v4.19.13 snapshot.
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
new file mode 100644
index 0000000..d4b0c79
--- /dev/null
+++ b/include/linux/mmzone.h
@@ -0,0 +1,1334 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_MMZONE_H
+#define _LINUX_MMZONE_H
+
+#ifndef __ASSEMBLY__
+#ifndef __GENERATING_BOUNDS_H
+
+#include <linux/spinlock.h>
+#include <linux/list.h>
+#include <linux/wait.h>
+#include <linux/bitops.h>
+#include <linux/cache.h>
+#include <linux/threads.h>
+#include <linux/numa.h>
+#include <linux/init.h>
+#include <linux/seqlock.h>
+#include <linux/nodemask.h>
+#include <linux/pageblock-flags.h>
+#include <linux/page-flags-layout.h>
+#include <linux/atomic.h>
+#include <asm/page.h>
+
+/* Free memory management - zoned buddy allocator. */
+#ifndef CONFIG_FORCE_MAX_ZONEORDER
+#define MAX_ORDER 11
+#else
+#define MAX_ORDER CONFIG_FORCE_MAX_ZONEORDER
+#endif
+#define MAX_ORDER_NR_PAGES (1 << (MAX_ORDER - 1))
+
+/*
+ * PAGE_ALLOC_COSTLY_ORDER is the order at which allocations are deemed
+ * costly to service. That is between allocation orders which should
+ * coalesce naturally under reasonable reclaim pressure and those which
+ * will not.
+ */
+#define PAGE_ALLOC_COSTLY_ORDER 3
+
+enum migratetype {
+ MIGRATE_UNMOVABLE,
+ MIGRATE_MOVABLE,
+ MIGRATE_RECLAIMABLE,
+ MIGRATE_PCPTYPES, /* the number of types on the pcp lists */
+ MIGRATE_HIGHATOMIC = MIGRATE_PCPTYPES,
+#ifdef CONFIG_CMA
+ /*
+ * MIGRATE_CMA migration type is designed to mimic the way
+ * ZONE_MOVABLE works. Only movable pages can be allocated
+ * from MIGRATE_CMA pageblocks and page allocator never
+ * implicitly change migration type of MIGRATE_CMA pageblock.
+ *
+ * The way to use it is to change migratetype of a range of
+ * pageblocks to MIGRATE_CMA which can be done by
+ * __free_pageblock_cma() function. What is important though
+ * is that a range of pageblocks must be aligned to
+ * MAX_ORDER_NR_PAGES should biggest page be bigger then
+ * a single pageblock.
+ */
+ MIGRATE_CMA,
+#endif
+#ifdef CONFIG_MEMORY_ISOLATION
+ MIGRATE_ISOLATE, /* can't allocate from here */
+#endif
+ MIGRATE_TYPES
+};
+
+/* In mm/page_alloc.c; keep in sync also with show_migration_types() there */
+extern char * const migratetype_names[MIGRATE_TYPES];
+
+#ifdef CONFIG_CMA
+# define is_migrate_cma(migratetype) unlikely((migratetype) == MIGRATE_CMA)
+# define is_migrate_cma_page(_page) (get_pageblock_migratetype(_page) == MIGRATE_CMA)
+#else
+# define is_migrate_cma(migratetype) false
+# define is_migrate_cma_page(_page) false
+#endif
+
+static inline bool is_migrate_movable(int mt)
+{
+ return is_migrate_cma(mt) || mt == MIGRATE_MOVABLE;
+}
+
+#define for_each_migratetype_order(order, type) \
+ for (order = 0; order < MAX_ORDER; order++) \
+ for (type = 0; type < MIGRATE_TYPES; type++)
+
+extern int page_group_by_mobility_disabled;
+
+#define NR_MIGRATETYPE_BITS (PB_migrate_end - PB_migrate + 1)
+#define MIGRATETYPE_MASK ((1UL << NR_MIGRATETYPE_BITS) - 1)
+
+#define get_pageblock_migratetype(page) \
+ get_pfnblock_flags_mask(page, page_to_pfn(page), \
+ PB_migrate_end, MIGRATETYPE_MASK)
+
+struct free_area {
+ struct list_head free_list[MIGRATE_TYPES];
+ unsigned long nr_free;
+};
+
+struct pglist_data;
+
+/*
+ * zone->lock and the zone lru_lock are two of the hottest locks in the kernel.
+ * So add a wild amount of padding here to ensure that they fall into separate
+ * cachelines. There are very few zone structures in the machine, so space
+ * consumption is not a concern here.
+ */
+#if defined(CONFIG_SMP)
+struct zone_padding {
+ char x[0];
+} ____cacheline_internodealigned_in_smp;
+#define ZONE_PADDING(name) struct zone_padding name;
+#else
+#define ZONE_PADDING(name)
+#endif
+
+#ifdef CONFIG_NUMA
+enum numa_stat_item {
+ NUMA_HIT, /* allocated in intended node */
+ NUMA_MISS, /* allocated in non intended node */
+ NUMA_FOREIGN, /* was intended here, hit elsewhere */
+ NUMA_INTERLEAVE_HIT, /* interleaver preferred this zone */
+ NUMA_LOCAL, /* allocation from local node */
+ NUMA_OTHER, /* allocation from other node */
+ NR_VM_NUMA_STAT_ITEMS
+};
+#else
+#define NR_VM_NUMA_STAT_ITEMS 0
+#endif
+
+enum zone_stat_item {
+ /* First 128 byte cacheline (assuming 64 bit words) */
+ NR_FREE_PAGES,
+ NR_ZONE_LRU_BASE, /* Used only for compaction and reclaim retry */
+ NR_ZONE_INACTIVE_ANON = NR_ZONE_LRU_BASE,
+ NR_ZONE_ACTIVE_ANON,
+ NR_ZONE_INACTIVE_FILE,
+ NR_ZONE_ACTIVE_FILE,
+ NR_ZONE_UNEVICTABLE,
+ NR_ZONE_WRITE_PENDING, /* Count of dirty, writeback and unstable pages */
+ NR_MLOCK, /* mlock()ed pages found and moved off LRU */
+ NR_PAGETABLE, /* used for pagetables */
+ NR_KERNEL_STACK_KB, /* measured in KiB */
+ /* Second 128 byte cacheline */
+ NR_BOUNCE,
+#if IS_ENABLED(CONFIG_ZSMALLOC)
+ NR_ZSPAGES, /* allocated in zsmalloc */
+#endif
+ NR_FREE_CMA_PAGES,
+ NR_VM_ZONE_STAT_ITEMS };
+
+enum node_stat_item {
+ NR_LRU_BASE,
+ NR_INACTIVE_ANON = NR_LRU_BASE, /* must match order of LRU_[IN]ACTIVE */
+ NR_ACTIVE_ANON, /* " " " " " */
+ NR_INACTIVE_FILE, /* " " " " " */
+ NR_ACTIVE_FILE, /* " " " " " */
+ NR_UNEVICTABLE, /* " " " " " */
+ NR_SLAB_RECLAIMABLE,
+ NR_SLAB_UNRECLAIMABLE,
+ NR_ISOLATED_ANON, /* Temporary isolated pages from anon lru */
+ NR_ISOLATED_FILE, /* Temporary isolated pages from file lru */
+ WORKINGSET_REFAULT,
+ WORKINGSET_ACTIVATE,
+ WORKINGSET_NODERECLAIM,
+ NR_ANON_MAPPED, /* Mapped anonymous pages */
+ NR_FILE_MAPPED, /* pagecache pages mapped into pagetables.
