hugetlb.c 141.6 KB
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// SPDX-License-Identifier: GPL-2.0-only
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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/memblock.h>
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#include <linux/sysfs.h>
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#include <linux/slab.h>
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#include <linux/mmdebug.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 <linux/numa.h>
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#include <linux/llist.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 <linux/page_owner.h>
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#include "internal.h"
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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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/*
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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;

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	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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/* Must be called with resv->lock held. Calling this with count_only == true
 * will count the number of pages to be added but will not modify the linked
 * list.
 */
static long add_reservation_in_range(struct resv_map *resv, long f, long t,
				     bool count_only)
{
	long chg = 0;
	struct list_head *head = &resv->regions;
	struct file_region *rg = NULL, *trg = NULL, *nrg = NULL;

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

	/* 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. */
	nrg = rg;
	list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
		if (&rg->link == head)
			break;
		if (rg->from > t)
			break;

		/* We overlap with this area, if it extends further than
		 * 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;

		if (!count_only && rg != nrg) {
			list_del(&rg->link);
			kfree(rg);
		}
	}

	if (!count_only) {
		nrg->from = f;
		nrg->to = t;
	}

	return chg;
}

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/*
 * Add the huge page range represented by [f, t) to the reserve
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 * map.  Existing regions will be expanded to accommodate the specified
 * range, or a region will be taken from the cache.  Sufficient regions
 * must exist in the cache due to the previous call to region_chg with
 * the same 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;
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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
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	 * specified range, pull a region descriptor from the cache
	 * and use it for this range.
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	 */
	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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	add = add_reservation_in_range(resv, f, t, false);
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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
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 * map.  A new file_region structure is added to the cache
 * as a placeholder, so that the subsequent region_add
 * call will have all the regions it needs and will not fail.
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 *
 * 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.
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 */
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static long region_chg(struct resv_map *resv, long f, long t)
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{
	long chg = 0;

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	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)
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			return -ENOMEM;

		spin_lock(&resv->lock);
		list_add(&trg->link, &resv->region_cache);
		resv->region_cache_count++;
		goto retry_locked;
	}

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	chg = add_reservation_in_range(resv, f, t, true);
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	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.
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 */
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static long region_del(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, *trg;
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	struct file_region *nrg = NULL;
	long del = 0;
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retry:
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	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))
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			continue;
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		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.
 */
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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);
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	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).
 */
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static long region_count(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;
	long chg = 0;

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	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;
	}
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	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)
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{
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	return ((address - vma->vm_start) >> huge_page_shift(h)) +
			(vma->vm_pgoff >> huge_page_order(h));
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}

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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);
}
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EXPORT_SYMBOL_GPL(linear_hugepage_index);
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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)
{
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	if (vma->vm_ops && vma->vm_ops->pagesize)
		return vma->vm_ops->pagesize(vma);
	return PAGE_SIZE;
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}
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EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
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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
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 * architectures where it differs, an architecture-specific 'strong'
 * version of this symbol is required.
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 */
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__weak unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
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{
	return vma_kernel_pagesize(vma);
}

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/*
 * 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)
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#define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
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/*
 * 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.
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 *
 * 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.
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 */
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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;
}

653
struct resv_map *resv_map_alloc(void)
654 655
{
	struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
656 657 658 659 660
	struct file_region *rg = kmalloc(sizeof(*rg), GFP_KERNEL);

	if (!resv_map || !rg) {
		kfree(resv_map);
		kfree(rg);
661
		return NULL;
662
	}
663 664

	kref_init(&resv_map->refs);
665
	spin_lock_init(&resv_map->lock);
666 667
	INIT_LIST_HEAD(&resv_map->regions);

668 669 670 671 672 673
	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;

674 675 676
	return resv_map;
}

677
void resv_map_release(struct kref *ref)
678 679
{
	struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
680 681
	struct list_head *head = &resv_map->region_cache;
	struct file_region *rg, *trg;
682 683

	/* Clear out any active regions before we release the map. */
684
	region_del(resv_map, 0, LONG_MAX);
685 686 687 688 689 690 691 692 693

	/* ... 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);

694 695 696
	kfree(resv_map);
}

697 698
static inline struct resv_map *inode_resv_map(struct inode *inode)
{
699 700 701 702 703 704 705 706 707
	/*
	 * At inode evict time, i_mapping may not point to the original
	 * address space within the inode.  This original address space
	 * contains the pointer to the resv_map.  So, always use the
	 * address space embedded within the inode.
	 * The VERY common case is inode->mapping == &inode->i_data but,
	 * this may not be true for device special inodes.
	 */
	return (struct resv_map *)(&inode->i_data)->private_data;
708 709
}

710
static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
711
{
712
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
713 714 715 716 717 718 719
	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 {
720 721
		return (struct resv_map *)(get_vma_private_data(vma) &
							~HPAGE_RESV_MASK);
722
	}
723 724
}

725
static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
726
{
727 728
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
	VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
729

730 731
	set_vma_private_data(vma, (get_vma_private_data(vma) &
				HPAGE_RESV_MASK) | (unsigned long)map);
732 733 734 735
}

static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
{
736 737
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
	VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
738 739

	set_vma_private_data(vma, get_vma_private_data(vma) | flags);
740 741 742 743
}

static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
{
744
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
745 746

	return (get_vma_private_data(vma) & flag) != 0;
747 748
}

749
/* Reset counters to 0 and clear all HPAGE_RESV_* flags */
750 751
void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
{
752
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
753
	if (!(vma->vm_flags & VM_MAYSHARE))
754 755 756 757
		vma->vm_private_data = (void *)0;
}

/* Returns true if the VMA has associated reserve pages */
758
static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
759
{
760 761 762 763 764 765 766 767 768 769 770
	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)
771
			return true;
772
		else
773
			return false;
774
	}
775 776

	/* Shared mappings always use reserves */
777 778 779 780 781 782 783 784 785 786 787 788 789
	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;
	}
790 791 792 793 794

	/*
	 * Only the process that called mmap() has reserves for
	 * private mappings.
	 */
795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815
	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;
	}
816

817
	return false;
818 819
}

820
static void enqueue_huge_page(struct hstate *h, struct page *page)
L
Linus Torvalds 已提交
821 822
{
	int nid = page_to_nid(page);
823
	list_move(&page->lru, &h->hugepage_freelists[nid]);
824 825
	h->free_huge_pages++;
	h->free_huge_pages_node[nid]++;
L
Linus Torvalds 已提交
826 827
}

828
static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid)
829 830 831
{
	struct page *page;

832
	list_for_each_entry(page, &h->hugepage_freelists[nid], lru)
833
		if (!PageHWPoison(page))
834 835 836 837 838 839
			break;
	/*
	 * if 'non-isolated free hugepage' not found on the list,
	 * the allocation fails.
	 */
	if (&h->hugepage_freelists[nid] == &page->lru)
840
		return NULL;
841
	list_move(&page->lru, &h->hugepage_activelist);
842
	set_page_refcounted(page);
843 844 845 846 847
	h->free_huge_pages--;
	h->free_huge_pages_node[nid]--;
	return page;
}

848 849
static struct page *dequeue_huge_page_nodemask(struct hstate *h, gfp_t gfp_mask, int nid,
		nodemask_t *nmask)
850
{
851 852 853 854
	unsigned int cpuset_mems_cookie;
	struct zonelist *zonelist;
	struct zone *zone;
	struct zoneref *z;
855
	int node = NUMA_NO_NODE;
856

857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872
	zonelist = node_zonelist(nid, gfp_mask);

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

		if (!cpuset_zone_allowed(zone, gfp_mask))
			continue;
		/*
		 * no need to ask again on the same node. Pool is node rather than
		 * zone aware
		 */
		if (zone_to_nid(zone) == node)
			continue;
		node = zone_to_nid(zone);
873 874 875 876 877

		page = dequeue_huge_page_node_exact(h, node);
		if (page)
			return page;
	}
878 879 880
	if (unlikely(read_mems_allowed_retry(cpuset_mems_cookie)))
		goto retry_cpuset;

881 882 883
	return NULL;
}

884 885 886
/* Movability of hugepages depends on migration support. */
static inline gfp_t htlb_alloc_mask(struct hstate *h)
{
887
	if (hugepage_movable_supported(h))
888 889 890 891 892
		return GFP_HIGHUSER_MOVABLE;
	else
		return GFP_HIGHUSER;
}

893 894
static struct page *dequeue_huge_page_vma(struct hstate *h,
				struct vm_area_struct *vma,
895 896
				unsigned long address, int avoid_reserve,
				long chg)
L
Linus Torvalds 已提交
897
{
898
	struct page *page;
899
	struct mempolicy *mpol;
900
	gfp_t gfp_mask;
901
	nodemask_t *nodemask;
902
	int nid;
L
Linus Torvalds 已提交
903

904 905 906 907 908
	/*
	 * 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
	 */
909
	if (!vma_has_reserves(vma, chg) &&
910
			h->free_huge_pages - h->resv_huge_pages == 0)
911
		goto err;
912

913
	/* If reserves cannot be used, ensure enough pages are in the pool */
914
	if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
915
		goto err;
916

917 918
	gfp_mask = htlb_alloc_mask(h);
	nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
919 920 921 922
	page = dequeue_huge_page_nodemask(h, gfp_mask, nid, nodemask);
	if (page && !avoid_reserve && vma_has_reserves(vma, chg)) {
		SetPagePrivate(page);
		h->resv_huge_pages--;
L
Linus Torvalds 已提交
923
	}
924

925
	mpol_cond_put(mpol);
L
Linus Torvalds 已提交
926
	return page;
927 928 929

err:
	return NULL;
L
Linus Torvalds 已提交
930 931
}

932 933 934 935 936 937 938 939 940
/*
 * 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)
{
941
	nid = next_node_in(nid, *nodes_allowed);
942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002
	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--)

1003
#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
1004
static void destroy_compound_gigantic_page(struct page *page,
1005
					unsigned int order)
1006 1007 1008 1009 1010
{
	int i;
	int nr_pages = 1 << order;
	struct page *p = page + 1;

1011
	atomic_set(compound_mapcount_ptr(page), 0);
1012 1013 1014
	if (hpage_pincount_available(page))
		atomic_set(compound_pincount_ptr(page), 0);

1015
	for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
1016
		clear_compound_head(p);
1017 1018 1019 1020 1021 1022 1023
		set_page_refcounted(p);
	}

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

1024
static void free_gigantic_page(struct page *page, unsigned int order)
1025 1026 1027 1028
{
	free_contig_range(page_to_pfn(page), 1 << order);
}

1029
#ifdef CONFIG_CONTIG_ALLOC
1030 1031
static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
		int nid, nodemask_t *nodemask)
1032
{
1033
	unsigned long nr_pages = 1UL << huge_page_order(h);
1034

1035
	return alloc_contig_pages(nr_pages, gfp_mask, nid, nodemask);
1036 1037 1038
}

static void prep_new_huge_page(struct hstate *h, struct page *page, int nid);
1039
static void prep_compound_gigantic_page(struct page *page, unsigned int order);
1040 1041 1042 1043 1044 1045 1046
#else /* !CONFIG_CONTIG_ALLOC */
static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
					int nid, nodemask_t *nodemask)
{
	return NULL;
}
#endif /* CONFIG_CONTIG_ALLOC */
1047

1048
#else /* !CONFIG_ARCH_HAS_GIGANTIC_PAGE */
1049
static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
1050 1051 1052 1053
					int nid, nodemask_t *nodemask)
{
	return NULL;
}
1054
static inline void free_gigantic_page(struct page *page, unsigned int order) { }
1055
static inline void destroy_compound_gigantic_page(struct page *page,
1056
						unsigned int order) { }
1057 1058
#endif

1059
static void update_and_free_page(struct hstate *h, struct page *page)
A
Adam Litke 已提交
1060 1061
{
	int i;
1062

1063
	if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
1064
		return;
1065

1066 1067 1068
	h->nr_huge_pages--;
	h->nr_huge_pages_node[page_to_nid(page)]--;
	for (i = 0; i < pages_per_huge_page(h); i++) {
1069 1070
		page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
				1 << PG_referenced | 1 << PG_dirty |
1071 1072
				1 << PG_active | 1 << PG_private |
				1 << PG_writeback);
A
Adam Litke 已提交
1073
	}
1074
	VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page);
1075
	set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
A
Adam Litke 已提交
1076
	set_page_refcounted(page);
1077 1078 1079 1080 1081 1082
	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
1083 1084
}

1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095
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;
}

1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120
/*
 * 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]);
}

1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142
/*
 * Internal hugetlb specific page flag. Do not use outside of the hugetlb
 * code
 */
static inline bool PageHugeTemporary(struct page *page)
{
	if (!PageHuge(page))
		return false;

	return (unsigned long)page[2].mapping == -1U;
}

static inline void SetPageHugeTemporary(struct page *page)
{
	page[2].mapping = (void *)-1U;
}

static inline void ClearPageHugeTemporary(struct page *page)
{
	page[2].mapping = NULL;
}

1143
static void __free_huge_page(struct page *page)
1144
{
1145 1146 1147 1148
	/*
	 * Can't pass hstate in here because it is called from the
	 * compound page destructor.
	 */
1149
	struct hstate *h = page_hstate(page);
1150
	int nid = page_to_nid(page);
1151 1152
	struct hugepage_subpool *spool =
		(struct hugepage_subpool *)page_private(page);
1153
	bool restore_reserve;
1154

1155 1156
	VM_BUG_ON_PAGE(page_count(page), page);
	VM_BUG_ON_PAGE(page_mapcount(page), page);
1157 1158 1159

	set_page_private(page, 0);
	page->mapping = NULL;
1160
	restore_reserve = PagePrivate(page);
1161
	ClearPagePrivate(page);
1162

1163
	/*
1164 1165 1166 1167 1168 1169
	 * If PagePrivate() was set on page, page allocation consumed a
	 * reservation.  If the page was associated with a subpool, there
	 * would have been a page reserved in the subpool before allocation
	 * via hugepage_subpool_get_pages().  Since we are 'restoring' the
	 * reservtion, do not call hugepage_subpool_put_pages() as this will
	 * remove the reserved page from the subpool.
1170
	 */
1171 1172 1173 1174 1175 1176 1177 1178 1179 1180
	if (!restore_reserve) {
		/*
		 * A return code of zero implies that the subpool will be
		 * under its minimum size if the reservation is not restored
		 * after page is free.  Therefore, force restore_reserve
		 * operation.
		 */
		if (hugepage_subpool_put_pages(spool, 1) == 0)
			restore_reserve = true;
	}
1181

