mm/hugetlb.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Generic hugetlb support.
 * (C) Nadia Yvette Chambers, April 2004
 */
#include <linux/list.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/seq_file.h>
#include <linux/sysctl.h>
#include <linux/highmem.h>
#include <linux/mmu_notifier.h>
#include <linux/nodemask.h>
#include <linux/pagemap.h>
#include <linux/mempolicy.h>
#include <linux/compiler.h>
#include <linux/cpuset.h>
#include <linux/mutex.h>
#include <linux/memblock.h>
#include <linux/sysfs.h>
#include <linux/slab.h>
#include <linux/sched/mm.h>
#include <linux/mmdebug.h>
#include <linux/sched/signal.h>
#include <linux/rmap.h>
#include <linux/string_helpers.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/jhash.h>
#include <linux/numa.h>
#include <linux/llist.h>
#include <linux/cma.h>
#include <linux/migrate.h>
#include <linux/nospec.h>
#include <linux/delayacct.h>
#include <linux/memory.h>
#include <linux/mm_inline.h>
#include <linux/padata.h>

#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>

#include <linux/io.h>
#include <linux/hugetlb.h>
#include <linux/hugetlb_cgroup.h>
#include <linux/node.h>
#include <linux/page_owner.h>
#include "internal.h"
#include "hugetlb_vmemmap.h"

int hugetlb_max_hstate __read_mostly;
unsigned int default_hstate_idx;
struct hstate hstates[HUGE_MAX_HSTATE];

#ifdef CONFIG_CMA
static struct cma *hugetlb_cma[MAX_NUMNODES];
static unsigned long hugetlb_cma_size_in_node[MAX_NUMNODES] __initdata;
static bool hugetlb_cma_folio(struct folio *folio, unsigned int order)
{
	return cma_pages_valid(hugetlb_cma[folio_nid(folio)], &folio->page,
				1 << order);
}
#else
static bool hugetlb_cma_folio(struct folio *folio, unsigned int order)
{
	return false;
}
#endif
static unsigned long hugetlb_cma_size __initdata;

__initdata struct list_head huge_boot_pages[MAX_NUMNODES];

/* for command line parsing */
static struct hstate * __initdata parsed_hstate;
static unsigned long __initdata default_hstate_max_huge_pages;
static bool __initdata parsed_valid_hugepagesz = true;
static bool __initdata parsed_default_hugepagesz;
static unsigned int default_hugepages_in_node[MAX_NUMNODES] __initdata;

/*
 * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages,
 * free_huge_pages, and surplus_huge_pages.
 */
DEFINE_SPINLOCK(hugetlb_lock);

/*
 * Serializes faults on the same logical page.  This is used to
 * prevent spurious OOMs when the hugepage pool is fully utilized.
 */
static int num_fault_mutexes;
struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp;

/* Forward declaration */
static int hugetlb_acct_memory(struct hstate *h, long delta);
static void hugetlb_vma_lock_free(struct vm_area_struct *vma);
static void hugetlb_vma_lock_alloc(struct vm_area_struct *vma);
static void __hugetlb_vma_unlock_write_free(struct vm_area_struct *vma);
static void hugetlb_unshare_pmds(struct vm_area_struct *vma,
		unsigned long start, unsigned long end);
static struct resv_map *vma_resv_map(struct vm_area_struct *vma);

static inline bool subpool_is_free(struct hugepage_subpool *spool)
{
	if (spool->count)
		return false;
	if (spool->max_hpages != -1)
		return spool->used_hpages == 0;
	if (spool->min_hpages != -1)
		return spool->rsv_hpages == spool->min_hpages;

	return true;
}

static inline void unlock_or_release_subpool(struct hugepage_subpool *spool,
						unsigned long irq_flags)
{
	spin_unlock_irqrestore(&spool->lock, irq_flags);

	/* If no pages are used, and no other handles to the subpool
	 * remain, give up any reservations based on minimum size and
	 * free the subpool */
	if (subpool_is_free(spool)) {
		if (spool->min_hpages != -1)
			hugetlb_acct_memory(spool->hstate,
						-spool->min_hpages);
		kfree(spool);
	}
}

struct hugepage_subpool *hugepage_new_subpool(struct hstate *h, long max_hpages,
						long min_hpages)
{
	struct hugepage_subpool *spool;

	spool = kzalloc(sizeof(*spool), GFP_KERNEL);
	if (!spool)
		return NULL;

	spin_lock_init(&spool->lock);
	spool->count = 1;
	spool->max_hpages = max_hpages;
	spool->hstate = h;
	spool->min_hpages = min_hpages;

	if (min_hpages != -1 && hugetlb_acct_memory(h, min_hpages)) {
		kfree(spool);
		return NULL;
	}
	spool->rsv_hpages = min_hpages;

	return spool;
}

void hugepage_put_subpool(struct hugepage_subpool *spool)
{
	unsigned long flags;

	spin_lock_irqsave(&spool->lock, flags);
	BUG_ON(!spool->count);
	spool->count--;
	unlock_or_release_subpool(spool, flags);
}

/*
 * Subpool accounting for allocating and reserving pages.
 * Return -ENOMEM if there are not enough resources to satisfy the
 * request.  Otherwise, return the number of pages by which the
 * global pools must be adjusted (upward).  The returned value may
 * only be different than the passed value (delta) in the case where
 * a subpool minimum size must be maintained.
 */
static long hugepage_subpool_get_pages(struct hugepage_subpool *spool,
				      long delta)
{
	long ret = delta;

	if (!spool)
		return ret;

	spin_lock_irq(&spool->lock);

	if (spool->max_hpages != -1) {		/* maximum size accounting */
		if ((spool->used_hpages + delta) <= spool->max_hpages)
			spool->used_hpages += delta;
		else {
			ret = -ENOMEM;
			goto unlock_ret;
		}
	}

	/* minimum size accounting */
	if (spool->min_hpages != -1 && spool->rsv_hpages) {
		if (delta > spool->rsv_hpages) {
			/*
			 * Asking for more reserves than those already taken on
			 * behalf of subpool.  Return difference.
			 */
			ret = delta - spool->rsv_hpages;
			spool->rsv_hpages = 0;
		} else {
			ret = 0;	/* reserves already accounted for */
			spool->rsv_hpages -= delta;
		}
	}

unlock_ret:
	spin_unlock_irq(&spool->lock);
	return ret;
}

/*
 * Subpool accounting for freeing and unreserving pages.
 * Return the number of global page reservations that must be dropped.
 * The return value may only be different than the passed value (delta)
 * in the case where a subpool minimum size must be maintained.
 */
static long hugepage_subpool_put_pages(struct hugepage_subpool *spool,
				       long delta)
{
	long ret = delta;
	unsigned long flags;

	if (!spool)
		return delta;

	spin_lock_irqsave(&spool->lock, flags);

	if (spool->max_hpages != -1)		/* maximum size accounting */
		spool->used_hpages -= delta;

	 /* minimum size accounting */
	if (spool->min_hpages != -1 && spool->used_hpages < spool->min_hpages) {
		if (spool->rsv_hpages + delta <= spool->min_hpages)
			ret = 0;
		else
			ret = spool->rsv_hpages + delta - spool->min_hpages;

		spool->rsv_hpages += delta;
		if (spool->rsv_hpages > spool->min_hpages)
			spool->rsv_hpages = spool->min_hpages;
	}

	/*
	 * If hugetlbfs_put_super couldn't free spool due to an outstanding
	 * quota reference, free it now.
	 */
	unlock_or_release_subpool(spool, flags);

	return ret;
}

static inline struct hugepage_subpool *subpool_inode(struct inode *inode)
{
	return HUGETLBFS_SB(inode->i_sb)->spool;
}

static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma)
{
	return subpool_inode(file_inode(vma->vm_file));
}

/*
 * hugetlb vma_lock helper routines
 */
void hugetlb_vma_lock_read(struct vm_area_struct *vma)
{
	if (__vma_shareable_lock(vma)) {
		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;

		down_read(&vma_lock->rw_sema);
	} else if (__vma_private_lock(vma)) {
		struct resv_map *resv_map = vma_resv_map(vma);

		down_read(&resv_map->rw_sema);
	}
}

void hugetlb_vma_unlock_read(struct vm_area_struct *vma)
{
	if (__vma_shareable_lock(vma)) {
		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;

		up_read(&vma_lock->rw_sema);
	} else if (__vma_private_lock(vma)) {
		struct resv_map *resv_map = vma_resv_map(vma);

		up_read(&resv_map->rw_sema);
	}
}

void hugetlb_vma_lock_write(struct vm_area_struct *vma)
{
	if (__vma_shareable_lock(vma)) {
		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;

		down_write(&vma_lock->rw_sema);
	} else if (__vma_private_lock(vma)) {
		struct resv_map *resv_map = vma_resv_map(vma);

		down_write(&resv_map->rw_sema);
	}
}

void hugetlb_vma_unlock_write(struct vm_area_struct *vma)
{
	if (__vma_shareable_lock(vma)) {
		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;

		up_write(&vma_lock->rw_sema);
	} else if (__vma_private_lock(vma)) {
		struct resv_map *resv_map = vma_resv_map(vma);

		up_write(&resv_map->rw_sema);
	}
}

int hugetlb_vma_trylock_write(struct vm_area_struct *vma)
{

	if (__vma_shareable_lock(vma)) {
		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;

		return down_write_trylock(&vma_lock->rw_sema);
	} else if (__vma_private_lock(vma)) {
		struct resv_map *resv_map = vma_resv_map(vma);

		return down_write_trylock(&resv_map->rw_sema);
	}

	return 1;
}

void hugetlb_vma_assert_locked(struct vm_area_struct *vma)
{
	if (__vma_shareable_lock(vma)) {
		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;

		lockdep_assert_held(&vma_lock->rw_sema);
	} else if (__vma_private_lock(vma)) {
		struct resv_map *resv_map = vma_resv_map(vma);

		lockdep_assert_held(&resv_map->rw_sema);
	}
}

void hugetlb_vma_lock_release(struct kref *kref)
{
	struct hugetlb_vma_lock *vma_lock = container_of(kref,
			struct hugetlb_vma_lock, refs);

	kfree(vma_lock);
}

static void __hugetlb_vma_unlock_write_put(struct hugetlb_vma_lock *vma_lock)
{
	struct vm_area_struct *vma = vma_lock->vma;

	/*
	 * vma_lock structure may or not be released as a result of put,
	 * it certainly will no longer be attached to vma so clear pointer.
	 * Semaphore synchronizes access to vma_lock->vma field.
	 */
	vma_lock->vma = NULL;
	vma->vm_private_data = NULL;
	up_write(&vma_lock->rw_sema);
	kref_put(&vma_lock->refs, hugetlb_vma_lock_release);
}

static void __hugetlb_vma_unlock_write_free(struct vm_area_struct *vma)
{
	if (__vma_shareable_lock(vma)) {
		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;

		__hugetlb_vma_unlock_write_put(vma_lock);
	} else if (__vma_private_lock(vma)) {
		struct resv_map *resv_map = vma_resv_map(vma);

		/* no free for anon vmas, but still need to unlock */
		up_write(&resv_map->rw_sema);
	}
}

static void hugetlb_vma_lock_free(struct vm_area_struct *vma)
{
	/*
	 * Only present in sharable vmas.
	 */
	if (!vma || !__vma_shareable_lock(vma))
		return;

	if (vma->vm_private_data) {
		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;

		down_write(&vma_lock->rw_sema);
		__hugetlb_vma_unlock_write_put(vma_lock);
	}
}

static void hugetlb_vma_lock_alloc(struct vm_area_struct *vma)
{
	struct hugetlb_vma_lock *vma_lock;

	/* Only establish in (flags) sharable vmas */
	if (!vma || !(vma->vm_flags & VM_MAYSHARE))
		return;

	/* Should never get here with non-NULL vm_private_data */
	if (vma->vm_private_data)
		return;

	vma_lock = kmalloc(sizeof(*vma_lock), GFP_KERNEL);
	if (!vma_lock) {
		/*
		 * If we can not allocate structure, then vma can not
		 * participate in pmd sharing.  This is only a possible
		 * performance enhancement and memory saving issue.
		 * However, the lock is also used to synchronize page
		 * faults with truncation.  If the lock is not present,
		 * unlikely races could leave pages in a file past i_size
		 * until the file is removed.  Warn in the unlikely case of
		 * allocation failure.
		 */
		pr_warn_once("HugeTLB: unable to allocate vma specific lock\n");
		return;
	}

	kref_init(&vma_lock->refs);
	init_rwsem(&vma_lock->rw_sema);
	vma_lock->vma = vma;
	vma->vm_private_data = vma_lock;
}

/* Helper that removes a struct file_region from the resv_map cache and returns
 * it for use.
 */
static struct file_region *
get_file_region_entry_from_cache(struct resv_map *resv, long from, long to)
{
	struct file_region *nrg;