+ only modified from process context */
+ NR_FILE_PAGES,
+ NR_FILE_DIRTY,
+ NR_WRITEBACK,
+ NR_WRITEBACK_TEMP, /* Writeback using temporary buffers */
+ NR_SHMEM, /* shmem pages (included tmpfs/GEM pages) */
+ NR_SHMEM_THPS,
+ NR_SHMEM_PMDMAPPED,
+ NR_ANON_THPS,
+ NR_UNSTABLE_NFS, /* NFS unstable pages */
+ NR_VMSCAN_WRITE,
+ NR_VMSCAN_IMMEDIATE, /* Prioritise for reclaim when writeback ends */
+ NR_DIRTIED, /* page dirtyings since bootup */
+ NR_WRITTEN, /* page writings since bootup */
+ NR_INDIRECTLY_RECLAIMABLE_BYTES, /* measured in bytes */
+ NR_VM_NODE_STAT_ITEMS
+};
+
+/*
+ * We do arithmetic on the LRU lists in various places in the code,
+ * so it is important to keep the active lists LRU_ACTIVE higher in
+ * the array than the corresponding inactive lists, and to keep
+ * the *_FILE lists LRU_FILE higher than the corresponding _ANON lists.
+ *
+ * This has to be kept in sync with the statistics in zone_stat_item
+ * above and the descriptions in vmstat_text in mm/vmstat.c
+ */
+#define LRU_BASE 0
+#define LRU_ACTIVE 1
+#define LRU_FILE 2
+
+enum lru_list {
+ LRU_INACTIVE_ANON = LRU_BASE,
+ LRU_ACTIVE_ANON = LRU_BASE + LRU_ACTIVE,
+ LRU_INACTIVE_FILE = LRU_BASE + LRU_FILE,
+ LRU_ACTIVE_FILE = LRU_BASE + LRU_FILE + LRU_ACTIVE,
+ LRU_UNEVICTABLE,
+ NR_LRU_LISTS
+};
+
+#define for_each_lru(lru) for (lru = 0; lru < NR_LRU_LISTS; lru++)
+
+#define for_each_evictable_lru(lru) for (lru = 0; lru <= LRU_ACTIVE_FILE; lru++)
+
+static inline int is_file_lru(enum lru_list lru)
+{
+ return (lru == LRU_INACTIVE_FILE || lru == LRU_ACTIVE_FILE);
+}
+
+static inline int is_active_lru(enum lru_list lru)
+{
+ return (lru == LRU_ACTIVE_ANON || lru == LRU_ACTIVE_FILE);
+}
+
+struct zone_reclaim_stat {
+ /*
+ * The pageout code in vmscan.c keeps track of how many of the
+ * mem/swap backed and file backed pages are referenced.
+ * The higher the rotated/scanned ratio, the more valuable
+ * that cache is.
+ *
+ * The anon LRU stats live in [0], file LRU stats in [1]
+ */
+ unsigned long recent_rotated[2];
+ unsigned long recent_scanned[2];
+};
+
+struct lruvec {
+ struct list_head lists[NR_LRU_LISTS];
+ struct zone_reclaim_stat reclaim_stat;
+ /* Evictions & activations on the inactive file list */
+ atomic_long_t inactive_age;
+ /* Refaults at the time of last reclaim cycle */
+ unsigned long refaults;
+#ifdef CONFIG_MEMCG
+ struct pglist_data *pgdat;
+#endif
+};
+
+/* Mask used at gathering information at once (see memcontrol.c) */
+#define LRU_ALL_FILE (BIT(LRU_INACTIVE_FILE) | BIT(LRU_ACTIVE_FILE))
+#define LRU_ALL_ANON (BIT(LRU_INACTIVE_ANON) | BIT(LRU_ACTIVE_ANON))
+#define LRU_ALL ((1 << NR_LRU_LISTS) - 1)
+
+/* Isolate unmapped file */
+#define ISOLATE_UNMAPPED ((__force isolate_mode_t)0x2)
+/* Isolate for asynchronous migration */
+#define ISOLATE_ASYNC_MIGRATE ((__force isolate_mode_t)0x4)
+/* Isolate unevictable pages */
+#define ISOLATE_UNEVICTABLE ((__force isolate_mode_t)0x8)
+
+/* LRU Isolation modes. */
+typedef unsigned __bitwise isolate_mode_t;
+
+enum zone_watermarks {
+ WMARK_MIN,
+ WMARK_LOW,
+ WMARK_HIGH,
+ NR_WMARK
+};
+
+#define min_wmark_pages(z) (z->watermark[WMARK_MIN])
+#define low_wmark_pages(z) (z->watermark[WMARK_LOW])
+#define high_wmark_pages(z) (z->watermark[WMARK_HIGH])
+
+struct per_cpu_pages {
+ int count; /* number of pages in the list */
+ int high; /* high watermark, emptying needed */
+ int batch; /* chunk size for buddy add/remove */
+
+ /* Lists of pages, one per migrate type stored on the pcp-lists */
+ struct list_head lists[MIGRATE_PCPTYPES];
+};
+
+struct per_cpu_pageset {
+ struct per_cpu_pages pcp;
+#ifdef CONFIG_NUMA
+ s8 expire;
+ u16 vm_numa_stat_diff[NR_VM_NUMA_STAT_ITEMS];
+#endif
+#ifdef CONFIG_SMP
+ s8 stat_threshold;
+ s8 vm_stat_diff[NR_VM_ZONE_STAT_ITEMS];
+#endif
+};
+
+struct per_cpu_nodestat {
+ s8 stat_threshold;
+ s8 vm_node_stat_diff[NR_VM_NODE_STAT_ITEMS];
+};
+
+#endif /* !__GENERATING_BOUNDS.H */
+
+enum zone_type {
+#ifdef CONFIG_ZONE_DMA
+ /*
+ * ZONE_DMA is used when there are devices that are not able
+ * to do DMA to all of addressable memory (ZONE_NORMAL). Then we
+ * carve out the portion of memory that is needed for these devices.
