hugetlb.c 128.9 KB
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/*
 * Generic hugetlb support.
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 * (C) Nadia Yvette Chambers, April 2004
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 */
#include <linux/list.h>
#include <linux/init.h>
#include <linux/mm.h>
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#include <linux/seq_file.h>
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#include <linux/sysctl.h>
#include <linux/highmem.h>
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#include <linux/mmu_notifier.h>
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#include <linux/nodemask.h>
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#include <linux/pagemap.h>
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#include <linux/mempolicy.h>
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#include <linux/compiler.h>
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#include <linux/cpuset.h>
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#include <linux/mutex.h>
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#include <linux/bootmem.h>
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#include <linux/sysfs.h>
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#include <linux/slab.h>
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#include <linux/sched/signal.h>
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#include <linux/rmap.h>
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#include <linux/string_helpers.h>
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#include <linux/swap.h>
#include <linux/swapops.h>
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#include <linux/jhash.h>
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#include <asm/page.h>
#include <asm/pgtable.h>
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#include <asm/tlb.h>
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#include <linux/io.h>
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#include <linux/hugetlb.h>
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#include <linux/hugetlb_cgroup.h>
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#include <linux/node.h>
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#include <linux/userfaultfd_k.h>
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#include "internal.h"
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39
int hugepages_treat_as_movable;
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41
int hugetlb_max_hstate __read_mostly;
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unsigned int default_hstate_idx;
struct hstate hstates[HUGE_MAX_HSTATE];
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/*
 * Minimum page order among possible hugepage sizes, set to a proper value
 * at boot time.
 */
static unsigned int minimum_order __read_mostly = UINT_MAX;
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__initdata LIST_HEAD(huge_boot_pages);

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/* for command line parsing */
static struct hstate * __initdata parsed_hstate;
static unsigned long __initdata default_hstate_max_huge_pages;
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static unsigned long __initdata default_hstate_size;
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static bool __initdata parsed_valid_hugepagesz = true;
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58
/*
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 * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages,
 * free_huge_pages, and surplus_huge_pages.
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 */
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DEFINE_SPINLOCK(hugetlb_lock);
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/*
 * 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;
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struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp;
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/* Forward declaration */
static int hugetlb_acct_memory(struct hstate *h, long delta);

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static inline void unlock_or_release_subpool(struct hugepage_subpool *spool)
{
	bool free = (spool->count == 0) && (spool->used_hpages == 0);

	spin_unlock(&spool->lock);

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

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

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

	spin_lock_init(&spool->lock);
	spool->count = 1;
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	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;
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	return spool;
}

void hugepage_put_subpool(struct hugepage_subpool *spool)
{
	spin_lock(&spool->lock);
	BUG_ON(!spool->count);
	spool->count--;
	unlock_or_release_subpool(spool);
}

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/*
 * Subpool accounting for allocating and reserving pages.
 * Return -ENOMEM if there are not enough resources to satisfy the
 * 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 manitained.
 */
static long hugepage_subpool_get_pages(struct hugepage_subpool *spool,
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				      long delta)
{
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	long ret = delta;
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	if (!spool)
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		return ret;
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	spin_lock(&spool->lock);
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	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;
		}
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	}

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	/* minimum size accounting */
	if (spool->min_hpages != -1 && spool->rsv_hpages) {
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		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(&spool->lock);
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	return ret;
}

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/*
 * 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,
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				       long delta)
{
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	long ret = delta;

181
	if (!spool)
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		return delta;
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	spin_lock(&spool->lock);
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	if (spool->max_hpages != -1)		/* maximum size accounting */
		spool->used_hpages -= delta;

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	 /* minimum size accounting */
	if (spool->min_hpages != -1 && spool->used_hpages < spool->min_hpages) {
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		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.
	 */
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	unlock_or_release_subpool(spool);
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	return ret;
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}

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)
{
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	return subpool_inode(file_inode(vma->vm_file));
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}

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/*
 * Region tracking -- allows tracking of reservations and instantiated pages
 *                    across the pages in a mapping.
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 *
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 * The region data structures are embedded into a resv_map and protected
 * by a resv_map's lock.  The set of regions within the resv_map represent
 * reservations for huge pages, or huge pages that have already been
 * instantiated within the map.  The from and to elements are huge page
 * indicies into the associated mapping.  from indicates the starting index
 * of the region.  to represents the first index past the end of  the region.
 *
 * For example, a file region structure with from == 0 and to == 4 represents
 * four huge pages in a mapping.  It is important to note that the to element
 * represents the first element past the end of the region. This is used in
 * arithmetic as 4(to) - 0(from) = 4 huge pages in the region.
 *
 * Interval notation of the form [from, to) will be used to indicate that
 * the endpoint from is inclusive and to is exclusive.
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 */
struct file_region {
	struct list_head link;
	long from;
	long to;
};

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/*
 * Add the huge page range represented by [f, t) to the reserve
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 * map.  In the normal case, existing regions will be expanded
 * to accommodate the specified range.  Sufficient regions should
 * exist for expansion due to the previous call to region_chg
 * with the same range.  However, it is possible that region_del
 * could have been called after region_chg and modifed the map
 * in such a way that no region exists to be expanded.  In this
 * case, pull a region descriptor from the cache associated with
 * the map and use that for the new range.
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 *
 * Return the number of new huge pages added to the map.  This
 * number is greater than or equal to zero.
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 */
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static long region_add(struct resv_map *resv, long f, long t)
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{
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	struct list_head *head = &resv->regions;
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	struct file_region *rg, *nrg, *trg;
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	long add = 0;
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	spin_lock(&resv->lock);
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	/* Locate the region we are either in or before. */
	list_for_each_entry(rg, head, link)
		if (f <= rg->to)
			break;

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	/*
	 * If no region exists which can be expanded to include the
	 * specified range, the list must have been modified by an
	 * interleving call to region_del().  Pull a region descriptor
	 * from the cache and use it for this range.
	 */
	if (&rg->link == head || t < rg->from) {
		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 = f;
		nrg->to = t;
		list_add(&nrg->link, rg->link.prev);

		add += t - f;
		goto out_locked;
	}

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	/* Round our left edge to the current segment if it encloses us. */
	if (f > rg->from)
		f = rg->from;

	/* Check for and consume any regions we now overlap with. */
	nrg = rg;
	list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
		if (&rg->link == head)
			break;
		if (rg->from > t)
			break;

		/* If this area reaches higher then extend our area to
		 * include it completely.  If this is not the first area
		 * which we intend to reuse, free it. */
		if (rg->to > t)
			t = rg->to;
		if (rg != nrg) {
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			/* Decrement return value by the deleted range.
			 * Another range will span this area so that by
			 * end of routine add will be >= zero
			 */
			add -= (rg->to - rg->from);
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			list_del(&rg->link);
			kfree(rg);
		}
	}
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	add += (nrg->from - f);		/* Added to beginning of region */
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	nrg->from = f;
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	add += t - nrg->to;		/* Added to end of region */
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	nrg->to = t;
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out_locked:
	resv->adds_in_progress--;
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	spin_unlock(&resv->lock);
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	VM_BUG_ON(add < 0);
	return add;
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}

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/*
 * 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.  However, if the existing regions in the map can not
 * be expanded to represent the new range, a new file_region
 * structure is added to the map as a placeholder.  This is
 * so that the subsequent region_add call will have all the
 * regions it needs and will not fail.
 *
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 * Upon entry, region_chg will also examine the cache of region descriptors
 * associated with the map.  If there are not enough descriptors cached, one
 * will be allocated for the in progress add operation.
 *
 * 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.
354
 */
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static long region_chg(struct resv_map *resv, long f, long t)
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{
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	struct list_head *head = &resv->regions;
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	struct file_region *rg, *nrg = NULL;
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	long chg = 0;

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retry:
	spin_lock(&resv->lock);
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retry_locked:
	resv->adds_in_progress++;

	/*
	 * Check for sufficient descriptors in the cache to accommodate
	 * the number of in progress add operations.
	 */
	if (resv->adds_in_progress > resv->region_cache_count) {
		struct file_region *trg;

		VM_BUG_ON(resv->adds_in_progress - resv->region_cache_count > 1);
		/* Must drop lock to allocate a new descriptor. */
		resv->adds_in_progress--;
		spin_unlock(&resv->lock);

		trg = kmalloc(sizeof(*trg), GFP_KERNEL);
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		if (!trg) {
			kfree(nrg);
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			return -ENOMEM;
382
		}
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		spin_lock(&resv->lock);
		list_add(&trg->link, &resv->region_cache);
		resv->region_cache_count++;
		goto retry_locked;
	}

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	/* Locate the region we are before or in. */
	list_for_each_entry(rg, head, link)
		if (f <= rg->to)
			break;

	/* If we are below the current region then a new region is required.
	 * Subtle, allocate a new region at the position but make it zero
	 * size such that we can guarantee to record the reservation. */
	if (&rg->link == head || t < rg->from) {
399
		if (!nrg) {
400
			resv->adds_in_progress--;
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			spin_unlock(&resv->lock);
			nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
			if (!nrg)
				return -ENOMEM;

			nrg->from = f;
			nrg->to   = f;
			INIT_LIST_HEAD(&nrg->link);
			goto retry;
		}
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		list_add(&nrg->link, rg->link.prev);
		chg = t - f;
		goto out_nrg;
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	}

	/* Round our left edge to the current segment if it encloses us. */
	if (f > rg->from)
		f = rg->from;
	chg = t - f;

	/* Check for and consume any regions we now overlap with. */
	list_for_each_entry(rg, rg->link.prev, link) {
		if (&rg->link == head)
			break;
		if (rg->from > t)
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			goto out;
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		/* We overlap with this area, if it extends further than
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		 * us then we must extend ourselves.  Account for its
		 * existing reservation. */
		if (rg->to > t) {
			chg += rg->to - t;
			t = rg->to;
		}
		chg -= rg->to - rg->from;
	}
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out:
	spin_unlock(&resv->lock);
	/*  We already know we raced and no longer need the new region */
	kfree(nrg);
	return chg;
out_nrg:
	spin_unlock(&resv->lock);
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	return chg;
}

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/*
 * 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.
 *
 * 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)
{
	spin_lock(&resv->lock);
	VM_BUG_ON(!resv->region_cache_count);
	resv->adds_in_progress--;
	spin_unlock(&resv->lock);
}

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/*
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 * 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.
481
 */
482
static long region_del(struct resv_map *resv, long f, long t)
483
{
484
	struct list_head *head = &resv->regions;
485
	struct file_region *rg, *trg;
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	struct file_region *nrg = NULL;
	long del = 0;
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retry:
490
	spin_lock(&resv->lock);
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	list_for_each_entry_safe(rg, trg, head, link) {
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		/*
		 * 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))
500
			continue;
501

502
		if (rg->from >= t)
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			break;

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

			del += t - f;

			/* New entry for end of split region */
			nrg->from = t;
			nrg->to = rg->to;
			INIT_LIST_HEAD(&nrg->link);

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

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

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

		if (f <= rg->from) {	/* Trim beginning of region */
			del += t - rg->from;
			rg->from = t;
		} else {		/* Trim end of region */
			del += rg->to - f;
			rg->to = f;
		}
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	}
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	spin_unlock(&resv->lock);
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	kfree(nrg);
	return del;
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}

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/*
 * 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.
 */
572
void hugetlb_fix_reserve_counts(struct inode *inode)
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{
	struct hugepage_subpool *spool = subpool_inode(inode);
	long rsv_adjust;

	rsv_adjust = hugepage_subpool_get_pages(spool, 1);
578
	if (rsv_adjust) {
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		struct hstate *h = hstate_inode(inode);

		hugetlb_acct_memory(h, 1);
	}
}

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/*
 * Count and return the number of huge pages in the reserve map
 * that intersect with the range [f, t).
 */
589
static long region_count(struct resv_map *resv, long f, long t)
590
{
591
	struct list_head *head = &resv->regions;
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	struct file_region *rg;
	long chg = 0;

595
	spin_lock(&resv->lock);
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	/* Locate each segment we overlap with, and count that overlap. */
	list_for_each_entry(rg, head, link) {
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		long seg_from;
		long seg_to;
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		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;
	}
611
	spin_unlock(&resv->lock);
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	return chg;
}

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/*
 * Convert the address within this vma to the page offset within
 * the mapping, in pagecache page units; huge pages here.
 */
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static pgoff_t vma_hugecache_offset(struct hstate *h,
			struct vm_area_struct *vma, unsigned long address)
622
{
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	return ((address - vma->vm_start) >> huge_page_shift(h)) +
			(vma->vm_pgoff >> huge_page_order(h));
625 626
}

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pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
				     unsigned long address)
{
	return vma_hugecache_offset(hstate_vma(vma), vma, address);
}
632
EXPORT_SYMBOL_GPL(linear_hugepage_index);
633

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/*
 * Return the size of the pages allocated when backing a VMA. In the majority
 * cases this will be same size as used by the page table entries.
 */
unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
{
	struct hstate *hstate;

	if (!is_vm_hugetlb_page(vma))
		return PAGE_SIZE;

	hstate = hstate_vma(vma);

647
	return 1UL << huge_page_shift(hstate);
648
}
649
EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
650

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/*
 * 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 version of this
 * function is required.
 */
#ifndef vma_mmu_pagesize
unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
{
	return vma_kernel_pagesize(vma);
}
#endif

664 665 666 667 668 669 670
/*
 * 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)
671
#define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
672

673 674 675 676 677 678 679 680 681
/*
 * 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 reset_vma_resv_huge_pages() 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.
682 683 684 685 686 687 688 689 690
 *
 * 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.
691
 */
692 693 694 695 696 697 698 699 700 701 702
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;
}

703
struct resv_map *resv_map_alloc(void)
704 705
{
	struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
706 707 708 709 710
	struct file_region *rg = kmalloc(sizeof(*rg), GFP_KERNEL);

	if (!resv_map || !rg) {
		kfree(resv_map);
		kfree(rg);
711
		return NULL;
712
	}
713 714

	kref_init(&resv_map->refs);
715
	spin_lock_init(&resv_map->lock);
716 717
	INIT_LIST_HEAD(&resv_map->regions);

718 719 720 721 722 723
	resv_map->adds_in_progress = 0;

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

724 725 726
	return resv_map;
}

727
void resv_map_release(struct kref *ref)
728 729
{
	struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
730 731
	struct list_head *head = &resv_map->region_cache;
	struct file_region *rg, *trg;
732 733

	/* Clear out any active regions before we release the map. */
734
	region_del(resv_map, 0, LONG_MAX);
735 736 737 738 739 740 741 742 743

	/* ... 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);

744 745 746
	kfree(resv_map);
}

747 748 749 750 751
static inline struct resv_map *inode_resv_map(struct inode *inode)
{
	return inode->i_mapping->private_data;
}

752
static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
753
{
754
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
755 756 757 758 759 760 761
	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 {
762 763
		return (struct resv_map *)(get_vma_private_data(vma) &
							~HPAGE_RESV_MASK);
764
	}
765 766
}

767
static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
768
{
769 770
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
	VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
771

772 773
	set_vma_private_data(vma, (get_vma_private_data(vma) &
				HPAGE_RESV_MASK) | (unsigned long)map);
774 775 776 777
}

static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
{
778 779
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
	VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
780 781

	set_vma_private_data(vma, get_vma_private_data(vma) | flags);
782 783 784 785
}

static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
{
786
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
787 788

	return (get_vma_private_data(vma) & flag) != 0;
789 790
}

791
/* Reset counters to 0 and clear all HPAGE_RESV_* flags */
792 793
void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
{
794
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
795
	if (!(vma->vm_flags & VM_MAYSHARE))
796 797 798 799
		vma->vm_private_data = (void *)0;
}

/* Returns true if the VMA has associated reserve pages */
800
static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
801
{
802 803 804 805 806 807 808 809 810 811 812
	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)
813
			return true;
814
		else
815
			return false;
816
	}
817 818

	/* Shared mappings always use reserves */
819 820 821 822 823 824 825 826 827 828 829 830 831
	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 reverves to
		 * use.  This situation is indicated if chg != 0.
		 */
		if (chg)
			return false;
		else
			return true;
	}
832 833 834 835 836

	/*
	 * Only the process that called mmap() has reserves for
	 * private mappings.
	 */
837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857
	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;
	}
858

859
	return false;
860 861
}

862
static void enqueue_huge_page(struct hstate *h, struct page *page)
L
Linus Torvalds 已提交
863 864
{
	int nid = page_to_nid(page);
865
	list_move(&page->lru, &h->hugepage_freelists[nid]);
866 867
	h->free_huge_pages++;
	h->free_huge_pages_node[nid]++;
L
Linus Torvalds 已提交
868 869
}

870
static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid)
871 872 873
{
	struct page *page;

874
	list_for_each_entry(page, &h->hugepage_freelists[nid], lru)
875
		if (!PageHWPoison(page))
876 877 878 879 880 881
			break;
	/*
	 * if 'non-isolated free hugepage' not found on the list,
	 * the allocation fails.
	 */
	if (&h->hugepage_freelists[nid] == &page->lru)
882
		return NULL;
883
	list_move(&page->lru, &h->hugepage_activelist);
884
	set_page_refcounted(page);
885 886 887 888 889
	h->free_huge_pages--;
	h->free_huge_pages_node[nid]--;
	return page;
}

890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905
static struct page *dequeue_huge_page_node(struct hstate *h, int nid)
{
	struct page *page;
	int node;

	if (nid != NUMA_NO_NODE)
		return dequeue_huge_page_node_exact(h, nid);

	for_each_online_node(node) {
		page = dequeue_huge_page_node_exact(h, node);
		if (page)
			return page;
	}
	return NULL;
}

906 907 908
/* Movability of hugepages depends on migration support. */
static inline gfp_t htlb_alloc_mask(struct hstate *h)
{
909
	if (hugepages_treat_as_movable || hugepage_migration_supported(h))
910 911 912 913 914
		return GFP_HIGHUSER_MOVABLE;
	else
		return GFP_HIGHUSER;
}

915 916
static struct page *dequeue_huge_page_vma(struct hstate *h,
				struct vm_area_struct *vma,
917 918
				unsigned long address, int avoid_reserve,
				long chg)
L
Linus Torvalds 已提交
919
{
920
	struct page *page = NULL;
921
	struct mempolicy *mpol;
922
	nodemask_t *nodemask;
923 924
	gfp_t gfp_mask;
	int nid;
925
	struct zonelist *zonelist;
926 927
	struct zone *zone;
	struct zoneref *z;
928
	unsigned int cpuset_mems_cookie;
L
Linus Torvalds 已提交
929

930 931 932 933 934
	/*
	 * 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
	 */
935
	if (!vma_has_reserves(vma, chg) &&
936
			h->free_huge_pages - h->resv_huge_pages == 0)
937
		goto err;
938

939
	/* If reserves cannot be used, ensure enough pages are in the pool */
940
	if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
941
		goto err;
942

943
retry_cpuset:
944
	cpuset_mems_cookie = read_mems_allowed_begin();
945 946 947
	gfp_mask = htlb_alloc_mask(h);
	nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
	zonelist = node_zonelist(nid, gfp_mask);
948

949 950
	for_each_zone_zonelist_nodemask(zone, z, zonelist,
						MAX_NR_ZONES - 1, nodemask) {
951
		if (cpuset_zone_allowed(zone, gfp_mask)) {
952 953
			page = dequeue_huge_page_node(h, zone_to_nid(zone));
			if (page) {
954 955 956 957 958
				if (avoid_reserve)
					break;
				if (!vma_has_reserves(vma, chg))
					break;

