map, 0, 0, NULL, ip);
+}
+
+void __fs_reclaim_release(unsigned long ip)
+{
+ lock_release(&__fs_reclaim_map, ip);
+}
+
+void fs_reclaim_acquire(gfp_t gfp_mask)
+{
+ gfp_mask = current_gfp_context(gfp_mask);
+
+ if (__need_reclaim(gfp_mask)) {
+ if (gfp_mask & __GFP_FS)
+ __fs_reclaim_acquire(_RET_IP_);
+
+#ifdef CONFIG_MMU_NOTIFIER
+ lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
+ lock_map_release(&__mmu_notifier_invalidate_range_start_map);
+#endif
+
+ }
+}
+EXPORT_SYMBOL_GPL(fs_reclaim_acquire);
+
+void fs_reclaim_release(gfp_t gfp_mask)
+{
+ gfp_mask = current_gfp_context(gfp_mask);
+
+ if (__need_reclaim(gfp_mask)) {
+ if (gfp_mask & __GFP_FS)
+ __fs_reclaim_release(_RET_IP_);
+ }
+}
+EXPORT_SYMBOL_GPL(fs_reclaim_release);
+#endif
+
+/*
+ * Zonelists may change due to hotplug during allocation. Detect when zonelists
+ * have been rebuilt so allocation retries. Reader side does not lock and
+ * retries the allocation if zonelist changes. Writer side is protected by the
+ * embedded spin_lock.
+ */
+static DEFINE_SEQLOCK(zonelist_update_seq);
+
+static unsigned int zonelist_iter_begin(void)
+{
+ if (IS_ENABLED(CONFIG_MEMORY_HOTREMOVE))
+ return read_seqbegin(&zonelist_update_seq);
+
+ return 0;
+}
+
+static unsigned int check_retry_zonelist(unsigned int seq)
+{
+ if (IS_ENABLED(CONFIG_MEMORY_HOTREMOVE))
+ return read_seqretry(&zonelist_update_seq, seq);
+
+ return seq;
+}
+
+/* Perform direct synchronous page reclaim */
+static unsigned long
+__perform_reclaim(gfp_t gfp_mask, unsigned int order,
+ const struct alloc_context *ac)
+{
+ unsigned int noreclaim_flag;
+ unsigned long progress;
+
+ cond_resched();
+
+ /* We now go into synchronous reclaim */
+ cpuset_memory_pressure_bump();
+ fs_reclaim_acquire(gfp_mask);
+ noreclaim_flag = memalloc_noreclaim_save();
+
+ progress = try_to_free_pages(ac->zonelist, order, gfp_mask,
+ ac->nodemask);
+
+ memalloc_noreclaim_restore(noreclaim_flag);
+ fs_reclaim_release(gfp_mask);
+
+ cond_resched();
+
+ return progress;
+}
+
+/* The really slow allocator path where we enter direct reclaim */
+static inline struct page *
+__alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order,
+ unsigned int alloc_flags, const struct alloc_context *ac,
+ unsigned long *did_some_progress)
+{
+ struct page *page = NULL;
+ unsigned long pflags;
+ bool drained = false;
+
+ psi_memstall_enter(&pflags);
+ *did_some_progress = __perform_reclaim(gfp_mask, order, ac);
+ if (unlikely(!(*did_some_progress)))
+ goto out;
+
+retry:
+ page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
+
+ /*
+ * If an allocation failed after direct reclaim, it could be because
+ * pages are pinned on the per-cpu lists or in high alloc reserves.
+ * Shrink them and try again
+ */
+ if (!page && !drained) {
+ unreserve_highatomic_pageblock(ac, false);
+ drain_all_pages(NULL);
+ drained = true;
+ goto retry;
+ }
+out:
+ psi_memstall_leave(&pflags);
+
+ return page;
+}
+
+static void wake_all_kswapds(unsigned int order, gfp_t gfp_mask,
+ const struct alloc_context *ac)
+{
+ struct zoneref *z;
+ struct zone *zone;
+ pg_data_t *last_pgdat = NULL;
+ enum zone_type highest_zoneidx = ac->highest_zoneidx;
+
+ for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, highest_zoneidx,
+ ac->nodemask) {
+ if (!managed_zone(zone))
+ continue;
+ if (last_pgdat != zone->zone_pgdat) {
+ wakeup_kswapd(zone, gfp_mask, order, highest_zoneidx);
+ last_pgdat = zone->zone_pgdat;
+ }
+ }
+}
+
+static inline unsigned int
+gfp_to_alloc_flags(gfp_t gfp_mask, unsigned int order)
+{
+ unsigned int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET;
+
+ /*
+ * __GFP_HIGH is assumed to be the same as ALLOC_MIN_RESERVE
+ * and __GFP_KSWAPD_RECLAIM is assumed to be the same as ALLOC_KSWAPD
+ * to save two branches.
+ */
+ BUILD_BUG_ON(__GFP_HIGH != (__force gfp_t) ALLOC_MIN_RESERVE);
+ BUILD_BUG_ON(__GFP_KSWAPD_RECLAIM != (__force gfp_t) ALLOC_KSWAPD);
+
+ /*
+ * The caller may dip into page reserves a bit more if the caller
+ * cannot run direct reclaim, or if the caller has realtime scheduling
+ * policy or is asking for __GFP_HIGH memory. GFP_ATOMIC requests will
+ * set both ALLOC_NON_BLOCK and ALLOC_MIN_RESERVE(__GFP_HIGH).
+ */
+ alloc_flags |= (__force int)
+ (gfp_mask & (__GFP_HIGH | __GFP_KSWAPD_RECLAIM));
+
+ if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) {
+ /*
+ * Not worth trying to allocate harder for __GFP_NOMEMALLOC even
+ * if it can't schedule.
+ */
+ if (!(gfp_mask & __GFP_NOMEMALLOC)) {
+ alloc_flags |= ALLOC_NON_BLOCK;
+
+ if (order > 0)
+ alloc_flags |= ALLOC_HIGHATOMIC;
+ }
+
+ /*
+ * Ignore cpuset mems for non-blocking __GFP_HIGH (probably
+ * GFP_ATOMIC) rather than fail, see the comment for
+ * cpuset_node_allowed().
+ */
+ if (alloc_flags & ALLOC_MIN_RESERVE)
+ alloc_flags &= ~ALLOC_CPUSET;
+ } else if (unlikely(rt_task(current)) && in_task())
+ alloc_flags |= ALLOC_MIN_RESERVE;
+
+ alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, alloc_flags);
+
+ return alloc_flags;
+}
+
+static bool oom_reserves_allowed(struct task_struct *tsk)
+{
+ if (!tsk_is_oom_victim(tsk))
+ return false;
+
+ /*
+ * !MMU doesn't have oom reaper so give access to memory reserves
+ * only to the thread with TIF_MEMDIE set
+ */
+ if (!IS_ENABLED(CONFIG_MMU) && !test_thread_flag(TIF_MEMDIE))
+ return false;
+
+ return true;
+}
+
+/*
+ * Distinguish requests which really need access to full memory
+ * reserves from oom victims which can live with a portion of it
+ */
+static inline int __gfp_pfmemalloc_flags(gfp_t gfp_mask)
+{
+ if (unlikely(gfp_mask & __GFP_NOMEMALLOC))
+ return 0;
+ if (gfp_mask & __GFP_MEMALLOC)
+ return ALLOC_NO_WATERMARKS;
+ if (in_serving_softirq() && (current->flags & PF_MEMALLOC))
+ return ALLOC_NO_WATERMARKS;
+ if (!in_interrupt()) {
+ if (current->flags & PF_MEMALLOC)
+ return ALLOC_NO_WATERMARKS;
+ else if (oom_reserves_allowed(current))
+ return ALLOC_OOM;
+ }
+
+ return 0;
+}
+
+bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
+{
+ return !!__gfp_pfmemalloc_flags(gfp_mask);
+}
+
+/*
+ * Checks whether it makes sense to retry the reclaim to make a forward progress
+ * for the given allocation request.
+ *
+ * We give up when we either have tried MAX_RECLAIM_RETRIES in a row
+ * without success, or when we couldn't even meet the watermark if we
+ * reclaimed all remaining pages on the LRU lists.
+ *
+ * Returns true if a retry is viable or false to enter the oom path.
+ */
+static inline bool
+should_reclaim_retry(gfp_t gfp_mask, unsigned order,
+ struct alloc_context *ac, int alloc_flags,
+ bool did_some_progress, int *no_progress_loops)
+{
+ struct zone *zone;
+ struct zoneref *z;
+ bool ret = false;
+
+ /*
+ * Costly allocations might have made a progress but this doesn't mean
+ * their order will become available due to high fragmentation so
+ * always increment the no progress counter for them
+ */
+ if (did_some_progress && order <= PAGE_ALLOC_COSTLY_ORDER)
+ *no_progress_loops = 0;
+ else
+ (*no_progress_loops)++;
+
+ 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;
+
+ 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 bool
+check_retry_cpuset(int cpuset_mems_cookie, struct alloc_context *ac)
+{
+ /*
+ * It's possible that cpuset's mems_allowed and the nodemask from
+ * mempolicy don't intersect. This should be normally dealt with by
+ * policy_nodemask(), but it's possible to race with cpuset update in
+ * such a way the check therein was true, and then it became false
+ * before we got our cpuset_mems_cookie here.
+ * This assumes that for all allocations, ac->nodemask can come only
+ * from MPOL_BIND mempolicy (whose documented semantics is to be ignored
+ * when it does not intersect with the cpuset restrictions) or the
+ * caller can deal with a violated nodemask.
+ */
+ if (cpusets_enabled() && ac->nodemask &&
+ !cpuset_nodemask_valid_mems_allowed(ac->nodemask)) {
+ ac->nodemask = NULL;
+ return true;
+ }
+
+ /*
+ * When updating a task's mems_allowed or mempolicy nodemask, it is
+ * possible to race with parallel threads in such a way that our
+ * allocation can fail while the mask is being updated. If we are about
+ * to fail, check if the cpuset changed during allocation and if so,
+ * retry.
+ */
+ if (read_mems_allowed_retry(cpuset_mems_cookie))
+ return true;
+
+ return false;
+}
+
+static inline struct page *
+__alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
+ struct alloc_context *ac)
+{
+ bool can_direct_reclaim = gfp_mask & __GFP_DIRECT_RECLAIM;
+ const bool costly_order = order > PAGE_ALLOC_COSTLY_ORDER;
+ struct page *page = NULL;
+ unsigned int alloc_flags;
+ unsigned long did_some_progress;
+ enum compact_priority compact_priority;
+ enum compact_result compact_result;
+ int compaction_retries;
+ int no_progress_loops;
+ unsigned int cpuset_mems_cookie;
+ unsigned int zonelist_iter_cookie;
+ int reserve_flags;
+
+restart:
+ compaction_retries = 0;
+ no_progress_loops = 0;
+ compact_priority = DEF_COMPACT_PRIORITY;
+ cpuset_mems_cookie = read_mems_allowed_begin();
+ zonelist_iter_cookie = zonelist_iter_begin();
+
+ /*
+ * The fast path uses conservative alloc_flags to succeed only until
+ * kswapd needs to be woken up, and to avoid the cost of setting up
+ * alloc_flags precisely. So we do that now.
+ */
+ alloc_flags = gfp_to_alloc_flags(gfp_mask, order);
+
+ /*
+ * We need to recalculate the starting point for the zonelist iterator
+ * because we might have used different nodemask in the fast path, or
+ * there was a cpuset modification and we are retrying - otherwise we
+ * could end up iterating over non-eligible zones endlessly.
+ */
+ ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
+ ac->highest_zoneidx, ac->nodemask);
+ if (!ac->preferred_zoneref->zone)
+ goto nopage;
+
+ /*
+ * Check for insane configurations where the cpuset doesn't contain
+ * any suitable zone to satisfy the request - e.g. non-movable
+ * GFP_HIGHUSER allocations from MOVABLE nodes only.
+ */
+ if (cpusets_insane_config() && (gfp_mask & __GFP_HARDWALL)) {
+ struct zoneref *z = first_zones_zonelist(ac->zonelist,
+ ac->highest_zoneidx,
+ &cpuset_current_mems_allowed);
+ if (!z->zone)
+ goto nopage;
+ }
+
+ if (alloc_flags & ALLOC_KSWAPD)
+ wake_all_kswapds(order, gfp_mask, ac);
+
+ /*
+ * The adjusted alloc_flags might result in immediate success, so try
+ * that first
+ */
+ page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
+ if (page)
+ goto got_pg;
+
+ /*
+ * For costly allocations, try direct compaction first, as it's likely
+ * that we have enough base pages and don't need to reclaim. For non-
+ * movable high-order allocations, do that as well, as compaction will
+ * try prevent permanent fragmentation by migrating from blocks of the
+ * same migratetype.
+ * Don't try this for allocations that are allowed to ignore
+ * watermarks, as the ALLOC_NO_WATERMARKS attempt didn't yet happen.