1182
	spin_lock(&hugetlb_lock);
1183
	clear_page_huge_active(page);
1184 1185
	hugetlb_cgroup_uncharge_page(hstate_index(h),
				     pages_per_huge_page(h), page);
1186 1187 1188
	if (restore_reserve)
		h->resv_huge_pages++;

1189 1190 1191 1192 1193
	if (PageHugeTemporary(page)) {
		list_del(&page->lru);
		ClearPageHugeTemporary(page);
		update_and_free_page(h, page);
	} else if (h->surplus_huge_pages_node[nid]) {
1194 1195
		/* remove the page from active list */
		list_del(&page->lru);
1196 1197 1198
		update_and_free_page(h, page);
		h->surplus_huge_pages--;
		h->surplus_huge_pages_node[nid]--;
1199
	} else {
1200
		arch_clear_hugepage_flags(page);
1201
		enqueue_huge_page(h, page);
1202
	}
1203 1204 1205
	spin_unlock(&hugetlb_lock);
}

1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 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 1249 1250 1251 1252 1253
/*
 * As free_huge_page() can be called from a non-task context, we have
 * to defer the actual freeing in a workqueue to prevent potential
 * hugetlb_lock deadlock.
 *
 * free_hpage_workfn() locklessly retrieves the linked list of pages to
 * be freed and frees them one-by-one. As the page->mapping pointer is
 * going to be cleared in __free_huge_page() anyway, it is reused as the
 * llist_node structure of a lockless linked list of huge pages to be freed.
 */
static LLIST_HEAD(hpage_freelist);

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

	node = llist_del_all(&hpage_freelist);

	while (node) {
		page = container_of((struct address_space **)node,
				     struct page, mapping);
		node = node->next;
		__free_huge_page(page);
	}
}
static DECLARE_WORK(free_hpage_work, free_hpage_workfn);

void free_huge_page(struct page *page)
{
	/*
	 * Defer freeing if in non-task context to avoid hugetlb_lock deadlock.
	 */
	if (!in_task()) {
		/*
		 * Only call schedule_work() if hpage_freelist is previously
		 * empty. Otherwise, schedule_work() had been called but the
		 * workfn hasn't retrieved the list yet.
		 */
		if (llist_add((struct llist_node *)&page->mapping,
			      &hpage_freelist))
			schedule_work(&free_hpage_work);
		return;
	}

	__free_huge_page(page);
}

1254
static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
1255
{
1256
	INIT_LIST_HEAD(&page->lru);
1257
	set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
1258
	spin_lock(&hugetlb_lock);
1259
	set_hugetlb_cgroup(page, NULL);
1260 1261
	h->nr_huge_pages++;
	h->nr_huge_pages_node[nid]++;
1262 1263 1264
	spin_unlock(&hugetlb_lock);
}

1265
static void prep_compound_gigantic_page(struct page *page, unsigned int order)
1266 1267 1268 1269 1270 1271 1272
{
	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);
1273
	__ClearPageReserved(page);
1274
	__SetPageHead(page);
1275
	for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288
		/*
		 * 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);
1289
		set_page_count(p, 0);
1290
		set_compound_head(p, page);
1291
	}
1292
	atomic_set(compound_mapcount_ptr(page), -1);
1293 1294 1295

	if (hpage_pincount_available(page))
		atomic_set(compound_pincount_ptr(page), 0);
1296 1297
}

A
Andrew Morton 已提交
1298 1299 1300 1301 1302
/*
 * PageHuge() only returns true for hugetlbfs pages, but not for normal or
 * transparent huge pages.  See the PageTransHuge() documentation for more
 * details.
 */
1303 1304 1305 1306 1307 1308
int PageHuge(struct page *page)
{
	if (!PageCompound(page))
		return 0;

	page = compound_head(page);
1309
	return page[1].compound_dtor == HUGETLB_PAGE_DTOR;
1310
}
1311 1312
EXPORT_SYMBOL_GPL(PageHuge);

1313 1314 1315 1316 1317 1318 1319 1320 1321
/*
 * 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;

1322
	return get_compound_page_dtor(page_head) == free_huge_page;
1323 1324
}

1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424
/*
 * Find address_space associated with hugetlbfs page.
 * Upon entry page is locked and page 'was' mapped although mapped state
 * could change.  If necessary, use anon_vma to find vma and associated
 * address space.  The returned mapping may be stale, but it can not be
 * invalid as page lock (which is held) is required to destroy mapping.
 */
static struct address_space *_get_hugetlb_page_mapping(struct page *hpage)
{
	struct anon_vma *anon_vma;
	pgoff_t pgoff_start, pgoff_end;
	struct anon_vma_chain *avc;
	struct address_space *mapping = page_mapping(hpage);

	/* Simple file based mapping */
	if (mapping)
		return mapping;

	/*
	 * Even anonymous hugetlbfs mappings are associated with an
	 * underlying hugetlbfs file (see hugetlb_file_setup in mmap
	 * code).  Find a vma associated with the anonymous vma, and
	 * use the file pointer to get address_space.
	 */
	anon_vma = page_lock_anon_vma_read(hpage);
	if (!anon_vma)
		return mapping;  /* NULL */

	/* Use first found vma */
	pgoff_start = page_to_pgoff(hpage);
	pgoff_end = pgoff_start + hpage_nr_pages(hpage) - 1;
	anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root,
					pgoff_start, pgoff_end) {
		struct vm_area_struct *vma = avc->vma;

		mapping = vma->vm_file->f_mapping;
		break;
	}

	anon_vma_unlock_read(anon_vma);
	return mapping;
}

/*
 * Find and lock address space (mapping) in write mode.
 *
 * Upon entry, the page is locked which allows us to find the mapping
 * even in the case of an anon page.  However, locking order dictates
 * the i_mmap_rwsem be acquired BEFORE the page lock.  This is hugetlbfs
 * specific.  So, we first try to lock the sema while still holding the
 * page lock.  If this works, great!  If not, then we need to drop the
 * page lock and then acquire i_mmap_rwsem and reacquire page lock.  Of
 * course, need to revalidate state along the way.
 */
struct address_space *hugetlb_page_mapping_lock_write(struct page *hpage)
{
	struct address_space *mapping, *mapping2;

	mapping = _get_hugetlb_page_mapping(hpage);
retry:
	if (!mapping)
		return mapping;

	/*
	 * If no contention, take lock and return
	 */
	if (i_mmap_trylock_write(mapping))
		return mapping;

	/*
	 * Must drop page lock and wait on mapping sema.
	 * Note:  Once page lock is dropped, mapping could become invalid.
	 * As a hack, increase map count until we lock page again.
	 */
	atomic_inc(&hpage->_mapcount);
	unlock_page(hpage);
	i_mmap_lock_write(mapping);
	lock_page(hpage);
	atomic_add_negative(-1, &hpage->_mapcount);

	/* verify page is still mapped */
	if (!page_mapped(hpage)) {
		i_mmap_unlock_write(mapping);
		return NULL;
	}

	/*
	 * Get address space again and verify it is the same one
	 * we locked.  If not, drop lock and retry.
	 */
	mapping2 = _get_hugetlb_page_mapping(hpage);
	if (mapping2 != mapping) {
		i_mmap_unlock_write(mapping);
		mapping = mapping2;
		goto retry;
	}

	return mapping;
}

1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441
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;
}

1442
static struct page *alloc_buddy_huge_page(struct hstate *h,
1443 1444
		gfp_t gfp_mask, int nid, nodemask_t *nmask,
		nodemask_t *node_alloc_noretry)
L
Linus Torvalds 已提交
1445
{
1446
	int order = huge_page_order(h);
L
Linus Torvalds 已提交
1447
	struct page *page;
1448
	bool alloc_try_hard = true;
1449

1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461
	/*
	 * By default we always try hard to allocate the page with
	 * __GFP_RETRY_MAYFAIL flag.  However, if we are allocating pages in
	 * a loop (to adjust global huge page counts) and previous allocation
	 * failed, do not continue to try hard on the same node.  Use the
	 * node_alloc_noretry bitmap to manage this state information.
	 */
	if (node_alloc_noretry && node_isset(nid, *node_alloc_noretry))
		alloc_try_hard = false;
	gfp_mask |= __GFP_COMP|__GFP_NOWARN;
	if (alloc_try_hard)
		gfp_mask |= __GFP_RETRY_MAYFAIL;
1462 1463 1464 1465 1466 1467 1468
	if (nid == NUMA_NO_NODE)
		nid = numa_mem_id();
	page = __alloc_pages_nodemask(gfp_mask, order, nid, nmask);
	if (page)
		__count_vm_event(HTLB_BUDDY_PGALLOC);
	else
		__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
1469

1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485
	/*
	 * If we did not specify __GFP_RETRY_MAYFAIL, but still got a page this
	 * indicates an overall state change.  Clear bit so that we resume
	 * normal 'try hard' allocations.
	 */
	if (node_alloc_noretry && page && !alloc_try_hard)
		node_clear(nid, *node_alloc_noretry);

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

1486 1487 1488
	return page;
}

1489 1490 1491 1492 1493
/*
 * Common helper to allocate a fresh hugetlb page. All specific allocators
 * should use this function to get new hugetlb pages
 */
static struct page *alloc_fresh_huge_page(struct hstate *h,
1494 1495
		gfp_t gfp_mask, int nid, nodemask_t *nmask,
		nodemask_t *node_alloc_noretry)
1496 1497 1498 1499 1500 1501 1502
{
	struct page *page;

	if (hstate_is_gigantic(h))
		page = alloc_gigantic_page(h, gfp_mask, nid, nmask);
	else
		page = alloc_buddy_huge_page(h, gfp_mask,
1503
				nid, nmask, node_alloc_noretry);
1504 1505 1506 1507 1508 1509 1510 1511 1512 1513
	if (!page)
		return NULL;

	if (hstate_is_gigantic(h))
		prep_compound_gigantic_page(page, huge_page_order(h));
	prep_new_huge_page(h, page, page_to_nid(page));

	return page;
}

1514 1515 1516 1517
/*
 * Allocates a fresh page to the hugetlb allocator pool in the node interleaved
 * manner.
 */
1518 1519
static int alloc_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
				nodemask_t *node_alloc_noretry)
1520 1521 1522
{
	struct page *page;
	int nr_nodes, node;
1523
	gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
1524 1525

	for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
1526 1527
		page = alloc_fresh_huge_page(h, gfp_mask, node, nodes_allowed,
						node_alloc_noretry);
1528
		if (page)
1529 1530 1531
			break;
	}

1532 1533
	if (!page)
		return 0;
1534

1535 1536 1537
	put_page(page); /* free it into the hugepage allocator */

	return 1;
1538 1539
}

1540 1541 1542 1543 1544 1545
/*
 * 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.
 */
1546 1547
static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
							 bool acct_surplus)
1548
{
1549
	int nr_nodes, node;
1550 1551
	int ret = 0;

1552
	for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
1553 1554 1555 1556
		/*
		 * If we're returning unused surplus pages, only examine
		 * nodes with surplus pages.
		 */
1557 1558
		if ((!acct_surplus || h->surplus_huge_pages_node[node]) &&
		    !list_empty(&h->hugepage_freelists[node])) {
1559
			struct page *page =
1560
				list_entry(h->hugepage_freelists[node].next,
1561 1562 1563
					  struct page, lru);
			list_del(&page->lru);
			h->free_huge_pages--;
1564
			h->free_huge_pages_node[node]--;
1565 1566
			if (acct_surplus) {
				h->surplus_huge_pages--;
1567
				h->surplus_huge_pages_node[node]--;
1568
			}
1569 1570
			update_and_free_page(h, page);
			ret = 1;
1571
			break;
1572
		}
1573
	}
1574 1575 1576 1577

	return ret;
}

1578 1579
/*
 * Dissolve a given free hugepage into free buddy pages. This function does
1580 1581 1582 1583 1584 1585 1586
 * nothing for in-use hugepages and non-hugepages.
 * This function returns values like below:
 *
 *  -EBUSY: failed to dissolved free hugepages or the hugepage is in-use
 *          (allocated or reserved.)
 *       0: successfully dissolved free hugepages or the page is not a
 *          hugepage (considered as already dissolved)
1587
 */
1588
int dissolve_free_huge_page(struct page *page)
1589
{
1590
	int rc = -EBUSY;
1591

1592 1593 1594 1595
	/* Not to disrupt normal path by vainly holding hugetlb_lock */
	if (!PageHuge(page))
		return 0;

1596
	spin_lock(&hugetlb_lock);
1597 1598 1599 1600 1601 1602
	if (!PageHuge(page)) {
		rc = 0;
		goto out;
	}

	if (!page_count(page)) {
1603 1604 1605
		struct page *head = compound_head(page);
		struct hstate *h = page_hstate(head);
		int nid = page_to_nid(head);
1606
		if (h->free_huge_pages - h->resv_huge_pages == 0)
1607
			goto out;
1608 1609 1610 1611 1612 1613 1614 1615
		/*
		 * 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);
		}
1616
		list_del(&head->lru);
1617 1618
		h->free_huge_pages--;
		h->free_huge_pages_node[nid]--;
1619
		h->max_huge_pages--;
1620
		update_and_free_page(h, head);
1621
		rc = 0;
1622
	}
1623
out:
1624
	spin_unlock(&hugetlb_lock);
1625
	return rc;
1626 1627 1628 1629 1630
}

/*
 * Dissolve free hugepages in a given pfn range. Used by memory hotplug to
 * make specified memory blocks removable from the system.
1631 1632
 * Note that this will dissolve a free gigantic hugepage completely, if any
 * part of it lies within the given range.
1633 1634
 * Also note that if dissolve_free_huge_page() returns with an error, all
 * free hugepages that were dissolved before that error are lost.
1635
 */
1636
int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
1637 1638
{
	unsigned long pfn;
1639
	struct page *page;
1640
	int rc = 0;
1641