959
				SetPagePrivate(page);
960
				h->resv_huge_pages--;
961 962
				break;
			}
A
Andrew Morton 已提交
963
		}
L
Linus Torvalds 已提交
964
	}
965

966
	mpol_cond_put(mpol);
967
	if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
968
		goto retry_cpuset;
L
Linus Torvalds 已提交
969
	return page;
970 971 972

err:
	return NULL;
L
Linus Torvalds 已提交
973 974
}

975 976 977 978 979 980 981 982 983
/*
 * 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)
{
984
	nid = next_node_in(nid, *nodes_allowed);
985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045
	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(struct hstate *h,
					nodemask_t *nodes_allowed)
{
	int nid;

	VM_BUG_ON(!nodes_allowed);

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

	return nid;
}

/*
 * helper for free_pool_huge_page() - 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(hs, nr_nodes, node, mask)		\
	for (nr_nodes = nodes_weight(*mask);				\
		nr_nodes > 0 &&						\
		((node = hstate_next_node_to_alloc(hs, 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--)

1046
#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
1047
static void destroy_compound_gigantic_page(struct page *page,
1048
					unsigned int order)
1049 1050 1051 1052 1053
{
	int i;
	int nr_pages = 1 << order;
	struct page *p = page + 1;

1054
	atomic_set(compound_mapcount_ptr(page), 0);
1055
	for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
1056
		clear_compound_head(p);
1057 1058 1059 1060 1061 1062 1063
		set_page_refcounted(p);
	}

	set_compound_order(page, 0);
	__ClearPageHead(page);
}

1064
static void free_gigantic_page(struct page *page, unsigned int order)
1065 1066 1067 1068 1069 1070 1071 1072
{
	free_contig_range(page_to_pfn(page), 1 << order);
}

static int __alloc_gigantic_page(unsigned long start_pfn,
				unsigned long nr_pages)
{
	unsigned long end_pfn = start_pfn + nr_pages;
1073 1074
	return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE,
				  GFP_KERNEL);
1075 1076
}

1077 1078
static bool pfn_range_valid_gigantic(struct zone *z,
			unsigned long start_pfn, unsigned long nr_pages)
1079 1080 1081 1082 1083 1084 1085 1086 1087 1088
{
	unsigned long i, end_pfn = start_pfn + nr_pages;
	struct page *page;

	for (i = start_pfn; i < end_pfn; i++) {
		if (!pfn_valid(i))
			return false;

		page = pfn_to_page(i);

1089 1090 1091
		if (page_zone(page) != z)
			return false;

1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111
		if (PageReserved(page))
			return false;

		if (page_count(page) > 0)
			return false;

		if (PageHuge(page))
			return false;
	}

	return true;
}

static bool zone_spans_last_pfn(const struct zone *zone,
			unsigned long start_pfn, unsigned long nr_pages)
{
	unsigned long last_pfn = start_pfn + nr_pages - 1;
	return zone_spans_pfn(zone, last_pfn);
}

1112
static struct page *alloc_gigantic_page(int nid, unsigned int order)
1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123
{
	unsigned long nr_pages = 1 << order;
	unsigned long ret, pfn, flags;
	struct zone *z;

	z = NODE_DATA(nid)->node_zones;
	for (; z - NODE_DATA(nid)->node_zones < MAX_NR_ZONES; z++) {
		spin_lock_irqsave(&z->lock, flags);

		pfn = ALIGN(z->zone_start_pfn, nr_pages);
		while (zone_spans_last_pfn(z, pfn, nr_pages)) {
1124
			if (pfn_range_valid_gigantic(z, pfn, nr_pages)) {
1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147
				/*
				 * We release the zone lock here because
				 * alloc_contig_range() will also lock the zone
				 * at some point. If there's an allocation
				 * spinning on this lock, it may win the race
				 * and cause alloc_contig_range() to fail...
				 */
				spin_unlock_irqrestore(&z->lock, flags);
				ret = __alloc_gigantic_page(pfn, nr_pages);
				if (!ret)
					return pfn_to_page(pfn);
				spin_lock_irqsave(&z->lock, flags);
			}
			pfn += nr_pages;
		}

		spin_unlock_irqrestore(&z->lock, flags);
	}

	return NULL;
}

static void prep_new_huge_page(struct hstate *h, struct page *page, int nid);
1148
static void prep_compound_gigantic_page(struct page *page, unsigned int order);
1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177

static struct page *alloc_fresh_gigantic_page_node(struct hstate *h, int nid)
{
	struct page *page;

	page = alloc_gigantic_page(nid, huge_page_order(h));
	if (page) {
		prep_compound_gigantic_page(page, huge_page_order(h));
		prep_new_huge_page(h, page, nid);
	}

	return page;
}

static int alloc_fresh_gigantic_page(struct hstate *h,
				nodemask_t *nodes_allowed)
{
	struct page *page = NULL;
	int nr_nodes, node;

	for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
		page = alloc_fresh_gigantic_page_node(h, node);
		if (page)
			return 1;
	}

	return 0;
}

1178
#else /* !CONFIG_ARCH_HAS_GIGANTIC_PAGE */
1179
static inline bool gigantic_page_supported(void) { return false; }
1180
static inline void free_gigantic_page(struct page *page, unsigned int order) { }
1181
static inline void destroy_compound_gigantic_page(struct page *page,
1182
						unsigned int order) { }
1183 1184 1185 1186
static inline int alloc_fresh_gigantic_page(struct hstate *h,
					nodemask_t *nodes_allowed) { return 0; }
#endif

1187
static void update_and_free_page(struct hstate *h, struct page *page)
A
Adam Litke 已提交
1188 1189
{
	int i;
1190

1191 1192
	if (hstate_is_gigantic(h) && !gigantic_page_supported())
		return;
1193

1194 1195 1196
	h->nr_huge_pages--;
	h->nr_huge_pages_node[page_to_nid(page)]--;
	for (i = 0; i < pages_per_huge_page(h); i++) {
1197 1198
		page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
				1 << PG_referenced | 1 << PG_dirty |
1199 1200
				1 << PG_active | 1 << PG_private |
				1 << PG_writeback);
A
Adam Litke 已提交
1201
	}
1202
	VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page);
1203
	set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
A
Adam Litke 已提交
1204
	set_page_refcounted(page);
1205 1206 1207 1208 1209 1210
	if (hstate_is_gigantic(h)) {
		destroy_compound_gigantic_page(page, huge_page_order(h));
		free_gigantic_page(page, huge_page_order(h));
	} else {
		__free_pages(page, huge_page_order(h));
	}
A
Adam Litke 已提交
1211 1212
}

1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223
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;
}

1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248
/*
 * Test to determine whether the hugepage is "active/in-use" (i.e. being linked
 * to hstate->hugepage_activelist.)
 *
 * This function can be called for tail pages, but never returns true for them.
 */
bool page_huge_active(struct page *page)
{
	VM_BUG_ON_PAGE(!PageHuge(page), page);
	return PageHead(page) && PagePrivate(&page[1]);
}

/* never called for tail page */
static void set_page_huge_active(struct page *page)
{
	VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
	SetPagePrivate(&page[1]);
}

static void clear_page_huge_active(struct page *page)
{
	VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
	ClearPagePrivate(&page[1]);
}

1249
void free_huge_page(struct page *page)
1250
{
1251 1252 1253 1254
	/*
	 * Can't pass hstate in here because it is called from the
	 * compound page destructor.
	 */
1255
	struct hstate *h = page_hstate(page);
1256
	int nid = page_to_nid(page);
1257 1258
	struct hugepage_subpool *spool =
		(struct hugepage_subpool *)page_private(page);
1259
	bool restore_reserve;
1260

1261
	set_page_private(page, 0);
1262
	page->mapping = NULL;
1263 1264
	VM_BUG_ON_PAGE(page_count(page), page);
	VM_BUG_ON_PAGE(page_mapcount(page), page);
1265
	restore_reserve = PagePrivate(page);
1266
	ClearPagePrivate(page);
1267

1268 1269 1270 1271 1272 1273 1274 1275
	/*
	 * 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;

1276
	spin_lock(&hugetlb_lock);
1277
	clear_page_huge_active(page);
1278 1279
	hugetlb_cgroup_uncharge_page(hstate_index(h),
				     pages_per_huge_page(h), page);
1280 1281 1282
	if (restore_reserve)
		h->resv_huge_pages++;

1283
	if (h->surplus_huge_pages_node[nid]) {
1284 1285
		/* remove the page from active list */
		list_del(&page->lru);
1286 1287 1288
		update_and_free_page(h, page);
		h->surplus_huge_pages--;
		h->surplus_huge_pages_node[nid]--;
1289
	} else {
1290
		arch_clear_hugepage_flags(page);
1291
		enqueue_huge_page(h, page);
1292
	}
1293 1294 1295
	spin_unlock(&hugetlb_lock);
}

1296
static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
1297
{
1298
	INIT_LIST_HEAD(&page->lru);
1299
	set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
1300
	spin_lock(&hugetlb_lock);
1301
	set_hugetlb_cgroup(page, NULL);
1302 1303
	h->nr_huge_pages++;
	h->nr_huge_pages_node[nid]++;
1304 1305 1306 1307
	spin_unlock(&hugetlb_lock);
	put_page(page); /* free it into the hugepage allocator */
}

1308
static void prep_compound_gigantic_page(struct page *page, unsigned int order)
1309 1310 1311 1312 1313 1314 1315
{
	int i;
	int nr_pages = 1 << order;
	struct page *p = page + 1;

	/* we rely on prep_new_huge_page to set the destructor */
	set_compound_order(page, order);
1316
	__ClearPageReserved(page);
1317
	__SetPageHead(page);
1318
	for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331
		/*
		 * 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.  Otherwse 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().
		 */
		__ClearPageReserved(p);
1332
		set_page_count(p, 0);
1333
		set_compound_head(p, page);
1334
	}
1335
	atomic_set(compound_mapcount_ptr(page), -1);
1336 1337
}

A
Andrew Morton 已提交
1338 1339 1340 1341 1342
/*
 * PageHuge() only returns true for hugetlbfs pages, but not for normal or
 * transparent huge pages.  See the PageTransHuge() documentation for more
 * details.
 */
1343 1344 1345 1346 1347 1348
int PageHuge(struct page *page)
{
	if (!PageCompound(page))
		return 0;

	page = compound_head(page);
1349
	return page[1].compound_dtor == HUGETLB_PAGE_DTOR;
1350
}
1351 1352
EXPORT_SYMBOL_GPL(PageHuge);

1353 1354 1355 1356 1357 1358 1359 1360 1361
/*
 * PageHeadHuge() only returns true for hugetlbfs head page, but not for
 * normal or transparent huge pages.
 */
int PageHeadHuge(struct page *page_head)
{
	if (!PageHead(page_head))
		return 0;

1362
	return get_compound_page_dtor(page_head) == free_huge_page;
1363 1364
}

1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381
pgoff_t __basepage_index(struct page *page)
{
	struct page *page_head = compound_head(page);
	pgoff_t index = page_index(page_head);
	unsigned long compound_idx;

	if (!PageHuge(page_head))
		return page_index(page);

	if (compound_order(page_head) >= MAX_ORDER)
		compound_idx = page_to_pfn(page) - page_to_pfn(page_head);
	else
		compound_idx = page - page_head;

	return (index << compound_order(page_head)) + compound_idx;
}

1382
static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
L
Linus Torvalds 已提交
1383 1384
{
	struct page *page;
1385

1386
	page = __alloc_pages_node(nid,
1387
		htlb_alloc_mask(h)|__GFP_COMP|__GFP_THISNODE|
1388
						__GFP_REPEAT|__GFP_NOWARN,
1389
		huge_page_order(h));
L
Linus Torvalds 已提交
1390
	if (page) {
1391
		prep_new_huge_page(h, page, nid);
L
Linus Torvalds 已提交
1392
	}
1393 1394 1395 1396

	return page;
}

1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418
static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
{
	struct page *page;
	int nr_nodes, node;
	int ret = 0;

	for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
		page = alloc_fresh_huge_page_node(h, node);
		if (page) {
			ret = 1;
			break;
		}
	}

	if (ret)
		count_vm_event(HTLB_BUDDY_PGALLOC);
	else
		count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);

	return ret;
}

1419 1420 1421 1422 1423 1424
/*
 * Free huge page from pool from next node to free.
 * Attempt to keep persistent huge pages more or less
 * balanced over allowed nodes.
 * Called with hugetlb_lock locked.
 */
1425 1426
static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
							 bool acct_surplus)
1427
{
1428
	int nr_nodes, node;
1429 1430
	int ret = 0;

1431
	for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
1432 1433 1434 1435
		/*
		 * If we're returning unused surplus pages, only examine
		 * nodes with surplus pages.
		 */
1436 1437
		if ((!acct_surplus || h->surplus_huge_pages_node[node]) &&
		    !list_empty(&h->hugepage_freelists[node])) {
1438
			struct page *page =
1439
				list_entry(h->hugepage_freelists[node].next,
1440 1441 1442
					  struct page, lru);
			list_del(&page->lru);
			h->free_huge_pages--;
1443
			h->free_huge_pages_node[node]--;
1444 1445
			if (acct_surplus) {
				h->surplus_huge_pages--;
1446
				h->surplus_huge_pages_node[node]--;
1447
			}
1448 1449
			update_and_free_page(h, page);
			ret = 1;
1450
			break;
1451
		}
1452
	}
1453 1454 1455 1456

	return ret;
}

1457 1458
/*
 * Dissolve a given free hugepage into free buddy pages. This function does
1459 1460 1461
 * nothing for in-use (including surplus) hugepages. Returns -EBUSY if the
 * number of free hugepages would be reduced below the number of reserved
 * hugepages.
1462
 */
1463
int dissolve_free_huge_page(struct page *page)
1464
{
1465 1466
	int rc = 0;

1467 1468
	spin_lock(&hugetlb_lock);
	if (PageHuge(page) && !page_count(page)) {
1469 1470 1471
		struct page *head = compound_head(page);
		struct hstate *h = page_hstate(head);
		int nid = page_to_nid(head);
1472 1473 1474 1475
		if (h->free_huge_pages - h->resv_huge_pages == 0) {
			rc = -EBUSY;
			goto out;
		}
1476 1477 1478 1479 1480 1481 1482 1483
		/*
		 * Move PageHWPoison flag from head page to the raw error page,
		 * which makes any subpages rather than the error page reusable.
		 */
		if (PageHWPoison(head) && page != head) {
			SetPageHWPoison(page);
			ClearPageHWPoison(head);
		}
1484
		list_del(&head->lru);
1485 1486
		h->free_huge_pages--;
		h->free_huge_pages_node[nid]--;
1487
		h->max_huge_pages--;
1488
		update_and_free_page(h, head);
1489
	}
1490
out:
1491
	spin_unlock(&hugetlb_lock);
1492
	return rc;
1493 1494 1495 1496 1497
}

/*
 * Dissolve free hugepages in a given pfn range. Used by memory hotplug to
 * make specified memory blocks removable from the system.
1498 1499
 * Note that this will dissolve a free gigantic hugepage completely, if any
 * part of it lies within the given range.
1500 1501
 * Also note that if dissolve_free_huge_page() returns with an error, all
 * free hugepages that were dissolved before that error are lost.
1502
 */
1503
int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
1504 1505
{
	unsigned long pfn;
1506
	struct page *page;
1507
	int rc = 0;
1508

1509
	if (!hugepages_supported())
1510
		return rc;
1511

1512 1513 1514 1515 1516 1517 1518 1519
	for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order) {
		page = pfn_to_page(pfn);
		if (PageHuge(page) && !page_count(page)) {
			rc = dissolve_free_huge_page(page);
			if (rc)
				break;
		}
	}
1520 1521

	return rc;
1522 1523
}

1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541
/*
 * There are 3 ways this can get called:
 * 1. With vma+addr: we use the VMA's memory policy
 * 2. With !vma, but nid=NUMA_NO_NODE:  We try to allocate a huge
 *    page from any node, and let the buddy allocator itself figure
 *    it out.
 * 3. With !vma, but nid!=NUMA_NO_NODE.  We allocate a huge page
 *    strictly from 'nid'
 */
static struct page *__hugetlb_alloc_buddy_huge_page(struct hstate *h,
		struct vm_area_struct *vma, unsigned long addr, int nid)
{
	int order = huge_page_order(h);
	gfp_t gfp = htlb_alloc_mask(h)|__GFP_COMP|__GFP_REPEAT|__GFP_NOWARN;
	unsigned int cpuset_mems_cookie;

	/*
	 * We need a VMA to get a memory policy.  If we do not
D
Dave Hansen 已提交
1542 1543 1544 1545 1546 1547
	 * have one, we use the 'nid' argument.
	 *
	 * The mempolicy stuff below has some non-inlined bits
	 * and calls ->vm_ops.  That makes it hard to optimize at
	 * compile-time, even when NUMA is off and it does
	 * nothing.  This helps the compiler optimize it out.
1548
	 */
D
Dave Hansen 已提交
1549
	if (!IS_ENABLED(CONFIG_NUMA) || !vma) {
1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565
		/*
		 * If a specific node is requested, make sure to
		 * get memory from there, but only when a node
		 * is explicitly specified.
		 */
		if (nid != NUMA_NO_NODE)
			gfp |= __GFP_THISNODE;
		/*
		 * Make sure to call something that can handle
		 * nid=NUMA_NO_NODE
		 */
		return alloc_pages_node(nid, gfp, order);
	}

	/*
	 * OK, so we have a VMA.  Fetch the mempolicy and try to
D
Dave Hansen 已提交
1566 1567
	 * allocate a huge page with it.  We will only reach this
	 * when CONFIG_NUMA=y.
1568 1569 1570 1571
	 */
	do {
		struct page *page;
		struct mempolicy *mpol;
1572
		int nid;
1573 1574 1575
		nodemask_t *nodemask;

		cpuset_mems_cookie = read_mems_allowed_begin();
1576
		nid = huge_node(vma, addr, gfp, &mpol, &nodemask);
1577
		mpol_cond_put(mpol);
1578
		page = __alloc_pages_nodemask(gfp, order, nid, nodemask);
1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599
		if (page)
			return page;
	} while (read_mems_allowed_retry(cpuset_mems_cookie));

	return NULL;
}

/*
 * There are two ways to allocate a huge page:
 * 1. When you have a VMA and an address (like a fault)
 * 2. When you have no VMA (like when setting /proc/.../nr_hugepages)
 *
 * 'vma' and 'addr' are only for (1).  'nid' is always NUMA_NO_NODE in
 * this case which signifies that the allocation should be done with
 * respect for the VMA's memory policy.
 *
 * For (2), we ignore 'vma' and 'addr' and use 'nid' exclusively. This
 * implies that memory policies will not be taken in to account.
 */
static struct page *__alloc_buddy_huge_page(struct hstate *h,
		struct vm_area_struct *vma, unsigned long addr, int nid)
1600 1601
{
	struct page *page;
1602
	unsigned int r_nid;
1603

1604
	if (hstate_is_gigantic(h))
1605 1606
		return NULL;