+ */
+ if (can_direct_reclaim &&
+ (costly_order ||
+ (order > 0 && ac->migratetype != MIGRATE_MOVABLE))
+ && !gfp_pfmemalloc_allowed(gfp_mask)) {
+ page = __alloc_pages_direct_compact(gfp_mask, order,
+ alloc_flags, ac,
+ INIT_COMPACT_PRIORITY,
+ &compact_result);
+ if (page)
+ goto got_pg;
+
+ /*
+ * Checks for costly allocations with __GFP_NORETRY, which
+ * includes some THP page fault allocations
+ */
+ if (costly_order && (gfp_mask & __GFP_NORETRY)) {
+ /*
+ * If allocating entire pageblock(s) and compaction
+ * failed because all zones are below low watermarks
+ * or is prohibited because it recently failed at this
+ * order, fail immediately unless the allocator has
+ * requested compaction and reclaim retry.
+ *
+ * Reclaim is
+ * - potentially very expensive because zones are far
+ * below their low watermarks or this is part of very
+ * bursty high order allocations,
+ * - not guaranteed to help because isolate_freepages()
+ * may not iterate over freed pages as part of its
+ * linear scan, and
+ * - unlikely to make entire pageblocks free on its
+ * own.
+ */
+ if (compact_result == COMPACT_SKIPPED ||
+ compact_result == COMPACT_DEFERRED)
+ goto nopage;
+
+ /*
+ * Looks like reclaim/compaction is worth trying, but
+ * sync compaction could be very expensive, so keep
+ * using async compaction.
+ */
+ compact_priority = INIT_COMPACT_PRIORITY;
+ }
+ }
+
+retry:
+ /* Ensure kswapd doesn't accidentally go to sleep as long as we loop */
+ if (alloc_flags & ALLOC_KSWAPD)
+ wake_all_kswapds(order, gfp_mask, ac);
+
+ reserve_flags = __gfp_pfmemalloc_flags(gfp_mask);
+ if (reserve_flags)
+ alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, reserve_flags) |
+ (alloc_flags & ALLOC_KSWAPD);
+
+ /*
+ * Reset the nodemask and zonelist iterators if memory policies can be
+ * ignored. These allocations are high priority and system rather than
+ * user oriented.
+ */
+ if (!(alloc_flags & ALLOC_CPUSET) || reserve_flags) {
+ ac->nodemask = NULL;
+ ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
+ ac->highest_zoneidx, ac->nodemask);
+ }
+
+ /* Attempt with potentially adjusted zonelist and alloc_flags */
+ page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
+ if (page)
+ goto got_pg;
+
+ /* Caller is not willing to reclaim, we can't balance anything */
+ if (!can_direct_reclaim)
+ goto nopage;
+
+ /* Avoid recursion of direct reclaim */
+ if (current->flags & PF_MEMALLOC)
+ goto nopage;
+
+ /* Try direct reclaim and then allocating */
+ page = __alloc_pages_direct_reclaim(gfp_mask, order, alloc_flags, ac,
+ &did_some_progress);
+ if (page)
+ goto got_pg;
+
+ /* Try direct compaction and then allocating */
+ page = __alloc_pages_direct_compact(gfp_mask, order, alloc_flags, ac,
+ compact_priority, &compact_result);
+ if (page)
+ goto got_pg;
+
+ /* Do not loop if specifically requested */
+ if (gfp_mask & __GFP_NORETRY)
+ goto nopage;
+
+ /*
+ * Do not retry costly high order allocations unless they are
+ * __GFP_RETRY_MAYFAIL
+ */
+ if (costly_order && !(gfp_mask & __GFP_RETRY_MAYFAIL))
+ goto nopage;
+
+ if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags,
+ did_some_progress > 0, &no_progress_loops))
+ goto retry;
+
+ /*
+ * It doesn't make any sense to retry for the compaction if the order-0
+ * reclaim is not able to make any progress because the current
+ * implementation of the compaction depends on the sufficient amount
+ * of free memory (see __compaction_suitable)
+ */
+ if (did_some_progress > 0 &&
+ should_compact_retry(ac, order, alloc_flags,
+ compact_result, &compact_priority,
+ &compaction_retries))
+ goto retry;
+
+
+ /*
+ * Deal with possible cpuset update races or zonelist updates to avoid
+ * a unnecessary OOM kill.
+ */
+ if (check_retry_cpuset(cpuset_mems_cookie, ac) ||
+ check_retry_zonelist(zonelist_iter_cookie))
+ goto restart;
+
+ /* Reclaim has failed us, start killing things */
+ page = __alloc_pages_may_oom(gfp_mask, order, ac, &did_some_progress);
+ if (page)
+ goto got_pg;
+
+ /* Avoid allocations with no watermarks from looping endlessly */
+ if (tsk_is_oom_victim(current) &&
+ (alloc_flags & ALLOC_OOM ||
+ (gfp_mask & __GFP_NOMEMALLOC)))
+ goto nopage;
+
+ /* Retry as long as the OOM killer is making progress */
+ if (did_some_progress) {
+ no_progress_loops = 0;
+ goto retry;
+ }
+
+nopage:
+ /*
+ * Deal with possible cpuset update races or zonelist updates to avoid
+ * a unnecessary OOM kill.
+ */
+ if (check_retry_cpuset(cpuset_mems_cookie, ac) ||
+ check_retry_zonelist(zonelist_iter_cookie))
+ goto restart;
+
+ /*
+ * Make sure that __GFP_NOFAIL request doesn't leak out and make sure
+ * we always retry
+ */
+ if (gfp_mask & __GFP_NOFAIL) {
+ /*
+ * All existing users of the __GFP_NOFAIL are blockable, so warn
+ * of any new users that actually require GFP_NOWAIT
+ */
+ if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
+ goto fail;
+
+ /*
+ * PF_MEMALLOC request from this context is rather bizarre
+ * because we cannot reclaim anything and only can loop waiting
+ * for somebody to do a work for us
+ */
+ WARN_ON_ONCE_GFP(current->flags & PF_MEMALLOC, gfp_mask);
+
+ /*
+ * non failing costly orders are a hard requirement which we
+ * are not prepared for much so let's warn about these users
+ * so that we can identify them and convert them to something
+ * else.
+ */
+ WARN_ON_ONCE_GFP(costly_order, gfp_mask);
+
+ /*
+ * Help non-failing allocations by giving some access to memory
+ * reserves normally used for high priority non-blocking
+ * allocations but do not use ALLOC_NO_WATERMARKS because this
+ * could deplete whole memory reserves which would just make
+ * the situation worse.
+ */
+ page = __alloc_pages_cpuset_fallback(gfp_mask, order, ALLOC_MIN_RESERVE, ac);
+ if (page)
+ goto got_pg;
+
+ cond_resched();
+ goto retry;
+ }
+fail:
+ warn_alloc(gfp_mask, ac->nodemask,
+ "page allocation failure: order:%u", order);
+got_pg:
+ return page;
+}
+
+static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
+ int preferred_nid, nodemask_t *nodemask,
+ struct alloc_context *ac, gfp_t *alloc_gfp,
+ unsigned int *alloc_flags)
+{
+ ac->highest_zoneidx = gfp_zone(gfp_mask);
+ ac->zonelist = node_zonelist(preferred_nid, gfp_mask);
+ ac->nodemask = nodemask;
+ ac->migratetype = gfp_migratetype(gfp_mask);
+
+ if (cpusets_enabled()) {
+ *alloc_gfp |= __GFP_HARDWALL;
+ /*
+ * When we are in the interrupt context, it is irrelevant
+ * to the current task context. It means that any node ok.
+ */
+ if (in_task() && !ac->nodemask)
+ ac->nodemask = &cpuset_current_mems_allowed;
+ else
+ *alloc_flags |= ALLOC_CPUSET;
+ }
+
+ might_alloc(gfp_mask);
+
+ if (should_fail_alloc_page(gfp_mask, order))
+ return false;
+
+ *alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, *alloc_flags);
+
+ /* Dirty zone balancing only done in the fast path */
+ ac->spread_dirty_pages = (gfp_mask & __GFP_WRITE);
+
+ /*
+ * The preferred zone is used for statistics but crucially it is
+ * also used as the starting point for the zonelist iterator. It
+ * may get reset for allocations that ignore memory policies.
+ */
+ ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
+ ac->highest_zoneidx, ac->nodemask);
+
+ return true;
+}
+
+/*
+ * __alloc_pages_bulk - Allocate a number of order-0 pages to a list or array
+ * @gfp: GFP flags for the allocation
+ * @preferred_nid: The preferred NUMA node ID to allocate from
+ * @nodemask: Set of nodes to allocate from, may be NULL
+ * @nr_pages: The number of pages desired on the list or array
+ * @page_list: Optional list to store the allocated pages
+ * @page_array: Optional array to store the pages
+ *
+ * This is a batched version of the page allocator that attempts to
+ * allocate nr_pages quickly. Pages are added to page_list if page_list
+ * is not NULL, otherwise it is assumed that the page_array is valid.
+ *
+ * For lists, nr_pages is the number of pages that should be allocated.
+ *
+ * For arrays, only NULL elements are populated with pages and nr_pages
+ * is the maximum number of pages that will be stored in the array.
+ *
+ * Returns the number of pages on the list or array.
+ */
+unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid,
+ nodemask_t *nodemask, int nr_pages,
+ struct list_head *page_list,
+ struct page **page_array)
+{
+ struct page *page;
+ unsigned long __maybe_unused UP_flags;
+ struct zone *zone;
+ struct zoneref *z;
+ struct per_cpu_pages *pcp;
+ struct list_head *pcp_list;
+ struct alloc_context ac;
+ gfp_t alloc_gfp;
+ unsigned int alloc_flags = ALLOC_WMARK_LOW;
+ int nr_populated = 0, nr_account = 0;
+
+ /*
+ * Skip populated array elements to determine if any pages need
+ * to be allocated before disabling IRQs.
+ */
+ while (page_array && nr_populated < nr_pages && page_array[nr_populated])
+ nr_populated++;
+
+ /* No pages requested? */
+ if (unlikely(nr_pages <= 0))
+ goto out;
+
+ /* Already populated array? */
+ if (unlikely(page_array && nr_pages - nr_populated == 0))
+ goto out;
+
+ /* Bulk allocator does not support memcg accounting. */
+ if (memcg_kmem_online() && (gfp & __GFP_ACCOUNT))
+ goto failed;
+
+ /* Use the single page allocator for one page. */
+ if (nr_pages - nr_populated == 1)
+ goto failed;
+
+#ifdef CONFIG_PAGE_OWNER
+ /*
+ * PAGE_OWNER may recurse into the allocator to allocate space to
+ * save the stack with pagesets.lock held. Releasing/reacquiring
+ * removes much of the performance benefit of bulk allocation so
+ * force the caller to allocate one page at a time as it'll have
+ * similar performance to added complexity to the bulk allocator.
+ */
+ if (static_branch_unlikely(&page_owner_inited))
+ goto failed;
+#endif
+
+ /* May set ALLOC_NOFRAGMENT, fragmentation will return 1 page. */
+ gfp &= gfp_allowed_mask;
+ alloc_gfp = gfp;
+ if (!prepare_alloc_pages(gfp, 0, preferred_nid, nodemask, &ac, &alloc_gfp, &alloc_flags))
+ goto out;
+ gfp = alloc_gfp;
+
+ /* Find an allowed local zone that meets the low watermark. */
+ for_each_zone_zonelist_nodemask(zone, z, ac.zonelist, ac.highest_zoneidx, ac.nodemask) {
+ unsigned long mark;
+
+ if (cpusets_enabled() && (alloc_flags & ALLOC_CPUSET) &&
+ !__cpuset_zone_allowed(zone, gfp)) {
+ continue;
+ }
+
+ if (nr_online_nodes > 1 && zone != ac.preferred_zoneref->zone &&
+ zone_to_nid(zone) != zone_to_nid(ac.preferred_zoneref->zone)) {
+ goto failed;
+ }
+
+ mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK) + nr_pages;
+ if (zone_watermark_fast(zone, 0, mark,
+ zonelist_zone_idx(ac.preferred_zoneref),
+ alloc_flags, gfp)) {
+ break;
+ }
+ }
+
+ /*
+ * If there are no allowed local zones that meets the watermarks then
+ * try to allocate a single page and reclaim if necessary.
+ */
+ if (unlikely(!zone))
+ goto failed;
+
+ /* spin_trylock may fail due to a parallel drain or IRQ reentrancy. */
+ pcp_trylock_prepare(UP_flags);
+ pcp = pcp_spin_trylock(zone->per_cpu_pageset);
+ if (!pcp)
+ goto failed_irq;
+
+ /* Attempt the batch allocation */
+ pcp_list = &pcp->lists[order_to_pindex(ac.migratetype, 0)];
+ while (nr_populated < nr_pages) {
+
+ /* Skip existing pages */
+ if (page_array && page_array[nr_populated]) {
+ nr_populated++;
+ continue;
+ }
+
+ page = __rmqueue_pcplist(zone, 0, ac.migratetype, alloc_flags,
+ pcp, pcp_list);
+ if (unlikely(!page)) {
+ /* Try and allocate at least one page */
+ if (!nr_account) {
+ pcp_spin_unlock(pcp);
+ goto failed_irq;
+ }
+ break;
+ }
+ nr_account++;
+
+ prep_new_page(page, 0, gfp, 0);
+ if (page_list)
+ list_add(&page->lru, page_list);
+ else
+ page_array[nr_populated] = page;
+ nr_populated++;
+ }
+
+ pcp_spin_unlock(pcp);
+ pcp_trylock_finish(UP_flags);
+
+ __count_zid_vm_events(PGALLOC, zone_idx(zone), nr_account);
+ zone_statistics(ac.preferred_zoneref->zone, zone, nr_account);
+
+out:
+ return nr_populated;
+
+failed_irq:
+ pcp_trylock_finish(UP_flags);
+
+failed:
+ page = __alloc_pages(gfp, 0, preferred_nid, nodemask);
+ if (page) {
+ if (page_list)
+ list_add(&page->lru, page_list);
+ else
+ page_array[nr_populated] = page;
+ nr_populated++;
+ }
+
+ goto out;
+}
+EXPORT_SYMBOL_GPL(__alloc_pages_bulk);
+
+/*
+ * This is the 'heart' of the zoned buddy allocator.