1642
	if (!hugepages_supported())
1643
		return rc;
1644

1645 1646
	for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order) {
		page = pfn_to_page(pfn);
1647 1648 1649
		rc = dissolve_free_huge_page(page);
		if (rc)
			break;
1650
	}
1651 1652

	return rc;
1653 1654
}

1655 1656 1657
/*
 * Allocates a fresh surplus page from the page allocator.
 */
1658
static struct page *alloc_surplus_huge_page(struct hstate *h, gfp_t gfp_mask,
1659
		int nid, nodemask_t *nmask)
1660
{
1661
	struct page *page = NULL;
1662

1663
	if (hstate_is_gigantic(h))
1664 1665
		return NULL;

1666
	spin_lock(&hugetlb_lock);
1667 1668
	if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages)
		goto out_unlock;
1669 1670
	spin_unlock(&hugetlb_lock);

1671
	page = alloc_fresh_huge_page(h, gfp_mask, nid, nmask, NULL);
1672
	if (!page)
1673
		return NULL;
1674 1675

	spin_lock(&hugetlb_lock);
1676 1677 1678 1679 1680 1681 1682 1683 1684
	/*
	 * We could have raced with the pool size change.
	 * Double check that and simply deallocate the new page
	 * if we would end up overcommiting the surpluses. Abuse
	 * temporary page to workaround the nasty free_huge_page
	 * codeflow
	 */
	if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
		SetPageHugeTemporary(page);
1685
		spin_unlock(&hugetlb_lock);
1686
		put_page(page);
1687
		return NULL;
1688 1689
	} else {
		h->surplus_huge_pages++;
1690
		h->surplus_huge_pages_node[page_to_nid(page)]++;
1691
	}
1692 1693

out_unlock:
1694
	spin_unlock(&hugetlb_lock);
1695 1696 1697 1698

	return page;
}

1699 1700
struct page *alloc_migrate_huge_page(struct hstate *h, gfp_t gfp_mask,
				     int nid, nodemask_t *nmask)
1701 1702 1703 1704 1705 1706
{
	struct page *page;

	if (hstate_is_gigantic(h))
		return NULL;

1707
	page = alloc_fresh_huge_page(h, gfp_mask, nid, nmask, NULL);
1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719
	if (!page)
		return NULL;

	/*
	 * We do not account these pages as surplus because they are only
	 * temporary and will be released properly on the last reference
	 */
	SetPageHugeTemporary(page);

	return page;
}

1720 1721 1722
/*
 * Use the VMA's mpolicy to allocate a huge page from the buddy.
 */
D
Dave Hansen 已提交
1723
static
1724
struct page *alloc_buddy_huge_page_with_mpol(struct hstate *h,
1725 1726
		struct vm_area_struct *vma, unsigned long addr)
{
1727 1728 1729 1730 1731 1732 1733
	struct page *page;
	struct mempolicy *mpol;
	gfp_t gfp_mask = htlb_alloc_mask(h);
	int nid;
	nodemask_t *nodemask;

	nid = huge_node(vma, addr, gfp_mask, &mpol, &nodemask);
1734
	page = alloc_surplus_huge_page(h, gfp_mask, nid, nodemask);
1735 1736 1737
	mpol_cond_put(mpol);

	return page;
1738 1739
}

1740
/* page migration callback function */
1741 1742
struct page *alloc_huge_page_node(struct hstate *h, int nid)
{
1743
	gfp_t gfp_mask = htlb_alloc_mask(h);
1744
	struct page *page = NULL;
1745

1746 1747 1748
	if (nid != NUMA_NO_NODE)
		gfp_mask |= __GFP_THISNODE;

1749
	spin_lock(&hugetlb_lock);
1750
	if (h->free_huge_pages - h->resv_huge_pages > 0)
1751
		page = dequeue_huge_page_nodemask(h, gfp_mask, nid, NULL);
1752 1753
	spin_unlock(&hugetlb_lock);

1754
	if (!page)
1755
		page = alloc_migrate_huge_page(h, gfp_mask, nid, NULL);
1756 1757 1758 1759

	return page;
}

1760
/* page migration callback function */
1761 1762
struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid,
		nodemask_t *nmask)
1763
{
1764
	gfp_t gfp_mask = htlb_alloc_mask(h);
1765 1766 1767

	spin_lock(&hugetlb_lock);
	if (h->free_huge_pages - h->resv_huge_pages > 0) {
1768 1769 1770 1771 1772 1773
		struct page *page;

		page = dequeue_huge_page_nodemask(h, gfp_mask, preferred_nid, nmask);
		if (page) {
			spin_unlock(&hugetlb_lock);
			return page;
1774 1775 1776 1777
		}
	}
	spin_unlock(&hugetlb_lock);

1778
	return alloc_migrate_huge_page(h, gfp_mask, preferred_nid, nmask);
1779 1780
}

1781
/* mempolicy aware migration callback */
1782 1783
struct page *alloc_huge_page_vma(struct hstate *h, struct vm_area_struct *vma,
		unsigned long address)
1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798
{
	struct mempolicy *mpol;
	nodemask_t *nodemask;
	struct page *page;
	gfp_t gfp_mask;
	int node;

	gfp_mask = htlb_alloc_mask(h);
	node = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
	page = alloc_huge_page_nodemask(h, node, nodemask);
	mpol_cond_put(mpol);

	return page;
}

1799
/*
L
Lucas De Marchi 已提交
1800
 * Increase the hugetlb pool such that it can accommodate a reservation
1801 1802
 * of size 'delta'.
 */
1803
static int gather_surplus_pages(struct hstate *h, int delta)
1804 1805 1806 1807 1808
{
	struct list_head surplus_list;
	struct page *page, *tmp;
	int ret, i;
	int needed, allocated;
1809
	bool alloc_ok = true;
1810

1811
	needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
1812
	if (needed <= 0) {
1813
		h->resv_huge_pages += delta;
1814
		return 0;
1815
	}
1816 1817 1818 1819 1820 1821 1822 1823

	allocated = 0;
	INIT_LIST_HEAD(&surplus_list);

	ret = -ENOMEM;
retry:
	spin_unlock(&hugetlb_lock);
	for (i = 0; i < needed; i++) {
1824
		page = alloc_surplus_huge_page(h, htlb_alloc_mask(h),
1825
				NUMA_NO_NODE, NULL);
1826 1827 1828 1829
		if (!page) {
			alloc_ok = false;
			break;
		}
1830
		list_add(&page->lru, &surplus_list);
1831
		cond_resched();
1832
	}
1833
	allocated += i;
1834 1835 1836 1837 1838 1839

	/*
	 * 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);
1840 1841
	needed = (h->resv_huge_pages + delta) -
			(h->free_huge_pages + allocated);
1842 1843 1844 1845 1846 1847 1848 1849 1850 1851
	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;
	}
1852 1853
	/*
	 * The surplus_list now contains _at_least_ the number of extra pages
L
Lucas De Marchi 已提交
1854
	 * needed to accommodate the reservation.  Add the appropriate number
1855
	 * of pages to the hugetlb pool and free the extras back to the buddy
1856 1857 1858
	 * 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.
1859 1860
	 */
	needed += allocated;
1861
	h->resv_huge_pages += delta;
1862
	ret = 0;
1863

1864
	/* Free the needed pages to the hugetlb pool */
1865
	list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
1866 1867
		if ((--needed) < 0)
			break;
1868 1869 1870 1871 1872
		/*
		 * This page is now managed by the hugetlb allocator and has
		 * no users -- drop the buddy allocator's reference.
		 */
		put_page_testzero(page);
1873
		VM_BUG_ON_PAGE(page_count(page), page);
1874
		enqueue_huge_page(h, page);
1875
	}
1876
free:
1877
	spin_unlock(&hugetlb_lock);
1878 1879

	/* Free unnecessary surplus pages to the buddy allocator */
1880 1881
	list_for_each_entry_safe(page, tmp, &surplus_list, lru)
		put_page(page);
1882
	spin_lock(&hugetlb_lock);
1883 1884 1885 1886 1887

	return ret;
}

/*
1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899
 * 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.
1900
 */
1901 1902
static void return_unused_surplus_pages(struct hstate *h,
					unsigned long unused_resv_pages)
1903 1904 1905
{
	unsigned long nr_pages;

1906
	/* Cannot return gigantic pages currently */
1907
	if (hstate_is_gigantic(h))
1908
		goto out;
1909

1910 1911 1912 1913
	/*
	 * Part (or even all) of the reservation could have been backed
	 * by pre-allocated pages. Only free surplus pages.
	 */
1914
	nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
1915

1916 1917
	/*
	 * We want to release as many surplus pages as possible, spread
1918 1919 1920 1921 1922
	 * 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.
1923 1924 1925 1926
	 *
	 * 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.
1927 1928
	 */
	while (nr_pages--) {
1929 1930
		h->resv_huge_pages--;
		unused_resv_pages--;
1931
		if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1))
1932
			goto out;
1933
		cond_resched_lock(&hugetlb_lock);
1934
	}
1935 1936 1937 1938

out:
	/* Fully uncommit the reservation */
	h->resv_huge_pages -= unused_resv_pages;
1939 1940
}

1941

1942
/*
1943
 * vma_needs_reservation, vma_commit_reservation and vma_end_reservation
1944
 * are used by the huge page allocation routines to manage reservations.
1945 1946 1947 1948 1949 1950
 *
 * 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
1951 1952 1953
 * 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.
1954 1955 1956 1957 1958 1959
 *
 * 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.
1960 1961 1962 1963 1964
 *
 * 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.
1965
 */
1966 1967 1968
enum vma_resv_mode {
	VMA_NEEDS_RESV,
	VMA_COMMIT_RESV,
1969
	VMA_END_RESV,
1970
	VMA_ADD_RESV,
1971
};
1972 1973
static long __vma_reservation_common(struct hstate *h,
				struct vm_area_struct *vma, unsigned long addr,
1974
				enum vma_resv_mode mode)
1975
{
1976 1977
	struct resv_map *resv;
	pgoff_t idx;
1978
	long ret;
1979

1980 1981
	resv = vma_resv_map(vma);
	if (!resv)
1982
		return 1;
1983

1984
	idx = vma_hugecache_offset(h, vma, addr);
1985 1986
	switch (mode) {
	case VMA_NEEDS_RESV:
1987
		ret = region_chg(resv, idx, idx + 1);
1988 1989 1990 1991
		break;
	case VMA_COMMIT_RESV:
		ret = region_add(resv, idx, idx + 1);
		break;
1992
	case VMA_END_RESV:
1993 1994 1995
		region_abort(resv, idx, idx + 1);
		ret = 0;
		break;
1996 1997 1998 1999 2000 2001 2002 2003
	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;
2004 2005 2006
	default:
		BUG();
	}
2007

2008
	if (vma->vm_flags & VM_MAYSHARE)
2009
		return ret;
2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028
	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;
	}
2029
	else
2030
		return ret < 0 ? ret : 0;
2031
}
2032 2033

static long vma_needs_reservation(struct hstate *h,
2034
			struct vm_area_struct *vma, unsigned long addr)
2035
{
2036
	return __vma_reservation_common(h, vma, addr, VMA_NEEDS_RESV);
2037
}
2038

2039 2040 2041
static long vma_commit_reservation(struct hstate *h,
			struct vm_area_struct *vma, unsigned long addr)
{
2042 2043 2044
	return __vma_reservation_common(h, vma, addr, VMA_COMMIT_RESV);
}

2045
static void vma_end_reservation(struct hstate *h,
2046 2047
			struct vm_area_struct *vma, unsigned long addr)
{
2048
	(void)__vma_reservation_common(h, vma, addr, VMA_END_RESV);
2049 2050
}

2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100
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);
	}
}

2101
struct page *alloc_huge_page(struct vm_area_struct *vma,
2102
				    unsigned long addr, int avoid_reserve)
L
Linus Torvalds 已提交
2103
{
2104
	struct hugepage_subpool *spool = subpool_vma(vma);
2105
	struct hstate *h = hstate_vma(vma);
2106
	struct page *page;
2107 2108
	long map_chg, map_commit;
	long gbl_chg;
2109 2110
	int ret, idx;
	struct hugetlb_cgroup *h_cg;
2111

2112
	idx = hstate_index(h);
2113
	/*
2114 2115 2116
	 * 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).
2117
	 */
2118 2119
	map_chg = gbl_chg = vma_needs_reservation(h, vma, addr);
	if (map_chg < 0)
2120
		return ERR_PTR(-ENOMEM);
2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131

	/*
	 * 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) {
2132
			vma_end_reservation(h, vma, addr);
2133
			return ERR_PTR(-ENOSPC);
2134
		}
L
Linus Torvalds 已提交
2135

2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147
		/*
		 * 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;
	}

2148
	ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
2149 2150 2151
	if (ret)
		goto out_subpool_put;

L
Linus Torvalds 已提交
2152
	spin_lock(&hugetlb_lock);
2153 2154 2155 2156 2157 2158
	/*
	 * 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);
2159
	if (!page) {
2160
		spin_unlock(&hugetlb_lock);
2161
		page = alloc_buddy_huge_page_with_mpol(h, vma, addr);
2162 2163
		if (!page)
			goto out_uncharge_cgroup;
2164 2165 2166 2167
		if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
			SetPagePrivate(page);
			h->resv_huge_pages--;
		}
2168 2169
		spin_lock(&hugetlb_lock);
		list_move(&page->lru, &h->hugepage_activelist);
2170
		/* Fall through */
K
Ken Chen 已提交
2171
	}
2172 2173
	hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
	spin_unlock(&hugetlb_lock);
2174

2175
	set_page_private(page, (unsigned long)spool);
2176

2177 2178
	map_commit = vma_commit_reservation(h, vma, addr);
	if (unlikely(map_chg > map_commit)) {
2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192
		/*
		 * 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);
	}
2193
	return page;
2194 2195 2196 2197

out_uncharge_cgroup:
	hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
out_subpool_put:
2198
	if (map_chg || avoid_reserve)
2199
		hugepage_subpool_put_pages(spool, 1);
2200
	vma_end_reservation(h, vma, addr);
2201
	return ERR_PTR(-ENOSPC);
2202 2203
}

2204 2205 2206
int alloc_bootmem_huge_page(struct hstate *h)
	__attribute__ ((weak, alias("__alloc_bootmem_huge_page")));
int __alloc_bootmem_huge_page(struct hstate *h)
2207 2208
{
	struct huge_bootmem_page *m;
2209
	int nr_nodes, node;
2210

2211
	for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) {
2212 2213
		void *addr;