+ * The range is arch specific.
+ *
+ * Some examples
+ *
+ * Architecture Limit
+ * ---------------------------
+ * parisc, ia64, sparc <4G
+ * s390 <2G
+ * arm Various
+ * alpha Unlimited or 0-16MB.
+ *
+ * i386, x86_64 and multiple other arches
+ * <16M.
+ */
+ ZONE_DMA,
+#endif
+#ifdef CONFIG_ZONE_DMA32
+ /*
+ * x86_64 needs two ZONE_DMAs because it supports devices that are
+ * only able to do DMA to the lower 16M but also 32 bit devices that
+ * can only do DMA areas below 4G.
+ */
+ ZONE_DMA32,
+#endif
+ /*
+ * Normal addressable memory is in ZONE_NORMAL. DMA operations can be
+ * performed on pages in ZONE_NORMAL if the DMA devices support
+ * transfers to all addressable memory.
+ */
+ ZONE_NORMAL,
+#ifdef CONFIG_HIGHMEM
+ /*
+ * A memory area that is only addressable by the kernel through
+ * mapping portions into its own address space. This is for example
+ * used by i386 to allow the kernel to address the memory beyond
+ * 900MB. The kernel will set up special mappings (page
+ * table entries on i386) for each page that the kernel needs to
+ * access.
+ */
+ ZONE_HIGHMEM,
+#endif
+ ZONE_MOVABLE,
+#ifdef CONFIG_ZONE_DEVICE
+ ZONE_DEVICE,
+#endif
+ __MAX_NR_ZONES
+
+};
+
+#ifndef __GENERATING_BOUNDS_H
+
+struct zone {
+ /* Read-mostly fields */
+
+ /* zone watermarks, access with *_wmark_pages(zone) macros */
+ unsigned long watermark[NR_WMARK];
+
+ unsigned long nr_reserved_highatomic;
+
+ /*
+ * We don't know if the memory that we're going to allocate will be
+ * freeable or/and it will be released eventually, so to avoid totally
+ * wasting several GB of ram we must reserve some of the lower zone
+ * memory (otherwise we risk to run OOM on the lower zones despite
+ * there being tons of freeable ram on the higher zones). This array is
+ * recalculated at runtime if the sysctl_lowmem_reserve_ratio sysctl
+ * changes.
+ */
+ long lowmem_reserve[MAX_NR_ZONES];
+
+#ifdef CONFIG_NUMA
+ int node;
+#endif
+ struct pglist_data *zone_pgdat;
+ struct per_cpu_pageset __percpu *pageset;
+
+#ifndef CONFIG_SPARSEMEM
+ /*
+ * Flags for a pageblock_nr_pages block. See pageblock-flags.h.
+ * In SPARSEMEM, this map is stored in struct mem_section
+ */
+ unsigned long *pageblock_flags;
+#endif /* CONFIG_SPARSEMEM */
+
+ /* zone_start_pfn == zone_start_paddr >> PAGE_SHIFT */
+ unsigned long zone_start_pfn;
+
+ /*
+ * spanned_pages is the total pages spanned by the zone, including
+ * holes, which is calculated as:
+ * spanned_pages = zone_end_pfn - zone_start_pfn;
+ *
+ * present_pages is physical pages existing within the zone, which
+ * is calculated as:
+ * present_pages = spanned_pages - absent_pages(pages in holes);
+ *
+ * managed_pages is present pages managed by the buddy system, which
+ * is calculated as (reserved_pages includes pages allocated by the
+ * bootmem allocator):
+ * managed_pages = present_pages - reserved_pages;
+ *
+ * So present_pages may be used by memory hotplug or memory power
+ * management logic to figure out unmanaged pages by checking
+ * (present_pages - managed_pages). And managed_pages should be used
+ * by page allocator and vm scanner to calculate all kinds of watermarks
+ * and thresholds.
+ *
+ * Locking rules:
+ *
+ * zone_start_pfn and spanned_pages are protected by span_seqlock.
+ * It is a seqlock because it has to be read outside of zone->lock,
+ * and it is done in the main allocator path. But, it is written
+ * quite infrequently.
+ *
+ * The span_seq lock is declared along with zone->lock because it is
+ * frequently read in proximity to zone->lock. It's good to
+ * give them a chance of being in the same cacheline.
+ *
+ * Write access to present_pages at runtime should be protected by
+ * mem_hotplug_begin/end(). Any reader who can't tolerant drift of
+ * present_pages should get_online_mems() to get a stable value.
+ *
+ * Read access to managed_pages should be safe because it's unsigned
+ * long. Write access to zone->managed_pages and totalram_pages are
+ * protected by managed_page_count_lock at runtime. Idealy only
+ * adjust_managed_page_count() should be used instead of directly
+ * touching zone->managed_pages and totalram_pages.
+ */
+ unsigned long managed_pages;
+ unsigned long spanned_pages;
+ unsigned long present_pages;
+
+ const char *name;
+
+#ifdef CONFIG_MEMORY_ISOLATION
+ /*
+ * Number of isolated pageblock. It is used to solve incorrect
+ * freepage counting problem due to racy retrieving migratetype
+ * of pageblock. Protected by zone->lock.
