Merge tag 'spi-fix-v6.9-merge-window' of git://git.kernel.org/pub/scm/linux/kernel...

[linux.git] / mm / mm_init.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * mm_init.c - Memory initialisation verification and debugging
 *
 * Copyright 2008 IBM Corporation, 2008
 * Author Mel Gorman <[email protected]>
 *
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/kobject.h>
#include <linux/export.h>
#include <linux/memory.h>
#include <linux/notifier.h>
#include <linux/sched.h>
#include <linux/mman.h>
#include <linux/memblock.h>
#include <linux/page-isolation.h>
#include <linux/padata.h>
#include <linux/nmi.h>
#include <linux/buffer_head.h>
#include <linux/kmemleak.h>
#include <linux/kfence.h>
#include <linux/page_ext.h>
#include <linux/pti.h>
#include <linux/pgtable.h>
#include <linux/swap.h>
#include <linux/cma.h>
#include <linux/crash_dump.h>
#include "internal.h"
#include "slab.h"
#include "shuffle.h"

#include <asm/setup.h>

#ifdef CONFIG_DEBUG_MEMORY_INIT
int __meminitdata mminit_loglevel;

/* The zonelists are simply reported, validation is manual. */
void __init mminit_verify_zonelist(void)
{
        int nid;

        if (mminit_loglevel < MMINIT_VERIFY)
                return;

        for_each_online_node(nid) {
                pg_data_t *pgdat = NODE_DATA(nid);
                struct zone *zone;
                struct zoneref *z;
                struct zonelist *zonelist;
                int i, listid, zoneid;

                BUILD_BUG_ON(MAX_ZONELISTS > 2);
                for (i = 0; i < MAX_ZONELISTS * MAX_NR_ZONES; i++) {

                        /* Identify the zone and nodelist */
                        zoneid = i % MAX_NR_ZONES;
                        listid = i / MAX_NR_ZONES;
                        zonelist = &pgdat->node_zonelists[listid];
                        zone = &pgdat->node_zones[zoneid];
                        if (!populated_zone(zone))
                                continue;

                        /* Print information about the zonelist */
                        printk(KERN_DEBUG "mminit::zonelist %s %d:%s = ",
                                listid > 0 ? "thisnode" : "general", nid,
                                zone->name);

                        /* Iterate the zonelist */
                        for_each_zone_zonelist(zone, z, zonelist, zoneid)
                                pr_cont("%d:%s ", zone_to_nid(zone), zone->name);
                        pr_cont("\n");
                }
        }
}

void __init mminit_verify_pageflags_layout(void)
{
        int shift, width;
        unsigned long or_mask, add_mask;

        shift = BITS_PER_LONG;
        width = shift - SECTIONS_WIDTH - NODES_WIDTH - ZONES_WIDTH
                - LAST_CPUPID_SHIFT - KASAN_TAG_WIDTH - LRU_GEN_WIDTH - LRU_REFS_WIDTH;
        mminit_dprintk(MMINIT_TRACE, "pageflags_layout_widths",
                "Section %d Node %d Zone %d Lastcpupid %d Kasantag %d Gen %d Tier %d Flags %d\n",
                SECTIONS_WIDTH,
                NODES_WIDTH,
                ZONES_WIDTH,
                LAST_CPUPID_WIDTH,
                KASAN_TAG_WIDTH,
                LRU_GEN_WIDTH,
                LRU_REFS_WIDTH,
                NR_PAGEFLAGS);
        mminit_dprintk(MMINIT_TRACE, "pageflags_layout_shifts",
                "Section %d Node %d Zone %d Lastcpupid %d Kasantag %d\n",
                SECTIONS_SHIFT,
                NODES_SHIFT,
                ZONES_SHIFT,
                LAST_CPUPID_SHIFT,
                KASAN_TAG_WIDTH);
        mminit_dprintk(MMINIT_TRACE, "pageflags_layout_pgshifts",
                "Section %lu Node %lu Zone %lu Lastcpupid %lu Kasantag %lu\n",
                (unsigned long)SECTIONS_PGSHIFT,
                (unsigned long)NODES_PGSHIFT,
                (unsigned long)ZONES_PGSHIFT,
                (unsigned long)LAST_CPUPID_PGSHIFT,
                (unsigned long)KASAN_TAG_PGSHIFT);
        mminit_dprintk(MMINIT_TRACE, "pageflags_layout_nodezoneid",
                "Node/Zone ID: %lu -> %lu\n",
                (unsigned long)(ZONEID_PGOFF + ZONEID_SHIFT),
                (unsigned long)ZONEID_PGOFF);
        mminit_dprintk(MMINIT_TRACE, "pageflags_layout_usage",
                "location: %d -> %d layout %d -> %d unused %d -> %d page-flags\n",
                shift, width, width, NR_PAGEFLAGS, NR_PAGEFLAGS, 0);
#ifdef NODE_NOT_IN_PAGE_FLAGS
        mminit_dprintk(MMINIT_TRACE, "pageflags_layout_nodeflags",
                "Node not in page flags");
#endif
#ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
        mminit_dprintk(MMINIT_TRACE, "pageflags_layout_nodeflags",
                "Last cpupid not in page flags");
#endif

        if (SECTIONS_WIDTH) {
                shift -= SECTIONS_WIDTH;
                BUG_ON(shift != SECTIONS_PGSHIFT);
        }
        if (NODES_WIDTH) {
                shift -= NODES_WIDTH;
                BUG_ON(shift != NODES_PGSHIFT);
        }
        if (ZONES_WIDTH) {
                shift -= ZONES_WIDTH;
                BUG_ON(shift != ZONES_PGSHIFT);
        }

        /* Check for bitmask overlaps */
        or_mask = (ZONES_MASK << ZONES_PGSHIFT) |
                        (NODES_MASK << NODES_PGSHIFT) |
                        (SECTIONS_MASK << SECTIONS_PGSHIFT);
        add_mask = (ZONES_MASK << ZONES_PGSHIFT) +
                        (NODES_MASK << NODES_PGSHIFT) +
                        (SECTIONS_MASK << SECTIONS_PGSHIFT);
        BUG_ON(or_mask != add_mask);
}

static __init int set_mminit_loglevel(char *str)
{
        get_option(&str, &mminit_loglevel);
        return 0;
}
early_param("mminit_loglevel", set_mminit_loglevel);
#endif /* CONFIG_DEBUG_MEMORY_INIT */

struct kobject *mm_kobj;

#ifdef CONFIG_SMP
s32 vm_committed_as_batch = 32;

void mm_compute_batch(int overcommit_policy)
{
        u64 memsized_batch;
        s32 nr = num_present_cpus();
        s32 batch = max_t(s32, nr*2, 32);
        unsigned long ram_pages = totalram_pages();

        /*
         * For policy OVERCOMMIT_NEVER, set batch size to 0.4% of
         * (total memory/#cpus), and lift it to 25% for other policies
         * to easy the possible lock contention for percpu_counter
         * vm_committed_as, while the max limit is INT_MAX
         */
        if (overcommit_policy == OVERCOMMIT_NEVER)
                memsized_batch = min_t(u64, ram_pages/nr/256, INT_MAX);
        else
                memsized_batch = min_t(u64, ram_pages/nr/4, INT_MAX);

        vm_committed_as_batch = max_t(s32, memsized_batch, batch);
}

static int __meminit mm_compute_batch_notifier(struct notifier_block *self,
                                        unsigned long action, void *arg)
{
        switch (action) {
        case MEM_ONLINE:
        case MEM_OFFLINE:
                mm_compute_batch(sysctl_overcommit_memory);
                break;
        default:
                break;
        }
        return NOTIFY_OK;
}

static int __init mm_compute_batch_init(void)
{
        mm_compute_batch(sysctl_overcommit_memory);
        hotplug_memory_notifier(mm_compute_batch_notifier, MM_COMPUTE_BATCH_PRI);
        return 0;
}

__initcall(mm_compute_batch_init);

#endif

static int __init mm_sysfs_init(void)
{
        mm_kobj = kobject_create_and_add("mm", kernel_kobj);
        if (!mm_kobj)
                return -ENOMEM;

        return 0;
}
postcore_initcall(mm_sysfs_init);

static unsigned long arch_zone_lowest_possible_pfn[MAX_NR_ZONES] __initdata;
static unsigned long arch_zone_highest_possible_pfn[MAX_NR_ZONES] __initdata;
static unsigned long zone_movable_pfn[MAX_NUMNODES] __initdata;

static unsigned long required_kernelcore __initdata;
static unsigned long required_kernelcore_percent __initdata;
static unsigned long required_movablecore __initdata;
static unsigned long required_movablecore_percent __initdata;

static unsigned long nr_kernel_pages __initdata;
static unsigned long nr_all_pages __initdata;
static unsigned long dma_reserve __initdata;

static bool deferred_struct_pages __meminitdata;

static DEFINE_PER_CPU(struct per_cpu_nodestat, boot_nodestats);

static int __init cmdline_parse_core(char *p, unsigned long *core,
                                     unsigned long *percent)
{
        unsigned long long coremem;
        char *endptr;

        if (!p)
                return -EINVAL;

        /* Value may be a percentage of total memory, otherwise bytes */
        coremem = simple_strtoull(p, &endptr, 0);
        if (*endptr == '%') {
                /* Paranoid check for percent values greater than 100 */
                WARN_ON(coremem > 100);

                *percent = coremem;
        } else {
                coremem = memparse(p, &p);
                /* Paranoid check that UL is enough for the coremem value */
                WARN_ON((coremem >> PAGE_SHIFT) > ULONG_MAX);

                *core = coremem >> PAGE_SHIFT;
                *percent = 0UL;
        }
        return 0;
}

bool mirrored_kernelcore __initdata_memblock;

/*
 * kernelcore=size sets the amount of memory for use for allocations that
 * cannot be reclaimed or migrated.
 */
static int __init cmdline_parse_kernelcore(char *p)
{
        /* parse kernelcore=mirror */
        if (parse_option_str(p, "mirror")) {
                mirrored_kernelcore = true;
                return 0;
        }

        return cmdline_parse_core(p, &required_kernelcore,
                                  &required_kernelcore_percent);
}
early_param("kernelcore", cmdline_parse_kernelcore);

/*
 * movablecore=size sets the amount of memory for use for allocations that
 * can be reclaimed or migrated.
 */
static int __init cmdline_parse_movablecore(char *p)
{
        return cmdline_parse_core(p, &required_movablecore,
                                  &required_movablecore_percent);
}
early_param("movablecore", cmdline_parse_movablecore);

/*
 * early_calculate_totalpages()
 * Sum pages in active regions for movable zone.
 * Populate N_MEMORY for calculating usable_nodes.
 */
static unsigned long __init early_calculate_totalpages(void)
{
        unsigned long totalpages = 0;
        unsigned long start_pfn, end_pfn;
        int i, nid;

        for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
                unsigned long pages = end_pfn - start_pfn;

                totalpages += pages;
                if (pages)
                        node_set_state(nid, N_MEMORY);
        }
        return totalpages;
}

/*
 * This finds a zone that can be used for ZONE_MOVABLE pages. The
 * assumption is made that zones within a node are ordered in monotonic
 * increasing memory addresses so that the "highest" populated zone is used
 */
static void __init find_usable_zone_for_movable(void)
{
        int zone_index;
        for (zone_index = MAX_NR_ZONES - 1; zone_index >= 0; zone_index--) {
                if (zone_index == ZONE_MOVABLE)
                        continue;

                if (arch_zone_highest_possible_pfn[zone_index] >
                                arch_zone_lowest_possible_pfn[zone_index])
                        break;
        }