2214
		addr = memblock_alloc_try_nid_raw(
2215
				huge_page_size(h), huge_page_size(h),
2216
				0, MEMBLOCK_ALLOC_ACCESSIBLE, node);
2217 2218 2219 2220 2221 2222 2223
		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;
2224
			goto found;
2225 2226 2227 2228 2229
		}
	}
	return 0;

found:
2230
	BUG_ON(!IS_ALIGNED(virt_to_phys(m), huge_page_size(h)));
2231
	/* Put them into a private list first because mem_map is not up yet */
2232
	INIT_LIST_HEAD(&m->list);
2233 2234 2235 2236 2237
	list_add(&m->list, &huge_boot_pages);
	m->hstate = h;
	return 1;
}

2238 2239
static void __init prep_compound_huge_page(struct page *page,
		unsigned int order)
2240 2241 2242 2243 2244 2245 2246
{
	if (unlikely(order > (MAX_ORDER - 1)))
		prep_compound_gigantic_page(page, order);
	else
		prep_compound_page(page, order);
}

2247 2248 2249 2250 2251 2252
/* 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) {
2253
		struct page *page = virt_to_page(m);
2254
		struct hstate *h = m->hstate;
2255

2256
		WARN_ON(page_count(page) != 1);
2257
		prep_compound_huge_page(page, h->order);
2258
		WARN_ON(PageReserved(page));
2259
		prep_new_huge_page(h, page, page_to_nid(page));
2260 2261
		put_page(page); /* free it into the hugepage allocator */

2262 2263 2264 2265 2266 2267
		/*
		 * 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.
		 */
2268
		if (hstate_is_gigantic(h))
2269
			adjust_managed_page_count(page, 1 << h->order);
2270
		cond_resched();
2271 2272 2273
	}
}

2274
static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
L
Linus Torvalds 已提交
2275 2276
{
	unsigned long i;
2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295
	nodemask_t *node_alloc_noretry;

	if (!hstate_is_gigantic(h)) {
		/*
		 * Bit mask controlling how hard we retry per-node allocations.
		 * Ignore errors as lower level routines can deal with
		 * node_alloc_noretry == NULL.  If this kmalloc fails at boot
		 * time, we are likely in bigger trouble.
		 */
		node_alloc_noretry = kmalloc(sizeof(*node_alloc_noretry),
						GFP_KERNEL);
	} else {
		/* allocations done at boot time */
		node_alloc_noretry = NULL;
	}

	/* bit mask controlling how hard we retry per-node allocations */
	if (node_alloc_noretry)
		nodes_clear(*node_alloc_noretry);
2296

2297
	for (i = 0; i < h->max_huge_pages; ++i) {
2298
		if (hstate_is_gigantic(h)) {
2299 2300
			if (!alloc_bootmem_huge_page(h))
				break;
2301
		} else if (!alloc_pool_huge_page(h,
2302 2303
					 &node_states[N_MEMORY],
					 node_alloc_noretry))
L
Linus Torvalds 已提交
2304
			break;
2305
		cond_resched();
L
Linus Torvalds 已提交
2306
	}
2307 2308 2309
	if (i < h->max_huge_pages) {
		char buf[32];

2310
		string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
2311 2312 2313 2314
		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;
	}
2315 2316

	kfree(node_alloc_noretry);
2317 2318 2319 2320 2321 2322 2323
}

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

	for_each_hstate(h) {
2324 2325 2326
		if (minimum_order > huge_page_order(h))
			minimum_order = huge_page_order(h);

2327
		/* oversize hugepages were init'ed in early boot */
2328
		if (!hstate_is_gigantic(h))
2329
			hugetlb_hstate_alloc_pages(h);
2330
	}
2331
	VM_BUG_ON(minimum_order == UINT_MAX);
2332 2333 2334 2335 2336 2337 2338
}

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

	for_each_hstate(h) {
A
Andi Kleen 已提交
2339
		char buf[32];
2340 2341

		string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
2342
		pr_info("HugeTLB registered %s page size, pre-allocated %ld pages\n",
2343
			buf, h->free_huge_pages);
2344 2345 2346
	}
}

L
Linus Torvalds 已提交
2347
#ifdef CONFIG_HIGHMEM
2348 2349
static void try_to_free_low(struct hstate *h, unsigned long count,
						nodemask_t *nodes_allowed)
L
Linus Torvalds 已提交
2350
{
2351 2352
	int i;

2353
	if (hstate_is_gigantic(h))
2354 2355
		return;

2356
	for_each_node_mask(i, *nodes_allowed) {
L
Linus Torvalds 已提交
2357
		struct page *page, *next;
2358 2359 2360
		struct list_head *freel = &h->hugepage_freelists[i];
		list_for_each_entry_safe(page, next, freel, lru) {
			if (count >= h->nr_huge_pages)
2361
				return;
L
Linus Torvalds 已提交
2362 2363 2364
			if (PageHighMem(page))
				continue;
			list_del(&page->lru);
2365
			update_and_free_page(h, page);
2366 2367
			h->free_huge_pages--;
			h->free_huge_pages_node[page_to_nid(page)]--;
L
Linus Torvalds 已提交
2368 2369 2370 2371
		}
	}
}
#else
2372 2373
static inline void try_to_free_low(struct hstate *h, unsigned long count,
						nodemask_t *nodes_allowed)
L
Linus Torvalds 已提交
2374 2375 2376 2377
{
}
#endif

2378 2379 2380 2381 2382
/*
 * 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.
 */
2383 2384
static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
				int delta)
2385
{
2386
	int nr_nodes, node;
2387 2388 2389

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

2390 2391 2392 2393
	if (delta < 0) {
		for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
			if (h->surplus_huge_pages_node[node])
				goto found;
2394
		}
2395 2396 2397 2398 2399
	} 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;
2400
		}
2401 2402
	}
	return 0;
2403

2404 2405 2406 2407
found:
	h->surplus_huge_pages += delta;
	h->surplus_huge_pages_node[node] += delta;
	return 1;
2408 2409
}

2410
#define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
2411
static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
2412
			      nodemask_t *nodes_allowed)
L
Linus Torvalds 已提交
2413
{
2414
	unsigned long min_count, ret;
2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425
	NODEMASK_ALLOC(nodemask_t, node_alloc_noretry, GFP_KERNEL);

	/*
	 * Bit mask controlling how hard we retry per-node allocations.
	 * If we can not allocate the bit mask, do not attempt to allocate
	 * the requested huge pages.
	 */
	if (node_alloc_noretry)
		nodes_clear(*node_alloc_noretry);
	else
		return -ENOMEM;
L
Linus Torvalds 已提交
2426

2427 2428
	spin_lock(&hugetlb_lock);

2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448
	/*
	 * Check for a node specific request.
	 * Changing node specific huge page count may require a corresponding
	 * change to the global count.  In any case, the passed node mask
	 * (nodes_allowed) will restrict alloc/free to the specified node.
	 */
	if (nid != NUMA_NO_NODE) {
		unsigned long old_count = count;

		count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
		/*
		 * User may have specified a large count value which caused the
		 * above calculation to overflow.  In this case, they wanted
		 * to allocate as many huge pages as possible.  Set count to
		 * largest possible value to align with their intention.
		 */
		if (count < old_count)
			count = ULONG_MAX;
	}

2449 2450 2451 2452 2453 2454 2455 2456 2457 2458
	/*
	 * Gigantic pages runtime allocation depend on the capability for large
	 * page range allocation.
	 * If the system does not provide this feature, return an error when
	 * the user tries to allocate gigantic pages but let the user free the
	 * boottime allocated gigantic pages.
	 */
	if (hstate_is_gigantic(h) && !IS_ENABLED(CONFIG_CONTIG_ALLOC)) {
		if (count > persistent_huge_pages(h)) {
			spin_unlock(&hugetlb_lock);
2459
			NODEMASK_FREE(node_alloc_noretry);
2460 2461 2462 2463
			return -EINVAL;
		}
		/* Fall through to decrease pool */
	}
2464

2465 2466 2467 2468
	/*
	 * Increase the pool size
	 * First take pages out of surplus state.  Then make up the
	 * remaining difference by allocating fresh huge pages.
2469
	 *
2470
	 * We might race with alloc_surplus_huge_page() here and be unable
2471 2472 2473 2474
	 * 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.
2475
	 */
2476
	while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
2477
		if (!adjust_pool_surplus(h, nodes_allowed, -1))
2478 2479 2480
			break;
	}

2481
	while (count > persistent_huge_pages(h)) {
2482 2483 2484 2485 2486 2487
		/*
		 * 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);
2488 2489 2490 2491

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

2492 2493
		ret = alloc_pool_huge_page(h, nodes_allowed,
						node_alloc_noretry);
2494 2495 2496 2497
		spin_lock(&hugetlb_lock);
		if (!ret)
			goto out;

2498 2499 2500
		/* Bail for signals. Probably ctrl-c from user */
		if (signal_pending(current))
			goto out;
2501 2502 2503 2504 2505 2506 2507 2508
	}

	/*
	 * 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.
2509 2510 2511 2512
	 *
	 * 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
2513
	 * alloc_surplus_huge_page() is checking the global counter,
2514 2515 2516
	 * 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.
2517
	 */
2518
	min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
2519
	min_count = max(count, min_count);
2520
	try_to_free_low(h, min_count, nodes_allowed);
2521
	while (min_count < persistent_huge_pages(h)) {
2522
		if (!free_pool_huge_page(h, nodes_allowed, 0))
L
Linus Torvalds 已提交
2523
			break;
2524
		cond_resched_lock(&hugetlb_lock);
L
Linus Torvalds 已提交
2525
	}
2526
	while (count < persistent_huge_pages(h)) {
2527
		if (!adjust_pool_surplus(h, nodes_allowed, 1))
2528 2529 2530
			break;
	}
out:
2531
	h->max_huge_pages = persistent_huge_pages(h);
L
Linus Torvalds 已提交
2532
	spin_unlock(&hugetlb_lock);
2533

2534 2535
	NODEMASK_FREE(node_alloc_noretry);

2536
	return 0;
L
Linus Torvalds 已提交
2537 2538
}

2539 2540 2541 2542 2543 2544 2545 2546 2547 2548
#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];

2549 2550 2551
static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);

static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
2552 2553
{
	int i;
2554

2555
	for (i = 0; i < HUGE_MAX_HSTATE; i++)
2556 2557 2558
		if (hstate_kobjs[i] == kobj) {
			if (nidp)
				*nidp = NUMA_NO_NODE;
2559
			return &hstates[i];
2560 2561 2562
		}

	return kobj_to_node_hstate(kobj, nidp);
2563 2564
}

2565
static ssize_t nr_hugepages_show_common(struct kobject *kobj,
2566 2567
					struct kobj_attribute *attr, char *buf)
{
2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578
	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);
2579
}
2580

2581 2582 2583
static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
					   struct hstate *h, int nid,
					   unsigned long count, size_t len)
2584 2585
{
	int err;
2586
	nodemask_t nodes_allowed, *n_mask;
2587

2588 2589
	if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
		return -EINVAL;
2590

2591 2592 2593 2594 2595
	if (nid == NUMA_NO_NODE) {
		/*
		 * global hstate attribute
		 */
		if (!(obey_mempolicy &&
2596 2597 2598 2599 2600
				init_nodemask_of_mempolicy(&nodes_allowed)))
			n_mask = &node_states[N_MEMORY];
		else
			n_mask = &nodes_allowed;
	} else {
2601
		/*
2602 2603
		 * Node specific request.  count adjustment happens in
		 * set_max_huge_pages() after acquiring hugetlb_lock.
2604
		 */
2605 2606
		init_nodemask_of_node(&nodes_allowed, nid);
		n_mask = &nodes_allowed;
2607
	}
2608

2609
	err = set_max_huge_pages(h, count, nid, n_mask);
2610

2611
	return err ? err : len;
2612 2613
}

2614 2615 2616 2617 2618 2619 2620 2621 2622 2623 2624 2625 2626 2627 2628 2629 2630
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);
}

2631 2632 2633 2634 2635 2636 2637 2638 2639
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)
{
2640
	return nr_hugepages_store_common(false, kobj, buf, len);
2641 2642 2643
}
HSTATE_ATTR(nr_hugepages);

2644 2645 2646 2647 2648 2649 2650 2651 2652 2653 2654 2655 2656 2657 2658
#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)
{
2659
	return nr_hugepages_store_common(true, kobj, buf, len);
2660 2661 2662 2663 2664
}
HSTATE_ATTR(nr_hugepages_mempolicy);
#endif


2665 2666 2667
static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
					struct kobj_attribute *attr, char *buf)
{
2668
	struct hstate *h = kobj_to_hstate(kobj, NULL);
2669 2670
	return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
}
2671

2672 2673 2674 2675 2676
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;
2677
	struct hstate *h = kobj_to_hstate(kobj, NULL);
2678

2679
	if (hstate_is_gigantic(h))
2680 2681
		return -EINVAL;

2682
	err = kstrtoul(buf, 10, &input);
2683
	if (err)
2684
		return err;
2685 2686 2687 2688 2689 2690 2691 2692 2693 2694 2695 2696

	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)
{
2697 2698 2699 2700 2701 2702 2703 2704 2705 2706 2707
	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);
2708 2709 2710 2711 2712 2713
}
HSTATE_ATTR_RO(free_hugepages);

static ssize_t resv_hugepages_show(struct kobject *kobj,
					struct kobj_attribute *attr, char *buf)
{
2714
	struct hstate *h = kobj_to_hstate(kobj, NULL);
2715 2716 2717 2718 2719 2720 2721
	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)
{
2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732
	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);
2733 2734 2735 2736 2737 2738 2739 2740 2741
}
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,
2742 2743 2744
#ifdef CONFIG_NUMA
	&nr_hugepages_mempolicy_attr.attr,
#endif
2745 2746 2747
	NULL,
};

2748
static const struct attribute_group hstate_attr_group = {
2749 2750 2751
	.attrs = hstate_attrs,
};

J
Jeff Mahoney 已提交
2752 2753
static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
				    struct kobject **hstate_kobjs,
2754
				    const struct attribute_group *hstate_attr_group)
2755 2756
{
	int retval;
2757
	int hi = hstate_index(h);
2758

2759 2760
	hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
	if (!hstate_kobjs[hi])
2761 2762
		return -ENOMEM;