+ */
+ unsigned long nr_isolate_pageblock;
+#endif
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+ /* see spanned/present_pages for more description */
+ seqlock_t span_seqlock;
+#endif
+
+ int initialized;
+
+ /* Write-intensive fields used from the page allocator */
+ ZONE_PADDING(_pad1_)
+
+ /* free areas of different sizes */
+ struct free_area free_area[MAX_ORDER];
+
+ /* zone flags, see below */
+ unsigned long flags;
+
+ /* Primarily protects free_area */
+ spinlock_t lock;
+
+ /* Write-intensive fields used by compaction and vmstats. */
+ ZONE_PADDING(_pad2_)
+
+ /*
+ * When free pages are below this point, additional steps are taken
+ * when reading the number of free pages to avoid per-cpu counter
+ * drift allowing watermarks to be breached
+ */
+ unsigned long percpu_drift_mark;
+
+#if defined CONFIG_COMPACTION || defined CONFIG_CMA
+ /* pfn where compaction free scanner should start */
+ unsigned long compact_cached_free_pfn;
+ /* pfn where async and sync compaction migration scanner should start */
+ unsigned long compact_cached_migrate_pfn[2];
+#endif
+
+#ifdef CONFIG_COMPACTION
+ /*
+ * On compaction failure, 1<<compact_defer_shift compactions
+ * are skipped before trying again. The number attempted since
+ * last failure is tracked with compact_considered.
+ */
+ unsigned int compact_considered;
+ unsigned int compact_defer_shift;
+ int compact_order_failed;
+#endif
+
+#if defined CONFIG_COMPACTION || defined CONFIG_CMA
+ /* Set to true when the PG_migrate_skip bits should be cleared */
+ bool compact_blockskip_flush;
+#endif
+
+ bool contiguous;
+
+ ZONE_PADDING(_pad3_)
+ /* Zone statistics */
+ atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS];
+ atomic_long_t vm_numa_stat[NR_VM_NUMA_STAT_ITEMS];
+} ____cacheline_internodealigned_in_smp;
+
+enum pgdat_flags {
+ PGDAT_CONGESTED, /* pgdat has many dirty pages backed by
+ * a congested BDI
+ */
+ PGDAT_DIRTY, /* reclaim scanning has recently found
+ * many dirty file pages at the tail
+ * of the LRU.
+ */
+ PGDAT_WRITEBACK, /* reclaim scanning has recently found
+ * many pages under writeback
+ */
+ PGDAT_RECLAIM_LOCKED, /* prevents concurrent reclaim */
+};
+
+static inline unsigned long zone_end_pfn(const struct zone *zone)
+{
+ return zone->zone_start_pfn + zone->spanned_pages;
+}
+
+static inline bool zone_spans_pfn(const struct zone *zone, unsigned long pfn)
+{
+ return zone->zone_start_pfn <= pfn && pfn < zone_end_pfn(zone);
+}
+
+static inline bool zone_is_initialized(struct zone *zone)
+{
+ return zone->initialized;
+}
+
+static inline bool zone_is_empty(struct zone *zone)
+{
+ return zone->spanned_pages == 0;
+}
+
+/*
+ * Return true if [start_pfn, start_pfn + nr_pages) range has a non-empty
+ * intersection with the given zone
+ */
+static inline bool zone_intersects(struct zone *zone,
+ unsigned long start_pfn, unsigned long nr_pages)
+{
+ if (zone_is_empty(zone))
+ return false;
+ if (start_pfn >= zone_end_pfn(zone) ||
+ start_pfn + nr_pages <= zone->zone_start_pfn)
+ return false;
+
+ return true;
+}
+
+/*
+ * The "priority" of VM scanning is how much of the queues we will scan in one
+ * go. A value of 12 for DEF_PRIORITY implies that we will scan 1/4096th of the
+ * queues ("queue_length >> 12") during an aging round.
+ */
+#define DEF_PRIORITY 12
+
+/* Maximum number of zones on a zonelist */
+#define MAX_ZONES_PER_ZONELIST (MAX_NUMNODES * MAX_NR_ZONES)
+
+enum {
+ ZONELIST_FALLBACK, /* zonelist with fallback */
+#ifdef CONFIG_NUMA
+ /*
+ * The NUMA zonelists are doubled because we need zonelists that
+ * restrict the allocations to a single node for __GFP_THISNODE.
+ */
+ ZONELIST_NOFALLBACK, /* zonelist without fallback (__GFP_THISNODE) */
+#endif
+ MAX_ZONELISTS
+};
+
+/*
+ * This struct contains information about a zone in a zonelist. It is stored
+ * here to avoid dereferences into large structures and lookups of tables
+ */
+struct zoneref {
+ struct zone *zone; /* Pointer to actual zone */
+ int zone_idx; /* zone_idx(zoneref->zone) */
+};
+
+/*
+ * One allocation request operates on a zonelist. A zonelist
+ * is a list of zones, the first one is the 'goal' of the
+ * allocation, the other zones are fallback zones, in decreasing
+ * priority.
+ *
+ * To speed the reading of the zonelist, the zonerefs contain the zone index
+ * of the entry being read. Helper functions to access information given
+ * a struct zoneref are
+ *
+ * zonelist_zone() - Return the struct zone * for an entry in _zonerefs
+ * zonelist_zone_idx() - Return the index of the zone for an entry
+ * zonelist_node_idx() - Return the index of the node for an entry
+ */
+struct zonelist {
+ struct zoneref _zonerefs[MAX_ZONES_PER_ZONELIST + 1];
+};
+
+#ifndef CONFIG_DISCONTIGMEM
+/* The array of struct pages - for discontigmem use pgdat->lmem_map */
+extern struct page *mem_map;
+#endif
+
+/*
+ * On NUMA machines, each NUMA node would have a pg_data_t to describe
+ * it's memory layout. On UMA machines there is a single pglist_data which
+ * describes the whole memory.
+ *
+ * Memory statistics and page replacement data structures are maintained on a
+ * per-zone basis.
+ */
+struct bootmem_data;
+typedef struct pglist_data {
+ struct zone node_zones[MAX_NR_ZONES];
+ struct zonelist node_zonelists[MAX_ZONELISTS];
+ int nr_zones;
+#ifdef CONFIG_FLAT_NODE_MEM_MAP /* means !SPARSEMEM */
+ struct page *node_mem_map;
+#ifdef CONFIG_PAGE_EXTENSION
+ struct page_ext *node_page_ext;
+#endif
+#endif
+#ifndef CONFIG_NO_BOOTMEM
+ struct bootmem_data *bdata;
+#endif
+#if defined(CONFIG_MEMORY_HOTPLUG) || defined(CONFIG_DEFERRED_STRUCT_PAGE_INIT)
+ /*
+ * Must be held any time you expect node_start_pfn, node_present_pages
+ * or node_spanned_pages stay constant. Holding this will also
+ * guarantee that any pfn_valid() stays that way.