+ */
+struct page *__alloc_pages(gfp_t gfp, unsigned int order, int preferred_nid,
+ nodemask_t *nodemask)
+{
+ struct page *page;
+ unsigned int alloc_flags = ALLOC_WMARK_LOW;
+ gfp_t alloc_gfp; /* The gfp_t that was actually used for allocation */
+ struct alloc_context ac = { };
+
+ /*
+ * There are several places where we assume that the order value is sane
+ * so bail out early if the request is out of bound.
+ */
+ if (WARN_ON_ONCE_GFP(order > MAX_ORDER, gfp))
+ return NULL;
+
+ gfp &= gfp_allowed_mask;
+ /*
+ * Apply scoped allocation constraints. This is mainly about GFP_NOFS
+ * resp. GFP_NOIO which has to be inherited for all allocation requests
+ * from a particular context which has been marked by
+ * memalloc_no{fs,io}_{save,restore}. And PF_MEMALLOC_PIN which ensures
+ * movable zones are not used during allocation.
+ */
+ gfp = current_gfp_context(gfp);
+ alloc_gfp = gfp;
+ if (!prepare_alloc_pages(gfp, order, preferred_nid, nodemask, &ac,
+ &alloc_gfp, &alloc_flags))
+ return NULL;
+
+ /*
+ * Forbid the first pass from falling back to types that fragment
+ * memory until all local zones are considered.
+ */
+ alloc_flags |= alloc_flags_nofragment(ac.preferred_zoneref->zone, gfp);
+
+ /* First allocation attempt */
+ page = get_page_from_freelist(alloc_gfp, order, alloc_flags, &ac);
+ if (likely(page))
+ goto out;
+
+ alloc_gfp = gfp;
+ ac.spread_dirty_pages = false;
+
+ /*
+ * Restore the original nodemask if it was potentially replaced with
+ * &cpuset_current_mems_allowed to optimize the fast-path attempt.
+ */
+ ac.nodemask = nodemask;
+
+ page = __alloc_pages_slowpath(alloc_gfp, order, &ac);
+
+out:
+ if (memcg_kmem_online() && (gfp & __GFP_ACCOUNT) && page &&
+ unlikely(__memcg_kmem_charge_page(page, gfp, order) != 0)) {
+ __free_pages(page, order);
+ page = NULL;
+ }
+
+ trace_mm_page_alloc(page, order, alloc_gfp, ac.migratetype);
+ kmsan_alloc_page(page, order, alloc_gfp);
+
+ return page;
+}
+EXPORT_SYMBOL(__alloc_pages);
+
+struct folio *__folio_alloc(gfp_t gfp, unsigned int order, int preferred_nid,
+ nodemask_t *nodemask)
+{
+ struct page *page = __alloc_pages(gfp | __GFP_COMP, order,
+ preferred_nid, nodemask);
+ struct folio *folio = (struct folio *)page;
+
+ if (folio && order > 1)
+ folio_prep_large_rmappable(folio);
+ return folio;
+}
+EXPORT_SYMBOL(__folio_alloc);
+
+/*
+ * Common helper functions. Never use with __GFP_HIGHMEM because the returned
+ * address cannot represent highmem pages. Use alloc_pages and then kmap if
+ * you need to access high mem.
+ */
+unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order)
+{
+ struct page *page;
+
+ page = alloc_pages(gfp_mask & ~__GFP_HIGHMEM, order);
+ if (!page)
+ return 0;
+ return (unsigned long) page_address(page);
+}
+EXPORT_SYMBOL(__get_free_pages);
+
+unsigned long get_zeroed_page(gfp_t gfp_mask)
+{
+ return __get_free_page(gfp_mask | __GFP_ZERO);
+}
+EXPORT_SYMBOL(get_zeroed_page);
+
+/**
+ * __free_pages - Free pages allocated with alloc_pages().
+ * @page: The page pointer returned from alloc_pages().
+ * @order: The order of the allocation.
+ *
+ * This function can free multi-page allocations that are not compound
+ * pages. It does not check that the @order passed in matches that of
+ * the allocation, so it is easy to leak memory. Freeing more memory
+ * than was allocated will probably emit a warning.
+ *
+ * If the last reference to this page is speculative, it will be released
+ * by put_page() which only frees the first page of a non-compound
+ * allocation. To prevent the remaining pages from being leaked, we free
+ * the subsequent pages here. If you want to use the page's reference
+ * count to decide when to free the allocation, you should allocate a
+ * compound page, and use put_page() instead of __free_pages().
+ *
+ * Context: May be called in interrupt context or while holding a normal
+ * spinlock, but not in NMI context or while holding a raw spinlock.
+ */
+void __free_pages(struct page *page, unsigned int order)
+{
+ /* get PageHead before we drop reference */
+ int head = PageHead(page);
+
+ if (put_page_testzero(page))
+ free_the_page(page, order);
+ else if (!head)
+ while (order-- > 0)
+ free_the_page(page + (1 << order), order);
+}
+EXPORT_SYMBOL(__free_pages);
+
+void free_pages(unsigned long addr, unsigned int order)
+{
+ if (addr != 0) {
+ VM_BUG_ON(!virt_addr_valid((void *)addr));
+ __free_pages(virt_to_page((void *)addr), order);
+ }
+}
+
+EXPORT_SYMBOL(free_pages);
+
+/*
+ * Page Fragment:
+ * An arbitrary-length arbitrary-offset area of memory which resides
+ * within a 0 or higher order page. Multiple fragments within that page
+ * are individually refcounted, in the page's reference counter.
+ *
+ * The page_frag functions below provide a simple allocation framework for
+ * page fragments. This is used by the network stack and network device
+ * drivers to provide a backing region of memory for use as either an
+ * sk_buff->head, or to be used in the "frags" portion of skb_shared_info.
+ */
+static struct page *__page_frag_cache_refill(struct page_frag_cache *nc,
+ gfp_t gfp_mask)
+{
+ struct page *page = NULL;
+ gfp_t gfp = gfp_mask;
+
+#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
+ gfp_mask |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY |
+ __GFP_NOMEMALLOC;
+ page = alloc_pages_node(NUMA_NO_NODE, gfp_mask,
+ PAGE_FRAG_CACHE_MAX_ORDER);
+ nc->size = page ? PAGE_FRAG_CACHE_MAX_SIZE : PAGE_SIZE;
+#endif
+ if (unlikely(!page))
+ page = alloc_pages_node(NUMA_NO_NODE, gfp, 0);
+
+ nc->va = page ? page_address(page) : NULL;
+
+ return page;
+}
+
+void __page_frag_cache_drain(struct page *page, unsigned int count)
+{
+ VM_BUG_ON_PAGE(page_ref_count(page) == 0, page);
+
+ if (page_ref_sub_and_test(page, count))
+ free_the_page(page, compound_order(page));
+}
+EXPORT_SYMBOL(__page_frag_cache_drain);
+
+void *page_frag_alloc_align(struct page_frag_cache *nc,
+ unsigned int fragsz, gfp_t gfp_mask,
+ unsigned int align_mask)
+{
+ unsigned int size = PAGE_SIZE;
+ struct page *page;
+ int offset;
+
+ if (unlikely(!nc->va)) {
+refill:
+ page = __page_frag_cache_refill(nc, gfp_mask);
+ if (!page)
+ return NULL;
+
+#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
+ /* if size can vary use size else just use PAGE_SIZE */
+ size = nc->size;
+#endif
+ /* Even if we own the page, we do not use atomic_set().
+ * This would break get_page_unless_zero() users.
+ */
+ page_ref_add(page, PAGE_FRAG_CACHE_MAX_SIZE);
+
+ /* reset page count bias and offset to start of new frag */
+ nc->pfmemalloc = page_is_pfmemalloc(page);
+ nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1;
+ nc->offset = size;
+ }
+
+ offset = nc->offset - fragsz;
+ if (unlikely(offset < 0)) {
+ page = virt_to_page(nc->va);
+
+ if (!page_ref_sub_and_test(page, nc->pagecnt_bias))
+ goto refill;
+
+ if (unlikely(nc->pfmemalloc)) {
+ free_the_page(page, compound_order(page));
+ goto refill;
+ }
+
+#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
+ /* if size can vary use size else just use PAGE_SIZE */
+ size = nc->size;
+#endif
+ /* OK, page count is 0, we can safely set it */
+ set_page_count(page, PAGE_FRAG_CACHE_MAX_SIZE + 1);
+
+ /* reset page count bias and offset to start of new frag */
+ nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1;
+ offset = size - fragsz;
+ if (unlikely(offset < 0)) {
+ /*
+ * The caller is trying to allocate a fragment
+ * with fragsz > PAGE_SIZE but the cache isn't big
+ * enough to satisfy the request, this may
+ * happen in low memory conditions.
+ * We don't release the cache page because
+ * it could make memory pressure worse
+ * so we simply return NULL here.
+ */
+ return NULL;
+ }
+ }
+
+ nc->pagecnt_bias--;
+ offset &= align_mask;
+ nc->offset = offset;
+
+ return nc->va + offset;
+}
+EXPORT_SYMBOL(page_frag_alloc_align);
+
+/*
+ * Frees a page fragment allocated out of either a compound or order 0 page.
+ */
+void page_frag_free(void *addr)
+{
+ struct page *page = virt_to_head_page(addr);
+
+ if (unlikely(put_page_testzero(page)))
+ free_the_page(page, compound_order(page));
+}
+EXPORT_SYMBOL(page_frag_free);
+
+static void *make_alloc_exact(unsigned long addr, unsigned int order,
+ size_t size)
+{
+ if (addr) {
+ unsigned long nr = DIV_ROUND_UP(size, PAGE_SIZE);
+ struct page *page = virt_to_page((void *)addr);
+ struct page *last = page + nr;
+
+ split_page_owner(page, 1 << order);
+ split_page_memcg(page, 1 << order);
+ while (page < --last)
+ set_page_refcounted(last);
+
+ last = page + (1UL << order);
+ for (page += nr; page < last; page++)
+ __free_pages_ok(page, 0, FPI_TO_TAIL);
+ }
+ return (void *)addr;
+}
+
+/**
+ * alloc_pages_exact - allocate an exact number physically-contiguous pages.
+ * @size: the number of bytes to allocate
+ * @gfp_mask: GFP flags for the allocation, must not contain __GFP_COMP
+ *
+ * This function is similar to alloc_pages(), except that it allocates the
+ * minimum number of pages to satisfy the request. alloc_pages() can only
+ * allocate memory in power-of-two pages.
+ *
+ * This function is also limited by MAX_ORDER.
+ *
+ * Memory allocated by this function must be released by free_pages_exact().
+ *
+ * Return: pointer to the allocated area or %NULL in case of error.
+ */
+void *alloc_pages_exact(size_t size, gfp_t gfp_mask)
+{
+ unsigned int order = get_order(size);
+ unsigned long addr;
+
+ if (WARN_ON_ONCE(gfp_mask & (__GFP_COMP | __GFP_HIGHMEM)))
+ gfp_mask &= ~(__GFP_COMP | __GFP_HIGHMEM);
+
+ addr = __get_free_pages(gfp_mask, order);
+ return make_alloc_exact(addr, order, size);
+}
+EXPORT_SYMBOL(alloc_pages_exact);
+
+/**
+ * alloc_pages_exact_nid - allocate an exact number of physically-contiguous
+ * pages on a node.
+ * @nid: the preferred node ID where memory should be allocated
+ * @size: the number of bytes to allocate
+ * @gfp_mask: GFP flags for the allocation, must not contain __GFP_COMP
+ *
+ * Like alloc_pages_exact(), but try to allocate on node nid first before falling
+ * back.
+ *
+ * Return: pointer to the allocated area or %NULL in case of error.
+ */
+void * __meminit alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask)
+{
+ unsigned int order = get_order(size);
+ struct page *p;
+
+ if (WARN_ON_ONCE(gfp_mask & (__GFP_COMP | __GFP_HIGHMEM)))
+ gfp_mask &= ~(__GFP_COMP | __GFP_HIGHMEM);
+
+ p = alloc_pages_node(nid, gfp_mask, order);
+ if (!p)
+ return NULL;
+ return make_alloc_exact((unsigned long)page_address(p), order, size);
+}
+
+/**
+ * free_pages_exact - release memory allocated via alloc_pages_exact()
+ * @virt: the value returned by alloc_pages_exact.