2763
	retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
2764
	if (retval)
2765
		kobject_put(hstate_kobjs[hi]);
2766 2767 2768 2769 2770 2771 2772 2773 2774 2775 2776 2777 2778 2779

	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) {
2780 2781
		err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
					 hstate_kobjs, &hstate_attr_group);
2782
		if (err)
2783
			pr_err("Hugetlb: Unable to add hstate %s", h->name);
2784 2785 2786
	}
}

2787 2788 2789 2790
#ifdef CONFIG_NUMA

/*
 * node_hstate/s - associate per node hstate attributes, via their kobjects,
2791 2792 2793
 * 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
2794 2795 2796 2797 2798 2799
 * the base kernel, on the hugetlb module.
 */
struct node_hstate {
	struct kobject		*hugepages_kobj;
	struct kobject		*hstate_kobjs[HUGE_MAX_HSTATE];
};
2800
static struct node_hstate node_hstates[MAX_NUMNODES];
2801 2802

/*
2803
 * A subset of global hstate attributes for node devices
2804 2805 2806 2807 2808 2809 2810 2811
 */
static struct attribute *per_node_hstate_attrs[] = {
	&nr_hugepages_attr.attr,
	&free_hugepages_attr.attr,
	&surplus_hugepages_attr.attr,
	NULL,
};

2812
static const struct attribute_group per_node_hstate_attr_group = {
2813 2814 2815 2816
	.attrs = per_node_hstate_attrs,
};

/*
2817
 * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
2818 2819 2820 2821 2822 2823 2824 2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838 2839
 * 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;
}

/*
2840
 * Unregister hstate attributes from a single node device.
2841 2842
 * No-op if no hstate attributes attached.
 */
2843
static void hugetlb_unregister_node(struct node *node)
2844 2845
{
	struct hstate *h;
2846
	struct node_hstate *nhs = &node_hstates[node->dev.id];
2847 2848

	if (!nhs->hugepages_kobj)
2849
		return;		/* no hstate attributes */
2850

2851 2852 2853 2854 2855
	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;
2856
		}
2857
	}
2858 2859 2860 2861 2862 2863 2864

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


/*
2865
 * Register hstate attributes for a single node device.
2866 2867
 * No-op if attributes already registered.
 */
2868
static void hugetlb_register_node(struct node *node)
2869 2870
{
	struct hstate *h;
2871
	struct node_hstate *nhs = &node_hstates[node->dev.id];
2872 2873 2874 2875 2876 2877
	int err;

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

	nhs->hugepages_kobj = kobject_create_and_add("hugepages",
2878
							&node->dev.kobj);
2879 2880 2881 2882 2883 2884 2885 2886
	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) {
2887 2888
			pr_err("Hugetlb: Unable to add hstate %s for node %d\n",
				h->name, node->dev.id);
2889 2890 2891 2892 2893 2894 2895
			hugetlb_unregister_node(node);
			break;
		}
	}
}

/*
2896
 * hugetlb init time:  register hstate attributes for all registered node
2897 2898
 * devices of nodes that have memory.  All on-line nodes should have
 * registered their associated device by this time.
2899
 */
2900
static void __init hugetlb_register_all_nodes(void)
2901 2902 2903
{
	int nid;

2904
	for_each_node_state(nid, N_MEMORY) {
2905
		struct node *node = node_devices[nid];
2906
		if (node->dev.id == nid)
2907 2908 2909 2910
			hugetlb_register_node(node);
	}

	/*
2911
	 * Let the node device driver know we're here so it can
2912 2913 2914 2915 2916 2917 2918 2919 2920 2921 2922 2923 2924 2925 2926 2927 2928 2929 2930
	 * [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

2931 2932
static int __init hugetlb_init(void)
{
2933 2934
	int i;

2935
	if (!hugepages_supported())
2936
		return 0;
2937

2938
	if (!size_to_hstate(default_hstate_size)) {
2939 2940 2941 2942 2943
		if (default_hstate_size != 0) {
			pr_err("HugeTLB: unsupported default_hugepagesz %lu. Reverting to %lu\n",
			       default_hstate_size, HPAGE_SIZE);
		}

2944 2945 2946
		default_hstate_size = HPAGE_SIZE;
		if (!size_to_hstate(default_hstate_size))
			hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
2947
	}
2948
	default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
2949 2950 2951 2952
	if (default_hstate_max_huge_pages) {
		if (!default_hstate.max_huge_pages)
			default_hstate.max_huge_pages = default_hstate_max_huge_pages;
	}
2953 2954

	hugetlb_init_hstates();
2955
	gather_bootmem_prealloc();
2956 2957 2958
	report_hugepages();

	hugetlb_sysfs_init();
2959
	hugetlb_register_all_nodes();
2960
	hugetlb_cgroup_file_init();
2961

2962 2963 2964 2965 2966
#ifdef CONFIG_SMP
	num_fault_mutexes = roundup_pow_of_two(8 * num_possible_cpus());
#else
	num_fault_mutexes = 1;
#endif
2967
	hugetlb_fault_mutex_table =
2968 2969
		kmalloc_array(num_fault_mutexes, sizeof(struct mutex),
			      GFP_KERNEL);
2970
	BUG_ON(!hugetlb_fault_mutex_table);
2971 2972

	for (i = 0; i < num_fault_mutexes; i++)
2973
		mutex_init(&hugetlb_fault_mutex_table[i]);
2974 2975
	return 0;
}
2976
subsys_initcall(hugetlb_init);
2977 2978

/* Should be called on processing a hugepagesz=... option */
2979 2980 2981 2982 2983
void __init hugetlb_bad_size(void)
{
	parsed_valid_hugepagesz = false;
}

2984
void __init hugetlb_add_hstate(unsigned int order)
2985 2986
{
	struct hstate *h;
2987 2988
	unsigned long i;

2989
	if (size_to_hstate(PAGE_SIZE << order)) {
J
Joe Perches 已提交
2990
		pr_warn("hugepagesz= specified twice, ignoring\n");
2991 2992
		return;
	}
2993
	BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
2994
	BUG_ON(order == 0);
2995
	h = &hstates[hugetlb_max_hstate++];
2996 2997
	h->order = order;
	h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
2998 2999 3000 3001
	h->nr_huge_pages = 0;
	h->free_huge_pages = 0;
	for (i = 0; i < MAX_NUMNODES; ++i)
		INIT_LIST_HEAD(&h->hugepage_freelists[i]);
3002
	INIT_LIST_HEAD(&h->hugepage_activelist);
3003 3004
	h->next_nid_to_alloc = first_memory_node;
	h->next_nid_to_free = first_memory_node;
3005 3006
	snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
					huge_page_size(h)/1024);
3007

3008 3009 3010
	parsed_hstate = h;
}

3011
static int __init hugetlb_nrpages_setup(char *s)
3012 3013
{
	unsigned long *mhp;
3014
	static unsigned long *last_mhp;
3015

3016 3017 3018 3019 3020 3021
	if (!parsed_valid_hugepagesz) {
		pr_warn("hugepages = %s preceded by "
			"an unsupported hugepagesz, ignoring\n", s);
		parsed_valid_hugepagesz = true;
		return 1;
	}
3022
	/*
3023
	 * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
3024 3025
	 * so this hugepages= parameter goes to the "default hstate".
	 */
3026
	else if (!hugetlb_max_hstate)
3027 3028 3029 3030
		mhp = &default_hstate_max_huge_pages;
	else
		mhp = &parsed_hstate->max_huge_pages;

3031
	if (mhp == last_mhp) {
J
Joe Perches 已提交
3032
		pr_warn("hugepages= specified twice without interleaving hugepagesz=, ignoring\n");
3033 3034 3035
		return 1;
	}

3036 3037 3038
	if (sscanf(s, "%lu", mhp) <= 0)
		*mhp = 0;

3039 3040 3041 3042 3043
	/*
	 * 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.
	 */
3044
	if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER)
3045 3046 3047 3048
		hugetlb_hstate_alloc_pages(parsed_hstate);

	last_mhp = mhp;

3049 3050
	return 1;
}
3051 3052 3053 3054 3055 3056 3057 3058
__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);
3059

3060 3061 3062 3063 3064 3065 3066 3067 3068 3069 3070 3071
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
3072 3073 3074
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
3075
{
3076
	struct hstate *h = &default_hstate;
3077
	unsigned long tmp = h->max_huge_pages;
3078
	int ret;
3079

3080
	if (!hugepages_supported())
3081
		return -EOPNOTSUPP;
3082

3083 3084
	table->data = &tmp;
	table->maxlen = sizeof(unsigned long);
3085 3086 3087
	ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
	if (ret)
		goto out;
3088

3089 3090 3091
	if (write)
		ret = __nr_hugepages_store_common(obey_mempolicy, h,
						  NUMA_NO_NODE, tmp, *length);
3092 3093
out:
	return ret;
L
Linus Torvalds 已提交
3094
}
3095

3096 3097 3098 3099 3100 3101 3102 3103 3104 3105 3106 3107 3108 3109 3110 3111 3112
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 */

3113
int hugetlb_overcommit_handler(struct ctl_table *table, int write,
3114
			void __user *buffer,
3115 3116
			size_t *length, loff_t *ppos)
{
3117
	struct hstate *h = &default_hstate;
3118
	unsigned long tmp;
3119
	int ret;
3120

3121
	if (!hugepages_supported())
3122
		return -EOPNOTSUPP;
3123

3124
	tmp = h->nr_overcommit_huge_pages;
3125

3126
	if (write && hstate_is_gigantic(h))
3127 3128
		return -EINVAL;

3129 3130
	table->data = &tmp;
	table->maxlen = sizeof(unsigned long);
3131 3132 3133
	ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
	if (ret)
		goto out;
3134 3135 3136 3137 3138 3139

	if (write) {
		spin_lock(&hugetlb_lock);
		h->nr_overcommit_huge_pages = tmp;
		spin_unlock(&hugetlb_lock);
	}
3140 3141
out:
	return ret;
3142 3143
}

L
Linus Torvalds 已提交
3144 3145
#endif /* CONFIG_SYSCTL */

3146
void hugetlb_report_meminfo(struct seq_file *m)
L
Linus Torvalds 已提交
3147
{
3148 3149 3150
	struct hstate *h;
	unsigned long total = 0;

3151 3152
	if (!hugepages_supported())
		return;
3153 3154 3155 3156 3157 3158 3159 3160 3161 3162 3163 3164 3165 3166 3167 3168 3169 3170 3171 3172 3173

	for_each_hstate(h) {
		unsigned long count = h->nr_huge_pages;

		total += (PAGE_SIZE << huge_page_order(h)) * count;

		if (h == &default_hstate)
			seq_printf(m,
				   "HugePages_Total:   %5lu\n"
				   "HugePages_Free:    %5lu\n"
				   "HugePages_Rsvd:    %5lu\n"
				   "HugePages_Surp:    %5lu\n"
				   "Hugepagesize:   %8lu kB\n",
				   count,
				   h->free_huge_pages,
				   h->resv_huge_pages,
				   h->surplus_huge_pages,
				   (PAGE_SIZE << huge_page_order(h)) / 1024);
	}

	seq_printf(m, "Hugetlb:        %8lu kB\n", total / 1024);
L
Linus Torvalds 已提交
3174 3175 3176 3177
}

int hugetlb_report_node_meminfo(int nid, char *buf)
{
3178
	struct hstate *h = &default_hstate;
3179 3180
	if (!hugepages_supported())
		return 0;
L
Linus Torvalds 已提交
3181 3182
	return sprintf(buf,
		"Node %d HugePages_Total: %5u\n"
3183 3184
		"Node %d HugePages_Free:  %5u\n"
		"Node %d HugePages_Surp:  %5u\n",
3185 3186 3187
		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
3188 3189
}

3190 3191 3192 3193 3194
void hugetlb_show_meminfo(void)
{
	struct hstate *h;
	int nid;

3195 3196 3197
	if (!hugepages_supported())
		return;

3198 3199 3200 3201 3202 3203 3204 3205 3206 3207
	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));
}

3208 3209 3210 3211 3212 3213
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
3214 3215 3216
/* Return the number pages of memory we physically have, in PAGE_SIZE units. */
unsigned long hugetlb_total_pages(void)
{
3217 3218 3219 3220 3221 3222
	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
3223 3224
}

3225
static int hugetlb_acct_memory(struct hstate *h, long delta)
M
Mel Gorman 已提交
3226 3227 3228 3229 3230 3231 3232 3233 3234 3235 3236 3237 3238 3239 3240 3241 3242 3243 3244 3245 3246 3247
{
	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) {
3248
		if (gather_surplus_pages(h, delta) < 0)
M
Mel Gorman 已提交
3249 3250
			goto out;

3251 3252
		if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
			return_unused_surplus_pages(h, delta);
M
Mel Gorman 已提交
3253 3254 3255 3256 3257 3258
			goto out;
		}
	}

	ret = 0;
	if (delta < 0)
3259
		return_unused_surplus_pages(h, (unsigned long) -delta);
M
Mel Gorman 已提交
3260 3261 3262 3263 3264 3265

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

3266 3267
static void hugetlb_vm_op_open(struct vm_area_struct *vma)
{
3268
	struct resv_map *resv = vma_resv_map(vma);
3269 3270 3271 3272 3273

	/*
	 * 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
3274
	 * has a reference to the reservation map it cannot disappear until
3275 3276 3277
	 * after this open call completes.  It is therefore safe to take a
	 * new reference here without additional locking.
	 */
3278
	if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
3279
		kref_get(&resv->refs);
3280 3281
}

3282 3283
static void hugetlb_vm_op_close(struct vm_area_struct *vma)
{
3284
	struct hstate *h = hstate_vma(vma);
3285
	struct resv_map *resv = vma_resv_map(vma);
3286
	struct hugepage_subpool *spool = subpool_vma(vma);
3287
	unsigned long reserve, start, end;
3288
	long gbl_reserve;
3289

3290 3291
	if (!resv || !is_vma_resv_set(vma, HPAGE_RESV_OWNER))
		return;
3292

3293 3294
	start = vma_hugecache_offset(h, vma, vma->vm_start);
	end = vma_hugecache_offset(h, vma, vma->vm_end);
3295

3296
	reserve = (end - start) - region_count(resv, start, end);
3297

3298 3299 3300
	kref_put(&resv->refs, resv_map_release);

	if (reserve) {
3301 3302 3303 3304 3305 3306
		/*
		 * 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);
3307
	}
3308 3309
}