	VM_BUG_ON(resv->region_cache_count <= 0);

	resv->region_cache_count--;
	nrg = list_first_entry(&resv->region_cache, struct file_region, link);
	list_del(&nrg->link);

	nrg->from = from;
	nrg->to = to;

	return nrg;
}

static void copy_hugetlb_cgroup_uncharge_info(struct file_region *nrg,
					      struct file_region *rg)
{
#ifdef CONFIG_CGROUP_HUGETLB
	nrg->reservation_counter = rg->reservation_counter;
	nrg->css = rg->css;
	if (rg->css)
		css_get(rg->css);
#endif
}

/* Helper that records hugetlb_cgroup uncharge info. */
static void record_hugetlb_cgroup_uncharge_info(struct hugetlb_cgroup *h_cg,
						struct hstate *h,
						struct resv_map *resv,
						struct file_region *nrg)
{
#ifdef CONFIG_CGROUP_HUGETLB
	if (h_cg) {
		nrg->reservation_counter =
			&h_cg->rsvd_hugepage[hstate_index(h)];
		nrg->css = &h_cg->css;
		/*
		 * The caller will hold exactly one h_cg->css reference for the
		 * whole contiguous reservation region. But this area might be
		 * scattered when there are already some file_regions reside in
		 * it. As a result, many file_regions may share only one css
		 * reference. In order to ensure that one file_region must hold
		 * exactly one h_cg->css reference, we should do css_get for
		 * each file_region and leave the reference held by caller
		 * untouched.
		 */
		css_get(&h_cg->css);
		if (!resv->pages_per_hpage)
			resv->pages_per_hpage = pages_per_huge_page(h);
		/* pages_per_hpage should be the same for all entries in
		 * a resv_map.
		 */
		VM_BUG_ON(resv->pages_per_hpage != pages_per_huge_page(h));
	} else {
		nrg->reservation_counter = NULL;
		nrg->css = NULL;
	}
#endif
}

static void put_uncharge_info(struct file_region *rg)
{
#ifdef CONFIG_CGROUP_HUGETLB
	if (rg->css)
		css_put(rg->css);
#endif
}

static bool has_same_uncharge_info(struct file_region *rg,
				   struct file_region *org)
{
#ifdef CONFIG_CGROUP_HUGETLB
	return rg->reservation_counter == org->reservation_counter &&
	       rg->css == org->css;

#else
	return true;
#endif
}

static void coalesce_file_region(struct resv_map *resv, struct file_region *rg)
{
	struct file_region *nrg, *prg;

	prg = list_prev_entry(rg, link);
	if (&prg->link != &resv->regions && prg->to == rg->from &&
	    has_same_uncharge_info(prg, rg)) {
		prg->to = rg->to;

		list_del(&rg->link);
		put_uncharge_info(rg);
		kfree(rg);

		rg = prg;
	}

	nrg = list_next_entry(rg, link);
	if (&nrg->link != &resv->regions && nrg->from == rg->to &&
	    has_same_uncharge_info(nrg, rg)) {
		nrg->from = rg->from;

		list_del(&rg->link);
		put_uncharge_info(rg);
		kfree(rg);
	}
}

static inline long
hugetlb_resv_map_add(struct resv_map *map, struct list_head *rg, long from,
		     long to, struct hstate *h, struct hugetlb_cgroup *cg,
		     long *regions_needed)
{
	struct file_region *nrg;

	if (!regions_needed) {
		nrg = get_file_region_entry_from_cache(map, from, to);
		record_hugetlb_cgroup_uncharge_info(cg, h, map, nrg);
		list_add(&nrg->link, rg);
		coalesce_file_region(map, nrg);
	} else
		*regions_needed += 1;

	return to - from;
}

/*
 * Must be called with resv->lock held.
 *
 * Calling this with regions_needed != NULL will count the number of pages
 * to be added but will not modify the linked list. And regions_needed will
 * indicate the number of file_regions needed in the cache to carry out to add
 * the regions for this range.
 */
static long add_reservation_in_range(struct resv_map *resv, long f, long t,
				     struct hugetlb_cgroup *h_cg,
				     struct hstate *h, long *regions_needed)
{
	long add = 0;
	struct list_head *head = &resv->regions;
	long last_accounted_offset = f;
	struct file_region *iter, *trg = NULL;
	struct list_head *rg = NULL;

	if (regions_needed)
		*regions_needed = 0;

	/* In this loop, we essentially handle an entry for the range
	 * [last_accounted_offset, iter->from), at every iteration, with some
	 * bounds checking.
	 */
	list_for_each_entry_safe(iter, trg, head, link) {
		/* Skip irrelevant regions that start before our range. */
		if (iter->from < f) {
			/* If this region ends after the last accounted offset,
			 * then we need to update last_accounted_offset.
			 */
			if (iter->to > last_accounted_offset)
				last_accounted_offset = iter->to;
			continue;
		}

		/* When we find a region that starts beyond our range, we've
		 * finished.
		 */
		if (iter->from >= t) {
			rg = iter->link.prev;
			break;
		}

		/* Add an entry for last_accounted_offset -> iter->from, and
		 * update last_accounted_offset.
		 */
		if (iter->from > last_accounted_offset)
			add += hugetlb_resv_map_add(resv, iter->link.prev,
						    last_accounted_offset,
						    iter->from, h, h_cg,
						    regions_needed);

		last_accounted_offset = iter->to;
	}

	/* Handle the case where our range extends beyond
	 * last_accounted_offset.
	 */
	if (!rg)
		rg = head->prev;
	if (last_accounted_offset < t)
		add += hugetlb_resv_map_add(resv, rg, last_accounted_offset,
					    t, h, h_cg, regions_needed);

	return add;
}

/* Must be called with resv->lock acquired. Will drop lock to allocate entries.
 */
static int allocate_file_region_entries(struct resv_map *resv,
					int regions_needed)
	__must_hold(&resv->lock)
{
	LIST_HEAD(allocated_regions);
	int to_allocate = 0, i = 0;
	struct file_region *trg = NULL, *rg = NULL;

	VM_BUG_ON(regions_needed < 0);

	/*
	 * Check for sufficient descriptors in the cache to accommodate
	 * the number of in progress add operations plus regions_needed.
	 *
	 * This is a while loop because when we drop the lock, some other call
	 * to region_add or region_del may have consumed some region_entries,
	 * so we keep looping here until we finally have enough entries for
	 * (adds_in_progress + regions_needed).
	 */
	while (resv->region_cache_count <
	       (resv->adds_in_progress + regions_needed)) {
		to_allocate = resv->adds_in_progress + regions_needed -
			      resv->region_cache_count;

		/* At this point, we should have enough entries in the cache
		 * for all the existing adds_in_progress. We should only be
		 * needing to allocate for regions_needed.
		 */
		VM_BUG_ON(resv->region_cache_count < resv->adds_in_progress);

		spin_unlock(&resv->lock);
		for (i = 0; i < to_allocate; i++) {
			trg = kmalloc(sizeof(*trg), GFP_KERNEL);
			if (!trg)
				goto out_of_memory;
			list_add(&trg->link, &allocated_regions);
		}

		spin_lock(&resv->lock);

		list_splice(&allocated_regions, &resv->region_cache);
		resv->region_cache_count += to_allocate;
	}

	return 0;

out_of_memory:
	list_for_each_entry_safe(rg, trg, &allocated_regions, link) {
		list_del(&rg->link);
		kfree(rg);
	}
	return -ENOMEM;
}

/*
 * Add the huge page range represented by [f, t) to the reserve
 * map.  Regions will be taken from the cache to fill in this range.
 * Sufficient regions should exist in the cache due to the previous
 * call to region_chg with the same range, but in some cases the cache will not
 * have sufficient entries due to races with other code doing region_add or
 * region_del.  The extra needed entries will be allocated.
 *
 * regions_needed is the out value provided by a previous call to region_chg.
 *
 * Return the number of new huge pages added to the map.  This number is greater
 * than or equal to zero.  If file_region entries needed to be allocated for
 * this operation and we were not able to allocate, it returns -ENOMEM.
 * region_add of regions of length 1 never allocate file_regions and cannot
 * fail; region_chg will always allocate at least 1 entry and a region_add for
 * 1 page will only require at most 1 entry.
 */
static long region_add(struct resv_map *resv, long f, long t,
		       long in_regions_needed, struct hstate *h,
		       struct hugetlb_cgroup *h_cg)
{
	long add = 0, actual_regions_needed = 0;

	spin_lock(&resv->lock);
retry:

	/* Count how many regions are actually needed to execute this add. */
	add_reservation_in_range(resv, f, t, NULL, NULL,
				 &actual_regions_needed);

	/*
	 * Check for sufficient descriptors in the cache to accommodate
	 * this add operation. Note that actual_regions_needed may be greater
	 * than in_regions_needed, as the resv_map may have been modified since
	 * the region_chg call. In this case, we need to make sure that we
	 * allocate extra entries, such that we have enough for all the
	 * existing adds_in_progress, plus the excess needed for this
	 * operation.
	 */
	if (actual_regions_needed > in_regions_needed &&
	    resv->region_cache_count <
		    resv->adds_in_progress +
			    (actual_regions_needed - in_regions_needed)) {
		/* region_add operation of range 1 should never need to
		 * allocate file_region entries.
		 */
		VM_BUG_ON(t - f <= 1);

		if (allocate_file_region_entries(
			    resv, actual_regions_needed - in_regions_needed)) {
			return -ENOMEM;
		}

		goto retry;
	}

	add = add_reservation_in_range(resv, f, t, h_cg, h, NULL);

	resv->adds_in_progress -= in_regions_needed;

	spin_unlock(&resv->lock);
	return add;
}

/*
 * Examine the existing reserve map and determine how many
 * huge pages in the specified range [f, t) are NOT currently
 * represented.  This routine is called before a subsequent
 * call to region_add that will actually modify the reserve
 * map to add the specified range [f, t).  region_chg does
 * not change the number of huge pages represented by the
 * map.  A number of new file_region structures is added to the cache as a
 * placeholder, for the subsequent region_add call to use. At least 1
 * file_region structure is added.
 *
 * out_regions_needed is the number of regions added to the
 * resv->adds_in_progress.  This value needs to be provided to a follow up call
 * to region_add or region_abort for proper accounting.
 *
 * Returns the number of huge pages that need to be added to the existing
 * reservation map for the range [f, t).  This number is greater or equal to
 * zero.  -ENOMEM is returned if a new file_region structure or cache entry
 * is needed and can not be allocated.
 */
static long region_chg(struct resv_map *resv, long f, long t,
		       long *out_regions_needed)
{
	long chg = 0;

	spin_lock(&resv->lock);

	/* Count how many hugepages in this range are NOT represented. */
	chg = add_reservation_in_range(resv, f, t, NULL, NULL,
				       out_regions_needed);

	if (*out_regions_needed == 0)
		*out_regions_needed = 1;

	if (allocate_file_region_entries(resv, *out_regions_needed))
		return -ENOMEM;

	resv->adds_in_progress += *out_regions_needed;

	spin_unlock(&resv->lock);
	return chg;
}

/*
 * Abort the in progress add operation.  The adds_in_progress field
 * of the resv_map keeps track of the operations in progress between
 * calls to region_chg and region_add.  Operations are sometimes
 * aborted after the call to region_chg.  In such cases, region_abort
 * is called to decrement the adds_in_progress counter. regions_needed
 * is the value returned by the region_chg call, it is used to decrement
 * the adds_in_progress counter.
 *
 * NOTE: The range arguments [f, t) are not needed or used in this
 * routine.  They are kept to make reading the calling code easier as
 * arguments will match the associated region_chg call.
 */
static void region_abort(struct resv_map *resv, long f, long t,
			 long regions_needed)
{
	spin_lock(&resv->lock);
	VM_BUG_ON(!resv->region_cache_count);
	resv->adds_in_progress -= regions_needed;
	spin_unlock(&resv->lock);
}

/*
 * Delete the specified range [f, t) from the reserve map.  If the
 * t parameter is LONG_MAX, this indicates that ALL regions after f
 * should be deleted.  Locate the regions which intersect [f, t)
 * and either trim, delete or split the existing regions.
 *
 * Returns the number of huge pages deleted from the reserve map.
 * In the normal case, the return value is zero or more.  In the
 * case where a region must be split, a new region descriptor must
 * be allocated.  If the allocation fails, -ENOMEM will be returned.
 * NOTE: If the parameter t == LONG_MAX, then we will never split
 * a region and possibly return -ENOMEM.  Callers specifying
 * t == LONG_MAX do not need to check for -ENOMEM error.
 */
static long region_del(struct resv_map *resv, long f, long t)
{
	struct list_head *head = &resv->regions;
	struct file_region *rg, *trg;
	struct file_region *nrg = NULL;
	long del = 0;

retry:
	spin_lock(&resv->lock);
	list_for_each_entry_safe(rg, trg, head, link) {
		/*
		 * Skip regions before the range to be deleted.  file_region
		 * ranges are normally of the form [from, to).  However, there
		 * may be a "placeholder" entry in the map which is of the form
		 * (from, to) with from == to.  Check for placeholder entries
		 * at the beginning of the range to be deleted.
		 */
		if (rg->to <= f && (rg->to != rg->from || rg->to != f))
			continue;

		if (rg->from >= t)
			break;

		if (f > rg->from && t < rg->to) { /* Must split region */
			/*
			 * Check for an entry in the cache before dropping
			 * lock and attempting allocation.
			 */
			if (!nrg &&
			    resv->region_cache_count > resv->adds_in_progress) {
				nrg = list_first_entry(&resv->region_cache,
							struct file_region,
							link);
				list_del(&nrg->link);
				resv->region_cache_count--;
			}

			if (!nrg) {
				spin_unlock(&resv->lock);
				nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
				if (!nrg)
					return -ENOMEM;
				goto retry;
			}

			del += t - f;
			hugetlb_cgroup_uncharge_file_region(
				resv, rg, t - f, false);