+ *
+ * pgdat_resize_lock() and pgdat_resize_unlock() are provided to
+ * manipulate node_size_lock without checking for CONFIG_MEMORY_HOTPLUG
+ * or CONFIG_DEFERRED_STRUCT_PAGE_INIT.
+ *
+ * Nests above zone->lock and zone->span_seqlock
+ */
+ spinlock_t node_size_lock;
+#endif
+ unsigned long node_start_pfn;
+ unsigned long node_present_pages; /* total number of physical pages */
+ unsigned long node_spanned_pages; /* total size of physical page
+ range, including holes */
+ int node_id;
+ wait_queue_head_t kswapd_wait;
+ wait_queue_head_t pfmemalloc_wait;
+ struct task_struct *kswapd; /* Protected by
+ mem_hotplug_begin/end() */
+ int kswapd_order;
+ enum zone_type kswapd_classzone_idx;
+
+ int kswapd_failures; /* Number of 'reclaimed == 0' runs */
+
+#ifdef CONFIG_COMPACTION
+ int kcompactd_max_order;
+ enum zone_type kcompactd_classzone_idx;
+ wait_queue_head_t kcompactd_wait;
+ struct task_struct *kcompactd;
+#endif
+ /*
+ * This is a per-node reserve of pages that are not available
+ * to userspace allocations.
+ */
+ unsigned long totalreserve_pages;
+
+#ifdef CONFIG_NUMA
+ /*
+ * zone reclaim becomes active if more unmapped pages exist.
+ */
+ unsigned long min_unmapped_pages;
+ unsigned long min_slab_pages;
+#endif /* CONFIG_NUMA */
+
+ /* Write-intensive fields used by page reclaim */
+ ZONE_PADDING(_pad1_)
+ spinlock_t lru_lock;
+
+#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
+ /*
+ * If memory initialisation on large machines is deferred then this
+ * is the first PFN that needs to be initialised.
+ */
+ unsigned long first_deferred_pfn;
+ /* Number of non-deferred pages */
+ unsigned long static_init_pgcnt;
+#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ spinlock_t split_queue_lock;
+ struct list_head split_queue;
+ unsigned long split_queue_len;
+#endif
+
+ /* Fields commonly accessed by the page reclaim scanner */
+ struct lruvec lruvec;
+
+ unsigned long flags;
+
+ ZONE_PADDING(_pad2_)
+
+ /* Per-node vmstats */
+ struct per_cpu_nodestat __percpu *per_cpu_nodestats;
+ atomic_long_t vm_stat[NR_VM_NODE_STAT_ITEMS];
+} pg_data_t;
+
+#define node_present_pages(nid) (NODE_DATA(nid)->node_present_pages)
+#define node_spanned_pages(nid) (NODE_DATA(nid)->node_spanned_pages)
+#ifdef CONFIG_FLAT_NODE_MEM_MAP
+#define pgdat_page_nr(pgdat, pagenr) ((pgdat)->node_mem_map + (pagenr))
+#else
+#define pgdat_page_nr(pgdat, pagenr) pfn_to_page((pgdat)->node_start_pfn + (pagenr))
+#endif
+#define nid_page_nr(nid, pagenr) pgdat_page_nr(NODE_DATA(nid),(pagenr))
+
+#define node_start_pfn(nid) (NODE_DATA(nid)->node_start_pfn)
+#define node_end_pfn(nid) pgdat_end_pfn(NODE_DATA(nid))
+static inline spinlock_t *zone_lru_lock(struct zone *zone)
+{
+ return &zone->zone_pgdat->lru_lock;
+}
+
+static inline struct lruvec *node_lruvec(struct pglist_data *pgdat)
+{
+ return &pgdat->lruvec;
+}
+
+static inline unsigned long pgdat_end_pfn(pg_data_t *pgdat)
+{
+ return pgdat->node_start_pfn + pgdat->node_spanned_pages;
+}
+
+static inline bool pgdat_is_empty(pg_data_t *pgdat)
+{
+ return !pgdat->node_start_pfn && !pgdat->node_spanned_pages;
+}
+
+#include <linux/memory_hotplug.h>
+
+void build_all_zonelists(pg_data_t *pgdat);
+void wakeup_kswapd(struct zone *zone, gfp_t gfp_mask, int order,
+ enum zone_type classzone_idx);
+bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
+ int classzone_idx, unsigned int alloc_flags,
+ long free_pages);
+bool zone_watermark_ok(struct zone *z, unsigned int order,
+ unsigned long mark, int classzone_idx,
+ unsigned int alloc_flags);
+bool zone_watermark_ok_safe(struct zone *z, unsigned int order,
+ unsigned long mark, int classzone_idx);
+enum memmap_context {
+ MEMMAP_EARLY,
+ MEMMAP_HOTPLUG,
+};
+extern void init_currently_empty_zone(struct zone *zone, unsigned long start_pfn,
+ unsigned long size);
+
+extern void lruvec_init(struct lruvec *lruvec);
+
+static inline struct pglist_data *lruvec_pgdat(struct lruvec *lruvec)
+{
+#ifdef CONFIG_MEMCG
+ return lruvec->pgdat;
+#else
+ return container_of(lruvec, struct pglist_data, lruvec);
+#endif
+}
+
+extern unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx);
+
+#ifdef CONFIG_HAVE_MEMORY_PRESENT
+void memory_present(int nid, unsigned long start, unsigned long end);
+#else
+static inline void memory_present(int nid, unsigned long start, unsigned long end) {}
+#endif
+
+#ifdef CONFIG_HAVE_MEMORYLESS_NODES
+int local_memory_node(int node_id);
+#else
+static inline int local_memory_node(int node_id) { return node_id; };
+#endif
+
+/*
+ * zone_idx() returns 0 for the ZONE_DMA zone, 1 for the ZONE_NORMAL zone, etc.
+ */
+#define zone_idx(zone) ((zone) - (zone)->zone_pgdat->node_zones)
+
+#ifdef CONFIG_ZONE_DEVICE
+static inline bool is_dev_zone(const struct zone *zone)
+{
+ return zone_idx(zone) == ZONE_DEVICE;
+}
+#else
+static inline bool is_dev_zone(const struct zone *zone)
+{
+ return false;
+}
+#endif
+
+/*
+ * Returns true if a zone has pages managed by the buddy allocator.
+ * All the reclaim decisions have to use this function rather than
+ * populated_zone(). If the whole zone is reserved then we can easily
+ * end up with populated_zone() && !managed_zone().