        VM_BUG_ON(zone_index == -1);
        movable_zone = zone_index;
}

/*
 * Find the PFN the Movable zone begins in each node. Kernel memory
 * is spread evenly between nodes as long as the nodes have enough
 * memory. When they don't, some nodes will have more kernelcore than
 * others
 */
static void __init find_zone_movable_pfns_for_nodes(void)
{
        int i, nid;
        unsigned long usable_startpfn;
        unsigned long kernelcore_node, kernelcore_remaining;
        /* save the state before borrow the nodemask */
        nodemask_t saved_node_state = node_states[N_MEMORY];
        unsigned long totalpages = early_calculate_totalpages();
        int usable_nodes = nodes_weight(node_states[N_MEMORY]);
        struct memblock_region *r;

        /* Need to find movable_zone earlier when movable_node is specified. */
        find_usable_zone_for_movable();

        /*
         * If movable_node is specified, ignore kernelcore and movablecore
         * options.
         */
        if (movable_node_is_enabled()) {
                for_each_mem_region(r) {
                        if (!memblock_is_hotpluggable(r))
                                continue;

                        nid = memblock_get_region_node(r);

                        usable_startpfn = PFN_DOWN(r->base);
                        zone_movable_pfn[nid] = zone_movable_pfn[nid] ?
                                min(usable_startpfn, zone_movable_pfn[nid]) :
                                usable_startpfn;
                }

                goto out2;
        }

        /*
         * If kernelcore=mirror is specified, ignore movablecore option
         */
        if (mirrored_kernelcore) {
                bool mem_below_4gb_not_mirrored = false;

                if (!memblock_has_mirror()) {
                        pr_warn("The system has no mirror memory, ignore kernelcore=mirror.\n");
                        goto out;
                }

                if (is_kdump_kernel()) {
                        pr_warn("The system is under kdump, ignore kernelcore=mirror.\n");
                        goto out;
                }

                for_each_mem_region(r) {
                        if (memblock_is_mirror(r))
                                continue;

                        nid = memblock_get_region_node(r);

                        usable_startpfn = memblock_region_memory_base_pfn(r);

                        if (usable_startpfn < PHYS_PFN(SZ_4G)) {
                                mem_below_4gb_not_mirrored = true;
                                continue;
                        }

                        zone_movable_pfn[nid] = zone_movable_pfn[nid] ?
                                min(usable_startpfn, zone_movable_pfn[nid]) :
                                usable_startpfn;
                }

                if (mem_below_4gb_not_mirrored)
                        pr_warn("This configuration results in unmirrored kernel memory.\n");

                goto out2;
        }

        /*
         * If kernelcore=nn% or movablecore=nn% was specified, calculate the
         * amount of necessary memory.
         */
        if (required_kernelcore_percent)
                required_kernelcore = (totalpages * 100 * required_kernelcore_percent) /
                                       10000UL;
        if (required_movablecore_percent)
                required_movablecore = (totalpages * 100 * required_movablecore_percent) /
                                        10000UL;

        /*
         * If movablecore= was specified, calculate what size of
         * kernelcore that corresponds so that memory usable for
         * any allocation type is evenly spread. If both kernelcore
         * and movablecore are specified, then the value of kernelcore
         * will be used for required_kernelcore if it's greater than
         * what movablecore would have allowed.
         */
        if (required_movablecore) {
                unsigned long corepages;

                /*
                 * Round-up so that ZONE_MOVABLE is at least as large as what
                 * was requested by the user
                 */
                required_movablecore =
                        roundup(required_movablecore, MAX_ORDER_NR_PAGES);
                required_movablecore = min(totalpages, required_movablecore);
                corepages = totalpages - required_movablecore;

                required_kernelcore = max(required_kernelcore, corepages);
        }

        /*
         * If kernelcore was not specified or kernelcore size is larger
         * than totalpages, there is no ZONE_MOVABLE.
         */
        if (!required_kernelcore || required_kernelcore >= totalpages)
                goto out;

        /* usable_startpfn is the lowest possible pfn ZONE_MOVABLE can be at */
        usable_startpfn = arch_zone_lowest_possible_pfn[movable_zone];

restart:
        /* Spread kernelcore memory as evenly as possible throughout nodes */
        kernelcore_node = required_kernelcore / usable_nodes;
        for_each_node_state(nid, N_MEMORY) {
                unsigned long start_pfn, end_pfn;

                /*
                 * Recalculate kernelcore_node if the division per node
                 * now exceeds what is necessary to satisfy the requested
                 * amount of memory for the kernel
                 */
                if (required_kernelcore < kernelcore_node)
                        kernelcore_node = required_kernelcore / usable_nodes;

                /*
                 * As the map is walked, we track how much memory is usable
                 * by the kernel using kernelcore_remaining. When it is
                 * 0, the rest of the node is usable by ZONE_MOVABLE
                 */
                kernelcore_remaining = kernelcore_node;

                /* Go through each range of PFNs within this node */
                for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
                        unsigned long size_pages;

                        start_pfn = max(start_pfn, zone_movable_pfn[nid]);
                        if (start_pfn >= end_pfn)
                                continue;

                        /* Account for what is only usable for kernelcore */
                        if (start_pfn < usable_startpfn) {
                                unsigned long kernel_pages;
                                kernel_pages = min(end_pfn, usable_startpfn)
                                                                - start_pfn;

                                kernelcore_remaining -= min(kernel_pages,
                                                        kernelcore_remaining);
                                required_kernelcore -= min(kernel_pages,
                                                        required_kernelcore);

                                /* Continue if range is now fully accounted */
                                if (end_pfn <= usable_startpfn) {

                                        /*
                                         * Push zone_movable_pfn to the end so
                                         * that if we have to rebalance
                                         * kernelcore across nodes, we will
                                         * not double account here
                                         */
                                        zone_movable_pfn[nid] = end_pfn;
                                        continue;
                                }
                                start_pfn = usable_startpfn;
                        }

                        /*
                         * The usable PFN range for ZONE_MOVABLE is from
                         * start_pfn->end_pfn. Calculate size_pages as the
                         * number of pages used as kernelcore
                         */
                        size_pages = end_pfn - start_pfn;
                        if (size_pages > kernelcore_remaining)
                                size_pages = kernelcore_remaining;
                        zone_movable_pfn[nid] = start_pfn + size_pages;

                        /*
                         * Some kernelcore has been met, update counts and
                         * break if the kernelcore for this node has been
                         * satisfied
                         */
                        required_kernelcore -= min(required_kernelcore,
                                                                size_pages);
                        kernelcore_remaining -= size_pages;
                        if (!kernelcore_remaining)
                                break;
                }
        }

        /*
         * If there is still required_kernelcore, we do another pass with one
         * less node in the count. This will push zone_movable_pfn[nid] further
         * along on the nodes that still have memory until kernelcore is
         * satisfied
         */
        usable_nodes--;
        if (usable_nodes && required_kernelcore > usable_nodes)
                goto restart;

out2:
        /* Align start of ZONE_MOVABLE on all nids to MAX_ORDER_NR_PAGES */
        for (nid = 0; nid < MAX_NUMNODES; nid++) {
                unsigned long start_pfn, end_pfn;

                zone_movable_pfn[nid] =
                        roundup(zone_movable_pfn[nid], MAX_ORDER_NR_PAGES);

                get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);
                if (zone_movable_pfn[nid] >= end_pfn)
                        zone_movable_pfn[nid] = 0;
        }

out:
        /* restore the node_state */
        node_states[N_MEMORY] = saved_node_state;
}

void __meminit __init_single_page(struct page *page, unsigned long pfn,
                                unsigned long zone, int nid)
{
        mm_zero_struct_page(page);
        set_page_links(page, zone, nid, pfn);
        init_page_count(page);
        page_mapcount_reset(page);
        page_cpupid_reset_last(page);
        page_kasan_tag_reset(page);

        INIT_LIST_HEAD(&page->lru);
#ifdef WANT_PAGE_VIRTUAL
        /* The shift won't overflow because ZONE_NORMAL is below 4G. */
        if (!is_highmem_idx(zone))
                set_page_address(page, __va(pfn << PAGE_SHIFT));
#endif
}

#ifdef CONFIG_NUMA
/*
 * During memory init memblocks map pfns to nids. The search is expensive and
 * this caches recent lookups. The implementation of __early_pfn_to_nid
 * treats start/end as pfns.
 */
struct mminit_pfnnid_cache {
        unsigned long last_start;
        unsigned long last_end;
        int last_nid;
};

static struct mminit_pfnnid_cache early_pfnnid_cache __meminitdata;

/*
 * Required by SPARSEMEM. Given a PFN, return what node the PFN is on.
 */
static int __meminit __early_pfn_to_nid(unsigned long pfn,
                                        struct mminit_pfnnid_cache *state)
{
        unsigned long start_pfn, end_pfn;
        int nid;

        if (state->last_start <= pfn && pfn < state->last_end)
                return state->last_nid;

        nid = memblock_search_pfn_nid(pfn, &start_pfn, &end_pfn);
        if (nid != NUMA_NO_NODE) {
                state->last_start = start_pfn;
                state->last_end = end_pfn;
                state->last_nid = nid;
        }

        return nid;
}

int __meminit early_pfn_to_nid(unsigned long pfn)
{
        static DEFINE_SPINLOCK(early_pfn_lock);
        int nid;

        spin_lock(&early_pfn_lock);
        nid = __early_pfn_to_nid(pfn, &early_pfnnid_cache);
        if (nid < 0)
                nid = first_online_node;
        spin_unlock(&early_pfn_lock);

        return nid;
}

int hashdist = HASHDIST_DEFAULT;

static int __init set_hashdist(char *str)
{
        if (!str)
                return 0;
        hashdist = simple_strtoul(str, &str, 0);
        return 1;
}
__setup("hashdist=", set_hashdist);

static inline void fixup_hashdist(void)
{
        if (num_node_state(N_MEMORY) == 1)
                hashdist = 0;
}
#else
static inline void fixup_hashdist(void) {}
#endif /* CONFIG_NUMA */

#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
static inline void pgdat_set_deferred_range(pg_data_t *pgdat)
{
        pgdat->first_deferred_pfn = ULONG_MAX;
}

/* Returns true if the struct page for the pfn is initialised */
static inline bool __meminit early_page_initialised(unsigned long pfn, int nid)
{
        if (node_online(nid) && pfn >= NODE_DATA(nid)->first_deferred_pfn)
                return false;

        return true;
}

/*
 * Returns true when the remaining initialisation should be deferred until
 * later in the boot cycle when it can be parallelised.
 */
static bool __meminit
defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
{
        static unsigned long prev_end_pfn, nr_initialised;

        if (early_page_ext_enabled())
                return false;
        /*
         * prev_end_pfn static that contains the end of previous zone
         * No need to protect because called very early in boot before smp_init.
         */
        if (prev_end_pfn != end_pfn) {
                prev_end_pfn = end_pfn;
                nr_initialised = 0;
        }

        /* Always populate low zones for address-constrained allocations */
        if (end_pfn < pgdat_end_pfn(NODE_DATA(nid)))
                return false;

        if (NODE_DATA(nid)->first_deferred_pfn != ULONG_MAX)
                return true;
        /*
         * We start only with one section of pages, more pages are added as
         * needed until the rest of deferred pages are initialized.
         */
        nr_initialised++;
        if ((nr_initialised > PAGES_PER_SECTION) &&
            (pfn & (PAGES_PER_SECTION - 1)) == 0) {
                NODE_DATA(nid)->first_deferred_pfn = pfn;
                return true;
        }
        return false;
}

static void __meminit init_reserved_page(unsigned long pfn, int nid)
{
        pg_data_t *pgdat;
        int zid;

        if (early_page_initialised(pfn, nid))
                return;

        pgdat = NODE_DATA(nid);

        for (zid = 0; zid < MAX_NR_ZONES; zid++) {
                struct zone *zone = &pgdat->node_zones[zid];

                if (zone_spans_pfn(zone, pfn))
                        break;
        }
        __init_single_page(pfn_to_page(pfn), pfn, zid, nid);
}
#else
static inline void pgdat_set_deferred_range(pg_data_t *pgdat) {}

static inline bool early_page_initialised(unsigned long pfn, int nid)
{
        return true;
}

static inline bool defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
{
        return false;
}

static inline void init_reserved_page(unsigned long pfn, int nid)
{
}
#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */

/*
 * Initialised pages do not have PageReserved set. This function is
 * called for each range allocated by the bootmem allocator and
 * marks the pages PageReserved. The remaining valid pages are later
 * sent to the buddy page allocator.
 */
void __meminit reserve_bootmem_region(phys_addr_t start,
                                      phys_addr_t end, int nid)
{
        unsigned long start_pfn = PFN_DOWN(start);
        unsigned long end_pfn = PFN_UP(end);

        for (; start_pfn < end_pfn; start_pfn++) {
                if (pfn_valid(start_pfn)) {
                        struct page *page = pfn_to_page(start_pfn);

                        init_reserved_page(start_pfn, nid);

                        /* Avoid false-positive PageTail() */
                        INIT_LIST_HEAD(&page->lru);

                        /*
                         * no need for atomic set_bit because the struct
                         * page is not visible yet so nobody should
                         * access it yet.
                         */
                        __SetPageReserved(page);
                }
        }
}

/* If zone is ZONE_MOVABLE but memory is mirrored, it is an overlapped init */
static bool __meminit
overlap_memmap_init(unsigned long zone, unsigned long *pfn)
{
        static struct memblock_region *r;

        if (mirrored_kernelcore && zone == ZONE_MOVABLE) {
                if (!r || *pfn >= memblock_region_memory_end_pfn(r)) {
                        for_each_mem_region(r) {
                                if (*pfn < memblock_region_memory_end_pfn(r))
                                        break;
                        }
                }
                if (*pfn >= memblock_region_memory_base_pfn(r) &&
                    memblock_is_mirror(r)) {
                        *pfn = memblock_region_memory_end_pfn(r);
                        return true;
                }
        }
        return false;
}

/*
 * Only struct pages that correspond to ranges defined by memblock.memory
 * are zeroed and initialized by going through __init_single_page() during
 * memmap_init_zone_range().
 *
 * But, there could be struct pages that correspond to holes in
 * memblock.memory. This can happen because of the following reasons:
 * - physical memory bank size is not necessarily the exact multiple of the
 *   arbitrary section size
 * - early reserved memory may not be listed in memblock.memory
 * - non-memory regions covered by the contigious flatmem mapping
 * - memory layouts defined with memmap= kernel parameter may not align
 *   nicely with memmap sections
 *
 * Explicitly initialize those struct pages so that:
 * - PG_Reserved is set
 * - zone and node links point to zone and node that span the page if the
 *   hole is in the middle of a zone
 * - zone and node links point to adjacent zone/node if the hole falls on
 *   the zone boundary; the pages in such holes will be prepended to the
 *   zone/node above the hole except for the trailing pages in the last
 *   section that will be appended to the zone/node below.
 */
static void __init init_unavailable_range(unsigned long spfn,
                                          unsigned long epfn,
                                          int zone, int node)
{
        unsigned long pfn;
        u64 pgcnt = 0;

        for (pfn = spfn; pfn < epfn; pfn++) {
                if (!pfn_valid(pageblock_start_pfn(pfn))) {
                        pfn = pageblock_end_pfn(pfn) - 1;
                        continue;
                }
                __init_single_page(pfn_to_page(pfn), pfn, zone, node);
                __SetPageReserved(pfn_to_page(pfn));
                pgcnt++;
        }

        if (pgcnt)
                pr_info("On node %d, zone %s: %lld pages in unavailable ranges\n",
                        node, zone_names[zone], pgcnt);
}

/*
 * Initially all pages are reserved - free ones are freed
 * up by memblock_free_all() once the early boot process is
 * done. Non-atomic initialization, single-pass.
 *
 * All aligned pageblocks are initialized to the specified migratetype
 * (usually MIGRATE_MOVABLE). Besides setting the migratetype, no related
 * zone stats (e.g., nr_isolate_pageblock) are touched.
 */
void __meminit memmap_init_range(unsigned long size, int nid, unsigned long zone,
                unsigned long start_pfn, unsigned long zone_end_pfn,
                enum meminit_context context,
                struct vmem_altmap *altmap, int migratetype)
{
        unsigned long pfn, end_pfn = start_pfn + size;
        struct page *page;

        if (highest_memmap_pfn < end_pfn - 1)
                highest_memmap_pfn = end_pfn - 1;

#ifdef CONFIG_ZONE_DEVICE
        /*
         * Honor reservation requested by the driver for this ZONE_DEVICE
         * memory. We limit the total number of pages to initialize to just
         * those that might contain the memory mapping. We will defer the
         * ZONE_DEVICE page initialization until after we have released
         * the hotplug lock.
         */
        if (zone == ZONE_DEVICE) {
                if (!altmap)
                        return;

                if (start_pfn == altmap->base_pfn)
                        start_pfn += altmap->reserve;
                end_pfn = altmap->base_pfn + vmem_altmap_offset(altmap);
        }
#endif

        for (pfn = start_pfn; pfn < end_pfn; ) {
                /*
                 * There can be holes in boot-time mem_map[]s handed to this
                 * function.  They do not exist on hotplugged memory.
                 */
                if (context == MEMINIT_EARLY) {
                        if (overlap_memmap_init(zone, &pfn))
                                continue;
                        if (defer_init(nid, pfn, zone_end_pfn)) {
                                deferred_struct_pages = true;
                                break;
                        }
                }

                page = pfn_to_page(pfn);
                __init_single_page(page, pfn, zone, nid);
                if (context == MEMINIT_HOTPLUG)
                        __SetPageReserved(page);

                /*
                 * Usually, we want to mark the pageblock MIGRATE_MOVABLE,
                 * such that unmovable allocations won't be scattered all
                 * over the place during system boot.
                 */
                if (pageblock_aligned(pfn)) {
                        set_pageblock_migratetype(page, migratetype);
                        cond_resched();
                }
                pfn++;
        }
}

static void __init memmap_init_zone_range(struct zone *zone,
                                          unsigned long start_pfn,
                                          unsigned long end_pfn,
                                          unsigned long *hole_pfn)
{
        unsigned long zone_start_pfn = zone->zone_start_pfn;
        unsigned long zone_end_pfn = zone_start_pfn + zone->spanned_pages;
        int nid = zone_to_nid(zone), zone_id = zone_idx(zone);

        start_pfn = clamp(start_pfn, zone_start_pfn, zone_end_pfn);
        end_pfn = clamp(end_pfn, zone_start_pfn, zone_end_pfn);

        if (start_pfn >= end_pfn)
                return;

        memmap_init_range(end_pfn - start_pfn, nid, zone_id, start_pfn,
                          zone_end_pfn, MEMINIT_EARLY, NULL, MIGRATE_MOVABLE);

        if (*hole_pfn < start_pfn)
                init_unavailable_range(*hole_pfn, start_pfn, zone_id, nid);

        *hole_pfn = end_pfn;
}

static void __init memmap_init(void)
{
        unsigned long start_pfn, end_pfn;
        unsigned long hole_pfn = 0;
        int i, j, zone_id = 0, nid;

        for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
                struct pglist_data *node = NODE_DATA(nid);

                for (j = 0; j < MAX_NR_ZONES; j++) {
                        struct zone *zone = node->node_zones + j;

                        if (!populated_zone(zone))
                                continue;

                        memmap_init_zone_range(zone, start_pfn, end_pfn,
                                               &hole_pfn);
                        zone_id = j;
                }
        }

#ifdef CONFIG_SPARSEMEM
        /*
         * Initialize the memory map for hole in the range [memory_end,
         * section_end].
         * Append the pages in this hole to the highest zone in the last
         * node.
         * The call to init_unavailable_range() is outside the ifdef to
         * silence the compiler warining about zone_id set but not used;
         * for FLATMEM it is a nop anyway
         */
        end_pfn = round_up(end_pfn, PAGES_PER_SECTION);
        if (hole_pfn < end_pfn)
#endif
                init_unavailable_range(hole_pfn, end_pfn, zone_id, nid);
}

#ifdef CONFIG_ZONE_DEVICE
static void __ref __init_zone_device_page(struct page *page, unsigned long pfn,
                                          unsigned long zone_idx, int nid,
                                          struct dev_pagemap *pgmap)
{

        __init_single_page(page, pfn, zone_idx, nid);

        /*
         * Mark page reserved as it will need to wait for onlining
         * phase for it to be fully associated with a zone.
         *
         * We can use the non-atomic __set_bit operation for setting
         * the flag as we are still initializing the pages.
         */
        __SetPageReserved(page);

        /*
         * ZONE_DEVICE pages union ->lru with a ->pgmap back pointer
         * and zone_device_data.  It is a bug if a ZONE_DEVICE page is
         * ever freed or placed on a driver-private list.
         */
        page->pgmap = pgmap;
        page->zone_device_data = NULL;

        /*
         * Mark the block movable so that blocks are reserved for
         * movable at startup. This will force kernel allocations
         * to reserve their blocks rather than leaking throughout
         * the address space during boot when many long-lived
         * kernel allocations are made.
         *
         * Please note that MEMINIT_HOTPLUG path doesn't clear memmap
         * because this is done early in section_activate()
         */
        if (pageblock_aligned(pfn)) {
                set_pageblock_migratetype(page, MIGRATE_MOVABLE);
                cond_resched();
        }

        /*
         * ZONE_DEVICE pages are released directly to the driver page allocator
         * which will set the page count to 1 when allocating the page.
         */
        if (pgmap->type == MEMORY_DEVICE_PRIVATE ||
            pgmap->type == MEMORY_DEVICE_COHERENT)
                set_page_count(page, 0);
}

/*
 * With compound page geometry and when struct pages are stored in ram most
 * tail pages are reused. Consequently, the amount of unique struct pages to
 * initialize is a lot smaller that the total amount of struct pages being
 * mapped. This is a paired / mild layering violation with explicit knowledge
 * of how the sparse_vmemmap internals handle compound pages in the lack
 * of an altmap. See vmemmap_populate_compound_pages().
 */
static inline unsigned long compound_nr_pages(struct vmem_altmap *altmap,
                                              struct dev_pagemap *pgmap)
{
        if (!vmemmap_can_optimize(altmap, pgmap))
                return pgmap_vmemmap_nr(pgmap);

        return VMEMMAP_RESERVE_NR * (PAGE_SIZE / sizeof(struct page));
}

static void __ref memmap_init_compound(struct page *head,
                                       unsigned long head_pfn,
                                       unsigned long zone_idx, int nid,
                                       struct dev_pagemap *pgmap,
                                       unsigned long nr_pages)
{
        unsigned long pfn, end_pfn = head_pfn + nr_pages;
        unsigned int order = pgmap->vmemmap_shift;

        __SetPageHead(head);
        for (pfn = head_pfn + 1; pfn < end_pfn; pfn++) {
                struct page *page = pfn_to_page(pfn);

                __init_zone_device_page(page, pfn, zone_idx, nid, pgmap);
                prep_compound_tail(head, pfn - head_pfn);
                set_page_count(page, 0);

                /*
                 * The first tail page stores important compound page info.
                 * Call prep_compound_head() after the first tail page has
                 * been initialized, to not have the data overwritten.
                 */
                if (pfn == head_pfn + 1)
                        prep_compound_head(head, order);
        }
}

void __ref memmap_init_zone_device(struct zone *zone,
                                   unsigned long start_pfn,
                                   unsigned long nr_pages,
                                   struct dev_pagemap *pgmap)
{
        unsigned long pfn, end_pfn = start_pfn + nr_pages;
        struct pglist_data *pgdat = zone->zone_pgdat;
        struct vmem_altmap *altmap = pgmap_altmap(pgmap);
        unsigned int pfns_per_compound = pgmap_vmemmap_nr(pgmap);
        unsigned long zone_idx = zone_idx(zone);
        unsigned long start = jiffies;
        int nid = pgdat->node_id;

        if (WARN_ON_ONCE(!pgmap || zone_idx != ZONE_DEVICE))
                return;