			/* New entry for end of split region */
			nrg->from = t;
			nrg->to = rg->to;

			copy_hugetlb_cgroup_uncharge_info(nrg, rg);

			INIT_LIST_HEAD(&nrg->link);

			/* Original entry is trimmed */
			rg->to = f;

			list_add(&nrg->link, &rg->link);
			nrg = NULL;
			break;
		}

		if (f <= rg->from && t >= rg->to) { /* Remove entire region */
			del += rg->to - rg->from;
			hugetlb_cgroup_uncharge_file_region(resv, rg,
							    rg->to - rg->from, true);
			list_del(&rg->link);
			kfree(rg);
			continue;
		}

		if (f <= rg->from) {	/* Trim beginning of region */
			hugetlb_cgroup_uncharge_file_region(resv, rg,
							    t - rg->from, false);

			del += t - rg->from;
			rg->from = t;
		} else {		/* Trim end of region */
			hugetlb_cgroup_uncharge_file_region(resv, rg,
							    rg->to - f, false);

			del += rg->to - f;
			rg->to = f;
		}
	}

	spin_unlock(&resv->lock);
	kfree(nrg);
	return del;
}

/*
 * A rare out of memory error was encountered which prevented removal of
 * the reserve map region for a page.  The huge page itself was free'ed
 * and removed from the page cache.  This routine will adjust the subpool
 * usage count, and the global reserve count if needed.  By incrementing
 * these counts, the reserve map entry which could not be deleted will
 * appear as a "reserved" entry instead of simply dangling with incorrect
 * counts.
 */
void hugetlb_fix_reserve_counts(struct inode *inode)
{
	struct hugepage_subpool *spool = subpool_inode(inode);
	long rsv_adjust;
	bool reserved = false;

	rsv_adjust = hugepage_subpool_get_pages(spool, 1);
	if (rsv_adjust > 0) {
		struct hstate *h = hstate_inode(inode);

		if (!hugetlb_acct_memory(h, 1))
			reserved = true;
	} else if (!rsv_adjust) {
		reserved = true;
	}

	if (!reserved)
		pr_warn("hugetlb: Huge Page Reserved count may go negative.\n");
}

/*
 * Count and return the number of huge pages in the reserve map
 * that intersect with the range [f, t).
 */
static long region_count(struct resv_map *resv, long f, long t)
{
	struct list_head *head = &resv->regions;
	struct file_region *rg;
	long chg = 0;

	spin_lock(&resv->lock);
	/* Locate each segment we overlap with, and count that overlap. */
	list_for_each_entry(rg, head, link) {
		long seg_from;
		long seg_to;

		if (rg->to <= f)
			continue;
		if (rg->from >= t)
			break;

		seg_from = max(rg->from, f);
		seg_to = min(rg->to, t);

		chg += seg_to - seg_from;
	}
	spin_unlock(&resv->lock);

	return chg;
}

/*
 * Convert the address within this vma to the page offset within
 * the mapping, huge page units here.
 */
static pgoff_t vma_hugecache_offset(struct hstate *h,
			struct vm_area_struct *vma, unsigned long address)
{
	return ((address - vma->vm_start) >> huge_page_shift(h)) +
			(vma->vm_pgoff >> huge_page_order(h));
}

/**
 * vma_kernel_pagesize - Page size granularity for this VMA.
 * @vma: The user mapping.
 *
 * Folios in this VMA will be aligned to, and at least the size of the
 * number of bytes returned by this function.
 *
 * Return: The default size of the folios allocated when backing a VMA.
 */
unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
{
	if (vma->vm_ops && vma->vm_ops->pagesize)
		return vma->vm_ops->pagesize(vma);
	return PAGE_SIZE;
}
EXPORT_SYMBOL_GPL(vma_kernel_pagesize);

/*
 * Return the page size being used by the MMU to back a VMA. In the majority
 * of cases, the page size used by the kernel matches the MMU size. On
 * architectures where it differs, an architecture-specific 'strong'
 * version of this symbol is required.
 */
__weak unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
{
	return vma_kernel_pagesize(vma);
}

/*
 * Flags for MAP_PRIVATE reservations.  These are stored in the bottom
 * bits of the reservation map pointer, which are always clear due to
 * alignment.
 */
#define HPAGE_RESV_OWNER    (1UL << 0)
#define HPAGE_RESV_UNMAPPED (1UL << 1)
#define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)

/*
 * These helpers are used to track how many pages are reserved for
 * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
 * is guaranteed to have their future faults succeed.
 *
 * With the exception of hugetlb_dup_vma_private() which is called at fork(),
 * the reserve counters are updated with the hugetlb_lock held. It is safe
 * to reset the VMA at fork() time as it is not in use yet and there is no
 * chance of the global counters getting corrupted as a result of the values.
 *
 * The private mapping reservation is represented in a subtly different
 * manner to a shared mapping.  A shared mapping has a region map associated
 * with the underlying file, this region map represents the backing file
 * pages which have ever had a reservation assigned which this persists even
 * after the page is instantiated.  A private mapping has a region map
 * associated with the original mmap which is attached to all VMAs which
 * reference it, this region map represents those offsets which have consumed
 * reservation ie. where pages have been instantiated.
 */
static unsigned long get_vma_private_data(struct vm_area_struct *vma)
{
	return (unsigned long)vma->vm_private_data;
}

static void set_vma_private_data(struct vm_area_struct *vma,
							unsigned long value)
{
	vma->vm_private_data = (void *)value;
}

static void
resv_map_set_hugetlb_cgroup_uncharge_info(struct resv_map *resv_map,
					  struct hugetlb_cgroup *h_cg,
					  struct hstate *h)
{
#ifdef CONFIG_CGROUP_HUGETLB
	if (!h_cg || !h) {
		resv_map->reservation_counter = NULL;
		resv_map->pages_per_hpage = 0;
		resv_map->css = NULL;
	} else {
		resv_map->reservation_counter =
			&h_cg->rsvd_hugepage[hstate_index(h)];
		resv_map->pages_per_hpage = pages_per_huge_page(h);
		resv_map->css = &h_cg->css;
	}
#endif
}

struct resv_map *resv_map_alloc(void)
{
	struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
	struct file_region *rg = kmalloc(sizeof(*rg), GFP_KERNEL);

	if (!resv_map || !rg) {
		kfree(resv_map);
		kfree(rg);
		return NULL;
	}

	kref_init(&resv_map->refs);
	spin_lock_init(&resv_map->lock);
	INIT_LIST_HEAD(&resv_map->regions);
	init_rwsem(&resv_map->rw_sema);

	resv_map->adds_in_progress = 0;
	/*
	 * Initialize these to 0. On shared mappings, 0's here indicate these
	 * fields don't do cgroup accounting. On private mappings, these will be
	 * re-initialized to the proper values, to indicate that hugetlb cgroup
	 * reservations are to be un-charged from here.
	 */
	resv_map_set_hugetlb_cgroup_uncharge_info(resv_map, NULL, NULL);

	INIT_LIST_HEAD(&resv_map->region_cache);
	list_add(&rg->link, &resv_map->region_cache);
	resv_map->region_cache_count = 1;

	return resv_map;
}

void resv_map_release(struct kref *ref)
{
	struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
	struct list_head *head = &resv_map->region_cache;
	struct file_region *rg, *trg;

	/* Clear out any active regions before we release the map. */
	region_del(resv_map, 0, LONG_MAX);

	/* ... and any entries left in the cache */
	list_for_each_entry_safe(rg, trg, head, link) {
		list_del(&rg->link);
		kfree(rg);
	}

	VM_BUG_ON(resv_map->adds_in_progress);

	kfree(resv_map);
}

static inline struct resv_map *inode_resv_map(struct inode *inode)
{
	/*
	 * At inode evict time, i_mapping may not point to the original
	 * address space within the inode.  This original address space
	 * contains the pointer to the resv_map.  So, always use the
	 * address space embedded within the inode.
	 * The VERY common case is inode->mapping == &inode->i_data but,
	 * this may not be true for device special inodes.
	 */
	return (struct resv_map *)(&inode->i_data)->i_private_data;
}

static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
{
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
	if (vma->vm_flags & VM_MAYSHARE) {
		struct address_space *mapping = vma->vm_file->f_mapping;
		struct inode *inode = mapping->host;

		return inode_resv_map(inode);

	} else {
		return (struct resv_map *)(get_vma_private_data(vma) &
							~HPAGE_RESV_MASK);
	}
}

static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
{
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
	VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);

	set_vma_private_data(vma, (unsigned long)map);
}

static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
{
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
	VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);

	set_vma_private_data(vma, get_vma_private_data(vma) | flags);
}

static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
{
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);

	return (get_vma_private_data(vma) & flag) != 0;
}

bool __vma_private_lock(struct vm_area_struct *vma)
{
	return !(vma->vm_flags & VM_MAYSHARE) &&
		get_vma_private_data(vma) & ~HPAGE_RESV_MASK &&
		is_vma_resv_set(vma, HPAGE_RESV_OWNER);
}

void hugetlb_dup_vma_private(struct vm_area_struct *vma)
{
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
	/*
	 * Clear vm_private_data
	 * - For shared mappings this is a per-vma semaphore that may be
	 *   allocated in a subsequent call to hugetlb_vm_op_open.
	 *   Before clearing, make sure pointer is not associated with vma
	 *   as this will leak the structure.  This is the case when called
	 *   via clear_vma_resv_huge_pages() and hugetlb_vm_op_open has already
	 *   been called to allocate a new structure.
	 * - For MAP_PRIVATE mappings, this is the reserve map which does
	 *   not apply to children.  Faults generated by the children are
	 *   not guaranteed to succeed, even if read-only.
	 */
	if (vma->vm_flags & VM_MAYSHARE) {
		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;

		if (vma_lock && vma_lock->vma != vma)
			vma->vm_private_data = NULL;
	} else
		vma->vm_private_data = NULL;
}

/*
 * Reset and decrement one ref on hugepage private reservation.
 * Called with mm->mmap_lock writer semaphore held.
 * This function should be only used by move_vma() and operate on
 * same sized vma. It should never come here with last ref on the
 * reservation.
 */
void clear_vma_resv_huge_pages(struct vm_area_struct *vma)
{
	/*
	 * Clear the old hugetlb private page reservation.
	 * It has already been transferred to new_vma.
	 *
	 * During a mremap() operation of a hugetlb vma we call move_vma()
	 * which copies vma into new_vma and unmaps vma. After the copy
	 * operation both new_vma and vma share a reference to the resv_map
	 * struct, and at that point vma is about to be unmapped. We don't
	 * want to return the reservation to the pool at unmap of vma because
	 * the reservation still lives on in new_vma, so simply decrement the
	 * ref here and remove the resv_map reference from this vma.
	 */
	struct resv_map *reservations = vma_resv_map(vma);

	if (reservations && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
		resv_map_put_hugetlb_cgroup_uncharge_info(reservations);
		kref_put(&reservations->refs, resv_map_release);
	}

	hugetlb_dup_vma_private(vma);
}

/* Returns true if the VMA has associated reserve pages */
static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
{
	if (vma->vm_flags & VM_NORESERVE) {
		/*
		 * This address is already reserved by other process(chg == 0),
		 * so, we should decrement reserved count. Without decrementing,
		 * reserve count remains after releasing inode, because this
		 * allocated page will go into page cache and is regarded as
		 * coming from reserved pool in releasing step.  Currently, we
		 * don't have any other solution to deal with this situation
		 * properly, so add work-around here.
		 */
		if (vma->vm_flags & VM_MAYSHARE && chg == 0)
			return true;
		else
			return false;
	}

	/* Shared mappings always use reserves */
	if (vma->vm_flags & VM_MAYSHARE) {
		/*
		 * We know VM_NORESERVE is not set.  Therefore, there SHOULD
		 * be a region map for all pages.  The only situation where
		 * there is no region map is if a hole was punched via
		 * fallocate.  In this case, there really are no reserves to
		 * use.  This situation is indicated if chg != 0.
		 */
		if (chg)
			return false;
		else
			return true;
	}