1607 1608 1609 1610 1611 1612
	/*
	 * Make sure that anyone specifying 'nid' is not also specifying a VMA.
	 * This makes sure the caller is picking _one_ of the modes with which
	 * we can call this function, not both.
	 */
	if (vma || (addr != -1)) {
D
Dave Hansen 已提交
1613 1614
		VM_WARN_ON_ONCE(addr == -1);
		VM_WARN_ON_ONCE(nid != NUMA_NO_NODE);
1615
	}
1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639
	/*
	 * Assume we will successfully allocate the surplus page to
	 * prevent racing processes from causing the surplus to exceed
	 * overcommit
	 *
	 * This however introduces a different race, where a process B
	 * tries to grow the static hugepage pool while alloc_pages() is
	 * called by process A. B will only examine the per-node
	 * counters in determining if surplus huge pages can be
	 * converted to normal huge pages in adjust_pool_surplus(). A
	 * won't be able to increment the per-node counter, until the
	 * lock is dropped by B, but B doesn't drop hugetlb_lock until
	 * no more huge pages can be converted from surplus to normal
	 * state (and doesn't try to convert again). Thus, we have a
	 * case where a surplus huge page exists, the pool is grown, and
	 * the surplus huge page still exists after, even though it
	 * should just have been converted to a normal huge page. This
	 * does not leak memory, though, as the hugepage will be freed
	 * once it is out of use. It also does not allow the counters to
	 * go out of whack in adjust_pool_surplus() as we don't modify
	 * the node values until we've gotten the hugepage and only the
	 * per-node value is checked there.
	 */
	spin_lock(&hugetlb_lock);
1640
	if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
1641 1642 1643
		spin_unlock(&hugetlb_lock);
		return NULL;
	} else {
1644 1645
		h->nr_huge_pages++;
		h->surplus_huge_pages++;
1646 1647 1648
	}
	spin_unlock(&hugetlb_lock);

1649
	page = __hugetlb_alloc_buddy_huge_page(h, vma, addr, nid);
1650 1651

	spin_lock(&hugetlb_lock);
1652
	if (page) {
1653
		INIT_LIST_HEAD(&page->lru);
1654
		r_nid = page_to_nid(page);
1655
		set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
1656
		set_hugetlb_cgroup(page, NULL);
1657 1658 1659
		/*
		 * We incremented the global counters already
		 */
1660 1661
		h->nr_huge_pages_node[r_nid]++;
		h->surplus_huge_pages_node[r_nid]++;
1662
		__count_vm_event(HTLB_BUDDY_PGALLOC);
1663
	} else {
1664 1665
		h->nr_huge_pages--;
		h->surplus_huge_pages--;
1666
		__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
1667
	}
1668
	spin_unlock(&hugetlb_lock);
1669 1670 1671 1672

	return page;
}

1673 1674 1675 1676 1677
/*
 * Allocate a huge page from 'nid'.  Note, 'nid' may be
 * NUMA_NO_NODE, which means that it may be allocated
 * anywhere.
 */
D
Dave Hansen 已提交
1678
static
1679 1680 1681 1682 1683 1684 1685 1686 1687 1688
struct page *__alloc_buddy_huge_page_no_mpol(struct hstate *h, int nid)
{
	unsigned long addr = -1;

	return __alloc_buddy_huge_page(h, NULL, addr, nid);
}

/*
 * Use the VMA's mpolicy to allocate a huge page from the buddy.
 */
D
Dave Hansen 已提交
1689
static
1690 1691 1692 1693 1694 1695
struct page *__alloc_buddy_huge_page_with_mpol(struct hstate *h,
		struct vm_area_struct *vma, unsigned long addr)
{
	return __alloc_buddy_huge_page(h, vma, addr, NUMA_NO_NODE);
}

1696 1697 1698 1699 1700 1701 1702
/*
 * This allocation function is useful in the context where vma is irrelevant.
 * E.g. soft-offlining uses this function because it only cares physical
 * address of error page.
 */
struct page *alloc_huge_page_node(struct hstate *h, int nid)
{
1703
	struct page *page = NULL;
1704 1705

	spin_lock(&hugetlb_lock);
1706 1707
	if (h->free_huge_pages - h->resv_huge_pages > 0)
		page = dequeue_huge_page_node(h, nid);
1708 1709
	spin_unlock(&hugetlb_lock);

1710
	if (!page)
1711
		page = __alloc_buddy_huge_page_no_mpol(h, nid);
1712 1713 1714 1715

	return page;
}

1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742
struct page *alloc_huge_page_nodemask(struct hstate *h, const nodemask_t *nmask)
{
	struct page *page = NULL;
	int node;

	spin_lock(&hugetlb_lock);
	if (h->free_huge_pages - h->resv_huge_pages > 0) {
		for_each_node_mask(node, *nmask) {
			page = dequeue_huge_page_node_exact(h, node);
			if (page)
				break;
		}
	}
	spin_unlock(&hugetlb_lock);
	if (page)
		return page;

	/* No reservations, try to overcommit */
	for_each_node_mask(node, *nmask) {
		page = __alloc_buddy_huge_page_no_mpol(h, node);
		if (page)
			return page;
	}

	return NULL;
}

1743
/*
L
Lucas De Marchi 已提交
1744
 * Increase the hugetlb pool such that it can accommodate a reservation
1745 1746
 * of size 'delta'.
 */
1747
static int gather_surplus_pages(struct hstate *h, int delta)
1748 1749 1750 1751 1752
{
	struct list_head surplus_list;
	struct page *page, *tmp;
	int ret, i;
	int needed, allocated;
1753
	bool alloc_ok = true;
1754

1755
	needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
1756
	if (needed <= 0) {
1757
		h->resv_huge_pages += delta;
1758
		return 0;
1759
	}
1760 1761 1762 1763 1764 1765 1766 1767

	allocated = 0;
	INIT_LIST_HEAD(&surplus_list);

	ret = -ENOMEM;
retry:
	spin_unlock(&hugetlb_lock);
	for (i = 0; i < needed; i++) {
1768
		page = __alloc_buddy_huge_page_no_mpol(h, NUMA_NO_NODE);
1769 1770 1771 1772
		if (!page) {
			alloc_ok = false;
			break;
		}
1773
		list_add(&page->lru, &surplus_list);
1774
		cond_resched();
1775
	}
1776
	allocated += i;
1777 1778 1779 1780 1781 1782

	/*
	 * After retaking hugetlb_lock, we need to recalculate 'needed'
	 * because either resv_huge_pages or free_huge_pages may have changed.
	 */
	spin_lock(&hugetlb_lock);
1783 1784
	needed = (h->resv_huge_pages + delta) -
			(h->free_huge_pages + allocated);
1785 1786 1787 1788 1789 1790 1791 1792 1793 1794
	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;
	}
1795 1796
	/*
	 * The surplus_list now contains _at_least_ the number of extra pages
L
Lucas De Marchi 已提交
1797
	 * needed to accommodate the reservation.  Add the appropriate number
1798
	 * of pages to the hugetlb pool and free the extras back to the buddy
1799 1800 1801
	 * 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.
1802 1803
	 */
	needed += allocated;
1804
	h->resv_huge_pages += delta;
1805
	ret = 0;
1806

1807
	/* Free the needed pages to the hugetlb pool */
1808
	list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
1809 1810
		if ((--needed) < 0)
			break;
1811 1812 1813 1814 1815
		/*
		 * This page is now managed by the hugetlb allocator and has
		 * no users -- drop the buddy allocator's reference.
		 */
		put_page_testzero(page);
1816
		VM_BUG_ON_PAGE(page_count(page), page);
1817
		enqueue_huge_page(h, page);
1818
	}
1819
free:
1820
	spin_unlock(&hugetlb_lock);
1821 1822

	/* Free unnecessary surplus pages to the buddy allocator */
1823 1824
	list_for_each_entry_safe(page, tmp, &surplus_list, lru)
		put_page(page);
1825
	spin_lock(&hugetlb_lock);
1826 1827 1828 1829 1830

	return ret;
}

/*
1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842
 * 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.
 *
 * Called with hugetlb_lock held.  However, the lock could be dropped (and
 * reacquired) during calls to cond_resched_lock.  Whenever dropping the lock,
 * we must make sure nobody else can claim pages we are in the process of
 * freeing.  Do this by ensuring resv_huge_page always is greater than the
 * number of huge pages we plan to free when dropping the lock.
1843
 */
1844 1845
static void return_unused_surplus_pages(struct hstate *h,
					unsigned long unused_resv_pages)
1846 1847 1848
{
	unsigned long nr_pages;

1849
	/* Cannot return gigantic pages currently */
1850
	if (hstate_is_gigantic(h))
1851
		goto out;
1852

1853 1854 1855 1856
	/*
	 * Part (or even all) of the reservation could have been backed
	 * by pre-allocated pages. Only free surplus pages.
	 */
1857
	nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
1858

1859 1860
	/*
	 * We want to release as many surplus pages as possible, spread
1861 1862 1863 1864 1865
	 * 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.
	 * free_pool_huge_page() will balance the the freed pages across the
	 * on-line nodes with memory and will handle the hstate accounting.
1866 1867 1868 1869
	 *
	 * Note that we decrement resv_huge_pages as we free the pages.  If
	 * we drop the lock, resv_huge_pages will still be sufficiently large
	 * to cover subsequent pages we may free.
1870 1871
	 */
	while (nr_pages--) {
1872 1873
		h->resv_huge_pages--;
		unused_resv_pages--;
1874
		if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1))
1875
			goto out;
1876
		cond_resched_lock(&hugetlb_lock);
1877
	}
1878 1879 1880 1881

out:
	/* Fully uncommit the reservation */
	h->resv_huge_pages -= unused_resv_pages;
1882 1883
}

1884

1885
/*
1886
 * vma_needs_reservation, vma_commit_reservation and vma_end_reservation
1887
 * are used by the huge page allocation routines to manage reservations.
1888 1889 1890 1891 1892 1893
 *
 * 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
1894 1895 1896
 * 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.
1897 1898 1899 1900 1901 1902
 *
 * 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.
1903 1904 1905 1906 1907
 *
 * 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.
1908
 */
1909 1910 1911
enum vma_resv_mode {
	VMA_NEEDS_RESV,
	VMA_COMMIT_RESV,
1912
	VMA_END_RESV,
1913
	VMA_ADD_RESV,
1914
};
1915 1916
static long __vma_reservation_common(struct hstate *h,
				struct vm_area_struct *vma, unsigned long addr,
1917
				enum vma_resv_mode mode)
1918
{
1919 1920
	struct resv_map *resv;
	pgoff_t idx;
1921
	long ret;
1922

1923 1924
	resv = vma_resv_map(vma);
	if (!resv)
1925
		return 1;
1926

1927
	idx = vma_hugecache_offset(h, vma, addr);
1928 1929
	switch (mode) {
	case VMA_NEEDS_RESV:
1930
		ret = region_chg(resv, idx, idx + 1);
1931 1932 1933 1934
		break;
	case VMA_COMMIT_RESV:
		ret = region_add(resv, idx, idx + 1);
		break;
1935
	case VMA_END_RESV:
1936 1937 1938
		region_abort(resv, idx, idx + 1);
		ret = 0;
		break;
1939 1940 1941 1942 1943 1944 1945 1946
	case VMA_ADD_RESV:
		if (vma->vm_flags & VM_MAYSHARE)
			ret = region_add(resv, idx, idx + 1);
		else {
			region_abort(resv, idx, idx + 1);
			ret = region_del(resv, idx, idx + 1);
		}
		break;
1947 1948 1949
	default:
		BUG();
	}
1950

1951
	if (vma->vm_flags & VM_MAYSHARE)
1952
		return ret;
1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971
	else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) && ret >= 0) {
		/*
		 * 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)
			return 0;
		else
			return 1;
	}
1972
	else
1973
		return ret < 0 ? ret : 0;
1974
}
1975 1976

static long vma_needs_reservation(struct hstate *h,
1977
			struct vm_area_struct *vma, unsigned long addr)
1978
{
1979
	return __vma_reservation_common(h, vma, addr, VMA_NEEDS_RESV);
1980
}
1981

1982 1983 1984
static long vma_commit_reservation(struct hstate *h,
			struct vm_area_struct *vma, unsigned long addr)
{
1985 1986 1987
	return __vma_reservation_common(h, vma, addr, VMA_COMMIT_RESV);
}

1988
static void vma_end_reservation(struct hstate *h,
1989 1990
			struct vm_area_struct *vma, unsigned long addr)
{
1991
	(void)__vma_reservation_common(h, vma, addr, VMA_END_RESV);
1992 1993
}

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043
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);
}

/*
 * This routine is called to restore a reservation on error paths.  In the
 * specific error paths, a huge page was allocated (via alloc_huge_page)
 * and is about to be freed.  If a reservation for the page existed,
 * alloc_huge_page would have consumed the reservation and set PagePrivate
 * in the newly allocated page.  When the page is freed via free_huge_page,
 * the global reservation count will be incremented if PagePrivate is set.
 * However, free_huge_page can not adjust the reserve map.  Adjust the
 * reserve map here to be consistent with global reserve count adjustments
 * to be made by free_huge_page.
 */
static void restore_reserve_on_error(struct hstate *h,
			struct vm_area_struct *vma, unsigned long address,
			struct page *page)
{
	if (unlikely(PagePrivate(page))) {
		long rc = vma_needs_reservation(h, vma, address);

		if (unlikely(rc < 0)) {
			/*
			 * Rare out of memory condition in reserve map
			 * manipulation.  Clear PagePrivate so that
			 * global reserve count will not be incremented
			 * by free_huge_page.  This will make it appear
			 * as though the reservation for this page was
			 * consumed.  This may prevent the task from
			 * faulting in the page at a later time.  This
			 * is better than inconsistent global huge page
			 * accounting of reserve counts.
			 */
			ClearPagePrivate(page);
		} else if (rc) {
			rc = vma_add_reservation(h, vma, address);
			if (unlikely(rc < 0))
				/*
				 * See above comment about rare out of
				 * memory condition.
				 */
				ClearPagePrivate(page);
		} else
			vma_end_reservation(h, vma, address);
	}
}

2044
struct page *alloc_huge_page(struct vm_area_struct *vma,
2045
				    unsigned long addr, int avoid_reserve)
L
Linus Torvalds 已提交
2046
{
2047
	struct hugepage_subpool *spool = subpool_vma(vma);
2048
	struct hstate *h = hstate_vma(vma);
2049
	struct page *page;
2050 2051
	long map_chg, map_commit;
	long gbl_chg;
2052 2053
	int ret, idx;
	struct hugetlb_cgroup *h_cg;
2054

2055
	idx = hstate_index(h);
2056
	/*
2057 2058 2059
	 * 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).
2060
	 */
2061 2062
	map_chg = gbl_chg = vma_needs_reservation(h, vma, addr);
	if (map_chg < 0)
2063
		return ERR_PTR(-ENOMEM);
2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074

	/*
	 * 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) {
2075
			vma_end_reservation(h, vma, addr);
2076
			return ERR_PTR(-ENOSPC);
2077
		}
L
Linus Torvalds 已提交
2078

2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090
		/*
		 * 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;
	}

2091
	ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
2092 2093 2094
	if (ret)
		goto out_subpool_put;

L
Linus Torvalds 已提交
2095
	spin_lock(&hugetlb_lock);
2096 2097 2098 2099 2100 2101
	/*
	 * 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.
	 */
	page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, gbl_chg);
2102
	if (!page) {
2103
		spin_unlock(&hugetlb_lock);
2104
		page = __alloc_buddy_huge_page_with_mpol(h, vma, addr);
2105 2106
		if (!page)
			goto out_uncharge_cgroup;
2107 2108 2109 2110
		if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
			SetPagePrivate(page);
			h->resv_huge_pages--;
		}
2111 2112
		spin_lock(&hugetlb_lock);
		list_move(&page->lru, &h->hugepage_activelist);
2113
		/* Fall through */
K
Ken Chen 已提交
2114
	}
2115 2116
	hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
	spin_unlock(&hugetlb_lock);
2117

2118
	set_page_private(page, (unsigned long)spool);
2119

2120 2121
	map_commit = vma_commit_reservation(h, vma, addr);
	if (unlikely(map_chg > map_commit)) {
2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135
		/*
		 * 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);
	}
2136
	return page;
2137 2138 2139 2140

out_uncharge_cgroup:
	hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
out_subpool_put:
2141
	if (map_chg || avoid_reserve)
2142
		hugepage_subpool_put_pages(spool, 1);
2143
	vma_end_reservation(h, vma, addr);
2144
	return ERR_PTR(-ENOSPC);
2145 2146
}

2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160
/*
 * alloc_huge_page()'s wrapper which simply returns the page if allocation
 * succeeds, otherwise NULL. This function is called from new_vma_page(),
 * where no ERR_VALUE is expected to be returned.
 */
struct page *alloc_huge_page_noerr(struct vm_area_struct *vma,
				unsigned long addr, int avoid_reserve)
{
	struct page *page = alloc_huge_page(vma, addr, avoid_reserve);
	if (IS_ERR(page))
		page = NULL;
	return page;
}

2161
int __weak alloc_bootmem_huge_page(struct hstate *h)
2162 2163
{
	struct huge_bootmem_page *m;
2164
	int nr_nodes, node;
2165

2166
	for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) {
2167 2168
		void *addr;

2169 2170 2171
		addr = memblock_virt_alloc_try_nid_nopanic(
				huge_page_size(h), huge_page_size(h),
				0, BOOTMEM_ALLOC_ACCESSIBLE, node);
2172 2173 2174 2175 2176 2177 2178
		if (addr) {
			/*
			 * Use the beginning of the huge page to store the
			 * huge_bootmem_page struct (until gather_bootmem
			 * puts them into the mem_map).
			 */
			m = addr;
2179
			goto found;
2180 2181 2182 2183 2184
		}
	}
	return 0;

found:
2185
	BUG_ON(!IS_ALIGNED(virt_to_phys(m), huge_page_size(h)));
2186 2187 2188 2189 2190 2191
	/* Put them into a private list first because mem_map is not up yet */
	list_add(&m->list, &huge_boot_pages);
	m->hstate = h;
	return 1;
}

2192 2193
static void __init prep_compound_huge_page(struct page *page,
		unsigned int order)
2194 2195 2196 2197 2198 2199 2200
{
	if (unlikely(order > (MAX_ORDER - 1)))
		prep_compound_gigantic_page(page, order);
	else
		prep_compound_page(page, order);
}

2201 2202 2203 2204 2205 2206 2207
/* Put bootmem huge pages into the standard lists after mem_map is up */
static void __init gather_bootmem_prealloc(void)
{
	struct huge_bootmem_page *m;

	list_for_each_entry(m, &huge_boot_pages, list) {
		struct hstate *h = m->hstate;
2208 2209 2210 2211
		struct page *page;

#ifdef CONFIG_HIGHMEM
		page = pfn_to_page(m->phys >> PAGE_SHIFT);
2212 2213
		memblock_free_late(__pa(m),
				   sizeof(struct huge_bootmem_page));
2214 2215 2216
#else
		page = virt_to_page(m);
#endif
2217
		WARN_ON(page_count(page) != 1);
2218
		prep_compound_huge_page(page, h->order);
2219
		WARN_ON(PageReserved(page));
2220
		prep_new_huge_page(h, page, page_to_nid(page));
2221 2222 2223 2224 2225 2226
		/*
		 * If we had gigantic hugepages allocated at boot time, we need
		 * to restore the 'stolen' pages to totalram_pages in order to
		 * fix confusing memory reports from free(1) and another
		 * side-effects, like CommitLimit going negative.
		 */
2227
		if (hstate_is_gigantic(h))
2228
			adjust_managed_page_count(page, 1 << h->order);
2229 2230 2231
	}
}