3310 3311 3312 3313 3314 3315 3316
static int hugetlb_vm_op_split(struct vm_area_struct *vma, unsigned long addr)
{
	if (addr & ~(huge_page_mask(hstate_vma(vma))))
		return -EINVAL;
	return 0;
}

3317 3318 3319 3320 3321 3322 3323
static unsigned long hugetlb_vm_op_pagesize(struct vm_area_struct *vma)
{
	struct hstate *hstate = hstate_vma(vma);

	return 1UL << huge_page_shift(hstate);
}

L
Linus Torvalds 已提交
3324 3325 3326 3327 3328 3329
/*
 * 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.
 */
3330
static vm_fault_t hugetlb_vm_op_fault(struct vm_fault *vmf)
L
Linus Torvalds 已提交
3331 3332
{
	BUG();
N
Nick Piggin 已提交
3333
	return 0;
L
Linus Torvalds 已提交
3334 3335
}

3336 3337 3338 3339 3340 3341 3342
/*
 * When a new function is introduced to vm_operations_struct and added
 * to hugetlb_vm_ops, please consider adding the function to shm_vm_ops.
 * This is because under System V memory model, mappings created via
 * shmget/shmat with "huge page" specified are backed by hugetlbfs files,
 * their original vm_ops are overwritten with shm_vm_ops.
 */
3343
const struct vm_operations_struct hugetlb_vm_ops = {
N
Nick Piggin 已提交
3344
	.fault = hugetlb_vm_op_fault,
3345
	.open = hugetlb_vm_op_open,
3346
	.close = hugetlb_vm_op_close,
3347
	.split = hugetlb_vm_op_split,
3348
	.pagesize = hugetlb_vm_op_pagesize,
L
Linus Torvalds 已提交
3349 3350
};

3351 3352
static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
				int writable)
D
David Gibson 已提交
3353 3354 3355
{
	pte_t entry;

3356
	if (writable) {
3357 3358
		entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page,
					 vma->vm_page_prot)));
D
David Gibson 已提交
3359
	} else {
3360 3361
		entry = huge_pte_wrprotect(mk_huge_pte(page,
					   vma->vm_page_prot));
D
David Gibson 已提交
3362 3363 3364
	}
	entry = pte_mkyoung(entry);
	entry = pte_mkhuge(entry);
3365
	entry = arch_make_huge_pte(entry, vma, page, writable);
D
David Gibson 已提交
3366 3367 3368 3369

	return entry;
}

3370 3371 3372 3373 3374
static void set_huge_ptep_writable(struct vm_area_struct *vma,
				   unsigned long address, pte_t *ptep)
{
	pte_t entry;

3375
	entry = huge_pte_mkwrite(huge_pte_mkdirty(huge_ptep_get(ptep)));
3376
	if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
3377
		update_mmu_cache(vma, address, ptep);
3378 3379
}

3380
bool is_hugetlb_entry_migration(pte_t pte)
3381 3382 3383 3384
{
	swp_entry_t swp;

	if (huge_pte_none(pte) || pte_present(pte))
3385
		return false;
3386 3387
	swp = pte_to_swp_entry(pte);
	if (non_swap_entry(swp) && is_migration_entry(swp))
3388
		return true;
3389
	else
3390
		return false;
3391 3392 3393 3394 3395 3396 3397 3398 3399 3400 3401 3402 3403 3404
}

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;
}
3405

D
David Gibson 已提交
3406 3407 3408
int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
			    struct vm_area_struct *vma)
{
3409
	pte_t *src_pte, *dst_pte, entry, dst_entry;
D
David Gibson 已提交
3410
	struct page *ptepage;
3411
	unsigned long addr;
3412
	int cow;
3413 3414
	struct hstate *h = hstate_vma(vma);
	unsigned long sz = huge_page_size(h);
3415
	struct address_space *mapping = vma->vm_file->f_mapping;
3416
	struct mmu_notifier_range range;
3417
	int ret = 0;
3418 3419

	cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
D
David Gibson 已提交
3420

3421
	if (cow) {
3422
		mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, src,
3423
					vma->vm_start,
3424 3425
					vma->vm_end);
		mmu_notifier_invalidate_range_start(&range);
3426 3427 3428 3429 3430 3431 3432 3433
	} else {
		/*
		 * For shared mappings i_mmap_rwsem must be held to call
		 * huge_pte_alloc, otherwise the returned ptep could go
		 * away if part of a shared pmd and another thread calls
		 * huge_pmd_unshare.
		 */
		i_mmap_lock_read(mapping);
3434
	}
3435

3436
	for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
3437
		spinlock_t *src_ptl, *dst_ptl;
3438
		src_pte = huge_pte_offset(src, addr, sz);
H
Hugh Dickins 已提交
3439 3440
		if (!src_pte)
			continue;
3441
		dst_pte = huge_pte_alloc(dst, addr, sz);
3442 3443 3444 3445
		if (!dst_pte) {
			ret = -ENOMEM;
			break;
		}
3446

3447 3448 3449 3450 3451 3452 3453 3454 3455 3456 3457
		/*
		 * If the pagetables are shared don't copy or take references.
		 * dst_pte == src_pte is the common case of src/dest sharing.
		 *
		 * However, src could have 'unshared' and dst shares with
		 * another vma.  If dst_pte !none, this implies sharing.
		 * Check here before taking page table lock, and once again
		 * after taking the lock below.
		 */
		dst_entry = huge_ptep_get(dst_pte);
		if ((dst_pte == src_pte) || !huge_pte_none(dst_entry))
3458 3459
			continue;

3460 3461 3462
		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);
3463
		entry = huge_ptep_get(src_pte);
3464 3465 3466 3467 3468 3469 3470
		dst_entry = huge_ptep_get(dst_pte);
		if (huge_pte_none(entry) || !huge_pte_none(dst_entry)) {
			/*
			 * Skip if src entry none.  Also, skip in the
			 * unlikely case dst entry !none as this implies
			 * sharing with another vma.
			 */
3471 3472 3473 3474 3475 3476 3477 3478 3479 3480 3481 3482
			;
		} 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);
3483 3484
				set_huge_swap_pte_at(src, addr, src_pte,
						     entry, sz);
3485
			}
3486
			set_huge_swap_pte_at(dst, addr, dst_pte, entry, sz);
3487
		} else {
3488
			if (cow) {
3489 3490 3491 3492 3493
				/*
				 * No need to notify as we are downgrading page
				 * table protection not changing it to point
				 * to a new page.
				 *
3494
				 * See Documentation/vm/mmu_notifier.rst
3495
				 */
3496
				huge_ptep_set_wrprotect(src, addr, src_pte);
3497
			}
3498
			entry = huge_ptep_get(src_pte);
3499 3500
			ptepage = pte_page(entry);
			get_page(ptepage);
3501
			page_dup_rmap(ptepage, true);
3502
			set_huge_pte_at(dst, addr, dst_pte, entry);
3503
			hugetlb_count_add(pages_per_huge_page(h), dst);
3504
		}
3505 3506
		spin_unlock(src_ptl);
		spin_unlock(dst_ptl);
D
David Gibson 已提交
3507 3508
	}

3509
	if (cow)
3510
		mmu_notifier_invalidate_range_end(&range);
3511 3512
	else
		i_mmap_unlock_read(mapping);
3513 3514

	return ret;
D
David Gibson 已提交
3515 3516
}

3517 3518 3519
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
3520 3521 3522
{
	struct mm_struct *mm = vma->vm_mm;
	unsigned long address;
3523
	pte_t *ptep;
D
David Gibson 已提交
3524
	pte_t pte;
3525
	spinlock_t *ptl;
D
David Gibson 已提交
3526
	struct page *page;
3527 3528
	struct hstate *h = hstate_vma(vma);
	unsigned long sz = huge_page_size(h);
3529
	struct mmu_notifier_range range;
3530

D
David Gibson 已提交
3531
	WARN_ON(!is_vm_hugetlb_page(vma));
3532 3533
	BUG_ON(start & ~huge_page_mask(h));
	BUG_ON(end & ~huge_page_mask(h));
D
David Gibson 已提交
3534

3535 3536 3537 3538
	/*
	 * This is a hugetlb vma, all the pte entries should point
	 * to huge page.
	 */
3539
	tlb_change_page_size(tlb, sz);
3540
	tlb_start_vma(tlb, vma);
3541 3542 3543 3544

	/*
	 * If sharing possible, alert mmu notifiers of worst case.
	 */
3545 3546
	mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, mm, start,
				end);
3547 3548
	adjust_range_if_pmd_sharing_possible(vma, &range.start, &range.end);
	mmu_notifier_invalidate_range_start(&range);
3549 3550
	address = start;
	for (; address < end; address += sz) {
3551
		ptep = huge_pte_offset(mm, address, sz);
A
Adam Litke 已提交
3552
		if (!ptep)
3553 3554
			continue;

3555
		ptl = huge_pte_lock(h, mm, ptep);
3556 3557
		if (huge_pmd_unshare(mm, &address, ptep)) {
			spin_unlock(ptl);
3558 3559 3560 3561
			/*
			 * We just unmapped a page of PMDs by clearing a PUD.
			 * The caller's TLB flush range should cover this area.
			 */
3562 3563
			continue;
		}
3564

3565
		pte = huge_ptep_get(ptep);
3566 3567 3568 3569
		if (huge_pte_none(pte)) {
			spin_unlock(ptl);
			continue;
		}
3570 3571

		/*
3572 3573
		 * Migrating hugepage or HWPoisoned hugepage is already
		 * unmapped and its refcount is dropped, so just clear pte here.
3574
		 */
3575
		if (unlikely(!pte_present(pte))) {
3576
			huge_pte_clear(mm, address, ptep, sz);
3577 3578
			spin_unlock(ptl);
			continue;
3579
		}
3580 3581

		page = pte_page(pte);
3582 3583 3584 3585 3586 3587
		/*
		 * 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) {
3588 3589 3590 3591
			if (page != ref_page) {
				spin_unlock(ptl);
				continue;
			}
3592 3593 3594 3595 3596 3597 3598 3599
			/*
			 * 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);
		}

3600
		pte = huge_ptep_get_and_clear(mm, address, ptep);
3601
		tlb_remove_huge_tlb_entry(h, tlb, ptep, address);
3602
		if (huge_pte_dirty(pte))
3603
			set_page_dirty(page);
3604

3605
		hugetlb_count_sub(pages_per_huge_page(h), mm);
3606
		page_remove_rmap(page, true);
3607

3608
		spin_unlock(ptl);
3609
		tlb_remove_page_size(tlb, page, huge_page_size(h));
3610 3611 3612 3613 3614
		/*
		 * Bail out after unmapping reference page if supplied
		 */
		if (ref_page)
			break;
3615
	}
3616
	mmu_notifier_invalidate_range_end(&range);
3617
	tlb_end_vma(tlb, vma);
L
Linus Torvalds 已提交
3618
}
D
David Gibson 已提交
3619

3620 3621 3622 3623 3624 3625 3626 3627 3628 3629 3630 3631
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
3632
	 * is to clear it before releasing the i_mmap_rwsem. This works
3633
	 * because in the context this is called, the VMA is about to be
3634
	 * destroyed and the i_mmap_rwsem is held.
3635 3636 3637 3638
	 */
	vma->vm_flags &= ~VM_MAYSHARE;
}

3639
void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
3640
			  unsigned long end, struct page *ref_page)
3641
{
3642 3643
	struct mm_struct *mm;
	struct mmu_gather tlb;
3644 3645 3646 3647 3648 3649 3650 3651 3652 3653 3654
	unsigned long tlb_start = start;
	unsigned long tlb_end = end;

	/*
	 * If shared PMDs were possibly used within this vma range, adjust
	 * start/end for worst case tlb flushing.
	 * Note that we can not be sure if PMDs are shared until we try to
	 * unmap pages.  However, we want to make sure TLB flushing covers
	 * the largest possible range.
	 */
	adjust_range_if_pmd_sharing_possible(vma, &tlb_start, &tlb_end);
3655 3656 3657

	mm = vma->vm_mm;

3658
	tlb_gather_mmu(&tlb, mm, tlb_start, tlb_end);
3659
	__unmap_hugepage_range(&tlb, vma, start, end, ref_page);
3660
	tlb_finish_mmu(&tlb, tlb_start, tlb_end);
3661 3662
}

3663 3664 3665 3666 3667 3668
/*
 * 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.
 */
3669 3670
static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
			      struct page *page, unsigned long address)
3671
{
3672
	struct hstate *h = hstate_vma(vma);
3673 3674 3675 3676 3677 3678 3679 3680
	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.
	 */
3681
	address = address & huge_page_mask(h);
3682 3683
	pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
			vma->vm_pgoff;
3684
	mapping = vma->vm_file->f_mapping;
3685

3686 3687 3688 3689 3690
	/*
	 * 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
	 */
3691
	i_mmap_lock_write(mapping);
3692
	vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) {
3693 3694 3695 3696
		/* Do not unmap the current VMA */
		if (iter_vma == vma)
			continue;

3697 3698 3699 3700 3701 3702 3703 3704
		/*
		 * 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;

3705 3706 3707 3708 3709 3710 3711 3712
		/*
		 * 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))
3713 3714
			unmap_hugepage_range(iter_vma, address,
					     address + huge_page_size(h), page);
3715
	}
3716
	i_mmap_unlock_write(mapping);
3717 3718
}

3719 3720
/*
 * Hugetlb_cow() should be called with page lock of the original hugepage held.
3721 3722 3723
 * 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.
3724
 */
3725
static vm_fault_t hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
3726
		       unsigned long address, pte_t *ptep,
3727
		       struct page *pagecache_page, spinlock_t *ptl)
3728
{
3729
	pte_t pte;
3730
	struct hstate *h = hstate_vma(vma);
3731
	struct page *old_page, *new_page;
3732 3733
	int outside_reserve = 0;
	vm_fault_t ret = 0;
3734
	unsigned long haddr = address & huge_page_mask(h);
3735
	struct mmu_notifier_range range;
3736

3737
	pte = huge_ptep_get(ptep);
3738 3739
	old_page = pte_page(pte);

3740
retry_avoidcopy:
3741 3742
	/* If no-one else is actually using this page, avoid the copy
	 * and just make the page writable */
3743
	if (page_mapcount(old_page) == 1 && PageAnon(old_page)) {
3744
		page_move_anon_rmap(old_page, vma);
3745
		set_huge_ptep_writable(vma, haddr, ptep);
N
Nick Piggin 已提交
3746
		return 0;
3747 3748
	}