+ */
+static inline bool managed_zone(struct zone *zone)
+{
+ return zone->managed_pages;
+}
+
+/* Returns true if a zone has memory */
+static inline bool populated_zone(struct zone *zone)
+{
+ return zone->present_pages;
+}
+
+#ifdef CONFIG_NUMA
+static inline int zone_to_nid(struct zone *zone)
+{
+ return zone->node;
+}
+
+static inline void zone_set_nid(struct zone *zone, int nid)
+{
+ zone->node = nid;
+}
+#else
+static inline int zone_to_nid(struct zone *zone)
+{
+ return 0;
+}
+
+static inline void zone_set_nid(struct zone *zone, int nid) {}
+#endif
+
+extern int movable_zone;
+
+#ifdef CONFIG_HIGHMEM
+static inline int zone_movable_is_highmem(void)
+{
+#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
+ return movable_zone == ZONE_HIGHMEM;
+#else
+ return (ZONE_MOVABLE - 1) == ZONE_HIGHMEM;
+#endif
+}
+#endif
+
+static inline int is_highmem_idx(enum zone_type idx)
+{
+#ifdef CONFIG_HIGHMEM
+ return (idx == ZONE_HIGHMEM ||
+ (idx == ZONE_MOVABLE && zone_movable_is_highmem()));
+#else
+ return 0;
+#endif
+}
+
+/**
+ * is_highmem - helper function to quickly check if a struct zone is a
+ * highmem zone or not. This is an attempt to keep references
+ * to ZONE_{DMA/NORMAL/HIGHMEM/etc} in general code to a minimum.
+ * @zone - pointer to struct zone variable
+ */
+static inline int is_highmem(struct zone *zone)
+{
+#ifdef CONFIG_HIGHMEM
+ return is_highmem_idx(zone_idx(zone));
+#else
+ return 0;
+#endif
+}
+
+/* These two functions are used to setup the per zone pages min values */
+struct ctl_table;
+int min_free_kbytes_sysctl_handler(struct ctl_table *, int,
+ void __user *, size_t *, loff_t *);
+int watermark_scale_factor_sysctl_handler(struct ctl_table *, int,
+ void __user *, size_t *, loff_t *);
+extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES];
+int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int,
+ void __user *, size_t *, loff_t *);
+int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *, int,
+ void __user *, size_t *, loff_t *);
+int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *, int,
+ void __user *, size_t *, loff_t *);
+int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int,
+ void __user *, size_t *, loff_t *);
+
+extern int numa_zonelist_order_handler(struct ctl_table *, int,
+ void __user *, size_t *, loff_t *);
+extern char numa_zonelist_order[];
+#define NUMA_ZONELIST_ORDER_LEN 16
+
+#ifndef CONFIG_NEED_MULTIPLE_NODES
+
+extern struct pglist_data contig_page_data;
+#define NODE_DATA(nid) (&contig_page_data)
+#define NODE_MEM_MAP(nid) mem_map
+
+#else /* CONFIG_NEED_MULTIPLE_NODES */
+
+#include <asm/mmzone.h>
+
+#endif /* !CONFIG_NEED_MULTIPLE_NODES */
+
+extern struct pglist_data *first_online_pgdat(void);
+extern struct pglist_data *next_online_pgdat(struct pglist_data *pgdat);
+extern struct zone *next_zone(struct zone *zone);
+
+/**
+ * for_each_online_pgdat - helper macro to iterate over all online nodes
+ * @pgdat - pointer to a pg_data_t variable
+ */
+#define for_each_online_pgdat(pgdat) \
+ for (pgdat = first_online_pgdat(); \
+ pgdat; \
+ pgdat = next_online_pgdat(pgdat))
+/**
+ * for_each_zone - helper macro to iterate over all memory zones
+ * @zone - pointer to struct zone variable
+ *
+ * The user only needs to declare the zone variable, for_each_zone
+ * fills it in.
+ */
+#define for_each_zone(zone) \
+ for (zone = (first_online_pgdat())->node_zones; \
+ zone; \
+ zone = next_zone(zone))
+
+#define for_each_populated_zone(zone) \
+ for (zone = (first_online_pgdat())->node_zones; \
+ zone; \
+ zone = next_zone(zone)) \
+ if (!populated_zone(zone)) \
+ ; /* do nothing */ \
+ else
+
+static inline struct zone *zonelist_zone(struct zoneref *zoneref)
+{
+ return zoneref->zone;
+}
+
+static inline int zonelist_zone_idx(struct zoneref *zoneref)
+{
+ return zoneref->zone_idx;
+}
+
+static inline int zonelist_node_idx(struct zoneref *zoneref)
+{
+ return zone_to_nid(zoneref->zone);
+}
+
+struct zoneref *__next_zones_zonelist(struct zoneref *z,
+ enum zone_type highest_zoneidx,
+ nodemask_t *nodes);
+
+/**
+ * next_zones_zonelist - Returns the next zone at or below highest_zoneidx within the allowed nodemask using a cursor within a zonelist as a starting point
+ * @z - The cursor used as a starting point for the search
+ * @highest_zoneidx - The zone index of the highest zone to return
+ * @nodes - An optional nodemask to filter the zonelist with
+ *
+ * This function returns the next zone at or below a given zone index that is
+ * within the allowed nodemask using a cursor as the starting point for the
+ * search. The zoneref returned is a cursor that represents the current zone
+ * being examined. It should be advanced by one before calling
+ * next_zones_zonelist again.
+ */
+static __always_inline struct zoneref *next_zones_zonelist(struct zoneref *z,
+ enum zone_type highest_zoneidx,
+ nodemask_t *nodes)
+{
+ if (likely(!nodes && zonelist_zone_idx(z) <= highest_zoneidx))
+ return z;
+ return __next_zones_zonelist(z, highest_zoneidx, nodes);
+}
+
+/**
+ * first_zones_zonelist - Returns the first zone at or below highest_zoneidx within the allowed nodemask in a zonelist
+ * @zonelist - The zonelist to search for a suitable zone
+ * @highest_zoneidx - The zone index of the highest zone to return
+ * @nodes - An optional nodemask to filter the zonelist with
+ * @return - Zoneref pointer for the first suitable zone found (see below)
+ *
+ * This function returns the first zone at or below a given zone index that is
+ * within the allowed nodemask. The zoneref returned is a cursor that can be
+ * used to iterate the zonelist with next_zones_zonelist by advancing it by
+ * one before calling.