	/*
	 * Only the process that called mmap() has reserves for
	 * private mappings.
	 */
	if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
		/*
		 * Like the shared case above, a hole punch or truncate
		 * could have been performed on the private mapping.
		 * Examine the value of chg to determine if reserves
		 * actually exist or were previously consumed.
		 * Very Subtle - The value of chg comes from a previous
		 * call to vma_needs_reserves().  The reserve map for
		 * private mappings has different (opposite) semantics
		 * than that of shared mappings.  vma_needs_reserves()
		 * has already taken this difference in semantics into
		 * account.  Therefore, the meaning of chg is the same
		 * as in the shared case above.  Code could easily be
		 * combined, but keeping it separate draws attention to
		 * subtle differences.
		 */
		if (chg)
			return false;
		else
			return true;
	}

	return false;
}

static void enqueue_hugetlb_folio(struct hstate *h, struct folio *folio)
{
	int nid = folio_nid(folio);

	lockdep_assert_held(&hugetlb_lock);
	VM_BUG_ON_FOLIO(folio_ref_count(folio), folio);

	list_move(&folio->lru, &h->hugepage_freelists[nid]);
	h->free_huge_pages++;
	h->free_huge_pages_node[nid]++;
	folio_set_hugetlb_freed(folio);
}

static struct folio *dequeue_hugetlb_folio_node_exact(struct hstate *h,
								int nid)
{
	struct folio *folio;
	bool pin = !!(current->flags & PF_MEMALLOC_PIN);

	lockdep_assert_held(&hugetlb_lock);
	list_for_each_entry(folio, &h->hugepage_freelists[nid], lru) {
		if (pin && !folio_is_longterm_pinnable(folio))
			continue;

		if (folio_test_hwpoison(folio))
			continue;

		list_move(&folio->lru, &h->hugepage_activelist);
		folio_ref_unfreeze(folio, 1);
		folio_clear_hugetlb_freed(folio);
		h->free_huge_pages--;
		h->free_huge_pages_node[nid]--;
		return folio;
	}

	return NULL;
}

static struct folio *dequeue_hugetlb_folio_nodemask(struct hstate *h, gfp_t gfp_mask,
							int nid, nodemask_t *nmask)
{
	unsigned int cpuset_mems_cookie;
	struct zonelist *zonelist;
	struct zone *zone;
	struct zoneref *z;
	int node = NUMA_NO_NODE;

	/* 'nid' should not be NUMA_NO_NODE. Try to catch any misuse of it and rectifiy. */
	if (nid == NUMA_NO_NODE)
		nid = numa_node_id();

	zonelist = node_zonelist(nid, gfp_mask);

retry_cpuset:
	cpuset_mems_cookie = read_mems_allowed_begin();
	for_each_zone_zonelist_nodemask(zone, z, zonelist, gfp_zone(gfp_mask), nmask) {
		struct folio *folio;

		if (!cpuset_zone_allowed(zone, gfp_mask))
			continue;
		/*
		 * no need to ask again on the same node. Pool is node rather than
		 * zone aware
		 */
		if (zone_to_nid(zone) == node)
			continue;
		node = zone_to_nid(zone);

		folio = dequeue_hugetlb_folio_node_exact(h, node);
		if (folio)
			return folio;
	}
	if (unlikely(read_mems_allowed_retry(cpuset_mems_cookie)))
		goto retry_cpuset;

	return NULL;
}

static unsigned long available_huge_pages(struct hstate *h)
{
	return h->free_huge_pages - h->resv_huge_pages;
}

static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h,
				struct vm_area_struct *vma,
				unsigned long address, int avoid_reserve,
				long chg)
{
	struct folio *folio = NULL;
	struct mempolicy *mpol;
	gfp_t gfp_mask;
	nodemask_t *nodemask;
	int nid;

	/*
	 * A child process with MAP_PRIVATE mappings created by their parent
	 * have no page reserves. This check ensures that reservations are
	 * not "stolen". The child may still get SIGKILLed
	 */
	if (!vma_has_reserves(vma, chg) && !available_huge_pages(h))
		goto err;

	/* If reserves cannot be used, ensure enough pages are in the pool */
	if (avoid_reserve && !available_huge_pages(h))
		goto err;

	gfp_mask = htlb_alloc_mask(h);
	nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask);

	if (mpol_is_preferred_many(mpol)) {
		folio = dequeue_hugetlb_folio_nodemask(h, gfp_mask,
							nid, nodemask);

		/* Fallback to all nodes if page==NULL */
		nodemask = NULL;
	}

	if (!folio)
		folio = dequeue_hugetlb_folio_nodemask(h, gfp_mask,
							nid, nodemask);

	if (folio && !avoid_reserve && vma_has_reserves(vma, chg)) {
		folio_set_hugetlb_restore_reserve(folio);
		h->resv_huge_pages--;
	}

	mpol_cond_put(mpol);
	return folio;

err:
	return NULL;
}

/*
 * common helper functions for hstate_next_node_to_{alloc|free}.
 * We may have allocated or freed a huge page based on a different
 * nodes_allowed previously, so h->next_node_to_{alloc|free} might
 * be outside of *nodes_allowed.  Ensure that we use an allowed
 * node for alloc or free.
 */
static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
{
	nid = next_node_in(nid, *nodes_allowed);
	VM_BUG_ON(nid >= MAX_NUMNODES);

	return nid;
}

static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
{
	if (!node_isset(nid, *nodes_allowed))
		nid = next_node_allowed(nid, nodes_allowed);
	return nid;
}

/*
 * returns the previously saved node ["this node"] from which to
 * allocate a persistent huge page for the pool and advance the
 * next node from which to allocate, handling wrap at end of node
 * mask.
 */
static int hstate_next_node_to_alloc(int *next_node,
					nodemask_t *nodes_allowed)
{
	int nid;

	VM_BUG_ON(!nodes_allowed);

	nid = get_valid_node_allowed(*next_node, nodes_allowed);
	*next_node = next_node_allowed(nid, nodes_allowed);

	return nid;
}

/*
 * helper for remove_pool_hugetlb_folio() - return the previously saved
 * node ["this node"] from which to free a huge page.  Advance the
 * next node id whether or not we find a free huge page to free so
 * that the next attempt to free addresses the next node.
 */
static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
{
	int nid;

	VM_BUG_ON(!nodes_allowed);

	nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
	h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);

	return nid;
}

#define for_each_node_mask_to_alloc(next_node, nr_nodes, node, mask)		\
	for (nr_nodes = nodes_weight(*mask);				\
		nr_nodes > 0 &&						\
		((node = hstate_next_node_to_alloc(next_node, mask)) || 1);	\
		nr_nodes--)

#define for_each_node_mask_to_free(hs, nr_nodes, node, mask)		\
	for (nr_nodes = nodes_weight(*mask);				\
		nr_nodes > 0 &&						\
		((node = hstate_next_node_to_free(hs, mask)) || 1);	\
		nr_nodes--)

/* used to demote non-gigantic_huge pages as well */
static void __destroy_compound_gigantic_folio(struct folio *folio,
					unsigned int order, bool demote)
{
	int i;
	int nr_pages = 1 << order;
	struct page *p;

	atomic_set(&folio->_entire_mapcount, 0);
	atomic_set(&folio->_large_mapcount, 0);
	atomic_set(&folio->_pincount, 0);

	for (i = 1; i < nr_pages; i++) {
		p = folio_page(folio, i);
		p->flags &= ~PAGE_FLAGS_CHECK_AT_FREE;
		p->mapping = NULL;
		clear_compound_head(p);
		if (!demote)
			set_page_refcounted(p);
	}

	__folio_clear_head(folio);
}

static void destroy_compound_hugetlb_folio_for_demote(struct folio *folio,
					unsigned int order)
{
	__destroy_compound_gigantic_folio(folio, order, true);
}

#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
static void destroy_compound_gigantic_folio(struct folio *folio,
					unsigned int order)
{
	__destroy_compound_gigantic_folio(folio, order, false);
}

static void free_gigantic_folio(struct folio *folio, unsigned int order)
{
	/*
	 * If the page isn't allocated using the cma allocator,
	 * cma_release() returns false.
	 */
#ifdef CONFIG_CMA
	int nid = folio_nid(folio);

	if (cma_release(hugetlb_cma[nid], &folio->page, 1 << order))
		return;
#endif

	free_contig_range(folio_pfn(folio), 1 << order);
}

#ifdef CONFIG_CONTIG_ALLOC
static struct folio *alloc_gigantic_folio(struct hstate *h, gfp_t gfp_mask,
		int nid, nodemask_t *nodemask)
{
	struct page *page;
	unsigned long nr_pages = pages_per_huge_page(h);
	if (nid == NUMA_NO_NODE)
		nid = numa_mem_id();

#ifdef CONFIG_CMA
	{
		int node;

		if (hugetlb_cma[nid]) {
			page = cma_alloc(hugetlb_cma[nid], nr_pages,
					huge_page_order(h), true);
			if (page)
				return page_folio(page);
		}

		if (!(gfp_mask & __GFP_THISNODE)) {
			for_each_node_mask(node, *nodemask) {
				if (node == nid || !hugetlb_cma[node])
					continue;

				page = cma_alloc(hugetlb_cma[node], nr_pages,
						huge_page_order(h), true);
				if (page)
					return page_folio(page);
			}
		}
	}
#endif

	page = alloc_contig_pages(nr_pages, gfp_mask, nid, nodemask);
	return page ? page_folio(page) : NULL;
}

#else /* !CONFIG_CONTIG_ALLOC */
static struct folio *alloc_gigantic_folio(struct hstate *h, gfp_t gfp_mask,
					int nid, nodemask_t *nodemask)
{
	return NULL;
}
#endif /* CONFIG_CONTIG_ALLOC */

#else /* !CONFIG_ARCH_HAS_GIGANTIC_PAGE */
static struct folio *alloc_gigantic_folio(struct hstate *h, gfp_t gfp_mask,
					int nid, nodemask_t *nodemask)
{
	return NULL;
}
static inline void free_gigantic_folio(struct folio *folio,
						unsigned int order) { }
static inline void destroy_compound_gigantic_folio(struct folio *folio,
						unsigned int order) { }
#endif

/*
 * Remove hugetlb folio from lists.
 * If vmemmap exists for the folio, clear the hugetlb flag so that the
 * folio appears as just a compound page.  Otherwise, wait until after
 * allocating vmemmap to clear the flag.
 *
 * Must be called with hugetlb lock held.
 */
static void remove_hugetlb_folio(struct hstate *h, struct folio *folio,
							bool adjust_surplus)
{
	int nid = folio_nid(folio);

	VM_BUG_ON_FOLIO(hugetlb_cgroup_from_folio(folio), folio);
	VM_BUG_ON_FOLIO(hugetlb_cgroup_from_folio_rsvd(folio), folio);

	lockdep_assert_held(&hugetlb_lock);
	if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
		return;

	list_del(&folio->lru);

	if (folio_test_hugetlb_freed(folio)) {
		folio_clear_hugetlb_freed(folio);
		h->free_huge_pages--;
		h->free_huge_pages_node[nid]--;
	}
	if (adjust_surplus) {
		h->surplus_huge_pages--;
		h->surplus_huge_pages_node[nid]--;
	}

	/*
	 * We can only clear the hugetlb flag after allocating vmemmap
	 * pages.  Otherwise, someone (memory error handling) may try to write
	 * to tail struct pages.
	 */
	if (!folio_test_hugetlb_vmemmap_optimized(folio))
		__folio_clear_hugetlb(folio);

	h->nr_huge_pages--;
	h->nr_huge_pages_node[nid]--;
}

static void add_hugetlb_folio(struct hstate *h, struct folio *folio,
			     bool adjust_surplus)
{
	int nid = folio_nid(folio);

	VM_BUG_ON_FOLIO(!folio_test_hugetlb_vmemmap_optimized(folio), folio);

	lockdep_assert_held(&hugetlb_lock);

	INIT_LIST_HEAD(&folio->lru);
	h->nr_huge_pages++;
	h->nr_huge_pages_node[nid]++;

	if (adjust_surplus) {
		h->surplus_huge_pages++;
		h->surplus_huge_pages_node[nid]++;
	}

	__folio_set_hugetlb(folio);
	folio_change_private(folio, NULL);
	/*
	 * We have to set hugetlb_vmemmap_optimized again as above
	 * folio_change_private(folio, NULL) cleared it.
	 */
	folio_set_hugetlb_vmemmap_optimized(folio);

	arch_clear_hugetlb_flags(folio);
	enqueue_hugetlb_folio(h, folio);
}

static void __update_and_free_hugetlb_folio(struct hstate *h,
						struct folio *folio)
{
	bool clear_flag = folio_test_hugetlb_vmemmap_optimized(folio);

	if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
		return;

	/*
	 * If we don't know which subpages are hwpoisoned, we can't free
	 * the hugepage, so it's leaked intentionally.
	 */
	if (folio_test_hugetlb_raw_hwp_unreliable(folio))
		return;

	/*
	 * If folio is not vmemmap optimized (!clear_flag), then the folio
	 * is no longer identified as a hugetlb page.  hugetlb_vmemmap_restore_folio
	 * can only be passed hugetlb pages and will BUG otherwise.
	 */
	if (clear_flag && hugetlb_vmemmap_restore_folio(h, folio)) {
		spin_lock_irq(&hugetlb_lock);
		/*
		 * If we cannot allocate vmemmap pages, just refuse to free the
		 * page and put the page back on the hugetlb free list and treat
		 * as a surplus page.
		 */
		add_hugetlb_folio(h, folio, true);
		spin_unlock_irq(&hugetlb_lock);
		return;
	}