        /*
         * The call to memmap_init should have already taken care
         * of the pages reserved for the memmap, so we can just jump to
         * the end of that region and start processing the device pages.
         */
        if (altmap) {
                start_pfn = altmap->base_pfn + vmem_altmap_offset(altmap);
                nr_pages = end_pfn - start_pfn;
        }

        for (pfn = start_pfn; pfn < end_pfn; pfn += pfns_per_compound) {
                struct page *page = pfn_to_page(pfn);

                __init_zone_device_page(page, pfn, zone_idx, nid, pgmap);

                if (pfns_per_compound == 1)
                        continue;

                memmap_init_compound(page, pfn, zone_idx, nid, pgmap,
                                     compound_nr_pages(altmap, pgmap));
        }

        pr_debug("%s initialised %lu pages in %ums\n", __func__,
                nr_pages, jiffies_to_msecs(jiffies - start));
}
#endif

/*
 * The zone ranges provided by the architecture do not include ZONE_MOVABLE
 * because it is sized independent of architecture. Unlike the other zones,
 * the starting point for ZONE_MOVABLE is not fixed. It may be different
 * in each node depending on the size of each node and how evenly kernelcore
 * is distributed. This helper function adjusts the zone ranges
 * provided by the architecture for a given node by using the end of the
 * highest usable zone for ZONE_MOVABLE. This preserves the assumption that
 * zones within a node are in order of monotonic increases memory addresses
 */
static void __init adjust_zone_range_for_zone_movable(int nid,
                                        unsigned long zone_type,
                                        unsigned long node_end_pfn,
                                        unsigned long *zone_start_pfn,
                                        unsigned long *zone_end_pfn)
{
        /* Only adjust if ZONE_MOVABLE is on this node */
        if (zone_movable_pfn[nid]) {
                /* Size ZONE_MOVABLE */
                if (zone_type == ZONE_MOVABLE) {
                        *zone_start_pfn = zone_movable_pfn[nid];
                        *zone_end_pfn = min(node_end_pfn,
                                arch_zone_highest_possible_pfn[movable_zone]);

                /* Adjust for ZONE_MOVABLE starting within this range */
                } else if (!mirrored_kernelcore &&
                        *zone_start_pfn < zone_movable_pfn[nid] &&
                        *zone_end_pfn > zone_movable_pfn[nid]) {
                        *zone_end_pfn = zone_movable_pfn[nid];

                /* Check if this whole range is within ZONE_MOVABLE */
                } else if (*zone_start_pfn >= zone_movable_pfn[nid])
                        *zone_start_pfn = *zone_end_pfn;
        }
}

/*
 * Return the number of holes in a range on a node. If nid is MAX_NUMNODES,
 * then all holes in the requested range will be accounted for.
 */
unsigned long __init __absent_pages_in_range(int nid,
                                unsigned long range_start_pfn,
                                unsigned long range_end_pfn)
{
        unsigned long nr_absent = range_end_pfn - range_start_pfn;
        unsigned long start_pfn, end_pfn;
        int i;

        for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
                start_pfn = clamp(start_pfn, range_start_pfn, range_end_pfn);
                end_pfn = clamp(end_pfn, range_start_pfn, range_end_pfn);
                nr_absent -= end_pfn - start_pfn;
        }
        return nr_absent;
}

/**
 * absent_pages_in_range - Return number of page frames in holes within a range
 * @start_pfn: The start PFN to start searching for holes
 * @end_pfn: The end PFN to stop searching for holes
 *
 * Return: the number of pages frames in memory holes within a range.
 */
unsigned long __init absent_pages_in_range(unsigned long start_pfn,
                                                        unsigned long end_pfn)
{
        return __absent_pages_in_range(MAX_NUMNODES, start_pfn, end_pfn);
}

/* Return the number of page frames in holes in a zone on a node */
static unsigned long __init zone_absent_pages_in_node(int nid,
                                        unsigned long zone_type,
                                        unsigned long zone_start_pfn,
                                        unsigned long zone_end_pfn)
{
        unsigned long nr_absent;

        /* zone is empty, we don't have any absent pages */
        if (zone_start_pfn == zone_end_pfn)
                return 0;

        nr_absent = __absent_pages_in_range(nid, zone_start_pfn, zone_end_pfn);

        /*
         * ZONE_MOVABLE handling.
         * Treat pages to be ZONE_MOVABLE in ZONE_NORMAL as absent pages
         * and vice versa.
         */
        if (mirrored_kernelcore && zone_movable_pfn[nid]) {
                unsigned long start_pfn, end_pfn;
                struct memblock_region *r;

                for_each_mem_region(r) {
                        start_pfn = clamp(memblock_region_memory_base_pfn(r),
                                          zone_start_pfn, zone_end_pfn);
                        end_pfn = clamp(memblock_region_memory_end_pfn(r),
                                        zone_start_pfn, zone_end_pfn);

                        if (zone_type == ZONE_MOVABLE &&
                            memblock_is_mirror(r))
                                nr_absent += end_pfn - start_pfn;

                        if (zone_type == ZONE_NORMAL &&
                            !memblock_is_mirror(r))
                                nr_absent += end_pfn - start_pfn;
                }
        }

        return nr_absent;
}

/*
 * Return the number of pages a zone spans in a node, including holes
 * present_pages = zone_spanned_pages_in_node() - zone_absent_pages_in_node()
 */
static unsigned long __init zone_spanned_pages_in_node(int nid,
                                        unsigned long zone_type,
                                        unsigned long node_start_pfn,
                                        unsigned long node_end_pfn,
                                        unsigned long *zone_start_pfn,
                                        unsigned long *zone_end_pfn)
{
        unsigned long zone_low = arch_zone_lowest_possible_pfn[zone_type];
        unsigned long zone_high = arch_zone_highest_possible_pfn[zone_type];

        /* Get the start and end of the zone */
        *zone_start_pfn = clamp(node_start_pfn, zone_low, zone_high);
        *zone_end_pfn = clamp(node_end_pfn, zone_low, zone_high);
        adjust_zone_range_for_zone_movable(nid, zone_type, node_end_pfn,
                                           zone_start_pfn, zone_end_pfn);

        /* Check that this node has pages within the zone's required range */
        if (*zone_end_pfn < node_start_pfn || *zone_start_pfn > node_end_pfn)
                return 0;

        /* Move the zone boundaries inside the node if necessary */
        *zone_end_pfn = min(*zone_end_pfn, node_end_pfn);
        *zone_start_pfn = max(*zone_start_pfn, node_start_pfn);

        /* Return the spanned pages */
        return *zone_end_pfn - *zone_start_pfn;
}

static void __init reset_memoryless_node_totalpages(struct pglist_data *pgdat)
{
        struct zone *z;

        for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++) {
                z->zone_start_pfn = 0;
                z->spanned_pages = 0;
                z->present_pages = 0;
#if defined(CONFIG_MEMORY_HOTPLUG)
                z->present_early_pages = 0;
#endif
        }

        pgdat->node_spanned_pages = 0;
        pgdat->node_present_pages = 0;
        pr_debug("On node %d totalpages: 0\n", pgdat->node_id);
}

static void __init calculate_node_totalpages(struct pglist_data *pgdat,
                                                unsigned long node_start_pfn,
                                                unsigned long node_end_pfn)
{
        unsigned long realtotalpages = 0, totalpages = 0;
        enum zone_type i;

        for (i = 0; i < MAX_NR_ZONES; i++) {
                struct zone *zone = pgdat->node_zones + i;
                unsigned long zone_start_pfn, zone_end_pfn;
                unsigned long spanned, absent;
                unsigned long real_size;

                spanned = zone_spanned_pages_in_node(pgdat->node_id, i,
                                                     node_start_pfn,
                                                     node_end_pfn,
                                                     &zone_start_pfn,
                                                     &zone_end_pfn);
                absent = zone_absent_pages_in_node(pgdat->node_id, i,
                                                   zone_start_pfn,
                                                   zone_end_pfn);

                real_size = spanned - absent;

                if (spanned)
                        zone->zone_start_pfn = zone_start_pfn;
                else
                        zone->zone_start_pfn = 0;
                zone->spanned_pages = spanned;
                zone->present_pages = real_size;
#if defined(CONFIG_MEMORY_HOTPLUG)
                zone->present_early_pages = real_size;
#endif

                totalpages += spanned;
                realtotalpages += real_size;
        }

        pgdat->node_spanned_pages = totalpages;
        pgdat->node_present_pages = realtotalpages;
        pr_debug("On node %d totalpages: %lu\n", pgdat->node_id, realtotalpages);
}

static unsigned long __init calc_memmap_size(unsigned long spanned_pages,
                                                unsigned long present_pages)
{
        unsigned long pages = spanned_pages;

        /*
         * Provide a more accurate estimation if there are holes within
         * the zone and SPARSEMEM is in use. If there are holes within the
         * zone, each populated memory region may cost us one or two extra
         * memmap pages due to alignment because memmap pages for each
         * populated regions may not be naturally aligned on page boundary.
         * So the (present_pages >> 4) heuristic is a tradeoff for that.
         */
        if (spanned_pages > present_pages + (present_pages >> 4) &&
            IS_ENABLED(CONFIG_SPARSEMEM))
                pages = present_pages;

        return PAGE_ALIGN(pages * sizeof(struct page)) >> PAGE_SHIFT;
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static void pgdat_init_split_queue(struct pglist_data *pgdat)
{
        struct deferred_split *ds_queue = &pgdat->deferred_split_queue;

        spin_lock_init(&ds_queue->split_queue_lock);
        INIT_LIST_HEAD(&ds_queue->split_queue);
        ds_queue->split_queue_len = 0;
}
#else
static void pgdat_init_split_queue(struct pglist_data *pgdat) {}
#endif

#ifdef CONFIG_COMPACTION
static void pgdat_init_kcompactd(struct pglist_data *pgdat)
{
        init_waitqueue_head(&pgdat->kcompactd_wait);
}
#else
static void pgdat_init_kcompactd(struct pglist_data *pgdat) {}
#endif

static void __meminit pgdat_init_internals(struct pglist_data *pgdat)
{
        int i;

        pgdat_resize_init(pgdat);
        pgdat_kswapd_lock_init(pgdat);

        pgdat_init_split_queue(pgdat);
        pgdat_init_kcompactd(pgdat);

        init_waitqueue_head(&pgdat->kswapd_wait);
        init_waitqueue_head(&pgdat->pfmemalloc_wait);

        for (i = 0; i < NR_VMSCAN_THROTTLE; i++)
                init_waitqueue_head(&pgdat->reclaim_wait[i]);

        pgdat_page_ext_init(pgdat);
        lruvec_init(&pgdat->__lruvec);
}

static void __meminit zone_init_internals(struct zone *zone, enum zone_type idx, int nid,
                                                        unsigned long remaining_pages)
{
        atomic_long_set(&zone->managed_pages, remaining_pages);
        zone_set_nid(zone, nid);
        zone->name = zone_names[idx];
        zone->zone_pgdat = NODE_DATA(nid);
        spin_lock_init(&zone->lock);
        zone_seqlock_init(zone);
        zone_pcp_init(zone);
}

static void __meminit zone_init_free_lists(struct zone *zone)
{
        unsigned int order, t;
        for_each_migratetype_order(order, t) {
                INIT_LIST_HEAD(&zone->free_area[order].free_list[t]);
                zone->free_area[order].nr_free = 0;
        }