+ * @size: size of allocation, same value as passed to alloc_pages_exact().
+ *
+ * Release the memory allocated by a previous call to alloc_pages_exact.
+ */
+void free_pages_exact(void *virt, size_t size)
+{
+ unsigned long addr = (unsigned long)virt;
+ unsigned long end = addr + PAGE_ALIGN(size);
+
+ while (addr < end) {
+ free_page(addr);
+ addr += PAGE_SIZE;
+ }
+}
+EXPORT_SYMBOL(free_pages_exact);
+
+/**
+ * nr_free_zone_pages - count number of pages beyond high watermark
+ * @offset: The zone index of the highest zone
+ *
+ * nr_free_zone_pages() counts the number of pages which are beyond the
+ * high watermark within all zones at or below a given zone index. For each
+ * zone, the number of pages is calculated as:
+ *
+ * nr_free_zone_pages = managed_pages - high_pages
+ *
+ * Return: number of pages beyond high watermark.
+ */
+static unsigned long nr_free_zone_pages(int offset)
+{
+ struct zoneref *z;
+ struct zone *zone;
+
+ /* Just pick one node, since fallback list is circular */
+ unsigned long sum = 0;
+
+ struct zonelist *zonelist = node_zonelist(numa_node_id(), GFP_KERNEL);
+
+ for_each_zone_zonelist(zone, z, zonelist, offset) {
+ unsigned long size = zone_managed_pages(zone);
+ unsigned long high = high_wmark_pages(zone);
+ if (size > high)
+ sum += size - high;
+ }
+
+ return sum;
+}
+
+/**
+ * nr_free_buffer_pages - count number of pages beyond high watermark
+ *
+ * nr_free_buffer_pages() counts the number of pages which are beyond the high
+ * watermark within ZONE_DMA and ZONE_NORMAL.
+ *
+ * Return: number of pages beyond high watermark within ZONE_DMA and
+ * ZONE_NORMAL.
+ */
+unsigned long nr_free_buffer_pages(void)
+{
+ return nr_free_zone_pages(gfp_zone(GFP_USER));
+}
+EXPORT_SYMBOL_GPL(nr_free_buffer_pages);
+
+static void zoneref_set_zone(struct zone *zone, struct zoneref *zoneref)
+{
+ zoneref->zone = zone;
+ zoneref->zone_idx = zone_idx(zone);
+}
+
+/*
+ * Builds allocation fallback zone lists.
+ *
+ * Add all populated zones of a node to the zonelist.
+ */
+static int build_zonerefs_node(pg_data_t *pgdat, struct zoneref *zonerefs)
+{
+ struct zone *zone;
+ enum zone_type zone_type = MAX_NR_ZONES;
+ int nr_zones = 0;
+
+ do {
+ zone_type--;
+ zone = pgdat->node_zones + zone_type;
+ if (populated_zone(zone)) {
+ zoneref_set_zone(zone, &zonerefs[nr_zones++]);
+ check_highest_zone(zone_type);
+ }
+ } while (zone_type);
+
+ return nr_zones;
+}
+
+#ifdef CONFIG_NUMA
+
+static int __parse_numa_zonelist_order(char *s)
+{
+ /*
+ * We used to support different zonelists modes but they turned
+ * out to be just not useful. Let's keep the warning in place
+ * if somebody still use the cmd line parameter so that we do
+ * not fail it silently
+ */
+ if (!(*s == 'd' || *s == 'D' || *s == 'n' || *s == 'N')) {
+ pr_warn("Ignoring unsupported numa_zonelist_order value: %s\n", s);
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static char numa_zonelist_order[] = "Node";
+#define NUMA_ZONELIST_ORDER_LEN 16
+/*
+ * sysctl handler for numa_zonelist_order
+ */
+static int numa_zonelist_order_handler(struct ctl_table *table, int write,
+ void *buffer, size_t *length, loff_t *ppos)
+{
+ if (write)
+ return __parse_numa_zonelist_order(buffer);
+ return proc_dostring(table, write, buffer, length, ppos);
+}
+
+static int node_load[MAX_NUMNODES];
+
+/**
+ * find_next_best_node - find the next node that should appear in a given node's fallback list
+ * @node: node whose fallback list we're appending
+ * @used_node_mask: nodemask_t of already used nodes
+ *
+ * We use a number of factors to determine which is the next node that should
+ * appear on a given node's fallback list. The node should not have appeared
+ * already in @node's fallback list, and it should be the next closest node
+ * according to the distance array (which contains arbitrary distance values
+ * from each node to each node in the system), and should also prefer nodes
+ * with no CPUs, since presumably they'll have very little allocation pressure
+ * on them otherwise.
+ *
+ * Return: node id of the found node or %NUMA_NO_NODE if no node is found.
+ */
+int find_next_best_node(int node, nodemask_t *used_node_mask)
+{
+ int n, val;
+ int min_val = INT_MAX;
+ int best_node = NUMA_NO_NODE;
+
+ /* Use the local node if we haven't already */
+ if (!node_isset(node, *used_node_mask)) {
+ node_set(node, *used_node_mask);
+ return node;
+ }
+
+ for_each_node_state(n, N_MEMORY) {
+
+ /* Don't want a node to appear more than once */
+ if (node_isset(n, *used_node_mask))
+ continue;
+
+ /* Use the distance array to find the distance */
+ val = node_distance(node, n);
+
+ /* Penalize nodes under us ("prefer the next node") */
+ val += (n < node);
+
+ /* Give preference to headless and unused nodes */
+ if (!cpumask_empty(cpumask_of_node(n)))
+ val += PENALTY_FOR_NODE_WITH_CPUS;
+
+ /* Slight preference for less loaded node */
+ val *= MAX_NUMNODES;
+ val += node_load[n];
+
+ if (val < min_val) {
+ min_val = val;
+ best_node = n;
+ }
+ }
+
+ if (best_node >= 0)
+ node_set(best_node, *used_node_mask);
+
+ return best_node;
+}
+
+
+/*
+ * Build zonelists ordered by node and zones within node.
+ * This results in maximum locality--normal zone overflows into local
+ * DMA zone, if any--but risks exhausting DMA zone.
+ */
+static void build_zonelists_in_node_order(pg_data_t *pgdat, int *node_order,
+ unsigned nr_nodes)
+{
+ struct zoneref *zonerefs;
+ int i;
+
+ zonerefs = pgdat->node_zonelists[ZONELIST_FALLBACK]._zonerefs;
+
+ for (i = 0; i < nr_nodes; i++) {
+ int nr_zones;
+
+ pg_data_t *node = NODE_DATA(node_order[i]);
+
+ nr_zones = build_zonerefs_node(node, zonerefs);
+ zonerefs += nr_zones;
+ }
+ zonerefs->zone = NULL;
+ zonerefs->zone_idx = 0;
+}
+
+/*
+ * Build gfp_thisnode zonelists
+ */
+static void build_thisnode_zonelists(pg_data_t *pgdat)
+{
+ struct zoneref *zonerefs;
+ int nr_zones;
+
+ zonerefs = pgdat->node_zonelists[ZONELIST_NOFALLBACK]._zonerefs;
+ nr_zones = build_zonerefs_node(pgdat, zonerefs);
+ zonerefs += nr_zones;
+ zonerefs->zone = NULL;
+ zonerefs->zone_idx = 0;
+}
+
+/*
+ * Build zonelists ordered by zone and nodes within zones.
+ * This results in conserving DMA zone[s] until all Normal memory is
+ * exhausted, but results in overflowing to remote node while memory
+ * may still exist in local DMA zone.
+ */
+
+static void build_zonelists(pg_data_t *pgdat)
+{
+ static int node_order[MAX_NUMNODES];
+ int node, nr_nodes = 0;
+ nodemask_t used_mask = NODE_MASK_NONE;
+ int local_node, prev_node;
+
+ /* NUMA-aware ordering of nodes */
+ local_node = pgdat->node_id;
+ prev_node = local_node;
+
+ memset(node_order, 0, sizeof(node_order));
+ while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
+ /*
+ * We don't want to pressure a particular node.
+ * So adding penalty to the first node in same
+ * distance group to make it round-robin.
+ */
+ if (node_distance(local_node, node) !=
+ node_distance(local_node, prev_node))
+ node_load[node] += 1;
+
+ node_order[nr_nodes++] = node;
+ prev_node = node;
+ }
+
+ build_zonelists_in_node_order(pgdat, node_order, nr_nodes);
+ build_thisnode_zonelists(pgdat);
+ pr_info("Fallback order for Node %d: ", local_node);
+ for (node = 0; node < nr_nodes; node++)
+ pr_cont("%d ", node_order[node]);
+ pr_cont("\n");
+}
+
+#ifdef CONFIG_HAVE_MEMORYLESS_NODES
+/*
+ * Return node id of node used for "local" allocations.
+ * I.e., first node id of first zone in arg node's generic zonelist.
+ * Used for initializing percpu 'numa_mem', which is used primarily
+ * for kernel allocations, so use GFP_KERNEL flags to locate zonelist.
+ */
+int local_memory_node(int node)
+{
+ struct zoneref *z;
+
+ z = first_zones_zonelist(node_zonelist(node, GFP_KERNEL),
+ gfp_zone(GFP_KERNEL),
+ NULL);
+ return zone_to_nid(z->zone);
+}
+#endif
+
+static void setup_min_unmapped_ratio(void);
+static void setup_min_slab_ratio(void);
+#else /* CONFIG_NUMA */
+
+static void build_zonelists(pg_data_t *pgdat)
+{
+ int node, local_node;
+ struct zoneref *zonerefs;
+ int nr_zones;
+
+ local_node = pgdat->node_id;
+
+ zonerefs = pgdat->node_zonelists[ZONELIST_FALLBACK]._zonerefs;
+ nr_zones = build_zonerefs_node(pgdat, zonerefs);
+ zonerefs += nr_zones;
+
+ /*
+ * Now we build the zonelist so that it contains the zones
+ * of all the other nodes.
+ * We don't want to pressure a particular node, so when
+ * building the zones for node N, we make sure that the
+ * zones coming right after the local ones are those from
+ * node N+1 (modulo N)
+ */
+ for (node = local_node + 1; node < MAX_NUMNODES; node++) {
+ if (!node_online(node))
+ continue;
+ nr_zones = build_zonerefs_node(NODE_DATA(node), zonerefs);
+ zonerefs += nr_zones;
+ }
+ for (node = 0; node < local_node; node++) {
+ if (!node_online(node))
+ continue;
+ nr_zones = build_zonerefs_node(NODE_DATA(node), zonerefs);
+ zonerefs += nr_zones;
+ }
+
+ zonerefs->zone = NULL;
+ zonerefs->zone_idx = 0;
+}
+
+#endif /* CONFIG_NUMA */
+
+/*
+ * Boot pageset table. One per cpu which is going to be used for all
+ * zones and all nodes. The parameters will be set in such a way
+ * that an item put on a list will immediately be handed over to
+ * the buddy list. This is safe since pageset manipulation is done
+ * with interrupts disabled.
+ *
+ * The boot_pagesets must be kept even after bootup is complete for
+ * unused processors and/or zones. They do play a role for bootstrapping
+ * hotplugged processors.
+ *
+ * zoneinfo_show() and maybe other functions do
+ * not check if the processor is online before following the pageset pointer.
+ * Other parts of the kernel may not check if the zone is available.
+ */
+static void per_cpu_pages_init(struct per_cpu_pages *pcp, struct per_cpu_zonestat *pzstats);
+/* These effectively disable the pcplists in the boot pageset completely */
+#define BOOT_PAGESET_HIGH 0
+#define BOOT_PAGESET_BATCH 1
+static DEFINE_PER_CPU(struct per_cpu_pages, boot_pageset);
+static DEFINE_PER_CPU(struct per_cpu_zonestat, boot_zonestats);
+
+static void __build_all_zonelists(void *data)
+{
+ int nid;
+ int __maybe_unused cpu;
+ pg_data_t *self = data;
+ unsigned long flags;
+
+ /*
+ * The zonelist_update_seq must be acquired with irqsave because the
+ * reader can be invoked from IRQ with GFP_ATOMIC.
+ */
+ write_seqlock_irqsave(&zonelist_update_seq, flags);
+ /*
+ * Also disable synchronous printk() to prevent any printk() from
+ * trying to hold port->lock, for
+ * tty_insert_flip_string_and_push_buffer() on other CPU might be
+ * calling kmalloc(GFP_ATOMIC | __GFP_NOWARN) with port->lock held.
+ */
+ printk_deferred_enter();
+
+#ifdef CONFIG_NUMA
+ memset(node_load, 0, sizeof(node_load));
+#endif
+
+ /*
+ * This node is hotadded and no memory is yet present. So just
+ * building zonelists is fine - no need to touch other nodes.
+ */
+ if (self && !node_online(self->node_id)) {
+ build_zonelists(self);
+ } else {
+ /*
+ * All possible nodes have pgdat preallocated
+ * in free_area_init
+ */
+ for_each_node(nid) {
+ pg_data_t *pgdat = NODE_DATA(nid);
+
+ build_zonelists(pgdat);
+ }
+
+#ifdef CONFIG_HAVE_MEMORYLESS_NODES
+ /*
+ * We now know the "local memory node" for each node--
+ * i.e., the node of the first zone in the generic zonelist.