2232
static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
L
Linus Torvalds 已提交
2233 2234
{
	unsigned long i;
2235

2236
	for (i = 0; i < h->max_huge_pages; ++i) {
2237
		if (hstate_is_gigantic(h)) {
2238 2239
			if (!alloc_bootmem_huge_page(h))
				break;
2240
		} else if (!alloc_fresh_huge_page(h,
2241
					 &node_states[N_MEMORY]))
L
Linus Torvalds 已提交
2242
			break;
2243
		cond_resched();
L
Linus Torvalds 已提交
2244
	}
2245 2246 2247
	if (i < h->max_huge_pages) {
		char buf[32];

2248
		string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
2249 2250 2251 2252
		pr_warn("HugeTLB: allocating %lu of page size %s failed.  Only allocated %lu hugepages.\n",
			h->max_huge_pages, buf, i);
		h->max_huge_pages = i;
	}
2253 2254 2255 2256 2257 2258 2259
}

static void __init hugetlb_init_hstates(void)
{
	struct hstate *h;

	for_each_hstate(h) {
2260 2261 2262
		if (minimum_order > huge_page_order(h))
			minimum_order = huge_page_order(h);

2263
		/* oversize hugepages were init'ed in early boot */
2264
		if (!hstate_is_gigantic(h))
2265
			hugetlb_hstate_alloc_pages(h);
2266
	}
2267
	VM_BUG_ON(minimum_order == UINT_MAX);
2268 2269 2270 2271 2272 2273 2274
}

static void __init report_hugepages(void)
{
	struct hstate *h;

	for_each_hstate(h) {
A
Andi Kleen 已提交
2275
		char buf[32];
2276 2277

		string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
2278
		pr_info("HugeTLB registered %s page size, pre-allocated %ld pages\n",
2279
			buf, h->free_huge_pages);
2280 2281 2282
	}
}

L
Linus Torvalds 已提交
2283
#ifdef CONFIG_HIGHMEM
2284 2285
static void try_to_free_low(struct hstate *h, unsigned long count,
						nodemask_t *nodes_allowed)
L
Linus Torvalds 已提交
2286
{
2287 2288
	int i;

2289
	if (hstate_is_gigantic(h))
2290 2291
		return;

2292
	for_each_node_mask(i, *nodes_allowed) {
L
Linus Torvalds 已提交
2293
		struct page *page, *next;
2294 2295 2296
		struct list_head *freel = &h->hugepage_freelists[i];
		list_for_each_entry_safe(page, next, freel, lru) {
			if (count >= h->nr_huge_pages)
2297
				return;
L
Linus Torvalds 已提交
2298 2299 2300
			if (PageHighMem(page))
				continue;
			list_del(&page->lru);
2301
			update_and_free_page(h, page);
2302 2303
			h->free_huge_pages--;
			h->free_huge_pages_node[page_to_nid(page)]--;
L
Linus Torvalds 已提交
2304 2305 2306 2307
		}
	}
}
#else
2308 2309
static inline void try_to_free_low(struct hstate *h, unsigned long count,
						nodemask_t *nodes_allowed)
L
Linus Torvalds 已提交
2310 2311 2312 2313
{
}
#endif

2314 2315 2316 2317 2318
/*
 * Increment or decrement surplus_huge_pages.  Keep node-specific counters
 * balanced by operating on them in a round-robin fashion.
 * Returns 1 if an adjustment was made.
 */
2319 2320
static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
				int delta)
2321
{
2322
	int nr_nodes, node;
2323 2324 2325

	VM_BUG_ON(delta != -1 && delta != 1);

2326 2327 2328 2329
	if (delta < 0) {
		for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
			if (h->surplus_huge_pages_node[node])
				goto found;
2330
		}
2331 2332 2333 2334 2335
	} else {
		for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
			if (h->surplus_huge_pages_node[node] <
					h->nr_huge_pages_node[node])
				goto found;
2336
		}
2337 2338
	}
	return 0;
2339

2340 2341 2342 2343
found:
	h->surplus_huge_pages += delta;
	h->surplus_huge_pages_node[node] += delta;
	return 1;
2344 2345
}

2346
#define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
2347 2348
static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
						nodemask_t *nodes_allowed)
L
Linus Torvalds 已提交
2349
{
2350
	unsigned long min_count, ret;
L
Linus Torvalds 已提交
2351

2352
	if (hstate_is_gigantic(h) && !gigantic_page_supported())
2353 2354
		return h->max_huge_pages;

2355 2356 2357 2358
	/*
	 * Increase the pool size
	 * First take pages out of surplus state.  Then make up the
	 * remaining difference by allocating fresh huge pages.
2359
	 *
N
Naoya Horiguchi 已提交
2360
	 * We might race with __alloc_buddy_huge_page() here and be unable
2361 2362 2363 2364
	 * to convert a surplus huge page to a normal huge page. That is
	 * not critical, though, it just means the overall size of the
	 * pool might be one hugepage larger than it needs to be, but
	 * within all the constraints specified by the sysctls.
2365
	 */
L
Linus Torvalds 已提交
2366
	spin_lock(&hugetlb_lock);
2367
	while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
2368
		if (!adjust_pool_surplus(h, nodes_allowed, -1))
2369 2370 2371
			break;
	}

2372
	while (count > persistent_huge_pages(h)) {
2373 2374 2375 2376 2377 2378
		/*
		 * If this allocation races such that we no longer need the
		 * page, free_huge_page will handle it by freeing the page
		 * and reducing the surplus.
		 */
		spin_unlock(&hugetlb_lock);
2379 2380 2381 2382

		/* yield cpu to avoid soft lockup */
		cond_resched();

2383 2384 2385 2386
		if (hstate_is_gigantic(h))
			ret = alloc_fresh_gigantic_page(h, nodes_allowed);
		else
			ret = alloc_fresh_huge_page(h, nodes_allowed);
2387 2388 2389 2390
		spin_lock(&hugetlb_lock);
		if (!ret)
			goto out;

2391 2392 2393
		/* Bail for signals. Probably ctrl-c from user */
		if (signal_pending(current))
			goto out;
2394 2395 2396 2397 2398 2399 2400 2401
	}

	/*
	 * Decrease the pool size
	 * First return free pages to the buddy allocator (being careful
	 * to keep enough around to satisfy reservations).  Then place
	 * pages into surplus state as needed so the pool will shrink
	 * to the desired size as pages become free.
2402 2403 2404 2405
	 *
	 * By placing pages into the surplus state independent of the
	 * overcommit value, we are allowing the surplus pool size to
	 * exceed overcommit. There are few sane options here. Since
N
Naoya Horiguchi 已提交
2406
	 * __alloc_buddy_huge_page() is checking the global counter,
2407 2408 2409
	 * though, we'll note that we're not allowed to exceed surplus
	 * and won't grow the pool anywhere else. Not until one of the
	 * sysctls are changed, or the surplus pages go out of use.
2410
	 */
2411
	min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
2412
	min_count = max(count, min_count);
2413
	try_to_free_low(h, min_count, nodes_allowed);
2414
	while (min_count < persistent_huge_pages(h)) {
2415
		if (!free_pool_huge_page(h, nodes_allowed, 0))
L
Linus Torvalds 已提交
2416
			break;
2417
		cond_resched_lock(&hugetlb_lock);
L
Linus Torvalds 已提交
2418
	}
2419
	while (count < persistent_huge_pages(h)) {
2420
		if (!adjust_pool_surplus(h, nodes_allowed, 1))
2421 2422 2423
			break;
	}
out:
2424
	ret = persistent_huge_pages(h);
L
Linus Torvalds 已提交
2425
	spin_unlock(&hugetlb_lock);
2426
	return ret;
L
Linus Torvalds 已提交
2427 2428
}

2429 2430 2431 2432 2433 2434 2435 2436 2437 2438
#define HSTATE_ATTR_RO(_name) \
	static struct kobj_attribute _name##_attr = __ATTR_RO(_name)

#define HSTATE_ATTR(_name) \
	static struct kobj_attribute _name##_attr = \
		__ATTR(_name, 0644, _name##_show, _name##_store)

static struct kobject *hugepages_kobj;
static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];

2439 2440 2441
static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);

static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
2442 2443
{
	int i;
2444

2445
	for (i = 0; i < HUGE_MAX_HSTATE; i++)
2446 2447 2448
		if (hstate_kobjs[i] == kobj) {
			if (nidp)
				*nidp = NUMA_NO_NODE;
2449
			return &hstates[i];
2450 2451 2452
		}

	return kobj_to_node_hstate(kobj, nidp);
2453 2454
}

2455
static ssize_t nr_hugepages_show_common(struct kobject *kobj,
2456 2457
					struct kobj_attribute *attr, char *buf)
{
2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468
	struct hstate *h;
	unsigned long nr_huge_pages;
	int nid;

	h = kobj_to_hstate(kobj, &nid);
	if (nid == NUMA_NO_NODE)
		nr_huge_pages = h->nr_huge_pages;
	else
		nr_huge_pages = h->nr_huge_pages_node[nid];

	return sprintf(buf, "%lu\n", nr_huge_pages);
2469
}
2470

2471 2472 2473
static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
					   struct hstate *h, int nid,
					   unsigned long count, size_t len)
2474 2475
{
	int err;
2476
	NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
2477

2478
	if (hstate_is_gigantic(h) && !gigantic_page_supported()) {
2479 2480 2481 2482
		err = -EINVAL;
		goto out;
	}

2483 2484 2485 2486 2487 2488 2489
	if (nid == NUMA_NO_NODE) {
		/*
		 * global hstate attribute
		 */
		if (!(obey_mempolicy &&
				init_nodemask_of_mempolicy(nodes_allowed))) {
			NODEMASK_FREE(nodes_allowed);
2490
			nodes_allowed = &node_states[N_MEMORY];
2491 2492 2493 2494 2495 2496 2497 2498 2499
		}
	} else if (nodes_allowed) {
		/*
		 * per node hstate attribute: adjust count to global,
		 * but restrict alloc/free to the specified node.
		 */
		count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
		init_nodemask_of_node(nodes_allowed, nid);
	} else
2500
		nodes_allowed = &node_states[N_MEMORY];
2501

2502
	h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
2503

2504
	if (nodes_allowed != &node_states[N_MEMORY])
2505 2506 2507
		NODEMASK_FREE(nodes_allowed);

	return len;
2508 2509 2510
out:
	NODEMASK_FREE(nodes_allowed);
	return err;
2511 2512
}

2513 2514 2515 2516 2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527 2528 2529
static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
					 struct kobject *kobj, const char *buf,
					 size_t len)
{
	struct hstate *h;
	unsigned long count;
	int nid;
	int err;

	err = kstrtoul(buf, 10, &count);
	if (err)
		return err;

	h = kobj_to_hstate(kobj, &nid);
	return __nr_hugepages_store_common(obey_mempolicy, h, nid, count, len);
}

2530 2531 2532 2533 2534 2535 2536 2537 2538
static ssize_t nr_hugepages_show(struct kobject *kobj,
				       struct kobj_attribute *attr, char *buf)
{
	return nr_hugepages_show_common(kobj, attr, buf);
}

static ssize_t nr_hugepages_store(struct kobject *kobj,
	       struct kobj_attribute *attr, const char *buf, size_t len)
{
2539
	return nr_hugepages_store_common(false, kobj, buf, len);
2540 2541 2542
}
HSTATE_ATTR(nr_hugepages);

2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557
#ifdef CONFIG_NUMA

/*
 * hstate attribute for optionally mempolicy-based constraint on persistent
 * huge page alloc/free.
 */
static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
				       struct kobj_attribute *attr, char *buf)
{
	return nr_hugepages_show_common(kobj, attr, buf);
}

static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
	       struct kobj_attribute *attr, const char *buf, size_t len)
{
2558
	return nr_hugepages_store_common(true, kobj, buf, len);
2559 2560 2561 2562 2563
}
HSTATE_ATTR(nr_hugepages_mempolicy);
#endif


2564 2565 2566
static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
					struct kobj_attribute *attr, char *buf)
{
2567
	struct hstate *h = kobj_to_hstate(kobj, NULL);
2568 2569
	return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
}
2570

2571 2572 2573 2574 2575
static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	int err;
	unsigned long input;
2576
	struct hstate *h = kobj_to_hstate(kobj, NULL);
2577

2578
	if (hstate_is_gigantic(h))
2579 2580
		return -EINVAL;

2581
	err = kstrtoul(buf, 10, &input);
2582
	if (err)
2583
		return err;
2584 2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595

	spin_lock(&hugetlb_lock);
	h->nr_overcommit_huge_pages = input;
	spin_unlock(&hugetlb_lock);

	return count;
}
HSTATE_ATTR(nr_overcommit_hugepages);

static ssize_t free_hugepages_show(struct kobject *kobj,
					struct kobj_attribute *attr, char *buf)
{
2596 2597 2598 2599 2600 2601 2602 2603 2604 2605 2606
	struct hstate *h;
	unsigned long free_huge_pages;
	int nid;

	h = kobj_to_hstate(kobj, &nid);
	if (nid == NUMA_NO_NODE)
		free_huge_pages = h->free_huge_pages;
	else
		free_huge_pages = h->free_huge_pages_node[nid];

	return sprintf(buf, "%lu\n", free_huge_pages);
2607 2608 2609 2610 2611 2612
}
HSTATE_ATTR_RO(free_hugepages);

static ssize_t resv_hugepages_show(struct kobject *kobj,
					struct kobj_attribute *attr, char *buf)
{
2613
	struct hstate *h = kobj_to_hstate(kobj, NULL);
2614 2615 2616 2617 2618 2619 2620
	return sprintf(buf, "%lu\n", h->resv_huge_pages);
}
HSTATE_ATTR_RO(resv_hugepages);

static ssize_t surplus_hugepages_show(struct kobject *kobj,
					struct kobj_attribute *attr, char *buf)
{
2621 2622 2623 2624 2625 2626 2627 2628 2629 2630 2631
	struct hstate *h;
	unsigned long surplus_huge_pages;
	int nid;

	h = kobj_to_hstate(kobj, &nid);
	if (nid == NUMA_NO_NODE)
		surplus_huge_pages = h->surplus_huge_pages;
	else
		surplus_huge_pages = h->surplus_huge_pages_node[nid];

	return sprintf(buf, "%lu\n", surplus_huge_pages);
2632 2633 2634 2635 2636 2637 2638 2639 2640
}
HSTATE_ATTR_RO(surplus_hugepages);

static struct attribute *hstate_attrs[] = {
	&nr_hugepages_attr.attr,
	&nr_overcommit_hugepages_attr.attr,
	&free_hugepages_attr.attr,
	&resv_hugepages_attr.attr,
	&surplus_hugepages_attr.attr,
2641 2642 2643
#ifdef CONFIG_NUMA
	&nr_hugepages_mempolicy_attr.attr,
#endif
2644 2645 2646 2647 2648 2649 2650
	NULL,
};

static struct attribute_group hstate_attr_group = {
	.attrs = hstate_attrs,
};

J
Jeff Mahoney 已提交
2651 2652 2653
static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
				    struct kobject **hstate_kobjs,
				    struct attribute_group *hstate_attr_group)
2654 2655
{
	int retval;
2656
	int hi = hstate_index(h);
2657

2658 2659
	hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
	if (!hstate_kobjs[hi])
2660 2661
		return -ENOMEM;

2662
	retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
2663
	if (retval)
2664
		kobject_put(hstate_kobjs[hi]);
2665 2666 2667 2668 2669 2670 2671 2672 2673 2674 2675 2676 2677 2678

	return retval;
}

static void __init hugetlb_sysfs_init(void)
{
	struct hstate *h;
	int err;

	hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
	if (!hugepages_kobj)
		return;

	for_each_hstate(h) {
2679 2680
		err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
					 hstate_kobjs, &hstate_attr_group);
2681
		if (err)
2682
			pr_err("Hugetlb: Unable to add hstate %s", h->name);
2683 2684 2685
	}
}

2686 2687 2688 2689
#ifdef CONFIG_NUMA

/*
 * node_hstate/s - associate per node hstate attributes, via their kobjects,
2690 2691 2692
 * with node devices in node_devices[] using a parallel array.  The array
 * index of a node device or _hstate == node id.
 * This is here to avoid any static dependency of the node device driver, in
2693 2694 2695 2696 2697 2698
 * the base kernel, on the hugetlb module.
 */
struct node_hstate {
	struct kobject		*hugepages_kobj;
	struct kobject		*hstate_kobjs[HUGE_MAX_HSTATE];
};
2699
static struct node_hstate node_hstates[MAX_NUMNODES];
2700 2701

/*
2702
 * A subset of global hstate attributes for node devices
2703 2704 2705 2706 2707 2708 2709 2710 2711 2712 2713 2714 2715
 */
static struct attribute *per_node_hstate_attrs[] = {
	&nr_hugepages_attr.attr,
	&free_hugepages_attr.attr,
	&surplus_hugepages_attr.attr,
	NULL,
};

static struct attribute_group per_node_hstate_attr_group = {
	.attrs = per_node_hstate_attrs,
};

/*
2716
 * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
2717 2718 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732 2733 2734 2735 2736 2737 2738
 * Returns node id via non-NULL nidp.
 */
static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
{
	int nid;

	for (nid = 0; nid < nr_node_ids; nid++) {
		struct node_hstate *nhs = &node_hstates[nid];
		int i;
		for (i = 0; i < HUGE_MAX_HSTATE; i++)
			if (nhs->hstate_kobjs[i] == kobj) {
				if (nidp)
					*nidp = nid;
				return &hstates[i];
			}
	}

	BUG();
	return NULL;
}

/*
2739
 * Unregister hstate attributes from a single node device.
2740 2741
 * No-op if no hstate attributes attached.
 */
2742
static void hugetlb_unregister_node(struct node *node)
2743 2744
{
	struct hstate *h;
2745
	struct node_hstate *nhs = &node_hstates[node->dev.id];
2746 2747

	if (!nhs->hugepages_kobj)
2748
		return;		/* no hstate attributes */
2749

2750 2751 2752 2753 2754
	for_each_hstate(h) {
		int idx = hstate_index(h);
		if (nhs->hstate_kobjs[idx]) {
			kobject_put(nhs->hstate_kobjs[idx]);
			nhs->hstate_kobjs[idx] = NULL;
2755
		}
2756
	}
2757 2758 2759 2760 2761 2762 2763

	kobject_put(nhs->hugepages_kobj);
	nhs->hugepages_kobj = NULL;
}


/*
2764
 * Register hstate attributes for a single node device.
2765 2766
 * No-op if attributes already registered.
 */
2767
static void hugetlb_register_node(struct node *node)
2768 2769
{
	struct hstate *h;
2770
	struct node_hstate *nhs = &node_hstates[node->dev.id];
2771 2772 2773 2774 2775 2776
	int err;

	if (nhs->hugepages_kobj)
		return;		/* already allocated */

	nhs->hugepages_kobj = kobject_create_and_add("hugepages",
2777
							&node->dev.kobj);
2778 2779 2780 2781 2782 2783 2784 2785
	if (!nhs->hugepages_kobj)
		return;

	for_each_hstate(h) {
		err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
						nhs->hstate_kobjs,
						&per_node_hstate_attr_group);
		if (err) {
2786 2787
			pr_err("Hugetlb: Unable to add hstate %s for node %d\n",
				h->name, node->dev.id);
2788 2789 2790 2791 2792 2793 2794
			hugetlb_unregister_node(node);
			break;
		}
	}
}