+ *
+ * When no eligible zone is found, zoneref->zone is NULL (zoneref itself is
+ * never NULL). This may happen either genuinely, or due to concurrent nodemask
+ * update due to cpuset modification.
+ */
+static inline struct zoneref *first_zones_zonelist(struct zonelist *zonelist,
+ enum zone_type highest_zoneidx,
+ nodemask_t *nodes)
+{
+ return next_zones_zonelist(zonelist->_zonerefs,
+ highest_zoneidx, nodes);
+}
+
+/**
+ * for_each_zone_zonelist_nodemask - helper macro to iterate over valid zones in a zonelist at or below a given zone index and within a nodemask
+ * @zone - The current zone in the iterator
+ * @z - The current pointer within zonelist->zones being iterated
+ * @zlist - The zonelist being iterated
+ * @highidx - The zone index of the highest zone to return
+ * @nodemask - Nodemask allowed by the allocator
+ *
+ * This iterator iterates though all zones at or below a given zone index and
+ * within a given nodemask
+ */
+#define for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, nodemask) \
+ for (z = first_zones_zonelist(zlist, highidx, nodemask), zone = zonelist_zone(z); \
+ zone; \
+ z = next_zones_zonelist(++z, highidx, nodemask), \
+ zone = zonelist_zone(z))
+
+#define for_next_zone_zonelist_nodemask(zone, z, zlist, highidx, nodemask) \
+ for (zone = z->zone; \
+ zone; \
+ z = next_zones_zonelist(++z, highidx, nodemask), \
+ zone = zonelist_zone(z))
+
+
+/**
+ * for_each_zone_zonelist - helper macro to iterate over valid zones in a zonelist at or below a given zone index
+ * @zone - The current zone in the iterator
+ * @z - The current pointer within zonelist->zones being iterated
+ * @zlist - The zonelist being iterated
+ * @highidx - The zone index of the highest zone to return
+ *
+ * This iterator iterates though all zones at or below a given zone index.
+ */
+#define for_each_zone_zonelist(zone, z, zlist, highidx) \
+ for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, NULL)
+
+#ifdef CONFIG_SPARSEMEM
+#include <asm/sparsemem.h>
+#endif
+
+#if !defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID) && \
+ !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
+static inline unsigned long early_pfn_to_nid(unsigned long pfn)
+{
+ BUILD_BUG_ON(IS_ENABLED(CONFIG_NUMA));
+ return 0;
+}
+#endif
+
+#ifdef CONFIG_FLATMEM
+#define pfn_to_nid(pfn) (0)
+#endif
+
+#ifdef CONFIG_SPARSEMEM
+
+/*
+ * SECTION_SHIFT #bits space required to store a section #
+ *
+ * PA_SECTION_SHIFT physical address to/from section number
+ * PFN_SECTION_SHIFT pfn to/from section number
+ */
+#define PA_SECTION_SHIFT (SECTION_SIZE_BITS)
+#define PFN_SECTION_SHIFT (SECTION_SIZE_BITS - PAGE_SHIFT)
+
+#define NR_MEM_SECTIONS (1UL << SECTIONS_SHIFT)
+
+#define PAGES_PER_SECTION (1UL << PFN_SECTION_SHIFT)
+#define PAGE_SECTION_MASK (~(PAGES_PER_SECTION-1))
+
+#define SECTION_BLOCKFLAGS_BITS \
+ ((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * NR_PAGEBLOCK_BITS)
+
+#if (MAX_ORDER - 1 + PAGE_SHIFT) > SECTION_SIZE_BITS
+#error Allocator MAX_ORDER exceeds SECTION_SIZE
+#endif
+
+static inline unsigned long pfn_to_section_nr(unsigned long pfn)
+{
+ return pfn >> PFN_SECTION_SHIFT;
+}
+static inline unsigned long section_nr_to_pfn(unsigned long sec)
+{
+ return sec << PFN_SECTION_SHIFT;
+}
+
+#define SECTION_ALIGN_UP(pfn) (((pfn) + PAGES_PER_SECTION - 1) & PAGE_SECTION_MASK)
+#define SECTION_ALIGN_DOWN(pfn) ((pfn) & PAGE_SECTION_MASK)
+
+struct page;
+struct page_ext;
+struct mem_section {
+ /*
+ * This is, logically, a pointer to an array of struct
+ * pages. However, it is stored with some other magic.
+ * (see sparse.c::sparse_init_one_section())
+ *
+ * Additionally during early boot we encode node id of
+ * the location of the section here to guide allocation.
+ * (see sparse.c::memory_present())
+ *
+ * Making it a UL at least makes someone do a cast
+ * before using it wrong.
+ */
+ unsigned long section_mem_map;
+
+ /* See declaration of similar field in struct zone */
+ unsigned long *pageblock_flags;
+#ifdef CONFIG_PAGE_EXTENSION
+ /*
+ * If SPARSEMEM, pgdat doesn't have page_ext pointer. We use
+ * section. (see page_ext.h about this.)
+ */
+ struct page_ext *page_ext;
+ unsigned long pad;
+#endif
+ /*
+ * WARNING: mem_section must be a power-of-2 in size for the
+ * calculation and use of SECTION_ROOT_MASK to make sense.
+ */
+};
+
+#ifdef CONFIG_SPARSEMEM_EXTREME
+#define SECTIONS_PER_ROOT (PAGE_SIZE / sizeof (struct mem_section))
+#else
+#define SECTIONS_PER_ROOT 1
+#endif
+
+#define SECTION_NR_TO_ROOT(sec) ((sec) / SECTIONS_PER_ROOT)
+#define NR_SECTION_ROOTS DIV_ROUND_UP(NR_MEM_SECTIONS, SECTIONS_PER_ROOT)
+#define SECTION_ROOT_MASK (SECTIONS_PER_ROOT - 1)
+
+#ifdef CONFIG_SPARSEMEM_EXTREME
+extern struct mem_section **mem_section;
+#else
+extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
+#endif
+
+static inline struct mem_section *__nr_to_section(unsigned long nr)
+{
+#ifdef CONFIG_SPARSEMEM_EXTREME
+ if (!mem_section)
+ return NULL;
+#endif
+ if (!mem_section[SECTION_NR_TO_ROOT(nr)])
+ return NULL;
+ return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
+}
+extern int __section_nr(struct mem_section* ms);
+extern unsigned long usemap_size(void);
+
+/*
+ * We use the lower bits of the mem_map pointer to store
+ * a little bit of information. The pointer is calculated
+ * as mem_map - section_nr_to_pfn(pnum). The result is
+ * aligned to the minimum alignment of the two values:
+ * 1. All mem_map arrays are page-aligned.