+ * Set up numa_mem percpu variable for on-line cpus. During
+ * boot, only the boot cpu should be on-line; we'll init the
+ * secondary cpus' numa_mem as they come on-line. During
+ * node/memory hotplug, we'll fixup all on-line cpus.
+ */
+ for_each_online_cpu(cpu)
+ set_cpu_numa_mem(cpu, local_memory_node(cpu_to_node(cpu)));
+#endif
+ }
+
+ printk_deferred_exit();
+ write_sequnlock_irqrestore(&zonelist_update_seq, flags);
+}
+
+static noinline void __init
+build_all_zonelists_init(void)
+{
+ int cpu;
+
+ __build_all_zonelists(NULL);
+
+ /*
+ * Initialize the boot_pagesets that are going to be used
+ * for bootstrapping processors. The real pagesets for
+ * each zone will be allocated later when the per cpu
+ * allocator is available.
+ *
+ * boot_pagesets are used also for bootstrapping offline
+ * cpus if the system is already booted because the pagesets
+ * are needed to initialize allocators on a specific cpu too.
+ * F.e. the percpu allocator needs the page allocator which
+ * needs the percpu allocator in order to allocate its pagesets
+ * (a chicken-egg dilemma).
+ */
+ for_each_possible_cpu(cpu)
+ per_cpu_pages_init(&per_cpu(boot_pageset, cpu), &per_cpu(boot_zonestats, cpu));
+
+ mminit_verify_zonelist();
+ cpuset_init_current_mems_allowed();
+}
+
+/*
+ * unless system_state == SYSTEM_BOOTING.
+ *
+ * __ref due to call of __init annotated helper build_all_zonelists_init
+ * [protected by SYSTEM_BOOTING].
+ */
+void __ref build_all_zonelists(pg_data_t *pgdat)
+{
+ unsigned long vm_total_pages;
+
+ if (system_state == SYSTEM_BOOTING) {
+ build_all_zonelists_init();
+ } else {
+ __build_all_zonelists(pgdat);
+ /* cpuset refresh routine should be here */
+ }
+ /* Get the number of free pages beyond high watermark in all zones. */
+ vm_total_pages = nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
+ /*
+ * Disable grouping by mobility if the number of pages in the
+ * system is too low to allow the mechanism to work. It would be
+ * more accurate, but expensive to check per-zone. This check is
+ * made on memory-hotadd so a system can start with mobility
+ * disabled and enable it later
+ */
+ if (vm_total_pages < (pageblock_nr_pages * MIGRATE_TYPES))
+ page_group_by_mobility_disabled = 1;
+ else
+ page_group_by_mobility_disabled = 0;
+
+ pr_info("Built %u zonelists, mobility grouping %s. Total pages: %ld\n",
+ nr_online_nodes,
+ page_group_by_mobility_disabled ? "off" : "on",
+ vm_total_pages);
+#ifdef CONFIG_NUMA
+ pr_info("Policy zone: %s\n", zone_names[policy_zone]);
+#endif
+}
+
+static int zone_batchsize(struct zone *zone)
+{
+#ifdef CONFIG_MMU
+ int batch;
+
+ /*
+ * The number of pages to batch allocate is either ~0.1%
+ * of the zone or 1MB, whichever is smaller. The batch
+ * size is striking a balance between allocation latency
+ * and zone lock contention.
+ */
+ batch = min(zone_managed_pages(zone) >> 10, SZ_1M / PAGE_SIZE);
+ batch /= 4; /* We effectively *= 4 below */
+ if (batch < 1)
+ batch = 1;
+
+ /*
+ * Clamp the batch to a 2^n - 1 value. Having a power
+ * of 2 value was found to be more likely to have
+ * suboptimal cache aliasing properties in some cases.
+ *
+ * For example if 2 tasks are alternately allocating
+ * batches of pages, one task can end up with a lot
+ * of pages of one half of the possible page colors
+ * and the other with pages of the other colors.
+ */
+ batch = rounddown_pow_of_two(batch + batch/2) - 1;
+
+ return batch;
+
+#else
+ /* The deferral and batching of frees should be suppressed under NOMMU
+ * conditions.
+ *
+ * The problem is that NOMMU needs to be able to allocate large chunks
+ * of contiguous memory as there's no hardware page translation to
+ * assemble apparent contiguous memory from discontiguous pages.
+ *
+ * Queueing large contiguous runs of pages for batching, however,
+ * causes the pages to actually be freed in smaller chunks. As there
+ * can be a significant delay between the individual batches being
+ * recycled, this leads to the once large chunks of space being
+ * fragmented and becoming unavailable for high-order allocations.
+ */
+ return 0;
+#endif
+}
+
+static int percpu_pagelist_high_fraction;
+static int zone_highsize(struct zone *zone, int batch, int cpu_online)
+{
+#ifdef CONFIG_MMU
+ int high;
+ int nr_split_cpus;
+ unsigned long total_pages;
+
+ if (!percpu_pagelist_high_fraction) {
+ /*
+ * By default, the high value of the pcp is based on the zone
+ * low watermark so that if they are full then background
+ * reclaim will not be started prematurely.
+ */
+ total_pages = low_wmark_pages(zone);
+ } else {
+ /*
+ * If percpu_pagelist_high_fraction is configured, the high
+ * value is based on a fraction of the managed pages in the
+ * zone.
+ */
+ total_pages = zone_managed_pages(zone) / percpu_pagelist_high_fraction;
+ }
+
+ /*
+ * Split the high value across all online CPUs local to the zone. Note
+ * that early in boot that CPUs may not be online yet and that during
+ * CPU hotplug that the cpumask is not yet updated when a CPU is being
+ * onlined. For memory nodes that have no CPUs, split pcp->high across
+ * all online CPUs to mitigate the risk that reclaim is triggered
+ * prematurely due to pages stored on pcp lists.
+ */
+ nr_split_cpus = cpumask_weight(cpumask_of_node(zone_to_nid(zone))) + cpu_online;
+ if (!nr_split_cpus)
+ nr_split_cpus = num_online_cpus();
+ high = total_pages / nr_split_cpus;
+
+ /*
+ * Ensure high is at least batch*4. The multiple is based on the
+ * historical relationship between high and batch.
+ */
+ high = max(high, batch << 2);
+
+ return high;
+#else
+ return 0;
+#endif
+}
+
+/*
+ * pcp->high and pcp->batch values are related and generally batch is lower
+ * than high. They are also related to pcp->count such that count is lower
+ * than high, and as soon as it reaches high, the pcplist is flushed.
+ *
+ * However, guaranteeing these relations at all times would require e.g. write
+ * barriers here but also careful usage of read barriers at the read side, and
+ * thus be prone to error and bad for performance. Thus the update only prevents
+ * store tearing. Any new users of pcp->batch and pcp->high should ensure they
+ * can cope with those fields changing asynchronously, and fully trust only the
+ * pcp->count field on the local CPU with interrupts disabled.
+ *
+ * mutex_is_locked(&pcp_batch_high_lock) required when calling this function
+ * outside of boot time (or some other assurance that no concurrent updaters
+ * exist).
+ */
+static void pageset_update(struct per_cpu_pages *pcp, unsigned long high,
+ unsigned long batch)
+{
+ WRITE_ONCE(pcp->batch, batch);
+ WRITE_ONCE(pcp->high, high);
+}
+
+static void per_cpu_pages_init(struct per_cpu_pages *pcp, struct per_cpu_zonestat *pzstats)
+{
+ int pindex;
+
+ memset(pcp, 0, sizeof(*pcp));
+ memset(pzstats, 0, sizeof(*pzstats));
+
+ spin_lock_init(&pcp->lock);
+ for (pindex = 0; pindex < NR_PCP_LISTS; pindex++)
+ INIT_LIST_HEAD(&pcp->lists[pindex]);
+
+ /*
+ * Set batch and high values safe for a boot pageset. A true percpu
+ * pageset's initialization will update them subsequently. Here we don't
+ * need to be as careful as pageset_update() as nobody can access the
+ * pageset yet.
+ */
+ pcp->high = BOOT_PAGESET_HIGH;
+ pcp->batch = BOOT_PAGESET_BATCH;
+ pcp->free_factor = 0;
+}
+
+static void __zone_set_pageset_high_and_batch(struct zone *zone, unsigned long high,
+ unsigned long batch)
+{
+ struct per_cpu_pages *pcp;
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
+ pageset_update(pcp, high, batch);
+ }
+}
+
+/*
+ * Calculate and set new high and batch values for all per-cpu pagesets of a
+ * zone based on the zone's size.
+ */
+static void zone_set_pageset_high_and_batch(struct zone *zone, int cpu_online)
+{
+ int new_high, new_batch;
+
+ new_batch = max(1, zone_batchsize(zone));
+ new_high = zone_highsize(zone, new_batch, cpu_online);
+
+ if (zone->pageset_high == new_high &&
+ zone->pageset_batch == new_batch)
+ return;
+
+ zone->pageset_high = new_high;
+ zone->pageset_batch = new_batch;
+
+ __zone_set_pageset_high_and_batch(zone, new_high, new_batch);
+}
+
+void __meminit setup_zone_pageset(struct zone *zone)
+{
+ int cpu;
+
+ /* Size may be 0 on !SMP && !NUMA */
+ if (sizeof(struct per_cpu_zonestat) > 0)
+ zone->per_cpu_zonestats = alloc_percpu(struct per_cpu_zonestat);
+
+ zone->per_cpu_pageset = alloc_percpu(struct per_cpu_pages);
+ for_each_possible_cpu(cpu) {
+ struct per_cpu_pages *pcp;
+ struct per_cpu_zonestat *pzstats;
+
+ pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
+ pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu);
+ per_cpu_pages_init(pcp, pzstats);
+ }
+
+ zone_set_pageset_high_and_batch(zone, 0);
+}
+
+/*
+ * The zone indicated has a new number of managed_pages; batch sizes and percpu
+ * page high values need to be recalculated.
+ */
+static void zone_pcp_update(struct zone *zone, int cpu_online)
+{
+ mutex_lock(&pcp_batch_high_lock);
+ zone_set_pageset_high_and_batch(zone, cpu_online);
+ mutex_unlock(&pcp_batch_high_lock);
+}
+
+/*
+ * Allocate per cpu pagesets and initialize them.
+ * Before this call only boot pagesets were available.
+ */
+void __init setup_per_cpu_pageset(void)
+{
+ struct pglist_data *pgdat;
+ struct zone *zone;
+ int __maybe_unused cpu;
+
+ for_each_populated_zone(zone)
+ setup_zone_pageset(zone);
+
+#ifdef CONFIG_NUMA
+ /*
+ * Unpopulated zones continue using the boot pagesets.
+ * The numa stats for these pagesets need to be reset.
+ * Otherwise, they will end up skewing the stats of
+ * the nodes these zones are associated with.
+ */
+ for_each_possible_cpu(cpu) {
+ struct per_cpu_zonestat *pzstats = &per_cpu(boot_zonestats, cpu);
+ memset(pzstats->vm_numa_event, 0,
+ sizeof(pzstats->vm_numa_event));
+ }
+#endif
+
+ for_each_online_pgdat(pgdat)
+ pgdat->per_cpu_nodestats =
+ alloc_percpu(struct per_cpu_nodestat);
+}
+
+__meminit void zone_pcp_init(struct zone *zone)
+{
+ /*
+ * per cpu subsystem is not up at this point. The following code
+ * relies on the ability of the linker to provide the
+ * offset of a (static) per cpu variable into the per cpu area.
+ */
+ zone->per_cpu_pageset = &boot_pageset;
+ zone->per_cpu_zonestats = &boot_zonestats;
+ zone->pageset_high = BOOT_PAGESET_HIGH;
+ zone->pageset_batch = BOOT_PAGESET_BATCH;
+
+ if (populated_zone(zone))
+ pr_debug(" %s zone: %lu pages, LIFO batch:%u\n", zone->name,
+ zone->present_pages, zone_batchsize(zone));
+}
+
+void adjust_managed_page_count(struct page *page, long count)
+{
+ atomic_long_add(count, &page_zone(page)->managed_pages);
+ totalram_pages_add(count);
+#ifdef CONFIG_HIGHMEM
+ if (PageHighMem(page))
+ totalhigh_pages_add(count);
+#endif
+}
+EXPORT_SYMBOL(adjust_managed_page_count);
+
+unsigned long free_reserved_area(void *start, void *end, int poison, const char *s)
+{
+ void *pos;
+ unsigned long pages = 0;
+
+ start = (void *)PAGE_ALIGN((unsigned long)start);
+ end = (void *)((unsigned long)end & PAGE_MASK);
+ for (pos = start; pos < end; pos += PAGE_SIZE, pages++) {
+ struct page *page = virt_to_page(pos);
+ void *direct_map_addr;
+
+ /*
+ * 'direct_map_addr' might be different from 'pos'
+ * because some architectures' virt_to_page()
+ * work with aliases. Getting the direct map
+ * address ensures that we get a _writeable_
+ * alias for the memset().
+ */
+ direct_map_addr = page_address(page);
+ /*
+ * Perform a kasan-unchecked memset() since this memory
+ * has not been initialized.