#ifdef CONFIG_UNACCEPTED_MEMORY
        INIT_LIST_HEAD(&zone->unaccepted_pages);
#endif
}

void __meminit init_currently_empty_zone(struct zone *zone,
                                        unsigned long zone_start_pfn,
                                        unsigned long size)
{
        struct pglist_data *pgdat = zone->zone_pgdat;
        int zone_idx = zone_idx(zone) + 1;

        if (zone_idx > pgdat->nr_zones)
                pgdat->nr_zones = zone_idx;

        zone->zone_start_pfn = zone_start_pfn;

        mminit_dprintk(MMINIT_TRACE, "memmap_init",
                        "Initialising map node %d zone %lu pfns %lu -> %lu\n",
                        pgdat->node_id,
                        (unsigned long)zone_idx(zone),
                        zone_start_pfn, (zone_start_pfn + size));

        zone_init_free_lists(zone);
        zone->initialized = 1;
}

#ifndef CONFIG_SPARSEMEM
/*
 * Calculate the size of the zone->blockflags rounded to an unsigned long
 * Start by making sure zonesize is a multiple of pageblock_order by rounding
 * up. Then use 1 NR_PAGEBLOCK_BITS worth of bits per pageblock, finally
 * round what is now in bits to nearest long in bits, then return it in
 * bytes.
 */
static unsigned long __init usemap_size(unsigned long zone_start_pfn, unsigned long zonesize)
{
        unsigned long usemapsize;

        zonesize += zone_start_pfn & (pageblock_nr_pages-1);
        usemapsize = roundup(zonesize, pageblock_nr_pages);
        usemapsize = usemapsize >> pageblock_order;
        usemapsize *= NR_PAGEBLOCK_BITS;
        usemapsize = roundup(usemapsize, BITS_PER_LONG);

        return usemapsize / BITS_PER_BYTE;
}

static void __ref setup_usemap(struct zone *zone)
{
        unsigned long usemapsize = usemap_size(zone->zone_start_pfn,
                                               zone->spanned_pages);
        zone->pageblock_flags = NULL;
        if (usemapsize) {
                zone->pageblock_flags =
                        memblock_alloc_node(usemapsize, SMP_CACHE_BYTES,
                                            zone_to_nid(zone));
                if (!zone->pageblock_flags)
                        panic("Failed to allocate %ld bytes for zone %s pageblock flags on node %d\n",
                              usemapsize, zone->name, zone_to_nid(zone));
        }
}
#else
static inline void setup_usemap(struct zone *zone) {}
#endif /* CONFIG_SPARSEMEM */

#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE

/* Initialise the number of pages represented by NR_PAGEBLOCK_BITS */
void __init set_pageblock_order(void)
{
        unsigned int order = MAX_PAGE_ORDER;

        /* Check that pageblock_nr_pages has not already been setup */
        if (pageblock_order)
                return;

        /* Don't let pageblocks exceed the maximum allocation granularity. */
        if (HPAGE_SHIFT > PAGE_SHIFT && HUGETLB_PAGE_ORDER < order)
                order = HUGETLB_PAGE_ORDER;

        /*
         * Assume the largest contiguous order of interest is a huge page.
         * This value may be variable depending on boot parameters on powerpc.
         */
        pageblock_order = order;
}
#else /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */

/*
 * When CONFIG_HUGETLB_PAGE_SIZE_VARIABLE is not set, set_pageblock_order()
 * is unused as pageblock_order is set at compile-time. See
 * include/linux/pageblock-flags.h for the values of pageblock_order based on
 * the kernel config
 */
void __init set_pageblock_order(void)
{
}

#endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */

/*
 * Set up the zone data structures
 * - init pgdat internals
 * - init all zones belonging to this node
 *
 * NOTE: this function is only called during memory hotplug
 */
#ifdef CONFIG_MEMORY_HOTPLUG
void __ref free_area_init_core_hotplug(struct pglist_data *pgdat)
{
        int nid = pgdat->node_id;
        enum zone_type z;
        int cpu;

        pgdat_init_internals(pgdat);

        if (pgdat->per_cpu_nodestats == &boot_nodestats)
                pgdat->per_cpu_nodestats = alloc_percpu(struct per_cpu_nodestat);

        /*
         * Reset the nr_zones, order and highest_zoneidx before reuse.
         * Note that kswapd will init kswapd_highest_zoneidx properly
         * when it starts in the near future.
         */
        pgdat->nr_zones = 0;
        pgdat->kswapd_order = 0;
        pgdat->kswapd_highest_zoneidx = 0;
        pgdat->node_start_pfn = 0;
        pgdat->node_present_pages = 0;

        for_each_online_cpu(cpu) {
                struct per_cpu_nodestat *p;

                p = per_cpu_ptr(pgdat->per_cpu_nodestats, cpu);
                memset(p, 0, sizeof(*p));
        }

        /*
         * When memory is hot-added, all the memory is in offline state. So
         * clear all zones' present_pages and managed_pages because they will
         * be updated in online_pages() and offline_pages().
         */
        for (z = 0; z < MAX_NR_ZONES; z++) {
                struct zone *zone = pgdat->node_zones + z;

                zone->present_pages = 0;
                zone_init_internals(zone, z, nid, 0);
        }
}
#endif

/*
 * Set up the zone data structures:
 *   - mark all pages reserved
 *   - mark all memory queues empty
 *   - clear the memory bitmaps
 *
 * NOTE: pgdat should get zeroed by caller.
 * NOTE: this function is only called during early init.
 */
static void __init free_area_init_core(struct pglist_data *pgdat)
{
        enum zone_type j;
        int nid = pgdat->node_id;

        pgdat_init_internals(pgdat);
        pgdat->per_cpu_nodestats = &boot_nodestats;

        for (j = 0; j < MAX_NR_ZONES; j++) {
                struct zone *zone = pgdat->node_zones + j;
                unsigned long size, freesize, memmap_pages;

                size = zone->spanned_pages;
                freesize = zone->present_pages;

                /*
                 * Adjust freesize so that it accounts for how much memory
                 * is used by this zone for memmap. This affects the watermark
                 * and per-cpu initialisations
                 */
                memmap_pages = calc_memmap_size(size, freesize);
                if (!is_highmem_idx(j)) {
                        if (freesize >= memmap_pages) {
                                freesize -= memmap_pages;
                                if (memmap_pages)
                                        pr_debug("  %s zone: %lu pages used for memmap\n",
                                                 zone_names[j], memmap_pages);
                        } else
                                pr_warn("  %s zone: %lu memmap pages exceeds freesize %lu\n",
                                        zone_names[j], memmap_pages, freesize);
                }

                /* Account for reserved pages */
                if (j == 0 && freesize > dma_reserve) {
                        freesize -= dma_reserve;
                        pr_debug("  %s zone: %lu pages reserved\n", zone_names[0], dma_reserve);
                }

                if (!is_highmem_idx(j))
                        nr_kernel_pages += freesize;
                /* Charge for highmem memmap if there are enough kernel pages */
                else if (nr_kernel_pages > memmap_pages * 2)
                        nr_kernel_pages -= memmap_pages;
                nr_all_pages += freesize;

                /*
                 * Set an approximate value for lowmem here, it will be adjusted
                 * when the bootmem allocator frees pages into the buddy system.
                 * And all highmem pages will be managed by the buddy system.
                 */
                zone_init_internals(zone, j, nid, freesize);

                if (!size)
                        continue;

                setup_usemap(zone);
                init_currently_empty_zone(zone, zone->zone_start_pfn, size);
        }
}

void __init *memmap_alloc(phys_addr_t size, phys_addr_t align,
                          phys_addr_t min_addr, int nid, bool exact_nid)
{
        void *ptr;

        if (exact_nid)
                ptr = memblock_alloc_exact_nid_raw(size, align, min_addr,
                                                   MEMBLOCK_ALLOC_ACCESSIBLE,
                                                   nid);
        else
                ptr = memblock_alloc_try_nid_raw(size, align, min_addr,
                                                 MEMBLOCK_ALLOC_ACCESSIBLE,
                                                 nid);

        if (ptr && size > 0)
                page_init_poison(ptr, size);

        return ptr;
}

#ifdef CONFIG_FLATMEM
static void __init alloc_node_mem_map(struct pglist_data *pgdat)
{
        unsigned long start, offset, size, end;
        struct page *map;

        /* Skip empty nodes */
        if (!pgdat->node_spanned_pages)
                return;

        start = pgdat->node_start_pfn & ~(MAX_ORDER_NR_PAGES - 1);
        offset = pgdat->node_start_pfn - start;
        /*
                 * The zone's endpoints aren't required to be MAX_PAGE_ORDER
         * aligned but the node_mem_map endpoints must be in order
         * for the buddy allocator to function correctly.
         */
        end = ALIGN(pgdat_end_pfn(pgdat), MAX_ORDER_NR_PAGES);
        size =  (end - start) * sizeof(struct page);
        map = memmap_alloc(size, SMP_CACHE_BYTES, MEMBLOCK_LOW_LIMIT,
                           pgdat->node_id, false);
        if (!map)
                panic("Failed to allocate %ld bytes for node %d memory map\n",
                      size, pgdat->node_id);
        pgdat->node_mem_map = map + offset;
        pr_debug("%s: node %d, pgdat %08lx, node_mem_map %08lx\n",
                 __func__, pgdat->node_id, (unsigned long)pgdat,
                 (unsigned long)pgdat->node_mem_map);
#ifndef CONFIG_NUMA
        /* the global mem_map is just set as node 0's */
        if (pgdat == NODE_DATA(0)) {
                mem_map = NODE_DATA(0)->node_mem_map;
                if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
                        mem_map -= offset;
        }
#endif
}
#else
static inline void alloc_node_mem_map(struct pglist_data *pgdat) { }
#endif /* CONFIG_FLATMEM */

/**
 * get_pfn_range_for_nid - Return the start and end page frames for a node
 * @nid: The nid to return the range for. If MAX_NUMNODES, the min and max PFN are returned.
 * @start_pfn: Passed by reference. On return, it will have the node start_pfn.
 * @end_pfn: Passed by reference. On return, it will have the node end_pfn.
 *
 * It returns the start and end page frame of a node based on information
 * provided by memblock_set_node(). If called for a node
 * with no available memory, the start and end PFNs will be 0.
 */
void __init get_pfn_range_for_nid(unsigned int nid,
                        unsigned long *start_pfn, unsigned long *end_pfn)
{
        unsigned long this_start_pfn, this_end_pfn;
        int i;

        *start_pfn = -1UL;
        *end_pfn = 0;

        for_each_mem_pfn_range(i, nid, &this_start_pfn, &this_end_pfn, NULL) {
                *start_pfn = min(*start_pfn, this_start_pfn);
                *end_pfn = max(*end_pfn, this_end_pfn);
        }

        if (*start_pfn == -1UL)
                *start_pfn = 0;
}

static void __init free_area_init_node(int nid)
{
        pg_data_t *pgdat = NODE_DATA(nid);
        unsigned long start_pfn = 0;
        unsigned long end_pfn = 0;

        /* pg_data_t should be reset to zero when it's allocated */
        WARN_ON(pgdat->nr_zones || pgdat->kswapd_highest_zoneidx);

        get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);

        pgdat->node_id = nid;
        pgdat->node_start_pfn = start_pfn;
        pgdat->per_cpu_nodestats = NULL;

        if (start_pfn != end_pfn) {
                pr_info("Initmem setup node %d [mem %#018Lx-%#018Lx]\n", nid,
                        (u64)start_pfn << PAGE_SHIFT,
                        end_pfn ? ((u64)end_pfn << PAGE_SHIFT) - 1 : 0);

                calculate_node_totalpages(pgdat, start_pfn, end_pfn);
        } else {
                pr_info("Initmem setup node %d as memoryless\n", nid);

                reset_memoryless_node_totalpages(pgdat);
        }

        alloc_node_mem_map(pgdat);
        pgdat_set_deferred_range(pgdat);

        free_area_init_core(pgdat);
        lru_gen_init_pgdat(pgdat);
}

/* Any regular or high memory on that node ? */
static void __init check_for_memory(pg_data_t *pgdat)
{
        enum zone_type zone_type;

        for (zone_type = 0; zone_type <= ZONE_MOVABLE - 1; zone_type++) {
                struct zone *zone = &pgdat->node_zones[zone_type];
                if (populated_zone(zone)) {
                        if (IS_ENABLED(CONFIG_HIGHMEM))
                                node_set_state(pgdat->node_id, N_HIGH_MEMORY);
                        if (zone_type <= ZONE_NORMAL)
                                node_set_state(pgdat->node_id, N_NORMAL_MEMORY);
                        break;
                }
        }
}