+ * 2. section_nr_to_pfn() always clears PFN_SECTION_SHIFT
+ * lowest bits. PFN_SECTION_SHIFT is arch-specific
+ * (equal SECTION_SIZE_BITS - PAGE_SHIFT), and the
+ * worst combination is powerpc with 256k pages,
+ * which results in PFN_SECTION_SHIFT equal 6.
+ * To sum it up, at least 6 bits are available.
+ */
+#define SECTION_MARKED_PRESENT (1UL<<0)
+#define SECTION_HAS_MEM_MAP (1UL<<1)
+#define SECTION_IS_ONLINE (1UL<<2)
+#define SECTION_MAP_LAST_BIT (1UL<<3)
+#define SECTION_MAP_MASK (~(SECTION_MAP_LAST_BIT-1))
+#define SECTION_NID_SHIFT 3
+
+static inline struct page *__section_mem_map_addr(struct mem_section *section)
+{
+ unsigned long map = section->section_mem_map;
+ map &= SECTION_MAP_MASK;
+ return (struct page *)map;
+}
+
+static inline int present_section(struct mem_section *section)
+{
+ return (section && (section->section_mem_map & SECTION_MARKED_PRESENT));
+}
+
+static inline int present_section_nr(unsigned long nr)
+{
+ return present_section(__nr_to_section(nr));
+}
+
+static inline int valid_section(struct mem_section *section)
+{
+ return (section && (section->section_mem_map & SECTION_HAS_MEM_MAP));
+}
+
+static inline int valid_section_nr(unsigned long nr)
+{
+ return valid_section(__nr_to_section(nr));
+}
+
+static inline int online_section(struct mem_section *section)
+{
+ return (section && (section->section_mem_map & SECTION_IS_ONLINE));
+}
+
+static inline int online_section_nr(unsigned long nr)
+{
+ return online_section(__nr_to_section(nr));
+}
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+void online_mem_sections(unsigned long start_pfn, unsigned long end_pfn);
+#ifdef CONFIG_MEMORY_HOTREMOVE
+void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn);
+#endif
+#endif
+
+static inline struct mem_section *__pfn_to_section(unsigned long pfn)
+{
+ return __nr_to_section(pfn_to_section_nr(pfn));
+}
+
+extern int __highest_present_section_nr;
+
+#ifndef CONFIG_HAVE_ARCH_PFN_VALID
+static inline int pfn_valid(unsigned long pfn)
+{
+ if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
+ return 0;
+ return valid_section(__nr_to_section(pfn_to_section_nr(pfn)));
+}
+#endif
+
+static inline int pfn_present(unsigned long pfn)
+{
+ if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
+ return 0;
+ return present_section(__nr_to_section(pfn_to_section_nr(pfn)));
+}
+
+/*
+ * These are _only_ used during initialisation, therefore they
+ * can use __initdata ... They could have names to indicate
+ * this restriction.
+ */
+#ifdef CONFIG_NUMA
+#define pfn_to_nid(pfn) \
+({ \
+ unsigned long __pfn_to_nid_pfn = (pfn); \
+ page_to_nid(pfn_to_page(__pfn_to_nid_pfn)); \
+})
+#else
+#define pfn_to_nid(pfn) (0)
+#endif
+
+#define early_pfn_valid(pfn) pfn_valid(pfn)
+void sparse_init(void);
+#else
+#define sparse_init() do {} while (0)
+#define sparse_index_init(_sec, _nid) do {} while (0)
+#endif /* CONFIG_SPARSEMEM */
+
+/*
+ * During memory init memblocks map pfns to nids. The search is expensive and
+ * this caches recent lookups. The implementation of __early_pfn_to_nid
+ * may treat start/end as pfns or sections.
+ */
+struct mminit_pfnnid_cache {
+ unsigned long last_start;
+ unsigned long last_end;
+ int last_nid;
+};
+
+#ifndef early_pfn_valid
+#define early_pfn_valid(pfn) (1)
+#endif
+
+void memory_present(int nid, unsigned long start, unsigned long end);
+
+/*
+ * If it is possible to have holes within a MAX_ORDER_NR_PAGES, then we
+ * need to check pfn validility within that MAX_ORDER_NR_PAGES block.
+ * pfn_valid_within() should be used in this case; we optimise this away
+ * when we have no holes within a MAX_ORDER_NR_PAGES block.
+ */
+#ifdef CONFIG_HOLES_IN_ZONE
+#define pfn_valid_within(pfn) pfn_valid(pfn)
+#else
+#define pfn_valid_within(pfn) (1)
+#endif
+
+#ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
+/*
+ * pfn_valid() is meant to be able to tell if a given PFN has valid memmap
+ * associated with it or not. This means that a struct page exists for this
+ * pfn. The caller cannot assume the page is fully initialized in general.
+ * Hotplugable pages might not have been onlined yet. pfn_to_online_page()
+ * will ensure the struct page is fully online and initialized. Special pages
+ * (e.g. ZONE_DEVICE) are never onlined and should be treated accordingly.
+ *
+ * In FLATMEM, it is expected that holes always have valid memmap as long as
+ * there is valid PFNs either side of the hole. In SPARSEMEM, it is assumed
+ * that a valid section has a memmap for the entire section.
+ *
+ * However, an ARM, and maybe other embedded architectures in the future
+ * free memmap backing holes to save memory on the assumption the memmap is
+ * never used. The page_zone linkages are then broken even though pfn_valid()
+ * returns true. A walker of the full memmap must then do this additional
+ * check to ensure the memmap they are looking at is sane by making sure
+ * the zone and PFN linkages are still valid. This is expensive, but walkers
+ * of the full memmap are extremely rare.
+ */
+bool memmap_valid_within(unsigned long pfn,
+ struct page *page, struct zone *zone);
+#else
+static inline bool memmap_valid_within(unsigned long pfn,
+ struct page *page, struct zone *zone)
+{
+ return true;
+}
+#endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */
+
+#endif /* !__GENERATING_BOUNDS.H */
+#endif /* !__ASSEMBLY__ */
+#endif /* _LINUX_MMZONE_H */