+ */
+ direct_map_addr = kasan_reset_tag(direct_map_addr);
+ if ((unsigned int)poison <= 0xFF)
+ memset(direct_map_addr, poison, PAGE_SIZE);
+
+ free_reserved_page(page);
+ }
+
+ if (pages && s)
+ pr_info("Freeing %s memory: %ldK\n", s, K(pages));
+
+ return pages;
+}
+
+static int page_alloc_cpu_dead(unsigned int cpu)
+{
+ struct zone *zone;
+
+ lru_add_drain_cpu(cpu);
+ mlock_drain_remote(cpu);
+ drain_pages(cpu);
+
+ /*
+ * Spill the event counters of the dead processor
+ * into the current processors event counters.
+ * This artificially elevates the count of the current
+ * processor.
+ */
+ vm_events_fold_cpu(cpu);
+
+ /*
+ * Zero the differential counters of the dead processor
+ * so that the vm statistics are consistent.
+ *
+ * This is only okay since the processor is dead and cannot
+ * race with what we are doing.
+ */
+ cpu_vm_stats_fold(cpu);
+
+ for_each_populated_zone(zone)
+ zone_pcp_update(zone, 0);
+
+ return 0;
+}
+
+static int page_alloc_cpu_online(unsigned int cpu)
+{
+ struct zone *zone;
+
+ for_each_populated_zone(zone)
+ zone_pcp_update(zone, 1);
+ return 0;
+}
+
+void __init page_alloc_init_cpuhp(void)
+{
+ int ret;
+
+ ret = cpuhp_setup_state_nocalls(CPUHP_PAGE_ALLOC,
+ "mm/page_alloc:pcp",
+ page_alloc_cpu_online,
+ page_alloc_cpu_dead);
+ WARN_ON(ret < 0);
+}
+
+/*
+ * calculate_totalreserve_pages - called when sysctl_lowmem_reserve_ratio
+ * or min_free_kbytes changes.
+ */
+static void calculate_totalreserve_pages(void)
+{
+ struct pglist_data *pgdat;
+ unsigned long reserve_pages = 0;
+ enum zone_type i, j;
+
+ for_each_online_pgdat(pgdat) {
+
+ pgdat->totalreserve_pages = 0;
+
+ for (i = 0; i < MAX_NR_ZONES; i++) {
+ struct zone *zone = pgdat->node_zones + i;
+ long max = 0;
+ unsigned long managed_pages = zone_managed_pages(zone);
+
+ /* Find valid and maximum lowmem_reserve in the zone */
+ for (j = i; j < MAX_NR_ZONES; j++) {
+ if (zone->lowmem_reserve[j] > max)
+ max = zone->lowmem_reserve[j];
+ }
+
+ /* we treat the high watermark as reserved pages. */
+ max += high_wmark_pages(zone);
+
+ if (max > managed_pages)
+ max = managed_pages;
+
+ pgdat->totalreserve_pages += max;
+
+ reserve_pages += max;
+ }
+ }
+ totalreserve_pages = reserve_pages;
+}
+
+/*
+ * setup_per_zone_lowmem_reserve - called whenever
+ * sysctl_lowmem_reserve_ratio changes. Ensures that each zone
+ * has a correct pages reserved value, so an adequate number of
+ * pages are left in the zone after a successful __alloc_pages().
+ */
+static void setup_per_zone_lowmem_reserve(void)
+{
+ struct pglist_data *pgdat;
+ enum zone_type i, j;
+
+ for_each_online_pgdat(pgdat) {
+ for (i = 0; i < MAX_NR_ZONES - 1; i++) {
+ struct zone *zone = &pgdat->node_zones[i];
+ int ratio = sysctl_lowmem_reserve_ratio[i];
+ bool clear = !ratio || !zone_managed_pages(zone);
+ unsigned long managed_pages = 0;
+
+ for (j = i + 1; j < MAX_NR_ZONES; j++) {
+ struct zone *upper_zone = &pgdat->node_zones[j];
+
+ managed_pages += zone_managed_pages(upper_zone);
+
+ if (clear)
+ zone->lowmem_reserve[j] = 0;
+ else
+ zone->lowmem_reserve[j] = managed_pages / ratio;
+ }
+ }
+ }
+
+ /* update totalreserve_pages */
+ calculate_totalreserve_pages();
+}
+
+static void __setup_per_zone_wmarks(void)
+{
+ unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10);
+ unsigned long lowmem_pages = 0;
+ struct zone *zone;
+ unsigned long flags;
+
+ /* Calculate total number of !ZONE_HIGHMEM and !ZONE_MOVABLE pages */
+ for_each_zone(zone) {
+ if (!is_highmem(zone) && zone_idx(zone) != ZONE_MOVABLE)
+ lowmem_pages += zone_managed_pages(zone);
+ }
+
+ for_each_zone(zone) {
+ u64 tmp;
+
+ spin_lock_irqsave(&zone->lock, flags);
+ tmp = (u64)pages_min * zone_managed_pages(zone);
+ do_div(tmp, lowmem_pages);
+ if (is_highmem(zone) || zone_idx(zone) == ZONE_MOVABLE) {
+ /*
+ * __GFP_HIGH and PF_MEMALLOC allocations usually don't
+ * need highmem and movable zones pages, so cap pages_min
+ * to a small value here.
+ *
+ * The WMARK_HIGH-WMARK_LOW and (WMARK_LOW-WMARK_MIN)
+ * deltas control async page reclaim, and so should
+ * not be capped for highmem and movable zones.
+ */
+ unsigned long min_pages;
+
+ min_pages = zone_managed_pages(zone) / 1024;
+ min_pages = clamp(min_pages, SWAP_CLUSTER_MAX, 128UL);
+ zone->_watermark[WMARK_MIN] = min_pages;
+ } else {
+ /*
+ * If it's a lowmem zone, reserve a number of pages
+ * proportionate to the zone's size.
+ */
+ zone->_watermark[WMARK_MIN] = tmp;
+ }
+
+ /*
+ * Set the kswapd watermarks distance according to the
+ * scale factor in proportion to available memory, but
+ * ensure a minimum size on small systems.
+ */
+ tmp = max_t(u64, tmp >> 2,
+ mult_frac(zone_managed_pages(zone),
+ watermark_scale_factor, 10000));
+
+ zone->watermark_boost = 0;
+ zone->_watermark[WMARK_LOW] = min_wmark_pages(zone) + tmp;
+ zone->_watermark[WMARK_HIGH] = low_wmark_pages(zone) + tmp;
+ zone->_watermark[WMARK_PROMO] = high_wmark_pages(zone) + tmp;
+
+ spin_unlock_irqrestore(&zone->lock, flags);
+ }
+
+ /* update totalreserve_pages */
+ calculate_totalreserve_pages();
+}
+
+/**
+ * setup_per_zone_wmarks - called when min_free_kbytes changes
+ * or when memory is hot-{added|removed}
+ *
+ * Ensures that the watermark[min,low,high] values for each zone are set
+ * correctly with respect to min_free_kbytes.
+ */
+void setup_per_zone_wmarks(void)
+{
+ struct zone *zone;
+ static DEFINE_SPINLOCK(lock);
+
+ spin_lock(&lock);
+ __setup_per_zone_wmarks();
+ spin_unlock(&lock);
+
+ /*
+ * The watermark size have changed so update the pcpu batch
+ * and high limits or the limits may be inappropriate.
+ */
+ for_each_zone(zone)
+ zone_pcp_update(zone, 0);
+}
+
+/*
+ * Initialise min_free_kbytes.
+ *
+ * For small machines we want it small (128k min). For large machines
+ * we want it large (256MB max). But it is not linear, because network
+ * bandwidth does not increase linearly with machine size. We use
+ *
+ * min_free_kbytes = 4 * sqrt(lowmem_kbytes), for better accuracy:
+ * min_free_kbytes = sqrt(lowmem_kbytes * 16)
+ *
+ * which yields
+ *
+ * 16MB: 512k
+ * 32MB: 724k
+ * 64MB: 1024k
+ * 128MB: 1448k
+ * 256MB: 2048k
+ * 512MB: 2896k
+ * 1024MB: 4096k
+ * 2048MB: 5792k
+ * 4096MB: 8192k
+ * 8192MB: 11584k
+ * 16384MB: 16384k
+ */
+void calculate_min_free_kbytes(void)
+{
+ unsigned long lowmem_kbytes;
+ int new_min_free_kbytes;
+
+ lowmem_kbytes = nr_free_buffer_pages() * (PAGE_SIZE >> 10);
+ new_min_free_kbytes = int_sqrt(lowmem_kbytes * 16);
+
+ if (new_min_free_kbytes > user_min_free_kbytes)
+ min_free_kbytes = clamp(new_min_free_kbytes, 128, 262144);
+ else
+ pr_warn("min_free_kbytes is not updated to %d because user defined value %d is preferred\n",
+ new_min_free_kbytes, user_min_free_kbytes);
+
+}
+
+int __meminit init_per_zone_wmark_min(void)
+{
+ calculate_min_free_kbytes();
+ setup_per_zone_wmarks();
+ refresh_zone_stat_thresholds();
+ setup_per_zone_lowmem_reserve();
+
+#ifdef CONFIG_NUMA
+ setup_min_unmapped_ratio();
+ setup_min_slab_ratio();
+#endif
+
+ khugepaged_min_free_kbytes_update();
+
+ return 0;
+}
+postcore_initcall(init_per_zone_wmark_min)
+
+/*
+ * min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so
+ * that we can call two helper functions whenever min_free_kbytes
+ * changes.
+ */
+static int min_free_kbytes_sysctl_handler(struct ctl_table *table, int write,
+ void *buffer, size_t *length, loff_t *ppos)
+{
+ int rc;
+
+ rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
+ if (rc)
+ return rc;
+
+ if (write) {
+ user_min_free_kbytes = min_free_kbytes;
+ setup_per_zone_wmarks();
+ }
+ return 0;
+}
+
+static int watermark_scale_factor_sysctl_handler(struct ctl_table *table, int write,
+ void *buffer, size_t *length, loff_t *ppos)
+{
+ int rc;
+
+ rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
+ if (rc)
+ return rc;
+
+ if (write)
+ setup_per_zone_wmarks();
+
+ return 0;
+}
+
+#ifdef CONFIG_NUMA
+static void setup_min_unmapped_ratio(void)
+{
+ pg_data_t *pgdat;
+ struct zone *zone;
+
+ for_each_online_pgdat(pgdat)
+ pgdat->min_unmapped_pages = 0;
+
+ for_each_zone(zone)
+ zone->zone_pgdat->min_unmapped_pages += (zone_managed_pages(zone) *
+ sysctl_min_unmapped_ratio) / 100;
+}
+
+
+static int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *table, int write,
+ void *buffer, size_t *length, loff_t *ppos)
+{
+ int rc;
+
+ rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
+ if (rc)
+ return rc;
+
+ setup_min_unmapped_ratio();
+
+ return 0;
+}
+
+static void setup_min_slab_ratio(void)
+{
+ pg_data_t *pgdat;
+ struct zone *zone;
+
+ for_each_online_pgdat(pgdat)
+ pgdat->min_slab_pages = 0;
+
+ for_each_zone(zone)
+ zone->zone_pgdat->min_slab_pages += (zone_managed_pages(zone) *
+ sysctl_min_slab_ratio) / 100;
+}
+
+static int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *table, int write,
+ void *buffer, size_t *length, loff_t *ppos)
+{
+ int rc;
+
+ rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
+ if (rc)
+ return rc;
+
+ setup_min_slab_ratio();
+
+ return 0;
+}
+#endif
+
+/*
+ * lowmem_reserve_ratio_sysctl_handler - just a wrapper around
+ * proc_dointvec() so that we can call setup_per_zone_lowmem_reserve()
+ * whenever sysctl_lowmem_reserve_ratio changes.
+ *
+ * The reserve ratio obviously has absolutely no relation with the
+ * minimum watermarks. The lowmem reserve ratio can only make sense
+ * if in function of the boot time zone sizes.
+ */
+static int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *table,
+ int write, void *buffer, size_t *length, loff_t *ppos)
+{
+ int i;
+
+ proc_dointvec_minmax(table, write, buffer, length, ppos);
+
+ for (i = 0; i < MAX_NR_ZONES; i++) {
+ if (sysctl_lowmem_reserve_ratio[i] < 1)
+ sysctl_lowmem_reserve_ratio[i] = 0;
+ }
+
+ setup_per_zone_lowmem_reserve();
+ return 0;
+}
+
+/*
+ * percpu_pagelist_high_fraction - changes the pcp->high for each zone on each
+ * cpu. It is the fraction of total pages in each zone that a hot per cpu
+ * pagelist can have before it gets flushed back to buddy allocator.