	/*
	 * If vmemmap pages were allocated above, then we need to clear the
	 * hugetlb flag under the hugetlb lock.
	 */
	if (folio_test_hugetlb(folio)) {
		spin_lock_irq(&hugetlb_lock);
		__folio_clear_hugetlb(folio);
		spin_unlock_irq(&hugetlb_lock);
	}

	/*
	 * Move PageHWPoison flag from head page to the raw error pages,
	 * which makes any healthy subpages reusable.
	 */
	if (unlikely(folio_test_hwpoison(folio)))
		folio_clear_hugetlb_hwpoison(folio);

	folio_ref_unfreeze(folio, 1);

	/*
	 * Non-gigantic pages demoted from CMA allocated gigantic pages
	 * need to be given back to CMA in free_gigantic_folio.
	 */
	if (hstate_is_gigantic(h) ||
	    hugetlb_cma_folio(folio, huge_page_order(h))) {
		destroy_compound_gigantic_folio(folio, huge_page_order(h));
		free_gigantic_folio(folio, huge_page_order(h));
	} else {
		INIT_LIST_HEAD(&folio->_deferred_list);
		folio_put(folio);
	}
}

/*
 * As update_and_free_hugetlb_folio() can be called under any context, so we cannot
 * use GFP_KERNEL to allocate vmemmap pages. However, we can defer the
 * actual freeing in a workqueue to prevent from using GFP_ATOMIC to allocate
 * the vmemmap pages.
 *
 * free_hpage_workfn() locklessly retrieves the linked list of pages to be
 * freed and frees them one-by-one. As the page->mapping pointer is going
 * to be cleared in free_hpage_workfn() anyway, it is reused as the llist_node
 * structure of a lockless linked list of huge pages to be freed.
 */
static LLIST_HEAD(hpage_freelist);

static void free_hpage_workfn(struct work_struct *work)
{
	struct llist_node *node;

	node = llist_del_all(&hpage_freelist);

	while (node) {
		struct folio *folio;
		struct hstate *h;

		folio = container_of((struct address_space **)node,
				     struct folio, mapping);
		node = node->next;
		folio->mapping = NULL;
		/*
		 * The VM_BUG_ON_FOLIO(!folio_test_hugetlb(folio), folio) in
		 * folio_hstate() is going to trigger because a previous call to
		 * remove_hugetlb_folio() will clear the hugetlb bit, so do
		 * not use folio_hstate() directly.
		 */
		h = size_to_hstate(folio_size(folio));

		__update_and_free_hugetlb_folio(h, folio);

		cond_resched();
	}
}
static DECLARE_WORK(free_hpage_work, free_hpage_workfn);

static inline void flush_free_hpage_work(struct hstate *h)
{
	if (hugetlb_vmemmap_optimizable(h))
		flush_work(&free_hpage_work);
}

static void update_and_free_hugetlb_folio(struct hstate *h, struct folio *folio,
				 bool atomic)
{
	if (!folio_test_hugetlb_vmemmap_optimized(folio) || !atomic) {
		__update_and_free_hugetlb_folio(h, folio);
		return;
	}

	/*
	 * Defer freeing to avoid using GFP_ATOMIC to allocate vmemmap pages.
	 *
	 * Only call schedule_work() if hpage_freelist is previously
	 * empty. Otherwise, schedule_work() had been called but the workfn
	 * hasn't retrieved the list yet.
	 */
	if (llist_add((struct llist_node *)&folio->mapping, &hpage_freelist))
		schedule_work(&free_hpage_work);
}

static void bulk_vmemmap_restore_error(struct hstate *h,
					struct list_head *folio_list,
					struct list_head *non_hvo_folios)
{
	struct folio *folio, *t_folio;

	if (!list_empty(non_hvo_folios)) {
		/*
		 * Free any restored hugetlb pages so that restore of the
		 * entire list can be retried.
		 * The idea is that in the common case of ENOMEM errors freeing
		 * hugetlb pages with vmemmap we will free up memory so that we
		 * can allocate vmemmap for more hugetlb pages.
		 */
		list_for_each_entry_safe(folio, t_folio, non_hvo_folios, lru) {
			list_del(&folio->lru);
			spin_lock_irq(&hugetlb_lock);
			__folio_clear_hugetlb(folio);
			spin_unlock_irq(&hugetlb_lock);
			update_and_free_hugetlb_folio(h, folio, false);
			cond_resched();
		}
	} else {
		/*
		 * In the case where there are no folios which can be
		 * immediately freed, we loop through the list trying to restore
		 * vmemmap individually in the hope that someone elsewhere may
		 * have done something to cause success (such as freeing some
		 * memory).  If unable to restore a hugetlb page, the hugetlb
		 * page is made a surplus page and removed from the list.
		 * If are able to restore vmemmap and free one hugetlb page, we
		 * quit processing the list to retry the bulk operation.
		 */
		list_for_each_entry_safe(folio, t_folio, folio_list, lru)
			if (hugetlb_vmemmap_restore_folio(h, folio)) {
				list_del(&folio->lru);
				spin_lock_irq(&hugetlb_lock);
				add_hugetlb_folio(h, folio, true);
				spin_unlock_irq(&hugetlb_lock);
			} else {
				list_del(&folio->lru);
				spin_lock_irq(&hugetlb_lock);
				__folio_clear_hugetlb(folio);
				spin_unlock_irq(&hugetlb_lock);
				update_and_free_hugetlb_folio(h, folio, false);
				cond_resched();
				break;
			}
	}
}

static void update_and_free_pages_bulk(struct hstate *h,
						struct list_head *folio_list)
{
	long ret;
	struct folio *folio, *t_folio;
	LIST_HEAD(non_hvo_folios);

	/*
	 * First allocate required vmemmmap (if necessary) for all folios.
	 * Carefully handle errors and free up any available hugetlb pages
	 * in an effort to make forward progress.
	 */
retry:
	ret = hugetlb_vmemmap_restore_folios(h, folio_list, &non_hvo_folios);
	if (ret < 0) {
		bulk_vmemmap_restore_error(h, folio_list, &non_hvo_folios);
		goto retry;
	}

	/*
	 * At this point, list should be empty, ret should be >= 0 and there
	 * should only be pages on the non_hvo_folios list.
	 * Do note that the non_hvo_folios list could be empty.
	 * Without HVO enabled, ret will be 0 and there is no need to call
	 * __folio_clear_hugetlb as this was done previously.
	 */
	VM_WARN_ON(!list_empty(folio_list));
	VM_WARN_ON(ret < 0);
	if (!list_empty(&non_hvo_folios) && ret) {
		spin_lock_irq(&hugetlb_lock);
		list_for_each_entry(folio, &non_hvo_folios, lru)
			__folio_clear_hugetlb(folio);
		spin_unlock_irq(&hugetlb_lock);
	}

	list_for_each_entry_safe(folio, t_folio, &non_hvo_folios, lru) {
		update_and_free_hugetlb_folio(h, folio, false);
		cond_resched();
	}
}

struct hstate *size_to_hstate(unsigned long size)
{
	struct hstate *h;

	for_each_hstate(h) {
		if (huge_page_size(h) == size)
			return h;
	}
	return NULL;
}

void free_huge_folio(struct folio *folio)
{
	/*
	 * Can't pass hstate in here because it is called from the
	 * generic mm code.
	 */
	struct hstate *h = folio_hstate(folio);
	int nid = folio_nid(folio);
	struct hugepage_subpool *spool = hugetlb_folio_subpool(folio);
	bool restore_reserve;
	unsigned long flags;

	VM_BUG_ON_FOLIO(folio_ref_count(folio), folio);
	VM_BUG_ON_FOLIO(folio_mapcount(folio), folio);

	hugetlb_set_folio_subpool(folio, NULL);
	if (folio_test_anon(folio))
		__ClearPageAnonExclusive(&folio->page);
	folio->mapping = NULL;
	restore_reserve = folio_test_hugetlb_restore_reserve(folio);
	folio_clear_hugetlb_restore_reserve(folio);

	/*
	 * If HPageRestoreReserve was set on page, page allocation consumed a
	 * reservation.  If the page was associated with a subpool, there
	 * would have been a page reserved in the subpool before allocation
	 * via hugepage_subpool_get_pages().  Since we are 'restoring' the
	 * reservation, do not call hugepage_subpool_put_pages() as this will
	 * remove the reserved page from the subpool.
	 */
	if (!restore_reserve) {
		/*
		 * A return code of zero implies that the subpool will be
		 * under its minimum size if the reservation is not restored
		 * after page is free.  Therefore, force restore_reserve
		 * operation.
		 */
		if (hugepage_subpool_put_pages(spool, 1) == 0)
			restore_reserve = true;
	}

	spin_lock_irqsave(&hugetlb_lock, flags);
	folio_clear_hugetlb_migratable(folio);
	hugetlb_cgroup_uncharge_folio(hstate_index(h),
				     pages_per_huge_page(h), folio);
	hugetlb_cgroup_uncharge_folio_rsvd(hstate_index(h),
					  pages_per_huge_page(h), folio);
	mem_cgroup_uncharge(folio);
	if (restore_reserve)
		h->resv_huge_pages++;

	if (folio_test_hugetlb_temporary(folio)) {
		remove_hugetlb_folio(h, folio, false);
		spin_unlock_irqrestore(&hugetlb_lock, flags);
		update_and_free_hugetlb_folio(h, folio, true);
	} else if (h->surplus_huge_pages_node[nid]) {
		/* remove the page from active list */
		remove_hugetlb_folio(h, folio, true);
		spin_unlock_irqrestore(&hugetlb_lock, flags);
		update_and_free_hugetlb_folio(h, folio, true);
	} else {
		arch_clear_hugetlb_flags(folio);
		enqueue_hugetlb_folio(h, folio);
		spin_unlock_irqrestore(&hugetlb_lock, flags);
	}
}

/*
 * Must be called with the hugetlb lock held
 */
static void __prep_account_new_huge_page(struct hstate *h, int nid)
{
	lockdep_assert_held(&hugetlb_lock);
	h->nr_huge_pages++;
	h->nr_huge_pages_node[nid]++;
}

static void init_new_hugetlb_folio(struct hstate *h, struct folio *folio)
{
	__folio_set_hugetlb(folio);
	INIT_LIST_HEAD(&folio->lru);
	hugetlb_set_folio_subpool(folio, NULL);
	set_hugetlb_cgroup(folio, NULL);
	set_hugetlb_cgroup_rsvd(folio, NULL);
}

static void __prep_new_hugetlb_folio(struct hstate *h, struct folio *folio)
{
	init_new_hugetlb_folio(h, folio);
	hugetlb_vmemmap_optimize_folio(h, folio);
}

static void prep_new_hugetlb_folio(struct hstate *h, struct folio *folio, int nid)
{
	__prep_new_hugetlb_folio(h, folio);
	spin_lock_irq(&hugetlb_lock);
	__prep_account_new_huge_page(h, nid);
	spin_unlock_irq(&hugetlb_lock);
}

static bool __prep_compound_gigantic_folio(struct folio *folio,
					unsigned int order, bool demote)
{
	int i, j;
	int nr_pages = 1 << order;
	struct page *p;

	__folio_clear_reserved(folio);
	for (i = 0; i < nr_pages; i++) {
		p = folio_page(folio, i);

		/*
		 * For gigantic hugepages allocated through bootmem at
		 * boot, it's safer to be consistent with the not-gigantic
		 * hugepages and clear the PG_reserved bit from all tail pages
		 * too.  Otherwise drivers using get_user_pages() to access tail
		 * pages may get the reference counting wrong if they see
		 * PG_reserved set on a tail page (despite the head page not
		 * having PG_reserved set).  Enforcing this consistency between
		 * head and tail pages allows drivers to optimize away a check
		 * on the head page when they need know if put_page() is needed
		 * after get_user_pages().
		 */
		if (i != 0)	/* head page cleared above */
			__ClearPageReserved(p);
		/*
		 * Subtle and very unlikely
		 *
		 * Gigantic 'page allocators' such as memblock or cma will
		 * return a set of pages with each page ref counted.  We need
		 * to turn this set of pages into a compound page with tail
		 * page ref counts set to zero.  Code such as speculative page
		 * cache adding could take a ref on a 'to be' tail page.
		 * We need to respect any increased ref count, and only set
		 * the ref count to zero if count is currently 1.  If count
		 * is not 1, we return an error.  An error return indicates
		 * the set of pages can not be converted to a gigantic page.
		 * The caller who allocated the pages should then discard the
		 * pages using the appropriate free interface.
		 *
		 * In the case of demote, the ref count will be zero.
		 */
		if (!demote) {
			if (!page_ref_freeze(p, 1)) {
				pr_warn("HugeTLB page can not be used due to unexpected inflated ref count\n");
				goto out_error;
			}
		} else {
			VM_BUG_ON_PAGE(page_count(p), p);
		}
		if (i != 0)
			set_compound_head(p, &folio->page);
	}
	__folio_set_head(folio);
	/* we rely on prep_new_hugetlb_folio to set the hugetlb flag */
	folio_set_order(folio, order);
	atomic_set(&folio->_entire_mapcount, -1);
	atomic_set(&folio->_large_mapcount, -1);
	atomic_set(&folio->_pincount, 0);
	return true;

out_error:
	/* undo page modifications made above */
	for (j = 0; j < i; j++) {
		p = folio_page(folio, j);
		if (j != 0)
			clear_compound_head(p);
		set_page_refcounted(p);
	}
	/* need to clear PG_reserved on remaining tail pages  */
	for (; j < nr_pages; j++) {
		p = folio_page(folio, j);
		__ClearPageReserved(p);
	}
	return false;
}

static bool prep_compound_gigantic_folio(struct folio *folio,
							unsigned int order)
{
	return __prep_compound_gigantic_folio(folio, order, false);
}

static bool prep_compound_gigantic_folio_for_demote(struct folio *folio,
							unsigned int order)
{
	return __prep_compound_gigantic_folio(folio, order, true);
}