3749 3750 3751 3752 3753 3754 3755 3756 3757
	/*
	 * 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.
	 */
3758
	if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
3759 3760 3761
			old_page != pagecache_page)
		outside_reserve = 1;

3762
	get_page(old_page);
3763

3764 3765 3766 3767
	/*
	 * Drop page table lock as buddy allocator may be called. It will
	 * be acquired again before returning to the caller, as expected.
	 */
3768
	spin_unlock(ptl);
3769
	new_page = alloc_huge_page(vma, haddr, outside_reserve);
3770

3771
	if (IS_ERR(new_page)) {
3772 3773 3774 3775 3776 3777 3778 3779
		/*
		 * 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) {
3780
			put_page(old_page);
3781
			BUG_ON(huge_pte_none(pte));
3782
			unmap_ref_private(mm, vma, old_page, haddr);
3783 3784
			BUG_ON(huge_pte_none(pte));
			spin_lock(ptl);
3785
			ptep = huge_pte_offset(mm, haddr, huge_page_size(h));
3786 3787 3788 3789 3790 3791 3792 3793
			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;
3794 3795
		}

3796
		ret = vmf_error(PTR_ERR(new_page));
3797
		goto out_release_old;
3798 3799
	}

3800 3801 3802 3803
	/*
	 * When the original hugepage is shared one, it does not have
	 * anon_vma prepared.
	 */
3804
	if (unlikely(anon_vma_prepare(vma))) {
3805 3806
		ret = VM_FAULT_OOM;
		goto out_release_all;
3807
	}
3808

3809
	copy_user_huge_page(new_page, old_page, address, vma,
A
Andrea Arcangeli 已提交
3810
			    pages_per_huge_page(h));
N
Nick Piggin 已提交
3811
	__SetPageUptodate(new_page);
3812

3813
	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, haddr,
3814
				haddr + huge_page_size(h));
3815
	mmu_notifier_invalidate_range_start(&range);
3816

3817
	/*
3818
	 * Retake the page table lock to check for racing updates
3819 3820
	 * before the page tables are altered
	 */
3821
	spin_lock(ptl);
3822
	ptep = huge_pte_offset(mm, haddr, huge_page_size(h));
3823
	if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) {
3824 3825
		ClearPagePrivate(new_page);

3826
		/* Break COW */
3827
		huge_ptep_clear_flush(vma, haddr, ptep);
3828
		mmu_notifier_invalidate_range(mm, range.start, range.end);
3829
		set_huge_pte_at(mm, haddr, ptep,
3830
				make_huge_pte(vma, new_page, 1));
3831
		page_remove_rmap(old_page, true);
3832
		hugepage_add_new_anon_rmap(new_page, vma, haddr);
3833
		set_page_huge_active(new_page);
3834 3835 3836
		/* Make the old page be freed below */
		new_page = old_page;
	}
3837
	spin_unlock(ptl);
3838
	mmu_notifier_invalidate_range_end(&range);
3839
out_release_all:
3840
	restore_reserve_on_error(h, vma, haddr, new_page);
3841
	put_page(new_page);
3842
out_release_old:
3843
	put_page(old_page);
3844

3845 3846
	spin_lock(ptl); /* Caller expects lock to be held */
	return ret;
3847 3848
}

3849
/* Return the pagecache page at a given address within a VMA */
3850 3851
static struct page *hugetlbfs_pagecache_page(struct hstate *h,
			struct vm_area_struct *vma, unsigned long address)
3852 3853
{
	struct address_space *mapping;
3854
	pgoff_t idx;
3855 3856

	mapping = vma->vm_file->f_mapping;
3857
	idx = vma_hugecache_offset(h, vma, address);
3858 3859 3860 3861

	return find_lock_page(mapping, idx);
}

H
Hugh Dickins 已提交
3862 3863 3864 3865 3866
/*
 * 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
3867 3868 3869 3870 3871 3872 3873 3874 3875 3876 3877 3878 3879 3880 3881
			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;
}

3882 3883 3884 3885 3886 3887 3888 3889 3890 3891 3892
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);

3893 3894 3895 3896 3897 3898
	/*
	 * set page dirty so that it will not be removed from cache/file
	 * by non-hugetlbfs specific code paths.
	 */
	set_page_dirty(page);

3899 3900 3901 3902 3903 3904
	spin_lock(&inode->i_lock);
	inode->i_blocks += blocks_per_huge_page(h);
	spin_unlock(&inode->i_lock);
	return 0;
}

3905 3906 3907 3908
static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
			struct vm_area_struct *vma,
			struct address_space *mapping, pgoff_t idx,
			unsigned long address, pte_t *ptep, unsigned int flags)
3909
{
3910
	struct hstate *h = hstate_vma(vma);
3911
	vm_fault_t ret = VM_FAULT_SIGBUS;
3912
	int anon_rmap = 0;
A
Adam Litke 已提交
3913 3914
	unsigned long size;
	struct page *page;
3915
	pte_t new_pte;
3916
	spinlock_t *ptl;
3917
	unsigned long haddr = address & huge_page_mask(h);
3918
	bool new_page = false;
A
Adam Litke 已提交
3919

3920 3921 3922
	/*
	 * 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
3923
	 * COW. Warn that such a situation has occurred as it may not be obvious
3924 3925
	 */
	if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
3926
		pr_warn_ratelimited("PID %d killed due to inadequate hugepage pool\n",
3927
			   current->pid);
3928 3929 3930
		return ret;
	}

A
Adam Litke 已提交
3931
	/*
3932 3933 3934
	 * We can not race with truncation due to holding i_mmap_rwsem.
	 * i_size is modified when holding i_mmap_rwsem, so check here
	 * once for faults beyond end of file.
A
Adam Litke 已提交
3935
	 */
3936 3937 3938 3939
	size = i_size_read(mapping->host) >> huge_page_shift(h);
	if (idx >= size)
		goto out;

3940 3941 3942
retry:
	page = find_lock_page(mapping, idx);
	if (!page) {
3943 3944 3945 3946 3947 3948 3949
		/*
		 * Check for page in userfault range
		 */
		if (userfaultfd_missing(vma)) {
			u32 hash;
			struct vm_fault vmf = {
				.vma = vma,
3950
				.address = haddr,
3951 3952 3953 3954 3955 3956 3957 3958 3959 3960 3961
				.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
				 */
			};

			/*
3962 3963 3964
			 * hugetlb_fault_mutex and i_mmap_rwsem must be
			 * dropped before handling userfault.  Reacquire
			 * after handling fault to make calling code simpler.
3965
			 */
3966
			hash = hugetlb_fault_mutex_hash(mapping, idx);
3967
			mutex_unlock(&hugetlb_fault_mutex_table[hash]);
3968
			i_mmap_unlock_read(mapping);
3969
			ret = handle_userfault(&vmf, VM_UFFD_MISSING);
3970
			i_mmap_lock_read(mapping);
3971 3972 3973 3974
			mutex_lock(&hugetlb_fault_mutex_table[hash]);
			goto out;
		}

3975
		page = alloc_huge_page(vma, haddr, 0);
3976
		if (IS_ERR(page)) {
3977 3978 3979 3980 3981 3982 3983 3984 3985 3986 3987 3988 3989 3990 3991 3992 3993 3994 3995
			/*
			 * Returning error will result in faulting task being
			 * sent SIGBUS.  The hugetlb fault mutex prevents two
			 * tasks from racing to fault in the same page which
			 * could result in false unable to allocate errors.
			 * Page migration does not take the fault mutex, but
			 * does a clear then write of pte's under page table
			 * lock.  Page fault code could race with migration,
			 * notice the clear pte and try to allocate a page
			 * here.  Before returning error, get ptl and make
			 * sure there really is no pte entry.
			 */
			ptl = huge_pte_lock(h, mm, ptep);
			if (!huge_pte_none(huge_ptep_get(ptep))) {
				ret = 0;
				spin_unlock(ptl);
				goto out;
			}
			spin_unlock(ptl);
3996
			ret = vmf_error(PTR_ERR(page));
3997 3998
			goto out;
		}
A
Andrea Arcangeli 已提交
3999
		clear_huge_page(page, address, pages_per_huge_page(h));
N
Nick Piggin 已提交
4000
		__SetPageUptodate(page);
4001
		new_page = true;
4002

4003
		if (vma->vm_flags & VM_MAYSHARE) {
4004
			int err = huge_add_to_page_cache(page, mapping, idx);
4005 4006 4007 4008 4009 4010
			if (err) {
				put_page(page);
				if (err == -EEXIST)
					goto retry;
				goto out;
			}
4011
		} else {
4012
			lock_page(page);
4013 4014 4015 4016
			if (unlikely(anon_vma_prepare(vma))) {
				ret = VM_FAULT_OOM;
				goto backout_unlocked;
			}
4017
			anon_rmap = 1;
4018
		}
4019
	} else {
4020 4021 4022 4023 4024 4025
		/*
		 * 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))) {
4026
			ret = VM_FAULT_HWPOISON |
4027
				VM_FAULT_SET_HINDEX(hstate_index(h));
4028 4029
			goto backout_unlocked;
		}
4030
	}
4031

4032 4033 4034 4035 4036 4037
	/*
	 * 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.
	 */
4038
	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
4039
		if (vma_needs_reservation(h, vma, haddr) < 0) {
4040 4041 4042
			ret = VM_FAULT_OOM;
			goto backout_unlocked;
		}
4043
		/* Just decrements count, does not deallocate */
4044
		vma_end_reservation(h, vma, haddr);
4045
	}
4046

4047
	ptl = huge_pte_lock(h, mm, ptep);
N
Nick Piggin 已提交
4048
	ret = 0;
4049
	if (!huge_pte_none(huge_ptep_get(ptep)))
A
Adam Litke 已提交
4050 4051
		goto backout;

4052 4053
	if (anon_rmap) {
		ClearPagePrivate(page);
4054
		hugepage_add_new_anon_rmap(page, vma, haddr);
4055
	} else
4056
		page_dup_rmap(page, true);
4057 4058
	new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
				&& (vma->vm_flags & VM_SHARED)));
4059
	set_huge_pte_at(mm, haddr, ptep, new_pte);
4060

4061
	hugetlb_count_add(pages_per_huge_page(h), mm);
4062
	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
4063
		/* Optimization, do the COW without a second fault */
4064
		ret = hugetlb_cow(mm, vma, address, ptep, page, ptl);
4065 4066
	}

4067
	spin_unlock(ptl);
4068 4069 4070 4071 4072 4073 4074 4075 4076

	/*
	 * Only make newly allocated pages active.  Existing pages found
	 * in the pagecache could be !page_huge_active() if they have been
	 * isolated for migration.
	 */
	if (new_page)
		set_page_huge_active(page);

A
Adam Litke 已提交
4077 4078
	unlock_page(page);
out:
4079
	return ret;
A
Adam Litke 已提交
4080 4081

backout:
4082
	spin_unlock(ptl);
4083
backout_unlocked:
A
Adam Litke 已提交
4084
	unlock_page(page);
4085
	restore_reserve_on_error(h, vma, haddr, page);
A
Adam Litke 已提交
4086 4087
	put_page(page);
	goto out;
4088 4089
}

4090
#ifdef CONFIG_SMP
4091
u32 hugetlb_fault_mutex_hash(struct address_space *mapping, pgoff_t idx)
4092 4093 4094 4095
{
	unsigned long key[2];
	u32 hash;

4096 4097
	key[0] = (unsigned long) mapping;
	key[1] = idx;
4098

4099
	hash = jhash2((u32 *)&key, sizeof(key)/(sizeof(u32)), 0);
4100 4101 4102 4103 4104 4105 4106 4107

	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.
 */
4108
u32 hugetlb_fault_mutex_hash(struct address_space *mapping, pgoff_t idx)
4109 4110 4111 4112 4113
{
	return 0;
}
#endif

4114
vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
4115
			unsigned long address, unsigned int flags)
4116
{
4117
	pte_t *ptep, entry;
4118
	spinlock_t *ptl;
4119
	vm_fault_t ret;
4120 4121
	u32 hash;
	pgoff_t idx;
4122
	struct page *page = NULL;
4123
	struct page *pagecache_page = NULL;
4124
	struct hstate *h = hstate_vma(vma);
4125
	struct address_space *mapping;
4126
	int need_wait_lock = 0;
4127
	unsigned long haddr = address & huge_page_mask(h);
4128

4129
	ptep = huge_pte_offset(mm, haddr, huge_page_size(h));
4130
	if (ptep) {
4131 4132 4133 4134 4135
		/*
		 * Since we hold no locks, ptep could be stale.  That is
		 * OK as we are only making decisions based on content and
		 * not actually modifying content here.
		 */
4136
		entry = huge_ptep_get(ptep);
N
Naoya Horiguchi 已提交
4137
		if (unlikely(is_hugetlb_entry_migration(entry))) {
4138
			migration_entry_wait_huge(vma, mm, ptep);
N
Naoya Horiguchi 已提交
4139 4140
			return 0;
		} else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
4141
			return VM_FAULT_HWPOISON_LARGE |
4142
				VM_FAULT_SET_HINDEX(hstate_index(h));
4143 4144 4145 4146
	} else {
		ptep = huge_pte_alloc(mm, haddr, huge_page_size(h));
		if (!ptep)
			return VM_FAULT_OOM;
4147 4148
	}

4149 4150
	/*
	 * Acquire i_mmap_rwsem before calling huge_pte_alloc and hold
4151 4152 4153 4154
	 * until finished with ptep.  This serves two purposes:
	 * 1) It prevents huge_pmd_unshare from being called elsewhere
	 *    and making the ptep no longer valid.
	 * 2) It synchronizes us with i_size modifications during truncation.
4155 4156 4157 4158 4159
	 *
	 * ptep could have already be assigned via huge_pte_offset.  That
	 * is OK, as huge_pte_alloc will return the same value unless
	 * something has changed.
	 */
4160
	mapping = vma->vm_file->f_mapping;
4161 4162 4163 4164 4165 4166
	i_mmap_lock_read(mapping);
	ptep = huge_pte_alloc(mm, haddr, huge_page_size(h));
	if (!ptep) {
		i_mmap_unlock_read(mapping);
		return VM_FAULT_OOM;
	}
4167