/*
2795
 * hugetlb init time:  register hstate attributes for all registered node
2796 2797
 * devices of nodes that have memory.  All on-line nodes should have
 * registered their associated device by this time.
2798
 */
2799
static void __init hugetlb_register_all_nodes(void)
2800 2801 2802
{
	int nid;

2803
	for_each_node_state(nid, N_MEMORY) {
2804
		struct node *node = node_devices[nid];
2805
		if (node->dev.id == nid)
2806 2807 2808 2809
			hugetlb_register_node(node);
	}

	/*
2810
	 * Let the node device driver know we're here so it can
2811 2812 2813 2814 2815 2816 2817 2818 2819 2820 2821 2822 2823 2824 2825 2826 2827 2828 2829
	 * [un]register hstate attributes on node hotplug.
	 */
	register_hugetlbfs_with_node(hugetlb_register_node,
				     hugetlb_unregister_node);
}
#else	/* !CONFIG_NUMA */

static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
{
	BUG();
	if (nidp)
		*nidp = -1;
	return NULL;
}

static void hugetlb_register_all_nodes(void) { }

#endif

2830 2831
static int __init hugetlb_init(void)
{
2832 2833
	int i;

2834
	if (!hugepages_supported())
2835
		return 0;
2836

2837
	if (!size_to_hstate(default_hstate_size)) {
2838 2839 2840 2841 2842
		if (default_hstate_size != 0) {
			pr_err("HugeTLB: unsupported default_hugepagesz %lu. Reverting to %lu\n",
			       default_hstate_size, HPAGE_SIZE);
		}

2843 2844 2845
		default_hstate_size = HPAGE_SIZE;
		if (!size_to_hstate(default_hstate_size))
			hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
2846
	}
2847
	default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
2848 2849 2850 2851
	if (default_hstate_max_huge_pages) {
		if (!default_hstate.max_huge_pages)
			default_hstate.max_huge_pages = default_hstate_max_huge_pages;
	}
2852 2853

	hugetlb_init_hstates();
2854
	gather_bootmem_prealloc();
2855 2856 2857
	report_hugepages();

	hugetlb_sysfs_init();
2858
	hugetlb_register_all_nodes();
2859
	hugetlb_cgroup_file_init();
2860

2861 2862 2863 2864 2865
#ifdef CONFIG_SMP
	num_fault_mutexes = roundup_pow_of_two(8 * num_possible_cpus());
#else
	num_fault_mutexes = 1;
#endif
2866
	hugetlb_fault_mutex_table =
2867
		kmalloc(sizeof(struct mutex) * num_fault_mutexes, GFP_KERNEL);
2868
	BUG_ON(!hugetlb_fault_mutex_table);
2869 2870

	for (i = 0; i < num_fault_mutexes; i++)
2871
		mutex_init(&hugetlb_fault_mutex_table[i]);
2872 2873
	return 0;
}
2874
subsys_initcall(hugetlb_init);
2875 2876

/* Should be called on processing a hugepagesz=... option */
2877 2878 2879 2880 2881
void __init hugetlb_bad_size(void)
{
	parsed_valid_hugepagesz = false;
}

2882
void __init hugetlb_add_hstate(unsigned int order)
2883 2884
{
	struct hstate *h;
2885 2886
	unsigned long i;

2887
	if (size_to_hstate(PAGE_SIZE << order)) {
J
Joe Perches 已提交
2888
		pr_warn("hugepagesz= specified twice, ignoring\n");
2889 2890
		return;
	}
2891
	BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
2892
	BUG_ON(order == 0);
2893
	h = &hstates[hugetlb_max_hstate++];
2894 2895
	h->order = order;
	h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
2896 2897 2898 2899
	h->nr_huge_pages = 0;
	h->free_huge_pages = 0;
	for (i = 0; i < MAX_NUMNODES; ++i)
		INIT_LIST_HEAD(&h->hugepage_freelists[i]);
2900
	INIT_LIST_HEAD(&h->hugepage_activelist);
2901 2902
	h->next_nid_to_alloc = first_memory_node;
	h->next_nid_to_free = first_memory_node;
2903 2904
	snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
					huge_page_size(h)/1024);
2905

2906 2907 2908
	parsed_hstate = h;
}

2909
static int __init hugetlb_nrpages_setup(char *s)
2910 2911
{
	unsigned long *mhp;
2912
	static unsigned long *last_mhp;
2913

2914 2915 2916 2917 2918 2919
	if (!parsed_valid_hugepagesz) {
		pr_warn("hugepages = %s preceded by "
			"an unsupported hugepagesz, ignoring\n", s);
		parsed_valid_hugepagesz = true;
		return 1;
	}
2920
	/*
2921
	 * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
2922 2923
	 * so this hugepages= parameter goes to the "default hstate".
	 */
2924
	else if (!hugetlb_max_hstate)
2925 2926 2927 2928
		mhp = &default_hstate_max_huge_pages;
	else
		mhp = &parsed_hstate->max_huge_pages;

2929
	if (mhp == last_mhp) {
J
Joe Perches 已提交
2930
		pr_warn("hugepages= specified twice without interleaving hugepagesz=, ignoring\n");
2931 2932 2933
		return 1;
	}

2934 2935 2936
	if (sscanf(s, "%lu", mhp) <= 0)
		*mhp = 0;

2937 2938 2939 2940 2941
	/*
	 * Global state is always initialized later in hugetlb_init.
	 * But we need to allocate >= MAX_ORDER hstates here early to still
	 * use the bootmem allocator.
	 */
2942
	if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER)
2943 2944 2945 2946
		hugetlb_hstate_alloc_pages(parsed_hstate);

	last_mhp = mhp;

2947 2948
	return 1;
}
2949 2950 2951 2952 2953 2954 2955 2956
__setup("hugepages=", hugetlb_nrpages_setup);

static int __init hugetlb_default_setup(char *s)
{
	default_hstate_size = memparse(s, &s);
	return 1;
}
__setup("default_hugepagesz=", hugetlb_default_setup);
2957

2958 2959 2960 2961 2962 2963 2964 2965 2966 2967 2968 2969
static unsigned int cpuset_mems_nr(unsigned int *array)
{
	int node;
	unsigned int nr = 0;

	for_each_node_mask(node, cpuset_current_mems_allowed)
		nr += array[node];

	return nr;
}

#ifdef CONFIG_SYSCTL
2970 2971 2972
static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
			 struct ctl_table *table, int write,
			 void __user *buffer, size_t *length, loff_t *ppos)
L
Linus Torvalds 已提交
2973
{
2974
	struct hstate *h = &default_hstate;
2975
	unsigned long tmp = h->max_huge_pages;
2976
	int ret;
2977

2978
	if (!hugepages_supported())
2979
		return -EOPNOTSUPP;
2980

2981 2982
	table->data = &tmp;
	table->maxlen = sizeof(unsigned long);
2983 2984 2985
	ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
	if (ret)
		goto out;
2986

2987 2988 2989
	if (write)
		ret = __nr_hugepages_store_common(obey_mempolicy, h,
						  NUMA_NO_NODE, tmp, *length);
2990 2991
out:
	return ret;
L
Linus Torvalds 已提交
2992
}
2993

2994 2995 2996 2997 2998 2999 3000 3001 3002 3003 3004 3005 3006 3007 3008 3009 3010
int hugetlb_sysctl_handler(struct ctl_table *table, int write,
			  void __user *buffer, size_t *length, loff_t *ppos)
{

	return hugetlb_sysctl_handler_common(false, table, write,
							buffer, length, ppos);
}

#ifdef CONFIG_NUMA
int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
			  void __user *buffer, size_t *length, loff_t *ppos)
{
	return hugetlb_sysctl_handler_common(true, table, write,
							buffer, length, ppos);
}
#endif /* CONFIG_NUMA */

3011
int hugetlb_overcommit_handler(struct ctl_table *table, int write,
3012
			void __user *buffer,
3013 3014
			size_t *length, loff_t *ppos)
{
3015
	struct hstate *h = &default_hstate;
3016
	unsigned long tmp;
3017
	int ret;
3018

3019
	if (!hugepages_supported())
3020
		return -EOPNOTSUPP;
3021

3022
	tmp = h->nr_overcommit_huge_pages;
3023

3024
	if (write && hstate_is_gigantic(h))
3025 3026
		return -EINVAL;

3027 3028
	table->data = &tmp;
	table->maxlen = sizeof(unsigned long);
3029 3030 3031
	ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
	if (ret)
		goto out;
3032 3033 3034 3035 3036 3037

	if (write) {
		spin_lock(&hugetlb_lock);
		h->nr_overcommit_huge_pages = tmp;
		spin_unlock(&hugetlb_lock);
	}
3038 3039
out:
	return ret;
3040 3041
}

L
Linus Torvalds 已提交
3042 3043
#endif /* CONFIG_SYSCTL */

3044
void hugetlb_report_meminfo(struct seq_file *m)
L
Linus Torvalds 已提交
3045
{
3046
	struct hstate *h = &default_hstate;
3047 3048
	if (!hugepages_supported())
		return;
3049
	seq_printf(m,
3050 3051 3052 3053 3054
			"HugePages_Total:   %5lu\n"
			"HugePages_Free:    %5lu\n"
			"HugePages_Rsvd:    %5lu\n"
			"HugePages_Surp:    %5lu\n"
			"Hugepagesize:   %8lu kB\n",
3055 3056 3057 3058 3059
			h->nr_huge_pages,
			h->free_huge_pages,
			h->resv_huge_pages,
			h->surplus_huge_pages,
			1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
L
Linus Torvalds 已提交
3060 3061 3062 3063
}

int hugetlb_report_node_meminfo(int nid, char *buf)
{
3064
	struct hstate *h = &default_hstate;
3065 3066
	if (!hugepages_supported())
		return 0;
L
Linus Torvalds 已提交
3067 3068
	return sprintf(buf,
		"Node %d HugePages_Total: %5u\n"
3069 3070
		"Node %d HugePages_Free:  %5u\n"
		"Node %d HugePages_Surp:  %5u\n",
3071 3072 3073
		nid, h->nr_huge_pages_node[nid],
		nid, h->free_huge_pages_node[nid],
		nid, h->surplus_huge_pages_node[nid]);
L
Linus Torvalds 已提交
3074 3075
}

3076 3077 3078 3079 3080
void hugetlb_show_meminfo(void)
{
	struct hstate *h;
	int nid;

3081 3082 3083
	if (!hugepages_supported())
		return;

3084 3085 3086 3087 3088 3089 3090 3091 3092 3093
	for_each_node_state(nid, N_MEMORY)
		for_each_hstate(h)
			pr_info("Node %d hugepages_total=%u hugepages_free=%u hugepages_surp=%u hugepages_size=%lukB\n",
				nid,
				h->nr_huge_pages_node[nid],
				h->free_huge_pages_node[nid],
				h->surplus_huge_pages_node[nid],
				1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
}

3094 3095 3096 3097 3098 3099
void hugetlb_report_usage(struct seq_file *m, struct mm_struct *mm)
{
	seq_printf(m, "HugetlbPages:\t%8lu kB\n",
		   atomic_long_read(&mm->hugetlb_usage) << (PAGE_SHIFT - 10));
}

L
Linus Torvalds 已提交
3100 3101 3102
/* Return the number pages of memory we physically have, in PAGE_SIZE units. */
unsigned long hugetlb_total_pages(void)
{
3103 3104 3105 3106 3107 3108
	struct hstate *h;
	unsigned long nr_total_pages = 0;

	for_each_hstate(h)
		nr_total_pages += h->nr_huge_pages * pages_per_huge_page(h);
	return nr_total_pages;
L
Linus Torvalds 已提交
3109 3110
}

3111
static int hugetlb_acct_memory(struct hstate *h, long delta)
M
Mel Gorman 已提交
3112 3113 3114 3115 3116 3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 3128 3129 3130 3131 3132 3133
{
	int ret = -ENOMEM;

	spin_lock(&hugetlb_lock);
	/*
	 * When cpuset is configured, it breaks the strict hugetlb page
	 * reservation as the accounting is done on a global variable. Such
	 * reservation is completely rubbish in the presence of cpuset because
	 * the reservation is not checked against page availability for the
	 * current cpuset. Application can still potentially OOM'ed by kernel
	 * with lack of free htlb page in cpuset that the task is in.
	 * Attempt to enforce strict accounting with cpuset is almost
	 * impossible (or too ugly) because cpuset is too fluid that
	 * task or memory node can be dynamically moved between cpusets.
	 *
	 * The change of semantics for shared hugetlb mapping with cpuset is
	 * undesirable. However, in order to preserve some of the semantics,
	 * we fall back to check against current free page availability as
	 * a best attempt and hopefully to minimize the impact of changing
	 * semantics that cpuset has.
	 */
	if (delta > 0) {
3134
		if (gather_surplus_pages(h, delta) < 0)
M
Mel Gorman 已提交
3135 3136
			goto out;

3137 3138
		if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
			return_unused_surplus_pages(h, delta);
M
Mel Gorman 已提交
3139 3140 3141 3142 3143 3144
			goto out;
		}
	}

	ret = 0;
	if (delta < 0)
3145
		return_unused_surplus_pages(h, (unsigned long) -delta);
M
Mel Gorman 已提交
3146 3147 3148 3149 3150 3151

out:
	spin_unlock(&hugetlb_lock);
	return ret;
}

3152 3153
static void hugetlb_vm_op_open(struct vm_area_struct *vma)
{
3154
	struct resv_map *resv = vma_resv_map(vma);
3155 3156 3157 3158 3159

	/*
	 * This new VMA should share its siblings reservation map if present.
	 * The VMA will only ever have a valid reservation map pointer where
	 * it is being copied for another still existing VMA.  As that VMA
L
Lucas De Marchi 已提交
3160
	 * has a reference to the reservation map it cannot disappear until
3161 3162 3163
	 * after this open call completes.  It is therefore safe to take a
	 * new reference here without additional locking.
	 */
3164
	if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
3165
		kref_get(&resv->refs);
3166 3167
}

3168 3169
static void hugetlb_vm_op_close(struct vm_area_struct *vma)
{
3170
	struct hstate *h = hstate_vma(vma);
3171
	struct resv_map *resv = vma_resv_map(vma);
3172
	struct hugepage_subpool *spool = subpool_vma(vma);
3173
	unsigned long reserve, start, end;
3174
	long gbl_reserve;
3175

3176 3177
	if (!resv || !is_vma_resv_set(vma, HPAGE_RESV_OWNER))
		return;
3178

3179 3180
	start = vma_hugecache_offset(h, vma, vma->vm_start);
	end = vma_hugecache_offset(h, vma, vma->vm_end);
3181

3182
	reserve = (end - start) - region_count(resv, start, end);
3183

3184 3185 3186
	kref_put(&resv->refs, resv_map_release);

	if (reserve) {
3187 3188 3189 3190 3191 3192
		/*
		 * Decrement reserve counts.  The global reserve count may be
		 * adjusted if the subpool has a minimum size.
		 */
		gbl_reserve = hugepage_subpool_put_pages(spool, reserve);
		hugetlb_acct_memory(h, -gbl_reserve);
3193
	}
3194 3195
}

L
Linus Torvalds 已提交
3196 3197 3198 3199 3200 3201
/*
 * We cannot handle pagefaults against hugetlb pages at all.  They cause
 * handle_mm_fault() to try to instantiate regular-sized pages in the
 * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
 * this far.
 */
3202
static int hugetlb_vm_op_fault(struct vm_fault *vmf)
L
Linus Torvalds 已提交
3203 3204
{
	BUG();
N
Nick Piggin 已提交
3205
	return 0;
L
Linus Torvalds 已提交
3206 3207
}

3208
const struct vm_operations_struct hugetlb_vm_ops = {
N
Nick Piggin 已提交
3209
	.fault = hugetlb_vm_op_fault,
3210
	.open = hugetlb_vm_op_open,
3211
	.close = hugetlb_vm_op_close,
L
Linus Torvalds 已提交
3212 3213
};

3214 3215
static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
				int writable)
D
David Gibson 已提交
3216 3217 3218
{
	pte_t entry;

3219
	if (writable) {
3220 3221
		entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page,
					 vma->vm_page_prot)));
D
David Gibson 已提交
3222
	} else {
3223 3224
		entry = huge_pte_wrprotect(mk_huge_pte(page,
					   vma->vm_page_prot));
D
David Gibson 已提交
3225 3226 3227
	}
	entry = pte_mkyoung(entry);
	entry = pte_mkhuge(entry);
3228
	entry = arch_make_huge_pte(entry, vma, page, writable);
D
David Gibson 已提交
3229 3230 3231 3232

	return entry;
}

3233 3234 3235 3236 3237
static void set_huge_ptep_writable(struct vm_area_struct *vma,
				   unsigned long address, pte_t *ptep)
{
	pte_t entry;

3238
	entry = huge_pte_mkwrite(huge_pte_mkdirty(huge_ptep_get(ptep)));
3239
	if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
3240
		update_mmu_cache(vma, address, ptep);
3241 3242
}

3243
bool is_hugetlb_entry_migration(pte_t pte)
3244 3245 3246 3247
{
	swp_entry_t swp;

	if (huge_pte_none(pte) || pte_present(pte))
3248
		return false;
3249 3250
	swp = pte_to_swp_entry(pte);
	if (non_swap_entry(swp) && is_migration_entry(swp))
3251
		return true;
3252
	else
3253
		return false;
3254 3255 3256 3257 3258 3259 3260 3261 3262 3263 3264 3265 3266 3267
}

static int is_hugetlb_entry_hwpoisoned(pte_t pte)
{
	swp_entry_t swp;

	if (huge_pte_none(pte) || pte_present(pte))
		return 0;
	swp = pte_to_swp_entry(pte);
	if (non_swap_entry(swp) && is_hwpoison_entry(swp))
		return 1;
	else
		return 0;
}
3268

D
David Gibson 已提交
3269 3270 3271 3272 3273
int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
			    struct vm_area_struct *vma)
{
	pte_t *src_pte, *dst_pte, entry;
	struct page *ptepage;
3274
	unsigned long addr;
3275
	int cow;
3276 3277
	struct hstate *h = hstate_vma(vma);
	unsigned long sz = huge_page_size(h);
3278 3279 3280
	unsigned long mmun_start;	/* For mmu_notifiers */
	unsigned long mmun_end;		/* For mmu_notifiers */
	int ret = 0;
3281 3282

	cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
D
David Gibson 已提交
3283

3284 3285 3286 3287 3288
	mmun_start = vma->vm_start;
	mmun_end = vma->vm_end;
	if (cow)
		mmu_notifier_invalidate_range_start(src, mmun_start, mmun_end);

3289
	for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
3290
		spinlock_t *src_ptl, *dst_ptl;
3291
		src_pte = huge_pte_offset(src, addr, sz);
H
Hugh Dickins 已提交
3292 3293
		if (!src_pte)
			continue;
3294
		dst_pte = huge_pte_alloc(dst, addr, sz);
3295 3296 3297 3298
		if (!dst_pte) {
			ret = -ENOMEM;
			break;
		}
3299 3300 3301 3302 3303

		/* If the pagetables are shared don't copy or take references */
		if (dst_pte == src_pte)
			continue;