/*
 * Find and lock address space (mapping) in write mode.
 *
 * Upon entry, the folio is locked which means that folio_mapping() is
 * stable.  Due to locking order, we can only trylock_write.  If we can
 * not get the lock, simply return NULL to caller.
 */
struct address_space *hugetlb_folio_mapping_lock_write(struct folio *folio)
{
	struct address_space *mapping = folio_mapping(folio);

	if (!mapping)
		return mapping;

	if (i_mmap_trylock_write(mapping))
		return mapping;

	return NULL;
}

static struct folio *alloc_buddy_hugetlb_folio(struct hstate *h,
		gfp_t gfp_mask, int nid, nodemask_t *nmask,
		nodemask_t *node_alloc_noretry)
{
	int order = huge_page_order(h);
	struct folio *folio;
	bool alloc_try_hard = true;
	bool retry = true;

	/*
	 * By default we always try hard to allocate the folio with
	 * __GFP_RETRY_MAYFAIL flag.  However, if we are allocating folios in
	 * a loop (to adjust global huge page counts) and previous allocation
	 * failed, do not continue to try hard on the same node.  Use the
	 * node_alloc_noretry bitmap to manage this state information.
	 */
	if (node_alloc_noretry && node_isset(nid, *node_alloc_noretry))
		alloc_try_hard = false;
	gfp_mask |= __GFP_COMP|__GFP_NOWARN;
	if (alloc_try_hard)
		gfp_mask |= __GFP_RETRY_MAYFAIL;
	if (nid == NUMA_NO_NODE)
		nid = numa_mem_id();
retry:
	folio = __folio_alloc(gfp_mask, order, nid, nmask);
	/* Ensure hugetlb folio won't have large_rmappable flag set. */
	if (folio)
		folio_clear_large_rmappable(folio);

	if (folio && !folio_ref_freeze(folio, 1)) {
		folio_put(folio);
		if (retry) {	/* retry once */
			retry = false;
			goto retry;
		}
		/* WOW!  twice in a row. */
		pr_warn("HugeTLB unexpected inflated folio ref count\n");
		folio = NULL;
	}

	/*
	 * If we did not specify __GFP_RETRY_MAYFAIL, but still got a
	 * folio this indicates an overall state change.  Clear bit so
	 * that we resume normal 'try hard' allocations.
	 */
	if (node_alloc_noretry && folio && !alloc_try_hard)
		node_clear(nid, *node_alloc_noretry);

	/*
	 * If we tried hard to get a folio but failed, set bit so that
	 * subsequent attempts will not try as hard until there is an
	 * overall state change.
	 */
	if (node_alloc_noretry && !folio && alloc_try_hard)
		node_set(nid, *node_alloc_noretry);

	if (!folio) {
		__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
		return NULL;
	}

	__count_vm_event(HTLB_BUDDY_PGALLOC);
	return folio;
}

static struct folio *__alloc_fresh_hugetlb_folio(struct hstate *h,
				gfp_t gfp_mask, int nid, nodemask_t *nmask,
				nodemask_t *node_alloc_noretry)
{
	struct folio *folio;
	bool retry = false;

retry:
	if (hstate_is_gigantic(h))
		folio = alloc_gigantic_folio(h, gfp_mask, nid, nmask);
	else
		folio = alloc_buddy_hugetlb_folio(h, gfp_mask,
				nid, nmask, node_alloc_noretry);
	if (!folio)
		return NULL;

	if (hstate_is_gigantic(h)) {
		if (!prep_compound_gigantic_folio(folio, huge_page_order(h))) {
			/*
			 * Rare failure to convert pages to compound page.
			 * Free pages and try again - ONCE!
			 */
			free_gigantic_folio(folio, huge_page_order(h));
			if (!retry) {
				retry = true;
				goto retry;
			}
			return NULL;
		}
	}

	return folio;
}

static struct folio *only_alloc_fresh_hugetlb_folio(struct hstate *h,
		gfp_t gfp_mask, int nid, nodemask_t *nmask,
		nodemask_t *node_alloc_noretry)
{
	struct folio *folio;

	folio = __alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask,
						node_alloc_noretry);
	if (folio)
		init_new_hugetlb_folio(h, folio);
	return folio;
}

/*
 * Common helper to allocate a fresh hugetlb page. All specific allocators
 * should use this function to get new hugetlb pages
 *
 * Note that returned page is 'frozen':  ref count of head page and all tail
 * pages is zero.
 */
static struct folio *alloc_fresh_hugetlb_folio(struct hstate *h,
		gfp_t gfp_mask, int nid, nodemask_t *nmask)
{
	struct folio *folio;

	folio = __alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask, NULL);
	if (!folio)
		return NULL;

	prep_new_hugetlb_folio(h, folio, folio_nid(folio));
	return folio;
}

static void prep_and_add_allocated_folios(struct hstate *h,
					struct list_head *folio_list)
{
	unsigned long flags;
	struct folio *folio, *tmp_f;

	/* Send list for bulk vmemmap optimization processing */
	hugetlb_vmemmap_optimize_folios(h, folio_list);

	/* Add all new pool pages to free lists in one lock cycle */
	spin_lock_irqsave(&hugetlb_lock, flags);
	list_for_each_entry_safe(folio, tmp_f, folio_list, lru) {
		__prep_account_new_huge_page(h, folio_nid(folio));
		enqueue_hugetlb_folio(h, folio);
	}
	spin_unlock_irqrestore(&hugetlb_lock, flags);
}

/*
 * Allocates a fresh hugetlb page in a node interleaved manner.  The page
 * will later be added to the appropriate hugetlb pool.
 */
static struct folio *alloc_pool_huge_folio(struct hstate *h,
					nodemask_t *nodes_allowed,
					nodemask_t *node_alloc_noretry,
					int *next_node)
{
	gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
	int nr_nodes, node;

	for_each_node_mask_to_alloc(next_node, nr_nodes, node, nodes_allowed) {
		struct folio *folio;

		folio = only_alloc_fresh_hugetlb_folio(h, gfp_mask, node,
					nodes_allowed, node_alloc_noretry);
		if (folio)
			return folio;
	}

	return NULL;
}

/*
 * Remove huge page from pool from next node to free.  Attempt to keep
 * persistent huge pages more or less balanced over allowed nodes.
 * This routine only 'removes' the hugetlb page.  The caller must make
 * an additional call to free the page to low level allocators.
 * Called with hugetlb_lock locked.
 */
static struct folio *remove_pool_hugetlb_folio(struct hstate *h,
		nodemask_t *nodes_allowed, bool acct_surplus)
{
	int nr_nodes, node;
	struct folio *folio = NULL;

	lockdep_assert_held(&hugetlb_lock);
	for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
		/*
		 * If we're returning unused surplus pages, only examine
		 * nodes with surplus pages.
		 */
		if ((!acct_surplus || h->surplus_huge_pages_node[node]) &&
		    !list_empty(&h->hugepage_freelists[node])) {
			folio = list_entry(h->hugepage_freelists[node].next,
					  struct folio, lru);
			remove_hugetlb_folio(h, folio, acct_surplus);
			break;
		}
	}

	return folio;
}

/*
 * Dissolve a given free hugetlb folio into free buddy pages. This function
 * does nothing for in-use hugetlb folios and non-hugetlb folios.
 * This function returns values like below:
 *
 *  -ENOMEM: failed to allocate vmemmap pages to free the freed hugepages
 *           when the system is under memory pressure and the feature of
 *           freeing unused vmemmap pages associated with each hugetlb page
 *           is enabled.
 *  -EBUSY:  failed to dissolved free hugepages or the hugepage is in-use
 *           (allocated or reserved.)
 *       0:  successfully dissolved free hugepages or the page is not a
 *           hugepage (considered as already dissolved)
 */
int dissolve_free_hugetlb_folio(struct folio *folio)
{
	int rc = -EBUSY;

retry:
	/* Not to disrupt normal path by vainly holding hugetlb_lock */
	if (!folio_test_hugetlb(folio))
		return 0;

	spin_lock_irq(&hugetlb_lock);
	if (!folio_test_hugetlb(folio)) {
		rc = 0;
		goto out;
	}

	if (!folio_ref_count(folio)) {
		struct hstate *h = folio_hstate(folio);
		if (!available_huge_pages(h))
			goto out;

		/*
		 * We should make sure that the page is already on the free list
		 * when it is dissolved.
		 */
		if (unlikely(!folio_test_hugetlb_freed(folio))) {
			spin_unlock_irq(&hugetlb_lock);
			cond_resched();

			/*
			 * Theoretically, we should return -EBUSY when we
			 * encounter this race. In fact, we have a chance
			 * to successfully dissolve the page if we do a
			 * retry. Because the race window is quite small.
			 * If we seize this opportunity, it is an optimization
			 * for increasing the success rate of dissolving page.
			 */
			goto retry;
		}

		remove_hugetlb_folio(h, folio, false);
		h->max_huge_pages--;
		spin_unlock_irq(&hugetlb_lock);

		/*
		 * Normally update_and_free_hugtlb_folio will allocate required vmemmmap
		 * before freeing the page.  update_and_free_hugtlb_folio will fail to
		 * free the page if it can not allocate required vmemmap.  We
		 * need to adjust max_huge_pages if the page is not freed.
		 * Attempt to allocate vmemmmap here so that we can take
		 * appropriate action on failure.
		 *
		 * The folio_test_hugetlb check here is because
		 * remove_hugetlb_folio will clear hugetlb folio flag for
		 * non-vmemmap optimized hugetlb folios.
		 */
		if (folio_test_hugetlb(folio)) {
			rc = hugetlb_vmemmap_restore_folio(h, folio);
			if (rc) {
				spin_lock_irq(&hugetlb_lock);
				add_hugetlb_folio(h, folio, false);
				h->max_huge_pages++;
				goto out;
			}
		} else
			rc = 0;

		update_and_free_hugetlb_folio(h, folio, false);
		return rc;
	}
out:
	spin_unlock_irq(&hugetlb_lock);
	return rc;
}

/*
 * Dissolve free hugepages in a given pfn range. Used by memory hotplug to
 * make specified memory blocks removable from the system.
 * Note that this will dissolve a free gigantic hugepage completely, if any
 * part of it lies within the given range.
 * Also note that if dissolve_free_hugetlb_folio() returns with an error, all
 * free hugetlb folios that were dissolved before that error are lost.
 */
int dissolve_free_hugetlb_folios(unsigned long start_pfn, unsigned long end_pfn)
{
	unsigned long pfn;
	struct folio *folio;
	int rc = 0;
	unsigned int order;
	struct hstate *h;

	if (!hugepages_supported())
		return rc;

	order = huge_page_order(&default_hstate);
	for_each_hstate(h)
		order = min(order, huge_page_order(h));

	for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << order) {
		folio = pfn_folio(pfn);
		rc = dissolve_free_hugetlb_folio(folio);
		if (rc)
			break;
	}

	return rc;
}

/*
 * Allocates a fresh surplus page from the page allocator.
 */
static struct folio *alloc_surplus_hugetlb_folio(struct hstate *h,
				gfp_t gfp_mask,	int nid, nodemask_t *nmask)
{
	struct folio *folio = NULL;

	if (hstate_is_gigantic(h))
		return NULL;

	spin_lock_irq(&hugetlb_lock);
	if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages)
		goto out_unlock;
	spin_unlock_irq(&hugetlb_lock);

	folio = alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask);
	if (!folio)
		return NULL;

	spin_lock_irq(&hugetlb_lock);
	/*
	 * We could have raced with the pool size change.
	 * Double check that and simply deallocate the new page
	 * if we would end up overcommiting the surpluses. Abuse
	 * temporary page to workaround the nasty free_huge_folio
	 * codeflow
	 */
	if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
		folio_set_hugetlb_temporary(folio);
		spin_unlock_irq(&hugetlb_lock);
		free_huge_folio(folio);
		return NULL;
	}

	h->surplus_huge_pages++;
	h->surplus_huge_pages_node[folio_nid(folio)]++;

out_unlock:
	spin_unlock_irq(&hugetlb_lock);

	return folio;
}

static struct folio *alloc_migrate_hugetlb_folio(struct hstate *h, gfp_t gfp_mask,
				     int nid, nodemask_t *nmask)
{
	struct folio *folio;

	if (hstate_is_gigantic(h))
		return NULL;

	folio = alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask);
	if (!folio)
		return NULL;