+ */
+static int percpu_pagelist_high_fraction_sysctl_handler(struct ctl_table *table,
+ int write, void *buffer, size_t *length, loff_t *ppos)
+{
+ struct zone *zone;
+ int old_percpu_pagelist_high_fraction;
+ int ret;
+
+ mutex_lock(&pcp_batch_high_lock);
+ old_percpu_pagelist_high_fraction = percpu_pagelist_high_fraction;
+
+ ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
+ if (!write || ret < 0)
+ goto out;
+
+ /* Sanity checking to avoid pcp imbalance */
+ if (percpu_pagelist_high_fraction &&
+ percpu_pagelist_high_fraction < MIN_PERCPU_PAGELIST_HIGH_FRACTION) {
+ percpu_pagelist_high_fraction = old_percpu_pagelist_high_fraction;
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /* No change? */
+ if (percpu_pagelist_high_fraction == old_percpu_pagelist_high_fraction)
+ goto out;
+
+ for_each_populated_zone(zone)
+ zone_set_pageset_high_and_batch(zone, 0);
+out:
+ mutex_unlock(&pcp_batch_high_lock);
+ return ret;
+}
+
+static struct ctl_table page_alloc_sysctl_table[] = {
+ {
+ .procname = "min_free_kbytes",
+ .data = &min_free_kbytes,
+ .maxlen = sizeof(min_free_kbytes),
+ .mode = 0644,
+ .proc_handler = min_free_kbytes_sysctl_handler,
+ .extra1 = SYSCTL_ZERO,
+ },
+ {
+ .procname = "watermark_boost_factor",
+ .data = &watermark_boost_factor,
+ .maxlen = sizeof(watermark_boost_factor),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ },
+ {
+ .procname = "watermark_scale_factor",
+ .data = &watermark_scale_factor,
+ .maxlen = sizeof(watermark_scale_factor),
+ .mode = 0644,
+ .proc_handler = watermark_scale_factor_sysctl_handler,
+ .extra1 = SYSCTL_ONE,
+ .extra2 = SYSCTL_THREE_THOUSAND,
+ },
+ {
+ .procname = "percpu_pagelist_high_fraction",
+ .data = &percpu_pagelist_high_fraction,
+ .maxlen = sizeof(percpu_pagelist_high_fraction),
+ .mode = 0644,
+ .proc_handler = percpu_pagelist_high_fraction_sysctl_handler,
+ .extra1 = SYSCTL_ZERO,
+ },
+ {
+ .procname = "lowmem_reserve_ratio",
+ .data = &sysctl_lowmem_reserve_ratio,
+ .maxlen = sizeof(sysctl_lowmem_reserve_ratio),
+ .mode = 0644,
+ .proc_handler = lowmem_reserve_ratio_sysctl_handler,
+ },
+#ifdef CONFIG_NUMA
+ {
+ .procname = "numa_zonelist_order",
+ .data = &numa_zonelist_order,
+ .maxlen = NUMA_ZONELIST_ORDER_LEN,
+ .mode = 0644,
+ .proc_handler = numa_zonelist_order_handler,
+ },
+ {
+ .procname = "min_unmapped_ratio",
+ .data = &sysctl_min_unmapped_ratio,
+ .maxlen = sizeof(sysctl_min_unmapped_ratio),
+ .mode = 0644,
+ .proc_handler = sysctl_min_unmapped_ratio_sysctl_handler,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE_HUNDRED,
+ },
+ {
+ .procname = "min_slab_ratio",
+ .data = &sysctl_min_slab_ratio,
+ .maxlen = sizeof(sysctl_min_slab_ratio),
+ .mode = 0644,
+ .proc_handler = sysctl_min_slab_ratio_sysctl_handler,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE_HUNDRED,
+ },
+#endif
+ {}
+};
+
+void __init page_alloc_sysctl_init(void)
+{
+ register_sysctl_init("vm", page_alloc_sysctl_table);
+}
+
+#ifdef CONFIG_CONTIG_ALLOC
+/* Usage: See admin-guide/dynamic-debug-howto.rst */
+static void alloc_contig_dump_pages(struct list_head *page_list)
+{
+ DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, "migrate failure");
+
+ if (DYNAMIC_DEBUG_BRANCH(descriptor)) {
+ struct page *page;
+
+ dump_stack();
+ list_for_each_entry(page, page_list, lru)
+ dump_page(page, "migration failure");
+ }
+}
+
+/* [start, end) must belong to a single zone. */
+int __alloc_contig_migrate_range(struct compact_control *cc,
+ unsigned long start, unsigned long end)
+{
+ /* This function is based on compact_zone() from compaction.c. */
+ unsigned int nr_reclaimed;
+ unsigned long pfn = start;
+ unsigned int tries = 0;
+ int ret = 0;
+ struct migration_target_control mtc = {
+ .nid = zone_to_nid(cc->zone),
+ .gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
+ };
+
+ lru_cache_disable();
+
+ while (pfn < end || !list_empty(&cc->migratepages)) {
+ if (fatal_signal_pending(current)) {
+ ret = -EINTR;
+ break;
+ }
+
+ if (list_empty(&cc->migratepages)) {
+ cc->nr_migratepages = 0;
+ ret = isolate_migratepages_range(cc, pfn, end);
+ if (ret && ret != -EAGAIN)
+ break;
+ pfn = cc->migrate_pfn;
+ tries = 0;
+ } else if (++tries == 5) {
+ ret = -EBUSY;
+ break;
+ }
+
+ nr_reclaimed = reclaim_clean_pages_from_list(cc->zone,
+ &cc->migratepages);
+ cc->nr_migratepages -= nr_reclaimed;
+
+ ret = migrate_pages(&cc->migratepages, alloc_migration_target,
+ NULL, (unsigned long)&mtc, cc->mode, MR_CONTIG_RANGE, NULL);
+
+ /*
+ * On -ENOMEM, migrate_pages() bails out right away. It is pointless
+ * to retry again over this error, so do the same here.
+ */
+ if (ret == -ENOMEM)
+ break;
+ }
+
+ lru_cache_enable();
+ if (ret < 0) {
+ if (!(cc->gfp_mask & __GFP_NOWARN) && ret == -EBUSY)
+ alloc_contig_dump_pages(&cc->migratepages);
+ putback_movable_pages(&cc->migratepages);
+ return ret;
+ }
+ return 0;
+}
+
+/**
+ * alloc_contig_range() -- tries to allocate given range of pages
+ * @start: start PFN to allocate
+ * @end: one-past-the-last PFN to allocate
+ * @migratetype: migratetype of the underlying pageblocks (either
+ * #MIGRATE_MOVABLE or #MIGRATE_CMA). All pageblocks
+ * in range must have the same migratetype and it must
+ * be either of the two.
+ * @gfp_mask: GFP mask to use during compaction
+ *
+ * The PFN range does not have to be pageblock aligned. The PFN range must
+ * belong to a single zone.
+ *
+ * The first thing this routine does is attempt to MIGRATE_ISOLATE all
+ * pageblocks in the range. Once isolated, the pageblocks should not
+ * be modified by others.
+ *
+ * Return: zero on success or negative error code. On success all
+ * pages which PFN is in [start, end) are allocated for the caller and
+ * need to be freed with free_contig_range().
+ */
+int alloc_contig_range(unsigned long start, unsigned long end,
+ unsigned migratetype, gfp_t gfp_mask)
+{
+ unsigned long outer_start, outer_end;
+ int order;
+ int ret = 0;
+
+ struct compact_control cc = {
+ .nr_migratepages = 0,
+ .order = -1,
+ .zone = page_zone(pfn_to_page(start)),
+ .mode = MIGRATE_SYNC,
+ .ignore_skip_hint = true,
+ .no_set_skip_hint = true,
+ .gfp_mask = current_gfp_context(gfp_mask),
+ .alloc_contig = true,
+ };
+ INIT_LIST_HEAD(&cc.migratepages);
+
+ /*
+ * What we do here is we mark all pageblocks in range as
+ * MIGRATE_ISOLATE. Because pageblock and max order pages may
+ * have different sizes, and due to the way page allocator
+ * work, start_isolate_page_range() has special handlings for this.
+ *
+ * Once the pageblocks are marked as MIGRATE_ISOLATE, we
+ * migrate the pages from an unaligned range (ie. pages that
+ * we are interested in). This will put all the pages in
+ * range back to page allocator as MIGRATE_ISOLATE.
+ *
+ * When this is done, we take the pages in range from page
+ * allocator removing them from the buddy system. This way
+ * page allocator will never consider using them.
+ *
+ * This lets us mark the pageblocks back as
+ * MIGRATE_CMA/MIGRATE_MOVABLE so that free pages in the
+ * aligned range but not in the unaligned, original range are
+ * put back to page allocator so that buddy can use them.
+ */
+
+ ret = start_isolate_page_range(start, end, migratetype, 0, gfp_mask);
+ if (ret)
+ goto done;
+
+ drain_all_pages(cc.zone);
+
+ /*
+ * In case of -EBUSY, we'd like to know which page causes problem.
+ * So, just fall through. test_pages_isolated() has a tracepoint
+ * which will report the busy page.
+ *
+ * It is possible that busy pages could become available before
+ * the call to test_pages_isolated, and the range will actually be
+ * allocated. So, if we fall through be sure to clear ret so that
+ * -EBUSY is not accidentally used or returned to caller.
+ */
+ ret = __alloc_contig_migrate_range(&cc, start, end);
+ if (ret && ret != -EBUSY)
+ goto done;
+ ret = 0;
+
+ /*
+ * Pages from [start, end) are within a pageblock_nr_pages
+ * aligned blocks that are marked as MIGRATE_ISOLATE. What's
+ * more, all pages in [start, end) are free in page allocator.
+ * What we are going to do is to allocate all pages from
+ * [start, end) (that is remove them from page allocator).
+ *
+ * The only problem is that pages at the beginning and at the
+ * end of interesting range may be not aligned with pages that
+ * page allocator holds, ie. they can be part of higher order
+ * pages. Because of this, we reserve the bigger range and
+ * once this is done free the pages we are not interested in.
+ *
+ * We don't have to hold zone->lock here because the pages are
+ * isolated thus they won't get removed from buddy.
+ */
+
+ order = 0;
+ outer_start = start;
+ while (!PageBuddy(pfn_to_page(outer_start))) {
+ if (++order > MAX_ORDER) {
+ outer_start = start;
+ break;
+ }
+ outer_start &= ~0UL << order;
+ }
+
+ if (outer_start != start) {
+ order = buddy_order(pfn_to_page(outer_start));
+
+ /*
+ * outer_start page could be small order buddy page and
+ * it doesn't include start page. Adjust outer_start
+ * in this case to report failed page properly
+ * on tracepoint in test_pages_isolated()
+ */
+ if (outer_start + (1UL << order) <= start)
+ outer_start = start;
+ }
+
+ /* Make sure the range is really isolated. */
+ if (test_pages_isolated(outer_start, end, 0)) {
+ ret = -EBUSY;
+ goto done;
+ }
+
+ /* Grab isolated pages from freelists. */
+ outer_end = isolate_freepages_range(&cc, outer_start, end);
+ if (!outer_end) {
+ ret = -EBUSY;
+ goto done;
+ }
+
+ /* Free head and tail (if any) */
+ if (start != outer_start)
+ free_contig_range(outer_start, start - outer_start);
+ if (end != outer_end)
+ free_contig_range(end, outer_end - end);
+
+done:
+ undo_isolate_page_range(start, end, migratetype);
+ return ret;
+}
+EXPORT_SYMBOL(alloc_contig_range);
+
+static int __alloc_contig_pages(unsigned long start_pfn,
+ unsigned long nr_pages, gfp_t gfp_mask)
+{
+ unsigned long end_pfn = start_pfn + nr_pages;
+
+ return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE,
+ gfp_mask);
+}
+
+static bool pfn_range_valid_contig(struct zone *z, unsigned long start_pfn,
+ unsigned long nr_pages)
+{
+ unsigned long i, end_pfn = start_pfn + nr_pages;
+ struct page *page;
+
+ for (i = start_pfn; i < end_pfn; i++) {
+ page = pfn_to_online_page(i);
+ if (!page)
+ return false;
+
+ if (page_zone(page) != z)
+ return false;
+
+ if (PageReserved(page))
+ return false;
+
+ if (PageHuge(page))
+ return false;
+ }
+ return true;
+}
+
+static bool zone_spans_last_pfn(const struct zone *zone,
+ unsigned long start_pfn, unsigned long nr_pages)
+{
+ unsigned long last_pfn = start_pfn + nr_pages - 1;
+
+ return zone_spans_pfn(zone, last_pfn);
+}
+
+/**
+ * alloc_contig_pages() -- tries to find and allocate contiguous range of pages
+ * @nr_pages: Number of contiguous pages to allocate
+ * @gfp_mask: GFP mask to limit search and used during compaction
+ * @nid: Target node
+ * @nodemask: Mask for other possible nodes
+ *
+ * This routine is a wrapper around alloc_contig_range(). It scans over zones
+ * on an applicable zonelist to find a contiguous pfn range which can then be
+ * tried for allocation with alloc_contig_range(). This routine is intended
+ * for allocation requests which can not be fulfilled with the buddy allocator.
+ *
+ * The allocated memory is always aligned to a page boundary. If nr_pages is a
+ * power of two, then allocated range is also guaranteed to be aligned to same
+ * nr_pages (e.g. 1GB request would be aligned to 1GB).
+ *
+ * Allocated pages can be freed with free_contig_range() or by manually calling
+ * __free_page() on each allocated page.
+ *
+ * Return: pointer to contiguous pages on success, or NULL if not successful.