3304 3305 3306
		dst_ptl = huge_pte_lock(h, dst, dst_pte);
		src_ptl = huge_pte_lockptr(h, src, src_pte);
		spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
3307 3308 3309 3310 3311 3312 3313 3314 3315 3316 3317 3318 3319 3320
		entry = huge_ptep_get(src_pte);
		if (huge_pte_none(entry)) { /* skip none entry */
			;
		} else if (unlikely(is_hugetlb_entry_migration(entry) ||
				    is_hugetlb_entry_hwpoisoned(entry))) {
			swp_entry_t swp_entry = pte_to_swp_entry(entry);

			if (is_write_migration_entry(swp_entry) && cow) {
				/*
				 * COW mappings require pages in both
				 * parent and child to be set to read.
				 */
				make_migration_entry_read(&swp_entry);
				entry = swp_entry_to_pte(swp_entry);
3321 3322
				set_huge_swap_pte_at(src, addr, src_pte,
						     entry, sz);
3323
			}
3324
			set_huge_swap_pte_at(dst, addr, dst_pte, entry, sz);
3325
		} else {
3326
			if (cow) {
3327
				huge_ptep_set_wrprotect(src, addr, src_pte);
3328 3329 3330
				mmu_notifier_invalidate_range(src, mmun_start,
								   mmun_end);
			}
3331
			entry = huge_ptep_get(src_pte);
3332 3333
			ptepage = pte_page(entry);
			get_page(ptepage);
3334
			page_dup_rmap(ptepage, true);
3335
			set_huge_pte_at(dst, addr, dst_pte, entry);
3336
			hugetlb_count_add(pages_per_huge_page(h), dst);
3337
		}
3338 3339
		spin_unlock(src_ptl);
		spin_unlock(dst_ptl);
D
David Gibson 已提交
3340 3341
	}

3342 3343 3344 3345
	if (cow)
		mmu_notifier_invalidate_range_end(src, mmun_start, mmun_end);

	return ret;
D
David Gibson 已提交
3346 3347
}

3348 3349 3350
void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
			    unsigned long start, unsigned long end,
			    struct page *ref_page)
D
David Gibson 已提交
3351 3352 3353
{
	struct mm_struct *mm = vma->vm_mm;
	unsigned long address;
3354
	pte_t *ptep;
D
David Gibson 已提交
3355
	pte_t pte;
3356
	spinlock_t *ptl;
D
David Gibson 已提交
3357
	struct page *page;
3358 3359
	struct hstate *h = hstate_vma(vma);
	unsigned long sz = huge_page_size(h);
3360 3361
	const unsigned long mmun_start = start;	/* For mmu_notifiers */
	const unsigned long mmun_end   = end;	/* For mmu_notifiers */
3362

D
David Gibson 已提交
3363
	WARN_ON(!is_vm_hugetlb_page(vma));
3364 3365
	BUG_ON(start & ~huge_page_mask(h));
	BUG_ON(end & ~huge_page_mask(h));
D
David Gibson 已提交
3366

3367 3368 3369 3370 3371
	/*
	 * This is a hugetlb vma, all the pte entries should point
	 * to huge page.
	 */
	tlb_remove_check_page_size_change(tlb, sz);
3372
	tlb_start_vma(tlb, vma);
3373
	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
3374 3375
	address = start;
	for (; address < end; address += sz) {
3376
		ptep = huge_pte_offset(mm, address, sz);
A
Adam Litke 已提交
3377
		if (!ptep)
3378 3379
			continue;

3380
		ptl = huge_pte_lock(h, mm, ptep);
3381 3382 3383 3384
		if (huge_pmd_unshare(mm, &address, ptep)) {
			spin_unlock(ptl);
			continue;
		}
3385

3386
		pte = huge_ptep_get(ptep);
3387 3388 3389 3390
		if (huge_pte_none(pte)) {
			spin_unlock(ptl);
			continue;
		}
3391 3392

		/*
3393 3394
		 * Migrating hugepage or HWPoisoned hugepage is already
		 * unmapped and its refcount is dropped, so just clear pte here.
3395
		 */
3396
		if (unlikely(!pte_present(pte))) {
3397
			huge_pte_clear(mm, address, ptep, sz);
3398 3399
			spin_unlock(ptl);
			continue;
3400
		}
3401 3402

		page = pte_page(pte);
3403 3404 3405 3406 3407 3408
		/*
		 * If a reference page is supplied, it is because a specific
		 * page is being unmapped, not a range. Ensure the page we
		 * are about to unmap is the actual page of interest.
		 */
		if (ref_page) {
3409 3410 3411 3412
			if (page != ref_page) {
				spin_unlock(ptl);
				continue;
			}
3413 3414 3415 3416 3417 3418 3419 3420
			/*
			 * Mark the VMA as having unmapped its page so that
			 * future faults in this VMA will fail rather than
			 * looking like data was lost
			 */
			set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
		}

3421
		pte = huge_ptep_get_and_clear(mm, address, ptep);
3422
		tlb_remove_huge_tlb_entry(h, tlb, ptep, address);
3423
		if (huge_pte_dirty(pte))
3424
			set_page_dirty(page);
3425

3426
		hugetlb_count_sub(pages_per_huge_page(h), mm);
3427
		page_remove_rmap(page, true);
3428

3429
		spin_unlock(ptl);
3430
		tlb_remove_page_size(tlb, page, huge_page_size(h));
3431 3432 3433 3434 3435
		/*
		 * Bail out after unmapping reference page if supplied
		 */
		if (ref_page)
			break;
3436
	}
3437
	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
3438
	tlb_end_vma(tlb, vma);
L
Linus Torvalds 已提交
3439
}
D
David Gibson 已提交
3440

3441 3442 3443 3444 3445 3446 3447 3448 3449 3450 3451 3452
void __unmap_hugepage_range_final(struct mmu_gather *tlb,
			  struct vm_area_struct *vma, unsigned long start,
			  unsigned long end, struct page *ref_page)
{
	__unmap_hugepage_range(tlb, vma, start, end, ref_page);

	/*
	 * Clear this flag so that x86's huge_pmd_share page_table_shareable
	 * test will fail on a vma being torn down, and not grab a page table
	 * on its way out.  We're lucky that the flag has such an appropriate
	 * name, and can in fact be safely cleared here. We could clear it
	 * before the __unmap_hugepage_range above, but all that's necessary
3453
	 * is to clear it before releasing the i_mmap_rwsem. This works
3454
	 * because in the context this is called, the VMA is about to be
3455
	 * destroyed and the i_mmap_rwsem is held.
3456 3457 3458 3459
	 */
	vma->vm_flags &= ~VM_MAYSHARE;
}

3460
void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
3461
			  unsigned long end, struct page *ref_page)
3462
{
3463 3464 3465 3466 3467
	struct mm_struct *mm;
	struct mmu_gather tlb;

	mm = vma->vm_mm;

3468
	tlb_gather_mmu(&tlb, mm, start, end);
3469 3470
	__unmap_hugepage_range(&tlb, vma, start, end, ref_page);
	tlb_finish_mmu(&tlb, start, end);
3471 3472
}

3473 3474 3475 3476 3477 3478
/*
 * This is called when the original mapper is failing to COW a MAP_PRIVATE
 * mappping it owns the reserve page for. The intention is to unmap the page
 * from other VMAs and let the children be SIGKILLed if they are faulting the
 * same region.
 */
3479 3480
static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
			      struct page *page, unsigned long address)
3481
{
3482
	struct hstate *h = hstate_vma(vma);
3483 3484 3485 3486 3487 3488 3489 3490
	struct vm_area_struct *iter_vma;
	struct address_space *mapping;
	pgoff_t pgoff;

	/*
	 * vm_pgoff is in PAGE_SIZE units, hence the different calculation
	 * from page cache lookup which is in HPAGE_SIZE units.
	 */
3491
	address = address & huge_page_mask(h);
3492 3493
	pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
			vma->vm_pgoff;
3494
	mapping = vma->vm_file->f_mapping;
3495

3496 3497 3498 3499 3500
	/*
	 * Take the mapping lock for the duration of the table walk. As
	 * this mapping should be shared between all the VMAs,
	 * __unmap_hugepage_range() is called as the lock is already held
	 */
3501
	i_mmap_lock_write(mapping);
3502
	vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) {
3503 3504 3505 3506
		/* Do not unmap the current VMA */
		if (iter_vma == vma)
			continue;

3507 3508 3509 3510 3511 3512 3513 3514
		/*
		 * Shared VMAs have their own reserves and do not affect
		 * MAP_PRIVATE accounting but it is possible that a shared
		 * VMA is using the same page so check and skip such VMAs.
		 */
		if (iter_vma->vm_flags & VM_MAYSHARE)
			continue;

3515 3516 3517 3518 3519 3520 3521 3522
		/*
		 * Unmap the page from other VMAs without their own reserves.
		 * They get marked to be SIGKILLed if they fault in these
		 * areas. This is because a future no-page fault on this VMA
		 * could insert a zeroed page instead of the data existing
		 * from the time of fork. This would look like data corruption
		 */
		if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
3523 3524
			unmap_hugepage_range(iter_vma, address,
					     address + huge_page_size(h), page);
3525
	}
3526
	i_mmap_unlock_write(mapping);
3527 3528
}

3529 3530
/*
 * Hugetlb_cow() should be called with page lock of the original hugepage held.
3531 3532 3533
 * Called with hugetlb_instantiation_mutex held and pte_page locked so we
 * cannot race with other handlers or page migration.
 * Keep the pte_same checks anyway to make transition from the mutex easier.
3534
 */
3535
static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
3536 3537
		       unsigned long address, pte_t *ptep,
		       struct page *pagecache_page, spinlock_t *ptl)
3538
{
3539
	pte_t pte;
3540
	struct hstate *h = hstate_vma(vma);
3541
	struct page *old_page, *new_page;
3542
	int ret = 0, outside_reserve = 0;
3543 3544
	unsigned long mmun_start;	/* For mmu_notifiers */
	unsigned long mmun_end;		/* For mmu_notifiers */
3545

3546
	pte = huge_ptep_get(ptep);
3547 3548
	old_page = pte_page(pte);

3549
retry_avoidcopy:
3550 3551
	/* If no-one else is actually using this page, avoid the copy
	 * and just make the page writable */
3552
	if (page_mapcount(old_page) == 1 && PageAnon(old_page)) {
3553
		page_move_anon_rmap(old_page, vma);
3554
		set_huge_ptep_writable(vma, address, ptep);
N
Nick Piggin 已提交
3555
		return 0;
3556 3557
	}

3558 3559 3560 3561 3562 3563 3564 3565 3566
	/*
	 * If the process that created a MAP_PRIVATE mapping is about to
	 * perform a COW due to a shared page count, attempt to satisfy
	 * the allocation without using the existing reserves. The pagecache
	 * page is used to determine if the reserve at this address was
	 * consumed or not. If reserves were used, a partial faulted mapping
	 * at the time of fork() could consume its reserves on COW instead
	 * of the full address range.
	 */
3567
	if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
3568 3569 3570
			old_page != pagecache_page)
		outside_reserve = 1;

3571
	get_page(old_page);
3572

3573 3574 3575 3576
	/*
	 * Drop page table lock as buddy allocator may be called. It will
	 * be acquired again before returning to the caller, as expected.
	 */
3577
	spin_unlock(ptl);
3578
	new_page = alloc_huge_page(vma, address, outside_reserve);
3579

3580
	if (IS_ERR(new_page)) {
3581 3582 3583 3584 3585 3586 3587 3588
		/*
		 * If a process owning a MAP_PRIVATE mapping fails to COW,
		 * it is due to references held by a child and an insufficient
		 * huge page pool. To guarantee the original mappers
		 * reliability, unmap the page from child processes. The child
		 * may get SIGKILLed if it later faults.
		 */
		if (outside_reserve) {
3589
			put_page(old_page);
3590
			BUG_ON(huge_pte_none(pte));
3591 3592 3593
			unmap_ref_private(mm, vma, old_page, address);
			BUG_ON(huge_pte_none(pte));
			spin_lock(ptl);
3594 3595
			ptep = huge_pte_offset(mm, address & huge_page_mask(h),
					       huge_page_size(h));
3596 3597 3598 3599 3600 3601 3602 3603
			if (likely(ptep &&
				   pte_same(huge_ptep_get(ptep), pte)))
				goto retry_avoidcopy;
			/*
			 * race occurs while re-acquiring page table
			 * lock, and our job is done.
			 */
			return 0;
3604 3605
		}

3606 3607 3608
		ret = (PTR_ERR(new_page) == -ENOMEM) ?
			VM_FAULT_OOM : VM_FAULT_SIGBUS;
		goto out_release_old;
3609 3610
	}

3611 3612 3613 3614
	/*
	 * When the original hugepage is shared one, it does not have
	 * anon_vma prepared.
	 */
3615
	if (unlikely(anon_vma_prepare(vma))) {
3616 3617
		ret = VM_FAULT_OOM;
		goto out_release_all;
3618
	}
3619

A
Andrea Arcangeli 已提交
3620 3621
	copy_user_huge_page(new_page, old_page, address, vma,
			    pages_per_huge_page(h));
N
Nick Piggin 已提交
3622
	__SetPageUptodate(new_page);
3623
	set_page_huge_active(new_page);
3624

3625 3626 3627
	mmun_start = address & huge_page_mask(h);
	mmun_end = mmun_start + huge_page_size(h);
	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
3628

3629
	/*
3630
	 * Retake the page table lock to check for racing updates
3631 3632
	 * before the page tables are altered
	 */
3633
	spin_lock(ptl);
3634 3635
	ptep = huge_pte_offset(mm, address & huge_page_mask(h),
			       huge_page_size(h));
3636
	if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) {
3637 3638
		ClearPagePrivate(new_page);

3639
		/* Break COW */
3640
		huge_ptep_clear_flush(vma, address, ptep);
3641
		mmu_notifier_invalidate_range(mm, mmun_start, mmun_end);
3642 3643
		set_huge_pte_at(mm, address, ptep,
				make_huge_pte(vma, new_page, 1));
3644
		page_remove_rmap(old_page, true);
3645
		hugepage_add_new_anon_rmap(new_page, vma, address);
3646 3647 3648
		/* Make the old page be freed below */
		new_page = old_page;
	}
3649
	spin_unlock(ptl);
3650
	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
3651
out_release_all:
3652
	restore_reserve_on_error(h, vma, address, new_page);
3653
	put_page(new_page);
3654
out_release_old:
3655
	put_page(old_page);
3656

3657 3658
	spin_lock(ptl); /* Caller expects lock to be held */
	return ret;
3659 3660
}

3661
/* Return the pagecache page at a given address within a VMA */
3662 3663
static struct page *hugetlbfs_pagecache_page(struct hstate *h,
			struct vm_area_struct *vma, unsigned long address)
3664 3665
{
	struct address_space *mapping;
3666
	pgoff_t idx;
3667 3668

	mapping = vma->vm_file->f_mapping;
3669
	idx = vma_hugecache_offset(h, vma, address);
3670 3671 3672 3673

	return find_lock_page(mapping, idx);
}

H
Hugh Dickins 已提交
3674 3675 3676 3677 3678
/*
 * Return whether there is a pagecache page to back given address within VMA.
 * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page.
 */
static bool hugetlbfs_pagecache_present(struct hstate *h,
H
Hugh Dickins 已提交
3679 3680 3681 3682 3683 3684 3685 3686 3687 3688 3689 3690 3691 3692 3693
			struct vm_area_struct *vma, unsigned long address)
{
	struct address_space *mapping;
	pgoff_t idx;
	struct page *page;

	mapping = vma->vm_file->f_mapping;
	idx = vma_hugecache_offset(h, vma, address);

	page = find_get_page(mapping, idx);
	if (page)
		put_page(page);
	return page != NULL;
}

3694 3695 3696 3697 3698 3699 3700 3701 3702 3703 3704 3705 3706 3707 3708 3709 3710
int huge_add_to_page_cache(struct page *page, struct address_space *mapping,
			   pgoff_t idx)
{
	struct inode *inode = mapping->host;
	struct hstate *h = hstate_inode(inode);
	int err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);

	if (err)
		return err;
	ClearPagePrivate(page);

	spin_lock(&inode->i_lock);
	inode->i_blocks += blocks_per_huge_page(h);
	spin_unlock(&inode->i_lock);
	return 0;
}

3711
static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
3712 3713
			   struct address_space *mapping, pgoff_t idx,
			   unsigned long address, pte_t *ptep, unsigned int flags)
3714
{
3715
	struct hstate *h = hstate_vma(vma);
3716
	int ret = VM_FAULT_SIGBUS;
3717
	int anon_rmap = 0;
A
Adam Litke 已提交
3718 3719
	unsigned long size;
	struct page *page;
3720
	pte_t new_pte;
3721
	spinlock_t *ptl;
A
Adam Litke 已提交
3722

3723 3724 3725
	/*
	 * Currently, we are forced to kill the process in the event the
	 * original mapper has unmapped pages from the child due to a failed
L
Lucas De Marchi 已提交
3726
	 * COW. Warn that such a situation has occurred as it may not be obvious
3727 3728
	 */
	if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
3729
		pr_warn_ratelimited("PID %d killed due to inadequate hugepage pool\n",
3730
			   current->pid);
3731 3732 3733
		return ret;
	}

A
Adam Litke 已提交
3734 3735 3736 3737
	/*
	 * Use page lock to guard against racing truncation
	 * before we get page_table_lock.
	 */
3738 3739 3740
retry:
	page = find_lock_page(mapping, idx);
	if (!page) {
3741
		size = i_size_read(mapping->host) >> huge_page_shift(h);
3742 3743
		if (idx >= size)
			goto out;
3744 3745 3746 3747 3748 3749 3750 3751 3752 3753 3754 3755 3756 3757 3758 3759 3760 3761 3762 3763 3764 3765 3766 3767 3768 3769 3770 3771 3772 3773 3774 3775

		/*
		 * Check for page in userfault range
		 */
		if (userfaultfd_missing(vma)) {
			u32 hash;
			struct vm_fault vmf = {
				.vma = vma,
				.address = address,
				.flags = flags,
				/*
				 * Hard to debug if it ends up being
				 * used by a callee that assumes
				 * something about the other
				 * uninitialized fields... same as in
				 * memory.c
				 */
			};

			/*
			 * hugetlb_fault_mutex must be dropped before
			 * handling userfault.  Reacquire after handling
			 * fault to make calling code simpler.
			 */
			hash = hugetlb_fault_mutex_hash(h, mm, vma, mapping,
							idx, address);
			mutex_unlock(&hugetlb_fault_mutex_table[hash]);
			ret = handle_userfault(&vmf, VM_UFFD_MISSING);
			mutex_lock(&hugetlb_fault_mutex_table[hash]);
			goto out;
		}

3776
		page = alloc_huge_page(vma, address, 0);
3777
		if (IS_ERR(page)) {
3778 3779 3780 3781 3782
			ret = PTR_ERR(page);
			if (ret == -ENOMEM)
				ret = VM_FAULT_OOM;
			else
				ret = VM_FAULT_SIGBUS;
3783 3784
			goto out;
		}
A
Andrea Arcangeli 已提交
3785
		clear_huge_page(page, address, pages_per_huge_page(h));
N
Nick Piggin 已提交
3786
		__SetPageUptodate(page);
3787
		set_page_huge_active(page);
3788