	/* fresh huge pages are frozen */
	folio_ref_unfreeze(folio, 1);
	/*
	 * We do not account these pages as surplus because they are only
	 * temporary and will be released properly on the last reference
	 */
	folio_set_hugetlb_temporary(folio);

	return folio;
}

/*
 * Use the VMA's mpolicy to allocate a huge page from the buddy.
 */
static
struct folio *alloc_buddy_hugetlb_folio_with_mpol(struct hstate *h,
		struct vm_area_struct *vma, unsigned long addr)
{
	struct folio *folio = NULL;
	struct mempolicy *mpol;
	gfp_t gfp_mask = htlb_alloc_mask(h);
	int nid;
	nodemask_t *nodemask;

	nid = huge_node(vma, addr, gfp_mask, &mpol, &nodemask);
	if (mpol_is_preferred_many(mpol)) {
		gfp_t gfp = gfp_mask | __GFP_NOWARN;

		gfp &=  ~(__GFP_DIRECT_RECLAIM | __GFP_NOFAIL);
		folio = alloc_surplus_hugetlb_folio(h, gfp, nid, nodemask);

		/* Fallback to all nodes if page==NULL */
		nodemask = NULL;
	}

	if (!folio)
		folio = alloc_surplus_hugetlb_folio(h, gfp_mask, nid, nodemask);
	mpol_cond_put(mpol);
	return folio;
}

/* folio migration callback function */
struct folio *alloc_hugetlb_folio_nodemask(struct hstate *h, int preferred_nid,
		nodemask_t *nmask, gfp_t gfp_mask, bool allow_alloc_fallback)
{
	spin_lock_irq(&hugetlb_lock);
	if (available_huge_pages(h)) {
		struct folio *folio;

		folio = dequeue_hugetlb_folio_nodemask(h, gfp_mask,
						preferred_nid, nmask);
		if (folio) {
			spin_unlock_irq(&hugetlb_lock);
			return folio;
		}
	}
	spin_unlock_irq(&hugetlb_lock);

	/* We cannot fallback to other nodes, as we could break the per-node pool. */
	if (!allow_alloc_fallback)
		gfp_mask |= __GFP_THISNODE;

	return alloc_migrate_hugetlb_folio(h, gfp_mask, preferred_nid, nmask);
}

static nodemask_t *policy_mbind_nodemask(gfp_t gfp)
{
#ifdef CONFIG_NUMA
	struct mempolicy *mpol = get_task_policy(current);

	/*
	 * Only enforce MPOL_BIND policy which overlaps with cpuset policy
	 * (from policy_nodemask) specifically for hugetlb case
	 */
	if (mpol->mode == MPOL_BIND &&
		(apply_policy_zone(mpol, gfp_zone(gfp)) &&
		 cpuset_nodemask_valid_mems_allowed(&mpol->nodes)))
		return &mpol->nodes;
#endif
	return NULL;
}

/*
 * Increase the hugetlb pool such that it can accommodate a reservation
 * of size 'delta'.
 */
static int gather_surplus_pages(struct hstate *h, long delta)
	__must_hold(&hugetlb_lock)
{
	LIST_HEAD(surplus_list);
	struct folio *folio, *tmp;
	int ret;
	long i;
	long needed, allocated;
	bool alloc_ok = true;
	int node;
	nodemask_t *mbind_nodemask = policy_mbind_nodemask(htlb_alloc_mask(h));

	lockdep_assert_held(&hugetlb_lock);
	needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
	if (needed <= 0) {
		h->resv_huge_pages += delta;
		return 0;
	}

	allocated = 0;

	ret = -ENOMEM;
retry:
	spin_unlock_irq(&hugetlb_lock);
	for (i = 0; i < needed; i++) {
		folio = NULL;
		for_each_node_mask(node, cpuset_current_mems_allowed) {
			if (!mbind_nodemask || node_isset(node, *mbind_nodemask)) {
				folio = alloc_surplus_hugetlb_folio(h, htlb_alloc_mask(h),
						node, NULL);
				if (folio)
					break;
			}
		}
		if (!folio) {
			alloc_ok = false;
			break;
		}
		list_add(&folio->lru, &surplus_list);
		cond_resched();
	}
	allocated += i;

	/*
	 * After retaking hugetlb_lock, we need to recalculate 'needed'
	 * because either resv_huge_pages or free_huge_pages may have changed.
	 */
	spin_lock_irq(&hugetlb_lock);
	needed = (h->resv_huge_pages + delta) -
			(h->free_huge_pages + allocated);
	if (needed > 0) {
		if (alloc_ok)
			goto retry;
		/*
		 * We were not able to allocate enough pages to
		 * satisfy the entire reservation so we free what
		 * we've allocated so far.
		 */
		goto free;
	}
	/*
	 * The surplus_list now contains _at_least_ the number of extra pages
	 * needed to accommodate the reservation.  Add the appropriate number
	 * of pages to the hugetlb pool and free the extras back to the buddy
	 * allocator.  Commit the entire reservation here to prevent another
	 * process from stealing the pages as they are added to the pool but
	 * before they are reserved.
	 */
	needed += allocated;
	h->resv_huge_pages += delta;
	ret = 0;

	/* Free the needed pages to the hugetlb pool */
	list_for_each_entry_safe(folio, tmp, &surplus_list, lru) {
		if ((--needed) < 0)
			break;
		/* Add the page to the hugetlb allocator */
		enqueue_hugetlb_folio(h, folio);
	}
free:
	spin_unlock_irq(&hugetlb_lock);

	/*
	 * Free unnecessary surplus pages to the buddy allocator.
	 * Pages have no ref count, call free_huge_folio directly.
	 */
	list_for_each_entry_safe(folio, tmp, &surplus_list, lru)
		free_huge_folio(folio);
	spin_lock_irq(&hugetlb_lock);

	return ret;
}

/*
 * This routine has two main purposes:
 * 1) Decrement the reservation count (resv_huge_pages) by the value passed
 *    in unused_resv_pages.  This corresponds to the prior adjustments made
 *    to the associated reservation map.
 * 2) Free any unused surplus pages that may have been allocated to satisfy
 *    the reservation.  As many as unused_resv_pages may be freed.
 */
static void return_unused_surplus_pages(struct hstate *h,
					unsigned long unused_resv_pages)
{
	unsigned long nr_pages;
	LIST_HEAD(page_list);

	lockdep_assert_held(&hugetlb_lock);
	/* Uncommit the reservation */
	h->resv_huge_pages -= unused_resv_pages;

	if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
		goto out;

	/*
	 * Part (or even all) of the reservation could have been backed
	 * by pre-allocated pages. Only free surplus pages.
	 */
	nr_pages = min(unused_resv_pages, h->surplus_huge_pages);

	/*
	 * We want to release as many surplus pages as possible, spread
	 * evenly across all nodes with memory. Iterate across these nodes
	 * until we can no longer free unreserved surplus pages. This occurs
	 * when the nodes with surplus pages have no free pages.
	 * remove_pool_hugetlb_folio() will balance the freed pages across the
	 * on-line nodes with memory and will handle the hstate accounting.
	 */
	while (nr_pages--) {
		struct folio *folio;

		folio = remove_pool_hugetlb_folio(h, &node_states[N_MEMORY], 1);
		if (!folio)
			goto out;

		list_add(&folio->lru, &page_list);
	}

out:
	spin_unlock_irq(&hugetlb_lock);
	update_and_free_pages_bulk(h, &page_list);
	spin_lock_irq(&hugetlb_lock);
}


/*
 * vma_needs_reservation, vma_commit_reservation and vma_end_reservation
 * are used by the huge page allocation routines to manage reservations.
 *
 * vma_needs_reservation is called to determine if the huge page at addr
 * within the vma has an associated reservation.  If a reservation is
 * needed, the value 1 is returned.  The caller is then responsible for
 * managing the global reservation and subpool usage counts.  After
 * the huge page has been allocated, vma_commit_reservation is called
 * to add the page to the reservation map.  If the page allocation fails,
 * the reservation must be ended instead of committed.  vma_end_reservation
 * is called in such cases.
 *
 * In the normal case, vma_commit_reservation returns the same value
 * as the preceding vma_needs_reservation call.  The only time this
 * is not the case is if a reserve map was changed between calls.  It
 * is the responsibility of the caller to notice the difference and
 * take appropriate action.
 *
 * vma_add_reservation is used in error paths where a reservation must
 * be restored when a newly allocated huge page must be freed.  It is
 * to be called after calling vma_needs_reservation to determine if a
 * reservation exists.
 *
 * vma_del_reservation is used in error paths where an entry in the reserve
 * map was created during huge page allocation and must be removed.  It is to
 * be called after calling vma_needs_reservation to determine if a reservation
 * exists.
 */
enum vma_resv_mode {
	VMA_NEEDS_RESV,
	VMA_COMMIT_RESV,
	VMA_END_RESV,
	VMA_ADD_RESV,
	VMA_DEL_RESV,
};
static long __vma_reservation_common(struct hstate *h,
				struct vm_area_struct *vma, unsigned long addr,
				enum vma_resv_mode mode)
{
	struct resv_map *resv;
	pgoff_t idx;
	long ret;
	long dummy_out_regions_needed;

	resv = vma_resv_map(vma);
	if (!resv)
		return 1;

	idx = vma_hugecache_offset(h, vma, addr);
	switch (mode) {
	case VMA_NEEDS_RESV:
		ret = region_chg(resv, idx, idx + 1, &dummy_out_regions_needed);
		/* We assume that vma_reservation_* routines always operate on
		 * 1 page, and that adding to resv map a 1 page entry can only
		 * ever require 1 region.
		 */
		VM_BUG_ON(dummy_out_regions_needed != 1);
		break;
	case VMA_COMMIT_RESV:
		ret = region_add(resv, idx, idx + 1, 1, NULL, NULL);
		/* region_add calls of range 1 should never fail. */
		VM_BUG_ON(ret < 0);
		break;
	case VMA_END_RESV:
		region_abort(resv, idx, idx + 1, 1);
		ret = 0;
		break;
	case VMA_ADD_RESV:
		if (vma->vm_flags & VM_MAYSHARE) {
			ret = region_add(resv, idx, idx + 1, 1, NULL, NULL);
			/* region_add calls of range 1 should never fail. */
			VM_BUG_ON(ret < 0);
		} else {
			region_abort(resv, idx, idx + 1, 1);
			ret = region_del(resv, idx, idx + 1);
		}
		break;
	case VMA_DEL_RESV:
		if (vma->vm_flags & VM_MAYSHARE) {
			region_abort(resv, idx, idx + 1, 1);
			ret = region_del(resv, idx, idx + 1);
		} else {
			ret = region_add(resv, idx, idx + 1, 1, NULL, NULL);
			/* region_add calls of range 1 should never fail. */
			VM_BUG_ON(ret < 0);
		}
		break;
	default:
		BUG();
	}

	if (vma->vm_flags & VM_MAYSHARE || mode == VMA_DEL_RESV)
		return ret;
	/*
	 * We know private mapping must have HPAGE_RESV_OWNER set.
	 *
	 * In most cases, reserves always exist for private mappings.
	 * However, a file associated with mapping could have been
	 * hole punched or truncated after reserves were consumed.
	 * As subsequent fault on such a range will not use reserves.
	 * Subtle - The reserve map for private mappings has the
	 * opposite meaning than that of shared mappings.  If NO
	 * entry is in the reserve map, it means a reservation exists.
	 * If an entry exists in the reserve map, it means the
	 * reservation has already been consumed.  As a result, the
	 * return value of this routine is the opposite of the
	 * value returned from reserve map manipulation routines above.
	 */
	if (ret > 0)
		return 0;
	if (ret == 0)
		return 1;
	return ret;
}

static long vma_needs_reservation(struct hstate *h,
			struct vm_area_struct *vma, unsigned long addr)
{
	return __vma_reservation_common(h, vma, addr, VMA_NEEDS_RESV);
}

static long vma_commit_reservation(struct hstate *h,
			struct vm_area_struct *vma, unsigned long addr)
{
	return __vma_reservation_common(h, vma, addr, VMA_COMMIT_RESV);
}

static void vma_end_reservation(struct hstate *h,
			struct vm_area_struct *vma, unsigned long addr)
{
	(void)__vma_reservation_common(h, vma, addr, VMA_END_RESV);
}

static long vma_add_reservation(struct hstate *h,
			struct vm_area_struct *vma, unsigned long addr)
{
	return __vma_reservation_common(h, vma, addr, VMA_ADD_RESV);
}

static long vma_del_reservation(struct hstate *h,
			struct vm_area_struct *vma, unsigned long addr)
{
	return __vma_reservation_common(h, vma, addr, VMA_DEL_RESV);
}