+ */
+struct page *alloc_contig_pages(unsigned long nr_pages, gfp_t gfp_mask,
+ int nid, nodemask_t *nodemask)
+{
+ unsigned long ret, pfn, flags;
+ struct zonelist *zonelist;
+ struct zone *zone;
+ struct zoneref *z;
+
+ zonelist = node_zonelist(nid, gfp_mask);
+ for_each_zone_zonelist_nodemask(zone, z, zonelist,
+ gfp_zone(gfp_mask), nodemask) {
+ spin_lock_irqsave(&zone->lock, flags);
+
+ pfn = ALIGN(zone->zone_start_pfn, nr_pages);
+ while (zone_spans_last_pfn(zone, pfn, nr_pages)) {
+ if (pfn_range_valid_contig(zone, pfn, nr_pages)) {
+ /*
+ * We release the zone lock here because
+ * alloc_contig_range() will also lock the zone
+ * at some point. If there's an allocation
+ * spinning on this lock, it may win the race
+ * and cause alloc_contig_range() to fail...
+ */
+ spin_unlock_irqrestore(&zone->lock, flags);
+ ret = __alloc_contig_pages(pfn, nr_pages,
+ gfp_mask);
+ if (!ret)
+ return pfn_to_page(pfn);
+ spin_lock_irqsave(&zone->lock, flags);
+ }
+ pfn += nr_pages;
+ }
+ spin_unlock_irqrestore(&zone->lock, flags);
+ }
+ return NULL;
+}
+#endif /* CONFIG_CONTIG_ALLOC */
+
+void free_contig_range(unsigned long pfn, unsigned long nr_pages)
+{
+ unsigned long count = 0;
+
+ for (; nr_pages--; pfn++) {
+ struct page *page = pfn_to_page(pfn);
+
+ count += page_count(page) != 1;
+ __free_page(page);
+ }
+ WARN(count != 0, "%lu pages are still in use!\n", count);
+}
+EXPORT_SYMBOL(free_contig_range);
+
+/*
+ * Effectively disable pcplists for the zone by setting the high limit to 0
+ * and draining all cpus. A concurrent page freeing on another CPU that's about
+ * to put the page on pcplist will either finish before the drain and the page
+ * will be drained, or observe the new high limit and skip the pcplist.
+ *
+ * Must be paired with a call to zone_pcp_enable().
+ */
+void zone_pcp_disable(struct zone *zone)
+{
+ mutex_lock(&pcp_batch_high_lock);
+ __zone_set_pageset_high_and_batch(zone, 0, 1);
+ __drain_all_pages(zone, true);
+}
+
+void zone_pcp_enable(struct zone *zone)
+{
+ __zone_set_pageset_high_and_batch(zone, zone->pageset_high, zone->pageset_batch);
+ mutex_unlock(&pcp_batch_high_lock);
+}
+
+void zone_pcp_reset(struct zone *zone)
+{
+ int cpu;
+ struct per_cpu_zonestat *pzstats;
+
+ if (zone->per_cpu_pageset != &boot_pageset) {
+ for_each_online_cpu(cpu) {
+ pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu);
+ drain_zonestat(zone, pzstats);
+ }
+ free_percpu(zone->per_cpu_pageset);
+ zone->per_cpu_pageset = &boot_pageset;
+ if (zone->per_cpu_zonestats != &boot_zonestats) {
+ free_percpu(zone->per_cpu_zonestats);
+ zone->per_cpu_zonestats = &boot_zonestats;
+ }
+ }
+}
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+/*
+ * All pages in the range must be in a single zone, must not contain holes,
+ * must span full sections, and must be isolated before calling this function.
+ */
+void __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
+{
+ unsigned long pfn = start_pfn;
+ struct page *page;
+ struct zone *zone;
+ unsigned int order;
+ unsigned long flags;
+
+ offline_mem_sections(pfn, end_pfn);
+ zone = page_zone(pfn_to_page(pfn));
+ spin_lock_irqsave(&zone->lock, flags);
+ while (pfn < end_pfn) {
+ page = pfn_to_page(pfn);
+ /*
+ * The HWPoisoned page may be not in buddy system, and
+ * page_count() is not 0.
+ */
+ if (unlikely(!PageBuddy(page) && PageHWPoison(page))) {
+ pfn++;
+ continue;
+ }
+ /*
+ * At this point all remaining PageOffline() pages have a
+ * reference count of 0 and can simply be skipped.
+ */
+ if (PageOffline(page)) {
+ BUG_ON(page_count(page));
+ BUG_ON(PageBuddy(page));
+ pfn++;
+ continue;
+ }
+
+ BUG_ON(page_count(page));
+ BUG_ON(!PageBuddy(page));
+ order = buddy_order(page);
+ del_page_from_free_list(page, zone, order);
+ pfn += (1 << order);
+ }
+ spin_unlock_irqrestore(&zone->lock, flags);
+}
+#endif
+
+/*
+ * This function returns a stable result only if called under zone lock.
+ */
+bool is_free_buddy_page(struct page *page)
+{
+ unsigned long pfn = page_to_pfn(page);
+ unsigned int order;
+
+ for (order = 0; order <= MAX_ORDER; order++) {
+ struct page *page_head = page - (pfn & ((1 << order) - 1));
+
+ if (PageBuddy(page_head) &&
+ buddy_order_unsafe(page_head) >= order)
+ break;
+ }
+
+ return order <= MAX_ORDER;
+}
+EXPORT_SYMBOL(is_free_buddy_page);
+
+#ifdef CONFIG_MEMORY_FAILURE
+/*
+ * Break down a higher-order page in sub-pages, and keep our target out of
+ * buddy allocator.
+ */
+static void break_down_buddy_pages(struct zone *zone, struct page *page,
+ struct page *target, int low, int high,
+ int migratetype)
+{
+ unsigned long size = 1 << high;
+ struct page *current_buddy, *next_page;
+
+ while (high > low) {
+ high--;
+ size >>= 1;
+
+ if (target >= &page[size]) {
+ next_page = page + size;
+ current_buddy = page;
+ } else {
+ next_page = page;
+ current_buddy = page + size;
+ }
+ page = next_page;
+
+ if (set_page_guard(zone, current_buddy, high, migratetype))
+ continue;
+
+ if (current_buddy != target) {
+ add_to_free_list(current_buddy, zone, high, migratetype);
+ set_buddy_order(current_buddy, high);
+ }
+ }
+}
+
+/*
+ * Take a page that will be marked as poisoned off the buddy allocator.
+ */
+bool take_page_off_buddy(struct page *page)
+{
+ struct zone *zone = page_zone(page);
+ unsigned long pfn = page_to_pfn(page);
+ unsigned long flags;
+ unsigned int order;
+ bool ret = false;
+
+ spin_lock_irqsave(&zone->lock, flags);
+ for (order = 0; order <= MAX_ORDER; order++) {
+ struct page *page_head = page - (pfn & ((1 << order) - 1));
+ int page_order = buddy_order(page_head);
+
+ if (PageBuddy(page_head) && page_order >= order) {
+ unsigned long pfn_head = page_to_pfn(page_head);
+ int migratetype = get_pfnblock_migratetype(page_head,
+ pfn_head);
+
+ del_page_from_free_list(page_head, zone, page_order);
+ break_down_buddy_pages(zone, page_head, page, 0,
+ page_order, migratetype);
+ SetPageHWPoisonTakenOff(page);
+ if (!is_migrate_isolate(migratetype))
+ __mod_zone_freepage_state(zone, -1, migratetype);
+ ret = true;
+ break;
+ }
+ if (page_count(page_head) > 0)
+ break;
+ }
+ spin_unlock_irqrestore(&zone->lock, flags);
+ return ret;
+}
+
+/*
+ * Cancel takeoff done by take_page_off_buddy().
+ */
+bool put_page_back_buddy(struct page *page)
+{
+ struct zone *zone = page_zone(page);
+ unsigned long pfn = page_to_pfn(page);
+ unsigned long flags;
+ int migratetype = get_pfnblock_migratetype(page, pfn);
+ bool ret = false;
+
+ spin_lock_irqsave(&zone->lock, flags);
+ if (put_page_testzero(page)) {
+ ClearPageHWPoisonTakenOff(page);
+ __free_one_page(page, pfn, zone, 0, migratetype, FPI_NONE);
+ if (TestClearPageHWPoison(page)) {
+ ret = true;
+ }
+ }
+ spin_unlock_irqrestore(&zone->lock, flags);
+
+ return ret;
+}
+#endif
+
+#ifdef CONFIG_ZONE_DMA
+bool has_managed_dma(void)
+{
+ struct pglist_data *pgdat;
+
+ for_each_online_pgdat(pgdat) {
+ struct zone *zone = &pgdat->node_zones[ZONE_DMA];
+
+ if (managed_zone(zone))
+ return true;
+ }
+ return false;
+}
+#endif /* CONFIG_ZONE_DMA */
+
+#ifdef CONFIG_UNACCEPTED_MEMORY
+
+/* Counts number of zones with unaccepted pages. */
+static DEFINE_STATIC_KEY_FALSE(zones_with_unaccepted_pages);
+
+static bool lazy_accept = true;
+
+static int __init accept_memory_parse(char *p)
+{
+ if (!strcmp(p, "lazy")) {
+ lazy_accept = true;
+ return 0;
+ } else if (!strcmp(p, "eager")) {
+ lazy_accept = false;
+ return 0;
+ } else {
+ return -EINVAL;
+ }
+}
+early_param("accept_memory", accept_memory_parse);
+
+static bool page_contains_unaccepted(struct page *page, unsigned int order)
+{
+ phys_addr_t start = page_to_phys(page);
+ phys_addr_t end = start + (PAGE_SIZE << order);
+
+ return range_contains_unaccepted_memory(start, end);
+}
+
+static void accept_page(struct page *page, unsigned int order)
+{
+ phys_addr_t start = page_to_phys(page);
+
+ accept_memory(start, start + (PAGE_SIZE << order));
+}
+
+static bool try_to_accept_memory_one(struct zone *zone)
+{
+ unsigned long flags;
+ struct page *page;
+ bool last;
+
+ if (list_empty(&zone->unaccepted_pages))
+ return false;
+
+ spin_lock_irqsave(&zone->lock, flags);
+ page = list_first_entry_or_null(&zone->unaccepted_pages,
+ struct page, lru);
+ if (!page) {
+ spin_unlock_irqrestore(&zone->lock, flags);
+ return false;
+ }
+
+ list_del(&page->lru);
+ last = list_empty(&zone->unaccepted_pages);
+
+ __mod_zone_freepage_state(zone, -MAX_ORDER_NR_PAGES, MIGRATE_MOVABLE);
+ __mod_zone_page_state(zone, NR_UNACCEPTED, -MAX_ORDER_NR_PAGES);
+ spin_unlock_irqrestore(&zone->lock, flags);
+
+ accept_page(page, MAX_ORDER);
+
+ __free_pages_ok(page, MAX_ORDER, FPI_TO_TAIL);
+
+ if (last)
+ static_branch_dec(&zones_with_unaccepted_pages);
+
+ return true;
+}
+
+static bool try_to_accept_memory(struct zone *zone, unsigned int order)
+{
+ long to_accept;
+ int ret = false;
+
+ /* How much to accept to get to high watermark? */
+ to_accept = high_wmark_pages(zone) -
+ (zone_page_state(zone, NR_FREE_PAGES) -
+ __zone_watermark_unusable_free(zone, order, 0));
+
+ /* Accept at least one page */
+ do {
+ if (!try_to_accept_memory_one(zone))
+ break;
+ ret = true;
+ to_accept -= MAX_ORDER_NR_PAGES;
+ } while (to_accept > 0);
+
+ return ret;
+}
+
+static inline bool has_unaccepted_memory(void)
+{
+ return static_branch_unlikely(&zones_with_unaccepted_pages);
+}
+
+static bool __free_unaccepted(struct page *page)
+{
+ struct zone *zone = page_zone(page);
+ unsigned long flags;
+ bool first = false;
+
+ if (!lazy_accept)
+ return false;
+
+ spin_lock_irqsave(&zone->lock, flags);
+ first = list_empty(&zone->unaccepted_pages);
+ list_add_tail(&page->lru, &zone->unaccepted_pages);
+ __mod_zone_freepage_state(zone, MAX_ORDER_NR_PAGES, MIGRATE_MOVABLE);
+ __mod_zone_page_state(zone, NR_UNACCEPTED, MAX_ORDER_NR_PAGES);
+ spin_unlock_irqrestore(&zone->lock, flags);
+
+ if (first)
+ static_branch_inc(&zones_with_unaccepted_pages);
+
+ return true;
+}
+
+#else
+
+static bool page_contains_unaccepted(struct page *page, unsigned int order)
+{
+ return false;
+}
+
+static void accept_page(struct page *page, unsigned int order)
+{
+}
+
+static bool try_to_accept_memory(struct zone *zone, unsigned int order)
+{
+ return false;
+}
+
+static inline bool has_unaccepted_memory(void)
+{
+ return false;
+}
+
+static bool __free_unaccepted(struct page *page)
+{
+ BUILD_BUG();
+ return false;
+}
+
+#endif /* CONFIG_UNACCEPTED_MEMORY */