#if MAX_NUMNODES > 1
/*
 * Figure out the number of possible node ids.
 */
void __init setup_nr_node_ids(void)
{
        unsigned int highest;

        highest = find_last_bit(node_possible_map.bits, MAX_NUMNODES);
        nr_node_ids = highest + 1;
}
#endif

/*
 * Some architectures, e.g. ARC may have ZONE_HIGHMEM below ZONE_NORMAL. For
 * such cases we allow max_zone_pfn sorted in the descending order
 */
static bool arch_has_descending_max_zone_pfns(void)
{
        return IS_ENABLED(CONFIG_ARC) && !IS_ENABLED(CONFIG_ARC_HAS_PAE40);
}

/**
 * free_area_init - Initialise all pg_data_t and zone data
 * @max_zone_pfn: an array of max PFNs for each zone
 *
 * This will call free_area_init_node() for each active node in the system.
 * Using the page ranges provided by memblock_set_node(), the size of each
 * zone in each node and their holes is calculated. If the maximum PFN
 * between two adjacent zones match, it is assumed that the zone is empty.
 * For example, if arch_max_dma_pfn == arch_max_dma32_pfn, it is assumed
 * that arch_max_dma32_pfn has no pages. It is also assumed that a zone
 * starts where the previous one ended. For example, ZONE_DMA32 starts
 * at arch_max_dma_pfn.
 */
void __init free_area_init(unsigned long *max_zone_pfn)
{
        unsigned long start_pfn, end_pfn;
        int i, nid, zone;
        bool descending;

        /* Record where the zone boundaries are */
        memset(arch_zone_lowest_possible_pfn, 0,
                                sizeof(arch_zone_lowest_possible_pfn));
        memset(arch_zone_highest_possible_pfn, 0,
                                sizeof(arch_zone_highest_possible_pfn));

        start_pfn = PHYS_PFN(memblock_start_of_DRAM());
        descending = arch_has_descending_max_zone_pfns();

        for (i = 0; i < MAX_NR_ZONES; i++) {
                if (descending)
                        zone = MAX_NR_ZONES - i - 1;
                else
                        zone = i;

                if (zone == ZONE_MOVABLE)
                        continue;

                end_pfn = max(max_zone_pfn[zone], start_pfn);
                arch_zone_lowest_possible_pfn[zone] = start_pfn;
                arch_zone_highest_possible_pfn[zone] = end_pfn;

                start_pfn = end_pfn;
        }

        /* Find the PFNs that ZONE_MOVABLE begins at in each node */
        memset(zone_movable_pfn, 0, sizeof(zone_movable_pfn));
        find_zone_movable_pfns_for_nodes();

        /* Print out the zone ranges */
        pr_info("Zone ranges:\n");
        for (i = 0; i < MAX_NR_ZONES; i++) {
                if (i == ZONE_MOVABLE)
                        continue;
                pr_info("  %-8s ", zone_names[i]);
                if (arch_zone_lowest_possible_pfn[i] ==
                                arch_zone_highest_possible_pfn[i])
                        pr_cont("empty\n");
                else
                        pr_cont("[mem %#018Lx-%#018Lx]\n",
                                (u64)arch_zone_lowest_possible_pfn[i]
                                        << PAGE_SHIFT,
                                ((u64)arch_zone_highest_possible_pfn[i]
                                        << PAGE_SHIFT) - 1);
        }

        /* Print out the PFNs ZONE_MOVABLE begins at in each node */
        pr_info("Movable zone start for each node\n");
        for (i = 0; i < MAX_NUMNODES; i++) {
                if (zone_movable_pfn[i])
                        pr_info("  Node %d: %#018Lx\n", i,
                               (u64)zone_movable_pfn[i] << PAGE_SHIFT);
        }

        /*
         * Print out the early node map, and initialize the
         * subsection-map relative to active online memory ranges to
         * enable future "sub-section" extensions of the memory map.
         */
        pr_info("Early memory node ranges\n");
        for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
                pr_info("  node %3d: [mem %#018Lx-%#018Lx]\n", nid,
                        (u64)start_pfn << PAGE_SHIFT,
                        ((u64)end_pfn << PAGE_SHIFT) - 1);
                subsection_map_init(start_pfn, end_pfn - start_pfn);
        }

        /* Initialise every node */
        mminit_verify_pageflags_layout();
        setup_nr_node_ids();
        set_pageblock_order();

        for_each_node(nid) {
                pg_data_t *pgdat;

                if (!node_online(nid)) {
                        /* Allocator not initialized yet */
                        pgdat = arch_alloc_nodedata(nid);
                        if (!pgdat)
                                panic("Cannot allocate %zuB for node %d.\n",
                                       sizeof(*pgdat), nid);
                        arch_refresh_nodedata(nid, pgdat);
                        free_area_init_node(nid);

                        /*
                         * We do not want to confuse userspace by sysfs
                         * files/directories for node without any memory
                         * attached to it, so this node is not marked as
                         * N_MEMORY and not marked online so that no sysfs
                         * hierarchy will be created via register_one_node for
                         * it. The pgdat will get fully initialized by
                         * hotadd_init_pgdat() when memory is hotplugged into
                         * this node.
                         */
                        continue;
                }

                pgdat = NODE_DATA(nid);
                free_area_init_node(nid);

                /* Any memory on that node */
                if (pgdat->node_present_pages)
                        node_set_state(nid, N_MEMORY);
                check_for_memory(pgdat);
        }

        memmap_init();

        /* disable hash distribution for systems with a single node */
        fixup_hashdist();
}

/**
 * node_map_pfn_alignment - determine the maximum internode alignment
 *
 * This function should be called after node map is populated and sorted.
 * It calculates the maximum power of two alignment which can distinguish
 * all the nodes.
 *
 * For example, if all nodes are 1GiB and aligned to 1GiB, the return value
 * would indicate 1GiB alignment with (1 << (30 - PAGE_SHIFT)).  If the
 * nodes are shifted by 256MiB, 256MiB.  Note that if only the last node is
 * shifted, 1GiB is enough and this function will indicate so.
 *
 * This is used to test whether pfn -> nid mapping of the chosen memory
 * model has fine enough granularity to avoid incorrect mapping for the
 * populated node map.
 *
 * Return: the determined alignment in pfn's.  0 if there is no alignment
 * requirement (single node).
 */
unsigned long __init node_map_pfn_alignment(void)
{
        unsigned long accl_mask = 0, last_end = 0;
        unsigned long start, end, mask;
        int last_nid = NUMA_NO_NODE;
        int i, nid;

        for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid) {
                if (!start || last_nid < 0 || last_nid == nid) {
                        last_nid = nid;
                        last_end = end;
                        continue;
                }

                /*
                 * Start with a mask granular enough to pin-point to the
                 * start pfn and tick off bits one-by-one until it becomes
                 * too coarse to separate the current node from the last.
                 */
                mask = ~((1 << __ffs(start)) - 1);
                while (mask && last_end <= (start & (mask << 1)))
                        mask <<= 1;

                /* accumulate all internode masks */
                accl_mask |= mask;
        }

        /* convert mask to number of pages */
        return ~accl_mask + 1;
}

#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
static void __init deferred_free_range(unsigned long pfn,
                                       unsigned long nr_pages)
{
        struct page *page;
        unsigned long i;

        if (!nr_pages)
                return;

        page = pfn_to_page(pfn);

        /* Free a large naturally-aligned chunk if possible */
        if (nr_pages == MAX_ORDER_NR_PAGES && IS_MAX_ORDER_ALIGNED(pfn)) {
                for (i = 0; i < nr_pages; i += pageblock_nr_pages)
                        set_pageblock_migratetype(page + i, MIGRATE_MOVABLE);
                __free_pages_core(page, MAX_PAGE_ORDER);
                return;
        }

        /* Accept chunks smaller than MAX_PAGE_ORDER upfront */
        accept_memory(PFN_PHYS(pfn), PFN_PHYS(pfn + nr_pages));

        for (i = 0; i < nr_pages; i++, page++, pfn++) {
                if (pageblock_aligned(pfn))
                        set_pageblock_migratetype(page, MIGRATE_MOVABLE);
                __free_pages_core(page, 0);
        }
}

/* Completion tracking for deferred_init_memmap() threads */
static atomic_t pgdat_init_n_undone __initdata;
static __initdata DECLARE_COMPLETION(pgdat_init_all_done_comp);

static inline void __init pgdat_init_report_one_done(void)
{
        if (atomic_dec_and_test(&pgdat_init_n_undone))
                complete(&pgdat_init_all_done_comp);
}

/*
 * Returns true if page needs to be initialized or freed to buddy allocator.
 *
 * We check if a current MAX_PAGE_ORDER block is valid by only checking the
 * validity of the head pfn.
 */
static inline bool __init deferred_pfn_valid(unsigned long pfn)
{
        if (IS_MAX_ORDER_ALIGNED(pfn) && !pfn_valid(pfn))
                return false;
        return true;
}

/*
 * Free pages to buddy allocator. Try to free aligned pages in
 * MAX_ORDER_NR_PAGES sizes.
 */
static void __init deferred_free_pages(unsigned long pfn,
                                       unsigned long end_pfn)
{
        unsigned long nr_free = 0;

        for (; pfn < end_pfn; pfn++) {
                if (!deferred_pfn_valid(pfn)) {
                        deferred_free_range(pfn - nr_free, nr_free);
                        nr_free = 0;
                } else if (IS_MAX_ORDER_ALIGNED(pfn)) {
                        deferred_free_range(pfn - nr_free, nr_free);
                        nr_free = 1;
                } else {
                        nr_free++;
                }
        }
        /* Free the last block of pages to allocator */
        deferred_free_range(pfn - nr_free, nr_free);
}

/*
 * Initialize struct pages.  We minimize pfn page lookups and scheduler checks
 * by performing it only once every MAX_ORDER_NR_PAGES.
 * Return number of pages initialized.
 */
static unsigned long  __init deferred_init_pages(struct zone *zone,
                                                 unsigned long pfn,
                                                 unsigned long end_pfn)
{
        int nid = zone_to_nid(zone);
        unsigned long nr_pages = 0;
        int zid = zone_idx(zone);
        struct page *page = NULL;

        for (; pfn < end_pfn; pfn++) {
                if (!deferred_pfn_valid(pfn)) {
                        page = NULL;
                        continue;
                } else if (!page || IS_MAX_ORDER_ALIGNED(pfn)) {
                        page = pfn_to_page(pfn);
                } else {
                        page++;
                }
                __init_single_page(page, pfn, zid, nid);
                nr_pages++;
        }
        return (nr_pages);
}

/*
 * This function is meant to pre-load the iterator for the zone init.
 * Specifically it walks through the ranges until we are caught up to the
 * first_init_pfn value and exits there. If we never encounter the value we
 * return false indicating there are no valid ranges left.
 */
static bool __init
deferred_init_mem_pfn_range_in_zone(u64 *i, struct zone *zone,
                                    unsigned long *spfn, unsigned long *epfn,
                                    unsigned long first_init_pfn)
{
        u64 j;