/*
 * This routine is called to restore reservation information on error paths.
 * It should ONLY be called for folios allocated via alloc_hugetlb_folio(),
 * and the hugetlb mutex should remain held when calling this routine.
 *
 * It handles two specific cases:
 * 1) A reservation was in place and the folio consumed the reservation.
 *    hugetlb_restore_reserve is set in the folio.
 * 2) No reservation was in place for the page, so hugetlb_restore_reserve is
 *    not set.  However, alloc_hugetlb_folio always updates the reserve map.
 *
 * In case 1, free_huge_folio later in the error path will increment the
 * global reserve count.  But, free_huge_folio does not have enough context
 * to adjust the reservation map.  This case deals primarily with private
 * mappings.  Adjust the reserve map here to be consistent with global
 * reserve count adjustments to be made by free_huge_folio.  Make sure the
 * reserve map indicates there is a reservation present.
 *
 * In case 2, simply undo reserve map modifications done by alloc_hugetlb_folio.
 */
void restore_reserve_on_error(struct hstate *h, struct vm_area_struct *vma,
			unsigned long address, struct folio *folio)
{
	long rc = vma_needs_reservation(h, vma, address);

	if (folio_test_hugetlb_restore_reserve(folio)) {
		if (unlikely(rc < 0))
			/*
			 * Rare out of memory condition in reserve map
			 * manipulation.  Clear hugetlb_restore_reserve so
			 * that global reserve count will not be incremented
			 * by free_huge_folio.  This will make it appear
			 * as though the reservation for this folio was
			 * consumed.  This may prevent the task from
			 * faulting in the folio at a later time.  This
			 * is better than inconsistent global huge page
			 * accounting of reserve counts.
			 */
			folio_clear_hugetlb_restore_reserve(folio);
		else if (rc)
			(void)vma_add_reservation(h, vma, address);
		else
			vma_end_reservation(h, vma, address);
	} else {
		if (!rc) {
			/*
			 * This indicates there is an entry in the reserve map
			 * not added by alloc_hugetlb_folio.  We know it was added
			 * before the alloc_hugetlb_folio call, otherwise
			 * hugetlb_restore_reserve would be set on the folio.
			 * Remove the entry so that a subsequent allocation
			 * does not consume a reservation.
			 */
			rc = vma_del_reservation(h, vma, address);
			if (rc < 0)
				/*
				 * VERY rare out of memory condition.  Since
				 * we can not delete the entry, set
				 * hugetlb_restore_reserve so that the reserve
				 * count will be incremented when the folio
				 * is freed.  This reserve will be consumed
				 * on a subsequent allocation.
				 */
				folio_set_hugetlb_restore_reserve(folio);
		} else if (rc < 0) {
			/*
			 * Rare out of memory condition from
			 * vma_needs_reservation call.  Memory allocation is
			 * only attempted if a new entry is needed.  Therefore,
			 * this implies there is not an entry in the
			 * reserve map.
			 *
			 * For shared mappings, no entry in the map indicates
			 * no reservation.  We are done.
			 */
			if (!(vma->vm_flags & VM_MAYSHARE))
				/*
				 * For private mappings, no entry indicates
				 * a reservation is present.  Since we can
				 * not add an entry, set hugetlb_restore_reserve
				 * on the folio so reserve count will be
				 * incremented when freed.  This reserve will
				 * be consumed on a subsequent allocation.
				 */
				folio_set_hugetlb_restore_reserve(folio);
		} else
			/*
			 * No reservation present, do nothing
			 */
			 vma_end_reservation(h, vma, address);
	}
}

/*
 * alloc_and_dissolve_hugetlb_folio - Allocate a new folio and dissolve
 * the old one
 * @h: struct hstate old page belongs to
 * @old_folio: Old folio to dissolve
 * @list: List to isolate the page in case we need to
 * Returns 0 on success, otherwise negated error.
 */
static int alloc_and_dissolve_hugetlb_folio(struct hstate *h,
			struct folio *old_folio, struct list_head *list)
{
	gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
	int nid = folio_nid(old_folio);
	struct folio *new_folio = NULL;
	int ret = 0;

retry:
	spin_lock_irq(&hugetlb_lock);
	if (!folio_test_hugetlb(old_folio)) {
		/*
		 * Freed from under us. Drop new_folio too.
		 */
		goto free_new;
	} else if (folio_ref_count(old_folio)) {
		bool isolated;

		/*
		 * Someone has grabbed the folio, try to isolate it here.
		 * Fail with -EBUSY if not possible.
		 */
		spin_unlock_irq(&hugetlb_lock);
		isolated = isolate_hugetlb(old_folio, list);
		ret = isolated ? 0 : -EBUSY;
		spin_lock_irq(&hugetlb_lock);
		goto free_new;
	} else if (!folio_test_hugetlb_freed(old_folio)) {
		/*
		 * Folio's refcount is 0 but it has not been enqueued in the
		 * freelist yet. Race window is small, so we can succeed here if
		 * we retry.
		 */
		spin_unlock_irq(&hugetlb_lock);
		cond_resched();
		goto retry;
	} else {
		if (!new_folio) {
			spin_unlock_irq(&hugetlb_lock);
			new_folio = alloc_buddy_hugetlb_folio(h, gfp_mask, nid,
							      NULL, NULL);
			if (!new_folio)
				return -ENOMEM;
			__prep_new_hugetlb_folio(h, new_folio);
			goto retry;
		}

		/*
		 * Ok, old_folio is still a genuine free hugepage. Remove it from
		 * the freelist and decrease the counters. These will be
		 * incremented again when calling __prep_account_new_huge_page()
		 * and enqueue_hugetlb_folio() for new_folio. The counters will
		 * remain stable since this happens under the lock.
		 */
		remove_hugetlb_folio(h, old_folio, false);

		/*
		 * Ref count on new_folio is already zero as it was dropped
		 * earlier.  It can be directly added to the pool free list.
		 */
		__prep_account_new_huge_page(h, nid);
		enqueue_hugetlb_folio(h, new_folio);

		/*
		 * Folio has been replaced, we can safely free the old one.
		 */
		spin_unlock_irq(&hugetlb_lock);
		update_and_free_hugetlb_folio(h, old_folio, false);
	}

	return ret;

free_new:
	spin_unlock_irq(&hugetlb_lock);
	if (new_folio)
		update_and_free_hugetlb_folio(h, new_folio, false);

	return ret;
}

int isolate_or_dissolve_huge_page(struct page *page, struct list_head *list)
{
	struct hstate *h;
	struct folio *folio = page_folio(page);
	int ret = -EBUSY;

	/*
	 * The page might have been dissolved from under our feet, so make sure
	 * to carefully check the state under the lock.
	 * Return success when racing as if we dissolved the page ourselves.
	 */
	spin_lock_irq(&hugetlb_lock);
	if (folio_test_hugetlb(folio)) {
		h = folio_hstate(folio);
	} else {
		spin_unlock_irq(&hugetlb_lock);
		return 0;
	}
	spin_unlock_irq(&hugetlb_lock);

	/*
	 * Fence off gigantic pages as there is a cyclic dependency between
	 * alloc_contig_range and them. Return -ENOMEM as this has the effect
	 * of bailing out right away without further retrying.
	 */
	if (hstate_is_gigantic(h))
		return -ENOMEM;

	if (folio_ref_count(folio) && isolate_hugetlb(folio, list))
		ret = 0;
	else if (!folio_ref_count(folio))
		ret = alloc_and_dissolve_hugetlb_folio(h, folio, list);

	return ret;
}

struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma,
				    unsigned long addr, int avoid_reserve)
{
	struct hugepage_subpool *spool = subpool_vma(vma);
	struct hstate *h = hstate_vma(vma);
	struct folio *folio;
	long map_chg, map_commit, nr_pages = pages_per_huge_page(h);
	long gbl_chg;
	int memcg_charge_ret, ret, idx;
	struct hugetlb_cgroup *h_cg = NULL;
	struct mem_cgroup *memcg;
	bool deferred_reserve;
	gfp_t gfp = htlb_alloc_mask(h) | __GFP_RETRY_MAYFAIL;

	memcg = get_mem_cgroup_from_current();
	memcg_charge_ret = mem_cgroup_hugetlb_try_charge(memcg, gfp, nr_pages);
	if (memcg_charge_ret == -ENOMEM) {
		mem_cgroup_put(memcg);
		return ERR_PTR(-ENOMEM);
	}

	idx = hstate_index(h);
	/*
	 * Examine the region/reserve map to determine if the process
	 * has a reservation for the page to be allocated.  A return
	 * code of zero indicates a reservation exists (no change).
	 */
	map_chg = gbl_chg = vma_needs_reservation(h, vma, addr);
	if (map_chg < 0) {
		if (!memcg_charge_ret)
			mem_cgroup_cancel_charge(memcg, nr_pages);
		mem_cgroup_put(memcg);
		return ERR_PTR(-ENOMEM);
	}

	/*
	 * Processes that did not create the mapping will have no
	 * reserves as indicated by the region/reserve map. Check
	 * that the allocation will not exceed the subpool limit.
	 * Allocations for MAP_NORESERVE mappings also need to be
	 * checked against any subpool limit.
	 */
	if (map_chg || avoid_reserve) {
		gbl_chg = hugepage_subpool_get_pages(spool, 1);
		if (gbl_chg < 0)
			goto out_end_reservation;

		/*
		 * Even though there was no reservation in the region/reserve
		 * map, there could be reservations associated with the
		 * subpool that can be used.  This would be indicated if the
		 * return value of hugepage_subpool_get_pages() is zero.
		 * However, if avoid_reserve is specified we still avoid even
		 * the subpool reservations.
		 */
		if (avoid_reserve)
			gbl_chg = 1;
	}

	/* If this allocation is not consuming a reservation, charge it now.
	 */
	deferred_reserve = map_chg || avoid_reserve;
	if (deferred_reserve) {
		ret = hugetlb_cgroup_charge_cgroup_rsvd(
			idx, pages_per_huge_page(h), &h_cg);
		if (ret)
			goto out_subpool_put;
	}

	ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
	if (ret)
		goto out_uncharge_cgroup_reservation;

	spin_lock_irq(&hugetlb_lock);
	/*
	 * glb_chg is passed to indicate whether or not a page must be taken
	 * from the global free pool (global change).  gbl_chg == 0 indicates
	 * a reservation exists for the allocation.
	 */
	folio = dequeue_hugetlb_folio_vma(h, vma, addr, avoid_reserve, gbl_chg);
	if (!folio) {
		spin_unlock_irq(&hugetlb_lock);
		folio = alloc_buddy_hugetlb_folio_with_mpol(h, vma, addr);
		if (!folio)
			goto out_uncharge_cgroup;
		spin_lock_irq(&hugetlb_lock);
		if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
			folio_set_hugetlb_restore_reserve(folio);
			h->resv_huge_pages--;
		}
		list_add(&folio->lru, &h->hugepage_activelist);
		folio_ref_unfreeze(folio, 1);
		/* Fall through */
	}

	hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, folio);
	/* If allocation is not consuming a reservation, also store the
	 * hugetlb_cgroup pointer on the page.
	 */
	if (deferred_reserve) {
		hugetlb_cgroup_commit_charge_rsvd(idx, pages_per_huge_page(h),
						  h_cg, folio);
	}

	spin_unlock_irq(&hugetlb_lock);

	hugetlb_set_folio_subpool(folio, spool);

	map_commit = vma_commit_reservation(h, vma, addr);
	if (unlikely(map_chg > map_commit)) {
		/*
		 * The page was added to the reservation map between
		 * vma_needs_reservation and vma_commit_reservation.
		 * This indicates a race with hugetlb_reserve_pages.
		 * Adjust for the subpool count incremented above AND
		 * in hugetlb_reserve_pages for the same page.  Also,
		 * the reservation count added in hugetlb_reserve_pages
		 * no longer applies.
		 */
		long rsv_adjust;

		rsv_adjust = hugepage_subpool_put_pages(spool, 1);
		hugetlb_acct_memory(h, -rsv_adjust);
		if (deferred_reserve) {
			spin_lock_irq(&hugetlb_lock);
			hugetlb_cgroup_uncharge_folio_rsvd(hstate_index(h),
					pages_per_huge_page(h), folio);
			spin_unlock_irq(&hugetlb_lock);
		}
	}

	if (!memcg_charge_ret)
		mem_cgroup_commit_charge(folio, memcg);
	mem_cgroup_put(memcg);

	return folio;

out_uncharge_cgroup:
	hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
out_uncharge_cgroup_reservation:
	if (deferred_reserve)
		hugetlb_cgroup_uncharge_cgroup_rsvd(idx, pages_per_huge_page(h),
						    h_cg);
out_subpool_put:
	if (map_chg || avoid_reserve)
		hugepage_subpool_put_pages(spool, 1);
out_end_reservation:
	vma_end_reservation(h, vma, addr);
	if (!memcg_charge_ret)
		mem_cgroup_cancel_charge(memcg, nr_pages);
	mem_cgroup_put(memcg);
	return ERR_PTR(-ENOSPC);
}

int alloc_bootmem_huge_page(struct hstate *h, int nid)
	__attribute__ ((weak, alias("__alloc_bootmem_huge_page")));
int __alloc_bootmem_huge_page(struct hstate *h, int nid)
{
	struct huge_bootmem_page *m = NULL; /* initialize for clang */
	int nr_nodes, node = nid;

	/* do node specific alloc */
	if (nid != NUMA_NO_NODE) {
		m = memblock_alloc_try_nid_raw(huge_page_size(h), huge_page_size(h),