3789
		if (vma->vm_flags & VM_MAYSHARE) {
3790
			int err = huge_add_to_page_cache(page, mapping, idx);
3791 3792 3793 3794 3795 3796
			if (err) {
				put_page(page);
				if (err == -EEXIST)
					goto retry;
				goto out;
			}
3797
		} else {
3798
			lock_page(page);
3799 3800 3801 3802
			if (unlikely(anon_vma_prepare(vma))) {
				ret = VM_FAULT_OOM;
				goto backout_unlocked;
			}
3803
			anon_rmap = 1;
3804
		}
3805
	} else {
3806 3807 3808 3809 3810 3811
		/*
		 * If memory error occurs between mmap() and fault, some process
		 * don't have hwpoisoned swap entry for errored virtual address.
		 * So we need to block hugepage fault by PG_hwpoison bit check.
		 */
		if (unlikely(PageHWPoison(page))) {
3812
			ret = VM_FAULT_HWPOISON |
3813
				VM_FAULT_SET_HINDEX(hstate_index(h));
3814 3815
			goto backout_unlocked;
		}
3816
	}
3817

3818 3819 3820 3821 3822 3823
	/*
	 * If we are going to COW a private mapping later, we examine the
	 * pending reservations for this page now. This will ensure that
	 * any allocations necessary to record that reservation occur outside
	 * the spinlock.
	 */
3824
	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3825 3826 3827 3828
		if (vma_needs_reservation(h, vma, address) < 0) {
			ret = VM_FAULT_OOM;
			goto backout_unlocked;
		}
3829
		/* Just decrements count, does not deallocate */
3830
		vma_end_reservation(h, vma, address);
3831
	}
3832

3833
	ptl = huge_pte_lock(h, mm, ptep);
3834
	size = i_size_read(mapping->host) >> huge_page_shift(h);
A
Adam Litke 已提交
3835 3836 3837
	if (idx >= size)
		goto backout;

N
Nick Piggin 已提交
3838
	ret = 0;
3839
	if (!huge_pte_none(huge_ptep_get(ptep)))
A
Adam Litke 已提交
3840 3841
		goto backout;

3842 3843
	if (anon_rmap) {
		ClearPagePrivate(page);
3844
		hugepage_add_new_anon_rmap(page, vma, address);
3845
	} else
3846
		page_dup_rmap(page, true);
3847 3848 3849 3850
	new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
				&& (vma->vm_flags & VM_SHARED)));
	set_huge_pte_at(mm, address, ptep, new_pte);

3851
	hugetlb_count_add(pages_per_huge_page(h), mm);
3852
	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3853
		/* Optimization, do the COW without a second fault */
3854
		ret = hugetlb_cow(mm, vma, address, ptep, page, ptl);
3855 3856
	}

3857
	spin_unlock(ptl);
A
Adam Litke 已提交
3858 3859
	unlock_page(page);
out:
3860
	return ret;
A
Adam Litke 已提交
3861 3862

backout:
3863
	spin_unlock(ptl);
3864
backout_unlocked:
A
Adam Litke 已提交
3865
	unlock_page(page);
3866
	restore_reserve_on_error(h, vma, address, page);
A
Adam Litke 已提交
3867 3868
	put_page(page);
	goto out;
3869 3870
}

3871
#ifdef CONFIG_SMP
3872
u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
3873 3874 3875 3876 3877 3878 3879 3880 3881 3882 3883 3884 3885 3886 3887 3888 3889 3890 3891 3892 3893 3894 3895 3896
			    struct vm_area_struct *vma,
			    struct address_space *mapping,
			    pgoff_t idx, unsigned long address)
{
	unsigned long key[2];
	u32 hash;

	if (vma->vm_flags & VM_SHARED) {
		key[0] = (unsigned long) mapping;
		key[1] = idx;
	} else {
		key[0] = (unsigned long) mm;
		key[1] = address >> huge_page_shift(h);
	}

	hash = jhash2((u32 *)&key, sizeof(key)/sizeof(u32), 0);

	return hash & (num_fault_mutexes - 1);
}
#else
/*
 * For uniprocesor systems we always use a single mutex, so just
 * return 0 and avoid the hashing overhead.
 */
3897
u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
3898 3899 3900 3901 3902 3903 3904 3905
			    struct vm_area_struct *vma,
			    struct address_space *mapping,
			    pgoff_t idx, unsigned long address)
{
	return 0;
}
#endif

3906
int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3907
			unsigned long address, unsigned int flags)
3908
{
3909
	pte_t *ptep, entry;
3910
	spinlock_t *ptl;
3911
	int ret;
3912 3913
	u32 hash;
	pgoff_t idx;
3914
	struct page *page = NULL;
3915
	struct page *pagecache_page = NULL;
3916
	struct hstate *h = hstate_vma(vma);
3917
	struct address_space *mapping;
3918
	int need_wait_lock = 0;
3919

3920 3921
	address &= huge_page_mask(h);

3922
	ptep = huge_pte_offset(mm, address, huge_page_size(h));
3923 3924
	if (ptep) {
		entry = huge_ptep_get(ptep);
N
Naoya Horiguchi 已提交
3925
		if (unlikely(is_hugetlb_entry_migration(entry))) {
3926
			migration_entry_wait_huge(vma, mm, ptep);
N
Naoya Horiguchi 已提交
3927 3928
			return 0;
		} else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
3929
			return VM_FAULT_HWPOISON_LARGE |
3930
				VM_FAULT_SET_HINDEX(hstate_index(h));
3931 3932 3933 3934
	} else {
		ptep = huge_pte_alloc(mm, address, huge_page_size(h));
		if (!ptep)
			return VM_FAULT_OOM;
3935 3936
	}

3937 3938 3939
	mapping = vma->vm_file->f_mapping;
	idx = vma_hugecache_offset(h, vma, address);

3940 3941 3942 3943 3944
	/*
	 * Serialize hugepage allocation and instantiation, so that we don't
	 * get spurious allocation failures if two CPUs race to instantiate
	 * the same page in the page cache.
	 */
3945 3946
	hash = hugetlb_fault_mutex_hash(h, mm, vma, mapping, idx, address);
	mutex_lock(&hugetlb_fault_mutex_table[hash]);
3947

3948 3949
	entry = huge_ptep_get(ptep);
	if (huge_pte_none(entry)) {
3950
		ret = hugetlb_no_page(mm, vma, mapping, idx, address, ptep, flags);
3951
		goto out_mutex;
3952
	}
3953

N
Nick Piggin 已提交
3954
	ret = 0;
3955

3956 3957 3958 3959 3960 3961 3962 3963 3964 3965
	/*
	 * entry could be a migration/hwpoison entry at this point, so this
	 * check prevents the kernel from going below assuming that we have
	 * a active hugepage in pagecache. This goto expects the 2nd page fault,
	 * and is_hugetlb_entry_(migration|hwpoisoned) check will properly
	 * handle it.
	 */
	if (!pte_present(entry))
		goto out_mutex;

3966 3967 3968 3969 3970 3971 3972 3973
	/*
	 * If we are going to COW the mapping later, we examine the pending
	 * reservations for this page now. This will ensure that any
	 * allocations necessary to record that reservation occur outside the
	 * spinlock. For private mappings, we also lookup the pagecache
	 * page now as it is used to determine if a reservation has been
	 * consumed.
	 */
3974
	if ((flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) {
3975 3976
		if (vma_needs_reservation(h, vma, address) < 0) {
			ret = VM_FAULT_OOM;
3977
			goto out_mutex;
3978
		}
3979
		/* Just decrements count, does not deallocate */
3980
		vma_end_reservation(h, vma, address);
3981

3982
		if (!(vma->vm_flags & VM_MAYSHARE))
3983 3984 3985 3986
			pagecache_page = hugetlbfs_pagecache_page(h,
								vma, address);
	}

3987 3988 3989 3990 3991 3992
	ptl = huge_pte_lock(h, mm, ptep);

	/* Check for a racing update before calling hugetlb_cow */
	if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
		goto out_ptl;

3993 3994 3995 3996 3997 3998 3999
	/*
	 * hugetlb_cow() requires page locks of pte_page(entry) and
	 * pagecache_page, so here we need take the former one
	 * when page != pagecache_page or !pagecache_page.
	 */
	page = pte_page(entry);
	if (page != pagecache_page)
4000 4001 4002 4003
		if (!trylock_page(page)) {
			need_wait_lock = 1;
			goto out_ptl;
		}
4004

4005
	get_page(page);
4006

4007
	if (flags & FAULT_FLAG_WRITE) {
4008
		if (!huge_pte_write(entry)) {
4009 4010
			ret = hugetlb_cow(mm, vma, address, ptep,
					  pagecache_page, ptl);
4011
			goto out_put_page;
4012
		}
4013
		entry = huge_pte_mkdirty(entry);
4014 4015
	}
	entry = pte_mkyoung(entry);
4016 4017
	if (huge_ptep_set_access_flags(vma, address, ptep, entry,
						flags & FAULT_FLAG_WRITE))
4018
		update_mmu_cache(vma, address, ptep);
4019 4020 4021 4022
out_put_page:
	if (page != pagecache_page)
		unlock_page(page);
	put_page(page);
4023 4024
out_ptl:
	spin_unlock(ptl);
4025 4026 4027 4028 4029

	if (pagecache_page) {
		unlock_page(pagecache_page);
		put_page(pagecache_page);
	}
4030
out_mutex:
4031
	mutex_unlock(&hugetlb_fault_mutex_table[hash]);
4032 4033 4034 4035 4036 4037 4038 4039 4040
	/*
	 * Generally it's safe to hold refcount during waiting page lock. But
	 * here we just wait to defer the next page fault to avoid busy loop and
	 * the page is not used after unlocked before returning from the current
	 * page fault. So we are safe from accessing freed page, even if we wait
	 * here without taking refcount.
	 */
	if (need_wait_lock)
		wait_on_page_locked(page);
4041
	return ret;
4042 4043
}

4044 4045 4046 4047 4048 4049 4050 4051 4052 4053 4054
/*
 * Used by userfaultfd UFFDIO_COPY.  Based on mcopy_atomic_pte with
 * modifications for huge pages.
 */
int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
			    pte_t *dst_pte,
			    struct vm_area_struct *dst_vma,
			    unsigned long dst_addr,
			    unsigned long src_addr,
			    struct page **pagep)
{
4055
	int vm_shared = dst_vma->vm_flags & VM_SHARED;
4056 4057 4058 4059 4060 4061 4062 4063 4064 4065 4066 4067 4068 4069
	struct hstate *h = hstate_vma(dst_vma);
	pte_t _dst_pte;
	spinlock_t *ptl;
	int ret;
	struct page *page;

	if (!*pagep) {
		ret = -ENOMEM;
		page = alloc_huge_page(dst_vma, dst_addr, 0);
		if (IS_ERR(page))
			goto out;

		ret = copy_huge_page_from_user(page,
						(const void __user *) src_addr,
4070
						pages_per_huge_page(h), false);
4071 4072 4073 4074 4075 4076 4077 4078 4079 4080 4081 4082 4083 4084 4085 4086 4087 4088 4089 4090 4091

		/* fallback to copy_from_user outside mmap_sem */
		if (unlikely(ret)) {
			ret = -EFAULT;
			*pagep = page;
			/* don't free the page */
			goto out;
		}
	} else {
		page = *pagep;
		*pagep = NULL;
	}

	/*
	 * The memory barrier inside __SetPageUptodate makes sure that
	 * preceding stores to the page contents become visible before
	 * the set_pte_at() write.
	 */
	__SetPageUptodate(page);
	set_page_huge_active(page);

4092 4093 4094 4095 4096 4097 4098 4099 4100 4101 4102 4103
	/*
	 * If shared, add to page cache
	 */
	if (vm_shared) {
		struct address_space *mapping = dst_vma->vm_file->f_mapping;
		pgoff_t idx = vma_hugecache_offset(h, dst_vma, dst_addr);

		ret = huge_add_to_page_cache(page, mapping, idx);
		if (ret)
			goto out_release_nounlock;
	}

4104 4105 4106 4107 4108 4109 4110
	ptl = huge_pte_lockptr(h, dst_mm, dst_pte);
	spin_lock(ptl);

	ret = -EEXIST;
	if (!huge_pte_none(huge_ptep_get(dst_pte)))
		goto out_release_unlock;

4111 4112 4113 4114 4115 4116
	if (vm_shared) {
		page_dup_rmap(page, true);
	} else {
		ClearPagePrivate(page);
		hugepage_add_new_anon_rmap(page, dst_vma, dst_addr);
	}
4117 4118 4119 4120 4121 4122 4123 4124 4125 4126 4127 4128 4129 4130 4131 4132

	_dst_pte = make_huge_pte(dst_vma, page, dst_vma->vm_flags & VM_WRITE);
	if (dst_vma->vm_flags & VM_WRITE)
		_dst_pte = huge_pte_mkdirty(_dst_pte);
	_dst_pte = pte_mkyoung(_dst_pte);

	set_huge_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);

	(void)huge_ptep_set_access_flags(dst_vma, dst_addr, dst_pte, _dst_pte,
					dst_vma->vm_flags & VM_WRITE);
	hugetlb_count_add(pages_per_huge_page(h), dst_mm);

	/* No need to invalidate - it was non-present before */
	update_mmu_cache(dst_vma, dst_addr, dst_pte);

	spin_unlock(ptl);
4133 4134
	if (vm_shared)
		unlock_page(page);
4135 4136 4137 4138 4139
	ret = 0;
out:
	return ret;
out_release_unlock:
	spin_unlock(ptl);
4140 4141 4142
out_release_nounlock:
	if (vm_shared)
		unlock_page(page);
4143 4144 4145 4146
	put_page(page);
	goto out;
}

4147 4148 4149
long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
			 struct page **pages, struct vm_area_struct **vmas,
			 unsigned long *position, unsigned long *nr_pages,
4150
			 long i, unsigned int flags, int *nonblocking)
D
David Gibson 已提交
4151
{
4152 4153
	unsigned long pfn_offset;
	unsigned long vaddr = *position;
4154
	unsigned long remainder = *nr_pages;
4155
	struct hstate *h = hstate_vma(vma);
D
David Gibson 已提交
4156 4157

	while (vaddr < vma->vm_end && remainder) {
A
Adam Litke 已提交
4158
		pte_t *pte;
4159
		spinlock_t *ptl = NULL;
H
Hugh Dickins 已提交
4160
		int absent;
A
Adam Litke 已提交
4161
		struct page *page;
D
David Gibson 已提交
4162

4163 4164 4165 4166 4167 4168 4169 4170 4171
		/*
		 * If we have a pending SIGKILL, don't keep faulting pages and
		 * potentially allocating memory.
		 */
		if (unlikely(fatal_signal_pending(current))) {
			remainder = 0;
			break;
		}

A
Adam Litke 已提交
4172 4173
		/*
		 * Some archs (sparc64, sh*) have multiple pte_ts to
H
Hugh Dickins 已提交
4174
		 * each hugepage.  We have to make sure we get the
A
Adam Litke 已提交
4175
		 * first, for the page indexing below to work.
4176 4177
		 *
		 * Note that page table lock is not held when pte is null.
A
Adam Litke 已提交
4178
		 */
4179 4180
		pte = huge_pte_offset(mm, vaddr & huge_page_mask(h),
				      huge_page_size(h));
4181 4182
		if (pte)
			ptl = huge_pte_lock(h, mm, pte);
H
Hugh Dickins 已提交
4183 4184 4185 4186
		absent = !pte || huge_pte_none(huge_ptep_get(pte));

		/*
		 * When coredumping, it suits get_dump_page if we just return
H
Hugh Dickins 已提交
4187 4188 4189 4190
		 * an error where there's an empty slot with no huge pagecache
		 * to back it.  This way, we avoid allocating a hugepage, and
		 * the sparse dumpfile avoids allocating disk blocks, but its
		 * huge holes still show up with zeroes where they need to be.
H
Hugh Dickins 已提交
4191
		 */
H
Hugh Dickins 已提交
4192 4193
		if (absent && (flags & FOLL_DUMP) &&
		    !hugetlbfs_pagecache_present(h, vma, vaddr)) {
4194 4195
			if (pte)
				spin_unlock(ptl);
H
Hugh Dickins 已提交
4196 4197 4198
			remainder = 0;
			break;
		}
D
David Gibson 已提交
4199

4200 4201 4202 4203 4204 4205 4206 4207 4208 4209 4210
		/*
		 * We need call hugetlb_fault for both hugepages under migration
		 * (in which case hugetlb_fault waits for the migration,) and
		 * hwpoisoned hugepages (in which case we need to prevent the
		 * caller from accessing to them.) In order to do this, we use
		 * here is_swap_pte instead of is_hugetlb_entry_migration and
		 * is_hugetlb_entry_hwpoisoned. This is because it simply covers
		 * both cases, and because we can't follow correct pages
		 * directly from any kind of swap entries.
		 */
		if (absent || is_swap_pte(huge_ptep_get(pte)) ||
4211 4212
		    ((flags & FOLL_WRITE) &&
		      !huge_pte_write(huge_ptep_get(pte)))) {
A
Adam Litke 已提交
4213
			int ret;
4214
			unsigned int fault_flags = 0;
D
David Gibson 已提交
4215

4216 4217
			if (pte)
				spin_unlock(ptl);
4218 4219 4220 4221 4222 4223 4224 4225 4226 4227 4228 4229 4230 4231
			if (flags & FOLL_WRITE)
				fault_flags |= FAULT_FLAG_WRITE;
			if (nonblocking)
				fault_flags |= FAULT_FLAG_ALLOW_RETRY;
			if (flags & FOLL_NOWAIT)
				fault_flags |= FAULT_FLAG_ALLOW_RETRY |
					FAULT_FLAG_RETRY_NOWAIT;
			if (flags & FOLL_TRIED) {
				VM_WARN_ON_ONCE(fault_flags &
						FAULT_FLAG_ALLOW_RETRY);
				fault_flags |= FAULT_FLAG_TRIED;
			}
			ret = hugetlb_fault(mm, vma, vaddr, fault_flags);
			if (ret & VM_FAULT_ERROR) {
4232 4233 4234 4235 4236
				int err = vm_fault_to_errno(ret, flags);

				if (err)
					return err;

4237 4238 4239 4240 4241 4242 4243 4244 4245 4246 4247 4248 4249 4250 4251 4252 4253 4254 4255
				remainder = 0;
				break;
			}
			if (ret & VM_FAULT_RETRY) {
				if (nonblocking)
					*nonblocking = 0;
				*nr_pages = 0;
				/*
				 * VM_FAULT_RETRY must not return an
				 * error, it will return zero
				 * instead.
				 *
				 * No need to update "position" as the
				 * caller will not check it after
				 * *nr_pages is set to 0.
				 */
				return i;
			}
			continue;
A
Adam Litke 已提交
4256 4257
		}

4258
		pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
4259
		page = pte_page(huge_ptep_get(pte));
4260
same_page:
4261
		if (pages) {
H
Hugh Dickins 已提交
4262
			pages[i] = mem_map_offset(page, pfn_offset);
4263
			get_page(pages[i]);
4264
		}
D
David Gibson 已提交
4265 4266 4267 4268 4269

		if (vmas)
			vmas[i] = vma;

		vaddr += PAGE_SIZE;
4270
		++pfn_offset;
D
David Gibson 已提交
4271 4272
		--remainder;
		++i;
4273
		if (vaddr < vma->vm_end && remainder &&
4274
				pfn_offset < pages_per_huge_page(h)) {
4275 4276 4277 4278 4279 4280
			/*
			 * We use pfn_offset to avoid touching the pageframes
			 * of this compound page.
			 */
			goto same_page;
		}
4281
		spin_unlock(ptl);
D
David Gibson 已提交
4282
	}
4283
	*nr_pages = remainder;
4284 4285 4286 4287 4288
	/*
	 * setting position is actually required only if remainder is
	 * not zero but it's faster not to add a "if (remainder)"
	 * branch.
	 */
D
David Gibson 已提交
4289 4290
	*position = vaddr;