        /*
         * Start out by walking through the ranges in this zone that have
         * already been initialized. We don't need to do anything with them
         * so we just need to flush them out of the system.
         */
        for_each_free_mem_pfn_range_in_zone(j, zone, spfn, epfn) {
                if (*epfn <= first_init_pfn)
                        continue;
                if (*spfn < first_init_pfn)
                        *spfn = first_init_pfn;
                *i = j;
                return true;
        }

        return false;
}

/*
 * Initialize and free pages. We do it in two loops: first we initialize
 * struct page, then free to buddy allocator, because while we are
 * freeing pages we can access pages that are ahead (computing buddy
 * page in __free_one_page()).
 *
 * In order to try and keep some memory in the cache we have the loop
 * broken along max page order boundaries. This way we will not cause
 * any issues with the buddy page computation.
 */
static unsigned long __init
deferred_init_maxorder(u64 *i, struct zone *zone, unsigned long *start_pfn,
                       unsigned long *end_pfn)
{
        unsigned long mo_pfn = ALIGN(*start_pfn + 1, MAX_ORDER_NR_PAGES);
        unsigned long spfn = *start_pfn, epfn = *end_pfn;
        unsigned long nr_pages = 0;
        u64 j = *i;

        /* First we loop through and initialize the page values */
        for_each_free_mem_pfn_range_in_zone_from(j, zone, start_pfn, end_pfn) {
                unsigned long t;

                if (mo_pfn <= *start_pfn)
                        break;

                t = min(mo_pfn, *end_pfn);
                nr_pages += deferred_init_pages(zone, *start_pfn, t);

                if (mo_pfn < *end_pfn) {
                        *start_pfn = mo_pfn;
                        break;
                }
        }

        /* Reset values and now loop through freeing pages as needed */
        swap(j, *i);

        for_each_free_mem_pfn_range_in_zone_from(j, zone, &spfn, &epfn) {
                unsigned long t;

                if (mo_pfn <= spfn)
                        break;

                t = min(mo_pfn, epfn);
                deferred_free_pages(spfn, t);

                if (mo_pfn <= epfn)
                        break;
        }

        return nr_pages;
}

static void __init
deferred_init_memmap_chunk(unsigned long start_pfn, unsigned long end_pfn,
                           void *arg)
{
        unsigned long spfn, epfn;
        struct zone *zone = arg;
        u64 i;

        deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn, start_pfn);

        /*
         * Initialize and free pages in MAX_PAGE_ORDER sized increments so that
         * we can avoid introducing any issues with the buddy allocator.
         */
        while (spfn < end_pfn) {
                deferred_init_maxorder(&i, zone, &spfn, &epfn);
                cond_resched();
        }
}

/* An arch may override for more concurrency. */
__weak int __init
deferred_page_init_max_threads(const struct cpumask *node_cpumask)
{
        return 1;
}

/* Initialise remaining memory on a node */
static int __init deferred_init_memmap(void *data)
{
        pg_data_t *pgdat = data;
        const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
        unsigned long spfn = 0, epfn = 0;
        unsigned long first_init_pfn, flags;
        unsigned long start = jiffies;
        struct zone *zone;
        int zid, max_threads;
        u64 i;

        /* Bind memory initialisation thread to a local node if possible */
        if (!cpumask_empty(cpumask))
                set_cpus_allowed_ptr(current, cpumask);

        pgdat_resize_lock(pgdat, &flags);
        first_init_pfn = pgdat->first_deferred_pfn;
        if (first_init_pfn == ULONG_MAX) {
                pgdat_resize_unlock(pgdat, &flags);
                pgdat_init_report_one_done();
                return 0;
        }

        /* Sanity check boundaries */
        BUG_ON(pgdat->first_deferred_pfn < pgdat->node_start_pfn);
        BUG_ON(pgdat->first_deferred_pfn > pgdat_end_pfn(pgdat));
        pgdat->first_deferred_pfn = ULONG_MAX;

        /*
         * Once we unlock here, the zone cannot be grown anymore, thus if an
         * interrupt thread must allocate this early in boot, zone must be
         * pre-grown prior to start of deferred page initialization.
         */
        pgdat_resize_unlock(pgdat, &flags);

        /* Only the highest zone is deferred so find it */
        for (zid = 0; zid < MAX_NR_ZONES; zid++) {
                zone = pgdat->node_zones + zid;
                if (first_init_pfn < zone_end_pfn(zone))
                        break;
        }

        /* If the zone is empty somebody else may have cleared out the zone */
        if (!deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
                                                 first_init_pfn))
                goto zone_empty;

        max_threads = deferred_page_init_max_threads(cpumask);

        while (spfn < epfn) {
                unsigned long epfn_align = ALIGN(epfn, PAGES_PER_SECTION);
                struct padata_mt_job job = {
                        .thread_fn   = deferred_init_memmap_chunk,
                        .fn_arg      = zone,
                        .start       = spfn,
                        .size        = epfn_align - spfn,
                        .align       = PAGES_PER_SECTION,
                        .min_chunk   = PAGES_PER_SECTION,
                        .max_threads = max_threads,
                        .numa_aware  = false,
                };

                padata_do_multithreaded(&job);
                deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
                                                    epfn_align);
        }
zone_empty:
        /* Sanity check that the next zone really is unpopulated */
        WARN_ON(++zid < MAX_NR_ZONES && populated_zone(++zone));

        pr_info("node %d deferred pages initialised in %ums\n",
                pgdat->node_id, jiffies_to_msecs(jiffies - start));

        pgdat_init_report_one_done();
        return 0;
}

/*
 * If this zone has deferred pages, try to grow it by initializing enough
 * deferred pages to satisfy the allocation specified by order, rounded up to
 * the nearest PAGES_PER_SECTION boundary.  So we're adding memory in increments
 * of SECTION_SIZE bytes by initializing struct pages in increments of
 * PAGES_PER_SECTION * sizeof(struct page) bytes.
 *
 * Return true when zone was grown, otherwise return false. We return true even
 * when we grow less than requested, to let the caller decide if there are
 * enough pages to satisfy the allocation.
 *
 * Note: We use noinline because this function is needed only during boot, and
 * it is called from a __ref function _deferred_grow_zone. This way we are
 * making sure that it is not inlined into permanent text section.
 */
bool __init deferred_grow_zone(struct zone *zone, unsigned int order)
{
        unsigned long nr_pages_needed = ALIGN(1 << order, PAGES_PER_SECTION);
        pg_data_t *pgdat = zone->zone_pgdat;
        unsigned long first_deferred_pfn = pgdat->first_deferred_pfn;
        unsigned long spfn, epfn, flags;
        unsigned long nr_pages = 0;
        u64 i;

        /* Only the last zone may have deferred pages */
        if (zone_end_pfn(zone) != pgdat_end_pfn(pgdat))
                return false;

        pgdat_resize_lock(pgdat, &flags);

        /*
         * If someone grew this zone while we were waiting for spinlock, return
         * true, as there might be enough pages already.
         */
        if (first_deferred_pfn != pgdat->first_deferred_pfn) {
                pgdat_resize_unlock(pgdat, &flags);
                return true;
        }

        /* If the zone is empty somebody else may have cleared out the zone */
        if (!deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
                                                 first_deferred_pfn)) {
                pgdat->first_deferred_pfn = ULONG_MAX;
                pgdat_resize_unlock(pgdat, &flags);
                /* Retry only once. */
                return first_deferred_pfn != ULONG_MAX;
        }

        /*
         * Initialize and free pages in MAX_PAGE_ORDER sized increments so
         * that we can avoid introducing any issues with the buddy
         * allocator.
         */
        while (spfn < epfn) {
                /* update our first deferred PFN for this section */
                first_deferred_pfn = spfn;

                nr_pages += deferred_init_maxorder(&i, zone, &spfn, &epfn);
                touch_nmi_watchdog();

                /* We should only stop along section boundaries */
                if ((first_deferred_pfn ^ spfn) < PAGES_PER_SECTION)
                        continue;

                /* If our quota has been met we can stop here */
                if (nr_pages >= nr_pages_needed)
                        break;
        }

        pgdat->first_deferred_pfn = spfn;
        pgdat_resize_unlock(pgdat, &flags);

        return nr_pages > 0;
}

#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */

#ifdef CONFIG_CMA
void __init init_cma_reserved_pageblock(struct page *page)
{
        unsigned i = pageblock_nr_pages;
        struct page *p = page;

        do {
                __ClearPageReserved(p);
                set_page_count(p, 0);
        } while (++p, --i);

        set_pageblock_migratetype(page, MIGRATE_CMA);
        set_page_refcounted(page);
        __free_pages(page, pageblock_order);

        adjust_managed_page_count(page, pageblock_nr_pages);
        page_zone(page)->cma_pages += pageblock_nr_pages;
}
#endif

void set_zone_contiguous(struct zone *zone)
{
        unsigned long block_start_pfn = zone->zone_start_pfn;
        unsigned long block_end_pfn;

        block_end_pfn = pageblock_end_pfn(block_start_pfn);
        for (; block_start_pfn < zone_end_pfn(zone);
                        block_start_pfn = block_end_pfn,
                         block_end_pfn += pageblock_nr_pages) {

                block_end_pfn = min(block_end_pfn, zone_end_pfn(zone));

                if (!__pageblock_pfn_to_page(block_start_pfn,
                                             block_end_pfn, zone))
                        return;
                cond_resched();
        }

        /* We confirm that there is no hole */
        zone->contiguous = true;
}

void __init page_alloc_init_late(void)
{
        struct zone *zone;
        int nid;

#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT

        /* There will be num_node_state(N_MEMORY) threads */
        atomic_set(&pgdat_init_n_undone, num_node_state(N_MEMORY));
        for_each_node_state(nid, N_MEMORY) {
                kthread_run(deferred_init_memmap, NODE_DATA(nid), "pgdatinit%d", nid);
        }

        /* Block until all are initialised */
        wait_for_completion(&pgdat_init_all_done_comp);

        /*
         * We initialized the rest of the deferred pages.  Permanently disable
         * on-demand struct page initialization.
         */
        static_branch_disable(&deferred_pages);

        /* Reinit limits that are based on free pages after the kernel is up */
        files_maxfiles_init();
#endif

        buffer_init();

        /* Discard memblock private memory */
        memblock_discard();

        for_each_node_state(nid, N_MEMORY)
                shuffle_free_memory(NODE_DATA(nid));

        for_each_populated_zone(zone)
                set_zone_contiguous(zone);

        /* Initialize page ext after all struct pages are initialized. */
        if (deferred_struct_pages)
                page_ext_init();

        page_alloc_sysctl_init();
}

#ifndef __HAVE_ARCH_RESERVED_KERNEL_PAGES
/*
 * Returns the number of pages that arch has reserved but
 * is not known to alloc_large_system_hash().
 */
static unsigned long __init arch_reserved_kernel_pages(void)
{
        return 0;
}
#endif

/*
 * Adaptive scale is meant to reduce sizes of hash tables on large memory
 * machines. As memory size is increased the scale is also increased but at
 * slower pace.  Starting from ADAPT_SCALE_BASE (64G), every time memory
 * quadruples the scale is increased by one, which means the size of hash table
 * only doubles, instead of quadrupling as well.
 * Because 32-bit systems cannot have large physical memory, where this scaling
 * makes sense, it is disabled on such platforms.
 */
#if __BITS_PER_LONG > 32
#define ADAPT_SCALE_BASE        (64ul << 30)
#define ADAPT_SCALE_SHIFT       2
#define ADAPT_SCALE_NPAGES      (ADAPT_SCALE_BASE >> PAGE_SHIFT)
#endif

/*
 * allocate a large system hash table from bootmem
 * - it is assumed that the hash table must contain an exact power-of-2
 *   quantity of entries
 * - limit is the number of hash buckets, not the total allocation size
 */
void *__init alloc_large_system_hash(const char *tablename,
                                     unsigned long bucketsize,
                                     unsigned long numentries,
                                     int scale,
                                     int flags,
                                     unsigned int *_hash_shift,
                                     unsigned int *_hash_mask,
                                     unsigned long low_limit,
                                     unsigned long high_limit)
{
        unsigned long long max = high_limit;
        unsigned long log2qty, size;
        void *table;
        gfp_t gfp_flags;
        bool virt;
        bool huge;