H
Hugh Dickins 已提交
4291
	return i ? i : -EFAULT;
D
David Gibson 已提交
4292
}
4293

4294 4295 4296 4297 4298 4299 4300 4301
#ifndef __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE
/*
 * ARCHes with special requirements for evicting HUGETLB backing TLB entries can
 * implement this.
 */
#define flush_hugetlb_tlb_range(vma, addr, end)	flush_tlb_range(vma, addr, end)
#endif

4302
unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
4303 4304 4305 4306 4307 4308
		unsigned long address, unsigned long end, pgprot_t newprot)
{
	struct mm_struct *mm = vma->vm_mm;
	unsigned long start = address;
	pte_t *ptep;
	pte_t pte;
4309
	struct hstate *h = hstate_vma(vma);
4310
	unsigned long pages = 0;
4311 4312 4313 4314

	BUG_ON(address >= end);
	flush_cache_range(vma, address, end);

4315
	mmu_notifier_invalidate_range_start(mm, start, end);
4316
	i_mmap_lock_write(vma->vm_file->f_mapping);
4317
	for (; address < end; address += huge_page_size(h)) {
4318
		spinlock_t *ptl;
4319
		ptep = huge_pte_offset(mm, address, huge_page_size(h));
4320 4321
		if (!ptep)
			continue;
4322
		ptl = huge_pte_lock(h, mm, ptep);
4323 4324
		if (huge_pmd_unshare(mm, &address, ptep)) {
			pages++;
4325
			spin_unlock(ptl);
4326
			continue;
4327
		}
4328 4329 4330 4331 4332 4333 4334 4335 4336 4337 4338 4339 4340
		pte = huge_ptep_get(ptep);
		if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) {
			spin_unlock(ptl);
			continue;
		}
		if (unlikely(is_hugetlb_entry_migration(pte))) {
			swp_entry_t entry = pte_to_swp_entry(pte);

			if (is_write_migration_entry(entry)) {
				pte_t newpte;

				make_migration_entry_read(&entry);
				newpte = swp_entry_to_pte(entry);
4341 4342
				set_huge_swap_pte_at(mm, address, ptep,
						     newpte, huge_page_size(h));
4343 4344 4345 4346 4347 4348
				pages++;
			}
			spin_unlock(ptl);
			continue;
		}
		if (!huge_pte_none(pte)) {
4349
			pte = huge_ptep_get_and_clear(mm, address, ptep);
4350
			pte = pte_mkhuge(huge_pte_modify(pte, newprot));
4351
			pte = arch_make_huge_pte(pte, vma, NULL, 0);
4352
			set_huge_pte_at(mm, address, ptep, pte);
4353
			pages++;
4354
		}
4355
		spin_unlock(ptl);
4356
	}
4357
	/*
4358
	 * Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare
4359
	 * may have cleared our pud entry and done put_page on the page table:
4360
	 * once we release i_mmap_rwsem, another task can do the final put_page
4361 4362
	 * and that page table be reused and filled with junk.
	 */
4363
	flush_hugetlb_tlb_range(vma, start, end);
4364
	mmu_notifier_invalidate_range(mm, start, end);
4365
	i_mmap_unlock_write(vma->vm_file->f_mapping);
4366
	mmu_notifier_invalidate_range_end(mm, start, end);
4367 4368

	return pages << h->order;
4369 4370
}

4371 4372
int hugetlb_reserve_pages(struct inode *inode,
					long from, long to,
4373
					struct vm_area_struct *vma,
4374
					vm_flags_t vm_flags)
4375
{
4376
	long ret, chg;
4377
	struct hstate *h = hstate_inode(inode);
4378
	struct hugepage_subpool *spool = subpool_inode(inode);
4379
	struct resv_map *resv_map;
4380
	long gbl_reserve;
4381

4382 4383 4384
	/*
	 * Only apply hugepage reservation if asked. At fault time, an
	 * attempt will be made for VM_NORESERVE to allocate a page
4385
	 * without using reserves
4386
	 */
4387
	if (vm_flags & VM_NORESERVE)
4388 4389
		return 0;

4390 4391 4392 4393 4394 4395
	/*
	 * Shared mappings base their reservation on the number of pages that
	 * are already allocated on behalf of the file. Private mappings need
	 * to reserve the full area even if read-only as mprotect() may be
	 * called to make the mapping read-write. Assume !vma is a shm mapping
	 */
4396
	if (!vma || vma->vm_flags & VM_MAYSHARE) {
4397
		resv_map = inode_resv_map(inode);
4398

4399
		chg = region_chg(resv_map, from, to);
4400 4401 4402

	} else {
		resv_map = resv_map_alloc();
4403 4404 4405
		if (!resv_map)
			return -ENOMEM;

4406
		chg = to - from;
4407

4408 4409 4410 4411
		set_vma_resv_map(vma, resv_map);
		set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
	}

4412 4413 4414 4415
	if (chg < 0) {
		ret = chg;
		goto out_err;
	}
4416

4417 4418 4419 4420 4421 4422 4423
	/*
	 * There must be enough pages in the subpool for the mapping. If
	 * the subpool has a minimum size, there may be some global
	 * reservations already in place (gbl_reserve).
	 */
	gbl_reserve = hugepage_subpool_get_pages(spool, chg);
	if (gbl_reserve < 0) {
4424 4425 4426
		ret = -ENOSPC;
		goto out_err;
	}
4427 4428

	/*
4429
	 * Check enough hugepages are available for the reservation.
4430
	 * Hand the pages back to the subpool if there are not
4431
	 */
4432
	ret = hugetlb_acct_memory(h, gbl_reserve);
K
Ken Chen 已提交
4433
	if (ret < 0) {
4434 4435
		/* put back original number of pages, chg */
		(void)hugepage_subpool_put_pages(spool, chg);
4436
		goto out_err;
K
Ken Chen 已提交
4437
	}
4438 4439 4440 4441 4442 4443 4444 4445 4446 4447 4448 4449

	/*
	 * Account for the reservations made. Shared mappings record regions
	 * that have reservations as they are shared by multiple VMAs.
	 * When the last VMA disappears, the region map says how much
	 * the reservation was and the page cache tells how much of
	 * the reservation was consumed. Private mappings are per-VMA and
	 * only the consumed reservations are tracked. When the VMA
	 * disappears, the original reservation is the VMA size and the
	 * consumed reservations are stored in the map. Hence, nothing
	 * else has to be done for private mappings here
	 */
4450 4451 4452 4453 4454 4455 4456 4457 4458 4459 4460 4461 4462 4463 4464 4465 4466 4467
	if (!vma || vma->vm_flags & VM_MAYSHARE) {
		long add = region_add(resv_map, from, to);

		if (unlikely(chg > add)) {
			/*
			 * pages in this range were added to the reserve
			 * map between region_chg and region_add.  This
			 * indicates a race with alloc_huge_page.  Adjust
			 * the subpool and reserve counts modified above
			 * based on the difference.
			 */
			long rsv_adjust;

			rsv_adjust = hugepage_subpool_put_pages(spool,
								chg - add);
			hugetlb_acct_memory(h, -rsv_adjust);
		}
	}
4468
	return 0;
4469
out_err:
4470
	if (!vma || vma->vm_flags & VM_MAYSHARE)
4471 4472 4473
		/* Don't call region_abort if region_chg failed */
		if (chg >= 0)
			region_abort(resv_map, from, to);
J
Joonsoo Kim 已提交
4474 4475
	if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
		kref_put(&resv_map->refs, resv_map_release);
4476
	return ret;
4477 4478
}

4479 4480
long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
								long freed)
4481
{
4482
	struct hstate *h = hstate_inode(inode);
4483
	struct resv_map *resv_map = inode_resv_map(inode);
4484
	long chg = 0;
4485
	struct hugepage_subpool *spool = subpool_inode(inode);
4486
	long gbl_reserve;
K
Ken Chen 已提交
4487

4488 4489 4490 4491 4492 4493 4494 4495 4496 4497 4498
	if (resv_map) {
		chg = region_del(resv_map, start, end);
		/*
		 * region_del() can fail in the rare case where a region
		 * must be split and another region descriptor can not be
		 * allocated.  If end == LONG_MAX, it will not fail.
		 */
		if (chg < 0)
			return chg;
	}

K
Ken Chen 已提交
4499
	spin_lock(&inode->i_lock);
4500
	inode->i_blocks -= (blocks_per_huge_page(h) * freed);
K
Ken Chen 已提交
4501 4502
	spin_unlock(&inode->i_lock);

4503 4504 4505 4506 4507 4508
	/*
	 * If the subpool has a minimum size, the number of global
	 * reservations to be released may be adjusted.
	 */
	gbl_reserve = hugepage_subpool_put_pages(spool, (chg - freed));
	hugetlb_acct_memory(h, -gbl_reserve);
4509 4510

	return 0;
4511
}
4512

4513 4514 4515 4516 4517 4518 4519 4520 4521 4522 4523
#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
static unsigned long page_table_shareable(struct vm_area_struct *svma,
				struct vm_area_struct *vma,
				unsigned long addr, pgoff_t idx)
{
	unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
				svma->vm_start;
	unsigned long sbase = saddr & PUD_MASK;
	unsigned long s_end = sbase + PUD_SIZE;

	/* Allow segments to share if only one is marked locked */
E
Eric B Munson 已提交
4524 4525
	unsigned long vm_flags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
	unsigned long svm_flags = svma->vm_flags & VM_LOCKED_CLEAR_MASK;
4526 4527 4528 4529 4530 4531 4532 4533 4534 4535 4536 4537 4538

	/*
	 * match the virtual addresses, permission and the alignment of the
	 * page table page.
	 */
	if (pmd_index(addr) != pmd_index(saddr) ||
	    vm_flags != svm_flags ||
	    sbase < svma->vm_start || svma->vm_end < s_end)
		return 0;

	return saddr;
}

4539
static bool vma_shareable(struct vm_area_struct *vma, unsigned long addr)
4540 4541 4542 4543 4544 4545 4546 4547 4548
{
	unsigned long base = addr & PUD_MASK;
	unsigned long end = base + PUD_SIZE;

	/*
	 * check on proper vm_flags and page table alignment
	 */
	if (vma->vm_flags & VM_MAYSHARE &&
	    vma->vm_start <= base && end <= vma->vm_end)
4549 4550
		return true;
	return false;
4551 4552 4553 4554 4555 4556 4557
}

/*
 * Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc()
 * and returns the corresponding pte. While this is not necessary for the
 * !shared pmd case because we can allocate the pmd later as well, it makes the
 * code much cleaner. pmd allocation is essential for the shared case because
4558
 * pud has to be populated inside the same i_mmap_rwsem section - otherwise
4559 4560 4561 4562 4563 4564 4565 4566 4567 4568 4569 4570 4571
 * racing tasks could either miss the sharing (see huge_pte_offset) or select a
 * bad pmd for sharing.
 */
pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
{
	struct vm_area_struct *vma = find_vma(mm, addr);
	struct address_space *mapping = vma->vm_file->f_mapping;
	pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
			vma->vm_pgoff;
	struct vm_area_struct *svma;
	unsigned long saddr;
	pte_t *spte = NULL;
	pte_t *pte;
4572
	spinlock_t *ptl;
4573 4574 4575 4576

	if (!vma_shareable(vma, addr))
		return (pte_t *)pmd_alloc(mm, pud, addr);

4577
	i_mmap_lock_write(mapping);
4578 4579 4580 4581 4582 4583
	vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) {
		if (svma == vma)
			continue;

		saddr = page_table_shareable(svma, vma, addr, idx);
		if (saddr) {
4584 4585
			spte = huge_pte_offset(svma->vm_mm, saddr,
					       vma_mmu_pagesize(svma));
4586 4587 4588 4589 4590 4591 4592 4593 4594 4595
			if (spte) {
				get_page(virt_to_page(spte));
				break;
			}
		}
	}

	if (!spte)
		goto out;

4596
	ptl = huge_pte_lock(hstate_vma(vma), mm, spte);
4597
	if (pud_none(*pud)) {
4598 4599
		pud_populate(mm, pud,
				(pmd_t *)((unsigned long)spte & PAGE_MASK));
4600
		mm_inc_nr_pmds(mm);
4601
	} else {
4602
		put_page(virt_to_page(spte));
4603
	}
4604
	spin_unlock(ptl);
4605 4606
out:
	pte = (pte_t *)pmd_alloc(mm, pud, addr);
4607
	i_mmap_unlock_write(mapping);
4608 4609 4610 4611 4612 4613 4614 4615 4616 4617
	return pte;
}

/*
 * unmap huge page backed by shared pte.
 *
 * Hugetlb pte page is ref counted at the time of mapping.  If pte is shared
 * indicated by page_count > 1, unmap is achieved by clearing pud and
 * decrementing the ref count. If count == 1, the pte page is not shared.
 *
4618
 * called with page table lock held.
4619 4620 4621 4622 4623 4624 4625
 *
 * returns: 1 successfully unmapped a shared pte page
 *	    0 the underlying pte page is not shared, or it is the last user
 */
int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
{
	pgd_t *pgd = pgd_offset(mm, *addr);
4626 4627
	p4d_t *p4d = p4d_offset(pgd, *addr);
	pud_t *pud = pud_offset(p4d, *addr);
4628 4629 4630 4631 4632 4633 4634

	BUG_ON(page_count(virt_to_page(ptep)) == 0);
	if (page_count(virt_to_page(ptep)) == 1)
		return 0;

	pud_clear(pud);
	put_page(virt_to_page(ptep));
4635
	mm_dec_nr_pmds(mm);
4636 4637 4638
	*addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
	return 1;
}
4639 4640 4641 4642 4643 4644
#define want_pmd_share()	(1)
#else /* !CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
{
	return NULL;
}
4645 4646 4647 4648 4649

int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
{
	return 0;
}
4650
#define want_pmd_share()	(0)
4651 4652
#endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */

4653 4654 4655 4656 4657
#ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
pte_t *huge_pte_alloc(struct mm_struct *mm,
			unsigned long addr, unsigned long sz)
{
	pgd_t *pgd;
4658
	p4d_t *p4d;
4659 4660 4661 4662
	pud_t *pud;
	pte_t *pte = NULL;

	pgd = pgd_offset(mm, addr);
4663 4664
	p4d = p4d_offset(pgd, addr);
	pud = pud_alloc(mm, p4d, addr);
4665 4666 4667 4668 4669 4670 4671 4672 4673 4674 4675
	if (pud) {
		if (sz == PUD_SIZE) {
			pte = (pte_t *)pud;
		} else {
			BUG_ON(sz != PMD_SIZE);
			if (want_pmd_share() && pud_none(*pud))
				pte = huge_pmd_share(mm, addr, pud);
			else
				pte = (pte_t *)pmd_alloc(mm, pud, addr);
		}
	}
4676
	BUG_ON(pte && pte_present(*pte) && !pte_huge(*pte));
4677 4678 4679 4680

	return pte;
}

4681 4682
pte_t *huge_pte_offset(struct mm_struct *mm,
		       unsigned long addr, unsigned long sz)
4683 4684
{
	pgd_t *pgd;
4685
	p4d_t *p4d;
4686
	pud_t *pud;
4687
	pmd_t *pmd;
4688 4689

	pgd = pgd_offset(mm, addr);
4690 4691 4692 4693 4694 4695 4696 4697 4698 4699 4700
	if (!pgd_present(*pgd))
		return NULL;
	p4d = p4d_offset(pgd, addr);
	if (!p4d_present(*p4d))
		return NULL;
	pud = pud_offset(p4d, addr);
	if (!pud_present(*pud))
		return NULL;
	if (pud_huge(*pud))
		return (pte_t *)pud;
	pmd = pmd_offset(pud, addr);
4701 4702 4703
	return (pte_t *) pmd;
}

4704 4705 4706 4707 4708 4709 4710 4711 4712 4713 4714 4715 4716
#endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */

/*
 * These functions are overwritable if your architecture needs its own
 * behavior.
 */
struct page * __weak
follow_huge_addr(struct mm_struct *mm, unsigned long address,
			      int write)
{
	return ERR_PTR(-EINVAL);
}

4717 4718 4719 4720 4721 4722 4723 4724
struct page * __weak
follow_huge_pd(struct vm_area_struct *vma,
	       unsigned long address, hugepd_t hpd, int flags, int pdshift)
{
	WARN(1, "hugepd follow called with no support for hugepage directory format\n");
	return NULL;
}

4725
struct page * __weak
4726
follow_huge_pmd(struct mm_struct *mm, unsigned long address,
4727
		pmd_t *pmd, int flags)
4728
{
4729 4730
	struct page *page = NULL;
	spinlock_t *ptl;
4731
	pte_t pte;
4732 4733 4734 4735 4736 4737 4738 4739 4740
retry:
	ptl = pmd_lockptr(mm, pmd);
	spin_lock(ptl);
	/*
	 * make sure that the address range covered by this pmd is not
	 * unmapped from other threads.
	 */
	if (!pmd_huge(*pmd))
		goto out;
4741 4742
	pte = huge_ptep_get((pte_t *)pmd);
	if (pte_present(pte)) {
4743
		page = pmd_page(*pmd) + ((address & ~PMD_MASK) >> PAGE_SHIFT);
4744 4745 4746
		if (flags & FOLL_GET)
			get_page(page);
	} else {
4747
		if (is_hugetlb_entry_migration(pte)) {
4748 4749 4750 4751 4752 4753 4754 4755 4756 4757 4758
			spin_unlock(ptl);
			__migration_entry_wait(mm, (pte_t *)pmd, ptl);
			goto retry;
		}
		/*
		 * hwpoisoned entry is treated as no_page_table in
		 * follow_page_mask().
		 */
	}
out:
	spin_unlock(ptl);
4759 4760 4761
	return page;
}

4762
struct page * __weak
4763
follow_huge_pud(struct mm_struct *mm, unsigned long address,
4764
		pud_t *pud, int flags)
4765
{
4766 4767
	if (flags & FOLL_GET)
		return NULL;
4768

4769
	return pte_page(*(pte_t *)pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT);
4770 4771
}

4772 4773 4774 4775 4776 4777 4778 4779 4780
struct page * __weak
follow_huge_pgd(struct mm_struct *mm, unsigned long address, pgd_t *pgd, int flags)
{
	if (flags & FOLL_GET)
		return NULL;

	return pte_page(*(pte_t *)pgd) + ((address & ~PGDIR_MASK) >> PAGE_SHIFT);
}

4781 4782
bool isolate_huge_page(struct page *page, struct list_head *list)
{
4783 4784
	bool ret = true;

4785
	VM_BUG_ON_PAGE(!PageHead(page), page);
4786
	spin_lock(&hugetlb_lock);
4787 4788 4789 4790 4791
	if (!page_huge_active(page) || !get_page_unless_zero(page)) {
		ret = false;
		goto unlock;
	}
	clear_page_huge_active(page);
4792
	list_move_tail(&page->lru, list);
4793
unlock:
4794
	spin_unlock(&hugetlb_lock);
4795
	return ret;
4796 4797 4798 4799
}

void putback_active_hugepage(struct page *page)
{
4800
	VM_BUG_ON_PAGE(!PageHead(page), page);
4801
	spin_lock(&hugetlb_lock);
4802
	set_page_huge_active(page);
4803 4804 4805 4806
	list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
	spin_unlock(&hugetlb_lock);
	put_page(page);
}