        /* allow the kernel cmdline to have a say */
        if (!numentries) {
                /* round applicable memory size up to nearest megabyte */
                numentries = nr_kernel_pages;
                numentries -= arch_reserved_kernel_pages();

                /* It isn't necessary when PAGE_SIZE >= 1MB */
                if (PAGE_SIZE < SZ_1M)
                        numentries = round_up(numentries, SZ_1M / PAGE_SIZE);

#if __BITS_PER_LONG > 32
                if (!high_limit) {
                        unsigned long adapt;

                        for (adapt = ADAPT_SCALE_NPAGES; adapt < numentries;
                             adapt <<= ADAPT_SCALE_SHIFT)
                                scale++;
                }
#endif

                /* limit to 1 bucket per 2^scale bytes of low memory */
                if (scale > PAGE_SHIFT)
                        numentries >>= (scale - PAGE_SHIFT);
                else
                        numentries <<= (PAGE_SHIFT - scale);

                if (unlikely((numentries * bucketsize) < PAGE_SIZE))
                        numentries = PAGE_SIZE / bucketsize;
        }
        numentries = roundup_pow_of_two(numentries);

        /* limit allocation size to 1/16 total memory by default */
        if (max == 0) {
                max = ((unsigned long long)nr_all_pages << PAGE_SHIFT) >> 4;
                do_div(max, bucketsize);
        }
        max = min(max, 0x80000000ULL);

        if (numentries < low_limit)
                numentries = low_limit;
        if (numentries > max)
                numentries = max;

        log2qty = ilog2(numentries);

        gfp_flags = (flags & HASH_ZERO) ? GFP_ATOMIC | __GFP_ZERO : GFP_ATOMIC;
        do {
                virt = false;
                size = bucketsize << log2qty;
                if (flags & HASH_EARLY) {
                        if (flags & HASH_ZERO)
                                table = memblock_alloc(size, SMP_CACHE_BYTES);
                        else
                                table = memblock_alloc_raw(size,
                                                           SMP_CACHE_BYTES);
                } else if (get_order(size) > MAX_PAGE_ORDER || hashdist) {
                        table = vmalloc_huge(size, gfp_flags);
                        virt = true;
                        if (table)
                                huge = is_vm_area_hugepages(table);
                } else {
                        /*
                         * If bucketsize is not a power-of-two, we may free
                         * some pages at the end of hash table which
                         * alloc_pages_exact() automatically does
                         */
                        table = alloc_pages_exact(size, gfp_flags);
                        kmemleak_alloc(table, size, 1, gfp_flags);
                }
        } while (!table && size > PAGE_SIZE && --log2qty);

        if (!table)
                panic("Failed to allocate %s hash table\n", tablename);

        pr_info("%s hash table entries: %ld (order: %d, %lu bytes, %s)\n",
                tablename, 1UL << log2qty, ilog2(size) - PAGE_SHIFT, size,
                virt ? (huge ? "vmalloc hugepage" : "vmalloc") : "linear");

        if (_hash_shift)
                *_hash_shift = log2qty;
        if (_hash_mask)
                *_hash_mask = (1 << log2qty) - 1;

        return table;
}

/**
 * set_dma_reserve - set the specified number of pages reserved in the first zone
 * @new_dma_reserve: The number of pages to mark reserved
 *
 * The per-cpu batchsize and zone watermarks are determined by managed_pages.
 * In the DMA zone, a significant percentage may be consumed by kernel image
 * and other unfreeable allocations which can skew the watermarks badly. This
 * function may optionally be used to account for unfreeable pages in the
 * first zone (e.g., ZONE_DMA). The effect will be lower watermarks and
 * smaller per-cpu batchsize.
 */
void __init set_dma_reserve(unsigned long new_dma_reserve)
{
        dma_reserve = new_dma_reserve;
}

void __init memblock_free_pages(struct page *page, unsigned long pfn,
                                                        unsigned int order)
{

        if (IS_ENABLED(CONFIG_DEFERRED_STRUCT_PAGE_INIT)) {
                int nid = early_pfn_to_nid(pfn);

                if (!early_page_initialised(pfn, nid))
                        return;
        }

        if (!kmsan_memblock_free_pages(page, order)) {
                /* KMSAN will take care of these pages. */
                return;
        }
        __free_pages_core(page, order);
}

DEFINE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, init_on_alloc);
EXPORT_SYMBOL(init_on_alloc);

DEFINE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_FREE_DEFAULT_ON, init_on_free);
EXPORT_SYMBOL(init_on_free);

static bool _init_on_alloc_enabled_early __read_mostly
                                = IS_ENABLED(CONFIG_INIT_ON_ALLOC_DEFAULT_ON);
static int __init early_init_on_alloc(char *buf)
{

        return kstrtobool(buf, &_init_on_alloc_enabled_early);
}
early_param("init_on_alloc", early_init_on_alloc);

static bool _init_on_free_enabled_early __read_mostly
                                = IS_ENABLED(CONFIG_INIT_ON_FREE_DEFAULT_ON);
static int __init early_init_on_free(char *buf)
{
        return kstrtobool(buf, &_init_on_free_enabled_early);
}
early_param("init_on_free", early_init_on_free);

DEFINE_STATIC_KEY_MAYBE(CONFIG_DEBUG_VM, check_pages_enabled);

/*
 * Enable static keys related to various memory debugging and hardening options.
 * Some override others, and depend on early params that are evaluated in the
 * order of appearance. So we need to first gather the full picture of what was
 * enabled, and then make decisions.
 */
static void __init mem_debugging_and_hardening_init(void)
{
        bool page_poisoning_requested = false;
        bool want_check_pages = false;

#ifdef CONFIG_PAGE_POISONING
        /*
         * Page poisoning is debug page alloc for some arches. If
         * either of those options are enabled, enable poisoning.
         */
        if (page_poisoning_enabled() ||
             (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) &&
              debug_pagealloc_enabled())) {
                static_branch_enable(&_page_poisoning_enabled);
                page_poisoning_requested = true;
                want_check_pages = true;
        }
#endif

        if ((_init_on_alloc_enabled_early || _init_on_free_enabled_early) &&
            page_poisoning_requested) {
                pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, "
                        "will take precedence over init_on_alloc and init_on_free\n");
                _init_on_alloc_enabled_early = false;
                _init_on_free_enabled_early = false;
        }

        if (_init_on_alloc_enabled_early) {
                want_check_pages = true;
                static_branch_enable(&init_on_alloc);
        } else {
                static_branch_disable(&init_on_alloc);
        }

        if (_init_on_free_enabled_early) {
                want_check_pages = true;
                static_branch_enable(&init_on_free);
        } else {
                static_branch_disable(&init_on_free);
        }

        if (IS_ENABLED(CONFIG_KMSAN) &&
            (_init_on_alloc_enabled_early || _init_on_free_enabled_early))
                pr_info("mem auto-init: please make sure init_on_alloc and init_on_free are disabled when running KMSAN\n");

#ifdef CONFIG_DEBUG_PAGEALLOC
        if (debug_pagealloc_enabled()) {
                want_check_pages = true;
                static_branch_enable(&_debug_pagealloc_enabled);

                if (debug_guardpage_minorder())
                        static_branch_enable(&_debug_guardpage_enabled);
        }
#endif

        /*
         * Any page debugging or hardening option also enables sanity checking
         * of struct pages being allocated or freed. With CONFIG_DEBUG_VM it's
         * enabled already.
         */
        if (!IS_ENABLED(CONFIG_DEBUG_VM) && want_check_pages)
                static_branch_enable(&check_pages_enabled);
}

/* Report memory auto-initialization states for this boot. */
static void __init report_meminit(void)
{
        const char *stack;

        if (IS_ENABLED(CONFIG_INIT_STACK_ALL_PATTERN))
                stack = "all(pattern)";
        else if (IS_ENABLED(CONFIG_INIT_STACK_ALL_ZERO))
                stack = "all(zero)";
        else if (IS_ENABLED(CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL))
                stack = "byref_all(zero)";
        else if (IS_ENABLED(CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF))
                stack = "byref(zero)";
        else if (IS_ENABLED(CONFIG_GCC_PLUGIN_STRUCTLEAK_USER))
                stack = "__user(zero)";
        else
                stack = "off";

        pr_info("mem auto-init: stack:%s, heap alloc:%s, heap free:%s\n",
                stack, want_init_on_alloc(GFP_KERNEL) ? "on" : "off",
                want_init_on_free() ? "on" : "off");
        if (want_init_on_free())
                pr_info("mem auto-init: clearing system memory may take some time...\n");
}

static void __init mem_init_print_info(void)
{
        unsigned long physpages, codesize, datasize, rosize, bss_size;
        unsigned long init_code_size, init_data_size;

        physpages = get_num_physpages();
        codesize = _etext - _stext;
        datasize = _edata - _sdata;
        rosize = __end_rodata - __start_rodata;
        bss_size = __bss_stop - __bss_start;
        init_data_size = __init_end - __init_begin;
        init_code_size = _einittext - _sinittext;

        /*
         * Detect special cases and adjust section sizes accordingly:
         * 1) .init.* may be embedded into .data sections
         * 2) .init.text.* may be out of [__init_begin, __init_end],
         *    please refer to arch/tile/kernel/vmlinux.lds.S.
         * 3) .rodata.* may be embedded into .text or .data sections.
         */
#define adj_init_size(start, end, size, pos, adj) \
        do { \
                if (&start[0] <= &pos[0] && &pos[0] < &end[0] && size > adj) \
                        size -= adj; \
        } while (0)

        adj_init_size(__init_begin, __init_end, init_data_size,
                     _sinittext, init_code_size);
        adj_init_size(_stext, _etext, codesize, _sinittext, init_code_size);
        adj_init_size(_sdata, _edata, datasize, __init_begin, init_data_size);
        adj_init_size(_stext, _etext, codesize, __start_rodata, rosize);
        adj_init_size(_sdata, _edata, datasize, __start_rodata, rosize);

#undef  adj_init_size

        pr_info("Memory: %luK/%luK available (%luK kernel code, %luK rwdata, %luK rodata, %luK init, %luK bss, %luK reserved, %luK cma-reserved"
#ifdef  CONFIG_HIGHMEM
                ", %luK highmem"
#endif
                ")\n",
                K(nr_free_pages()), K(physpages),
                codesize / SZ_1K, datasize / SZ_1K, rosize / SZ_1K,
                (init_data_size + init_code_size) / SZ_1K, bss_size / SZ_1K,
                K(physpages - totalram_pages() - totalcma_pages),
                K(totalcma_pages)
#ifdef  CONFIG_HIGHMEM
                , K(totalhigh_pages())
#endif
                );
}

/*
 * Set up kernel memory allocators
 */
void __init mm_core_init(void)
{
        /* Initializations relying on SMP setup */
        build_all_zonelists(NULL);
        page_alloc_init_cpuhp();

        /*
         * page_ext requires contiguous pages,
         * bigger than MAX_PAGE_ORDER unless SPARSEMEM.
         */
        page_ext_init_flatmem();
        mem_debugging_and_hardening_init();
        kfence_alloc_pool_and_metadata();
        report_meminit();
        kmsan_init_shadow();
        stack_depot_early_init();
        mem_init();
        mem_init_print_info();
        kmem_cache_init();
        /*
         * page_owner must be initialized after buddy is ready, and also after
         * slab is ready so that stack_depot_init() works properly
         */
        page_ext_init_flatmem_late();
        kmemleak_init();
        ptlock_cache_init();
        pgtable_cache_init();
        debug_objects_mem_init();
        vmalloc_init();
        /* If no deferred init page_ext now, as vmap is fully initialized */
        if (!deferred_struct_pages)
                page_ext_init();
        /* Should be run before the first non-init thread is created */
        init_espfix_bsp();
        /* Should be run after espfix64 is set up. */
        pti_init();
        kmsan_init_runtime();
        mm_cache_init();
}