4168 4169 4170 4171 4172
	/*
	 * 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.
	 */
4173
	idx = vma_hugecache_offset(h, vma, haddr);
4174
	hash = hugetlb_fault_mutex_hash(mapping, idx);
4175
	mutex_lock(&hugetlb_fault_mutex_table[hash]);
4176

4177 4178
	entry = huge_ptep_get(ptep);
	if (huge_pte_none(entry)) {
4179
		ret = hugetlb_no_page(mm, vma, mapping, idx, address, ptep, flags);
4180
		goto out_mutex;
4181
	}
4182

N
Nick Piggin 已提交
4183
	ret = 0;
4184

4185 4186 4187 4188 4189 4190 4191 4192 4193 4194
	/*
	 * 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;

4195 4196 4197 4198 4199 4200 4201 4202
	/*
	 * 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.
	 */
4203
	if ((flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) {
4204
		if (vma_needs_reservation(h, vma, haddr) < 0) {
4205
			ret = VM_FAULT_OOM;
4206
			goto out_mutex;
4207
		}
4208
		/* Just decrements count, does not deallocate */
4209
		vma_end_reservation(h, vma, haddr);
4210

4211
		if (!(vma->vm_flags & VM_MAYSHARE))
4212
			pagecache_page = hugetlbfs_pagecache_page(h,
4213
								vma, haddr);
4214 4215
	}

4216 4217 4218 4219 4220 4221
	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;

4222 4223 4224 4225 4226 4227 4228
	/*
	 * 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)
4229 4230 4231 4232
		if (!trylock_page(page)) {
			need_wait_lock = 1;
			goto out_ptl;
		}
4233

4234
	get_page(page);
4235

4236
	if (flags & FAULT_FLAG_WRITE) {
4237
		if (!huge_pte_write(entry)) {
4238
			ret = hugetlb_cow(mm, vma, address, ptep,
4239
					  pagecache_page, ptl);
4240
			goto out_put_page;
4241
		}
4242
		entry = huge_pte_mkdirty(entry);
4243 4244
	}
	entry = pte_mkyoung(entry);
4245
	if (huge_ptep_set_access_flags(vma, haddr, ptep, entry,
4246
						flags & FAULT_FLAG_WRITE))
4247
		update_mmu_cache(vma, haddr, ptep);
4248 4249 4250 4251
out_put_page:
	if (page != pagecache_page)
		unlock_page(page);
	put_page(page);
4252 4253
out_ptl:
	spin_unlock(ptl);
4254 4255 4256 4257 4258

	if (pagecache_page) {
		unlock_page(pagecache_page);
		put_page(pagecache_page);
	}
4259
out_mutex:
4260
	mutex_unlock(&hugetlb_fault_mutex_table[hash]);
4261
	i_mmap_unlock_read(mapping);
4262 4263 4264 4265 4266 4267 4268 4269 4270
	/*
	 * 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);
4271
	return ret;
4272 4273
}

4274 4275 4276 4277 4278 4279 4280 4281 4282 4283 4284
/*
 * 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)
{
4285 4286 4287
	struct address_space *mapping;
	pgoff_t idx;
	unsigned long size;
4288
	int vm_shared = dst_vma->vm_flags & VM_SHARED;
4289 4290 4291 4292 4293 4294 4295 4296 4297 4298 4299 4300 4301 4302
	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,
4303
						pages_per_huge_page(h), false);
4304 4305 4306

		/* fallback to copy_from_user outside mmap_sem */
		if (unlikely(ret)) {
4307
			ret = -ENOENT;
4308 4309 4310 4311 4312 4313 4314 4315 4316 4317 4318 4319 4320 4321 4322 4323
			*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);

4324 4325 4326
	mapping = dst_vma->vm_file->f_mapping;
	idx = vma_hugecache_offset(h, dst_vma, dst_addr);

4327 4328 4329 4330
	/*
	 * If shared, add to page cache
	 */
	if (vm_shared) {
4331 4332 4333 4334
		size = i_size_read(mapping->host) >> huge_page_shift(h);
		ret = -EFAULT;
		if (idx >= size)
			goto out_release_nounlock;
4335

4336 4337 4338 4339 4340 4341
		/*
		 * Serialization between remove_inode_hugepages() and
		 * huge_add_to_page_cache() below happens through the
		 * hugetlb_fault_mutex_table that here must be hold by
		 * the caller.
		 */
4342 4343 4344 4345 4346
		ret = huge_add_to_page_cache(page, mapping, idx);
		if (ret)
			goto out_release_nounlock;
	}

4347 4348 4349
	ptl = huge_pte_lockptr(h, dst_mm, dst_pte);
	spin_lock(ptl);

4350 4351 4352 4353 4354 4355 4356 4357 4358 4359 4360 4361 4362 4363
	/*
	 * Recheck the i_size after holding PT lock to make sure not
	 * to leave any page mapped (as page_mapped()) beyond the end
	 * of the i_size (remove_inode_hugepages() is strict about
	 * enforcing that). If we bail out here, we'll also leave a
	 * page in the radix tree in the vm_shared case beyond the end
	 * of the i_size, but remove_inode_hugepages() will take care
	 * of it as soon as we drop the hugetlb_fault_mutex_table.
	 */
	size = i_size_read(mapping->host) >> huge_page_shift(h);
	ret = -EFAULT;
	if (idx >= size)
		goto out_release_unlock;

4364 4365 4366 4367
	ret = -EEXIST;
	if (!huge_pte_none(huge_ptep_get(dst_pte)))
		goto out_release_unlock;

4368 4369 4370 4371 4372 4373
	if (vm_shared) {
		page_dup_rmap(page, true);
	} else {
		ClearPagePrivate(page);
		hugepage_add_new_anon_rmap(page, dst_vma, dst_addr);
	}
4374 4375 4376 4377 4378 4379 4380 4381 4382 4383 4384 4385 4386 4387 4388 4389

	_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);
4390
	set_page_huge_active(page);
4391 4392
	if (vm_shared)
		unlock_page(page);
4393 4394 4395 4396 4397
	ret = 0;
out:
	return ret;
out_release_unlock:
	spin_unlock(ptl);
4398 4399
	if (vm_shared)
		unlock_page(page);
4400
out_release_nounlock:
4401 4402 4403 4404
	put_page(page);
	goto out;
}

4405 4406 4407
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,
4408
			 long i, unsigned int flags, int *locked)
D
David Gibson 已提交
4409
{
4410 4411
	unsigned long pfn_offset;
	unsigned long vaddr = *position;
4412
	unsigned long remainder = *nr_pages;
4413
	struct hstate *h = hstate_vma(vma);
4414
	int err = -EFAULT;
D
David Gibson 已提交
4415 4416

	while (vaddr < vma->vm_end && remainder) {
A
Adam Litke 已提交
4417
		pte_t *pte;
4418
		spinlock_t *ptl = NULL;
H
Hugh Dickins 已提交
4419
		int absent;
A
Adam Litke 已提交
4420
		struct page *page;
D
David Gibson 已提交
4421

4422 4423 4424 4425
		/*
		 * If we have a pending SIGKILL, don't keep faulting pages and
		 * potentially allocating memory.
		 */
4426
		if (fatal_signal_pending(current)) {
4427 4428 4429 4430
			remainder = 0;
			break;
		}

A
Adam Litke 已提交
4431 4432
		/*
		 * Some archs (sparc64, sh*) have multiple pte_ts to
H
Hugh Dickins 已提交
4433
		 * each hugepage.  We have to make sure we get the
A
Adam Litke 已提交
4434
		 * first, for the page indexing below to work.
4435 4436
		 *
		 * Note that page table lock is not held when pte is null.
A
Adam Litke 已提交
4437
		 */
4438 4439
		pte = huge_pte_offset(mm, vaddr & huge_page_mask(h),
				      huge_page_size(h));
4440 4441
		if (pte)
			ptl = huge_pte_lock(h, mm, pte);
H
Hugh Dickins 已提交
4442 4443 4444 4445
		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
4446 4447 4448 4449
		 * 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
4450
		 */
H
Hugh Dickins 已提交
4451 4452
		if (absent && (flags & FOLL_DUMP) &&
		    !hugetlbfs_pagecache_present(h, vma, vaddr)) {
4453 4454
			if (pte)
				spin_unlock(ptl);
H
Hugh Dickins 已提交
4455 4456 4457
			remainder = 0;
			break;
		}
D
David Gibson 已提交
4458

4459 4460 4461 4462 4463 4464 4465 4466 4467 4468 4469
		/*
		 * 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)) ||
4470 4471
		    ((flags & FOLL_WRITE) &&
		      !huge_pte_write(huge_ptep_get(pte)))) {
4472
			vm_fault_t ret;
4473
			unsigned int fault_flags = 0;
D
David Gibson 已提交
4474

4475 4476
			if (pte)
				spin_unlock(ptl);
4477 4478
			if (flags & FOLL_WRITE)
				fault_flags |= FAULT_FLAG_WRITE;
4479
			if (locked)
4480 4481
				fault_flags |= FAULT_FLAG_ALLOW_RETRY |
					FAULT_FLAG_KILLABLE;
4482 4483 4484 4485
			if (flags & FOLL_NOWAIT)
				fault_flags |= FAULT_FLAG_ALLOW_RETRY |
					FAULT_FLAG_RETRY_NOWAIT;
			if (flags & FOLL_TRIED) {
4486 4487 4488 4489
				/*
				 * Note: FAULT_FLAG_ALLOW_RETRY and
				 * FAULT_FLAG_TRIED can co-exist
				 */
4490 4491 4492 4493
				fault_flags |= FAULT_FLAG_TRIED;
			}
			ret = hugetlb_fault(mm, vma, vaddr, fault_flags);
			if (ret & VM_FAULT_ERROR) {
4494
				err = vm_fault_to_errno(ret, flags);
4495 4496 4497 4498
				remainder = 0;
				break;
			}
			if (ret & VM_FAULT_RETRY) {
4499
				if (locked &&
4500
				    !(fault_flags & FAULT_FLAG_RETRY_NOWAIT))
4501
					*locked = 0;
4502 4503 4504 4505 4506 4507 4508 4509 4510 4511 4512 4513 4514
				*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
4515 4516
		}

4517
		pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
4518
		page = pte_page(huge_ptep_get(pte));
4519

4520 4521 4522 4523 4524 4525 4526 4527 4528 4529 4530 4531 4532 4533
		/*
		 * If subpage information not requested, update counters
		 * and skip the same_page loop below.
		 */
		if (!pages && !vmas && !pfn_offset &&
		    (vaddr + huge_page_size(h) < vma->vm_end) &&
		    (remainder >= pages_per_huge_page(h))) {
			vaddr += huge_page_size(h);
			remainder -= pages_per_huge_page(h);
			i += pages_per_huge_page(h);
			spin_unlock(ptl);
			continue;
		}

4534
same_page:
4535
		if (pages) {
H
Hugh Dickins 已提交
4536
			pages[i] = mem_map_offset(page, pfn_offset);
J
John Hubbard 已提交
4537 4538 4539 4540 4541 4542 4543 4544 4545 4546 4547 4548 4549 4550 4551 4552
			/*
			 * try_grab_page() should always succeed here, because:
			 * a) we hold the ptl lock, and b) we've just checked
			 * that the huge page is present in the page tables. If
			 * the huge page is present, then the tail pages must
			 * also be present. The ptl prevents the head page and
			 * tail pages from being rearranged in any way. So this
			 * page must be available at this point, unless the page
			 * refcount overflowed:
			 */
			if (WARN_ON_ONCE(!try_grab_page(pages[i], flags))) {
				spin_unlock(ptl);
				remainder = 0;
				err = -ENOMEM;
				break;
			}
4553
		}
D
David Gibson 已提交
4554 4555 4556 4557 4558

		if (vmas)
			vmas[i] = vma;

		vaddr += PAGE_SIZE;
4559
		++pfn_offset;
D
David Gibson 已提交
4560 4561
		--remainder;
		++i;
4562
		if (vaddr < vma->vm_end && remainder &&
4563
				pfn_offset < pages_per_huge_page(h)) {
4564 4565 4566 4567 4568 4569
			/*
			 * We use pfn_offset to avoid touching the pageframes
			 * of this compound page.
			 */
			goto same_page;
		}
4570
		spin_unlock(ptl);
D
David Gibson 已提交
4571
	}
4572
	*nr_pages = remainder;
4573 4574 4575 4576 4577
	/*
	 * 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
4578 4579
	*position = vaddr;

4580
	return i ? i : err;
D
David Gibson 已提交
4581
}
4582

4583 4584 4585 4586 4587 4588 4589 4590
#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

4591
unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
4592 4593 4594 4595 4596 4597
		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;
4598
	struct hstate *h = hstate_vma(vma);
4599
	unsigned long pages = 0;
4600
	bool shared_pmd = false;
4601
	struct mmu_notifier_range range;
4602 4603 4604

	/*
	 * In the case of shared PMDs, the area to flush could be beyond
4605
	 * start/end.  Set range.start/range.end to cover the maximum possible
4606 4607
	 * range if PMD sharing is possible.
	 */
4608 4609
	mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_VMA,
				0, vma, mm, start, end);
4610
	adjust_range_if_pmd_sharing_possible(vma, &range.start, &range.end);
4611 4612

	BUG_ON(address >= end);
4613
	flush_cache_range(vma, range.start, range.end);
4614

4615
	mmu_notifier_invalidate_range_start(&range);
4616
	i_mmap_lock_write(vma->vm_file->f_mapping);
4617
	for (; address < end; address += huge_page_size(h)) {
4618
		spinlock_t *ptl;
4619
		ptep = huge_pte_offset(mm, address, huge_page_size(h));
4620 4621
		if (!ptep)
			continue;
4622
		ptl = huge_pte_lock(h, mm, ptep);
4623 4624
		if (huge_pmd_unshare(mm, &address, ptep)) {
			pages++;
4625
			spin_unlock(ptl);
4626
			shared_pmd = true;
4627
			continue;
4628
		}
4629 4630 4631 4632 4633 4634 4635 4636 4637 4638 4639 4640 4641
		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);
4642 4643
				set_huge_swap_pte_at(mm, address, ptep,
						     newpte, huge_page_size(h));
4644 4645 4646 4647 4648 4649
				pages++;
			}
			spin_unlock(ptl);
			continue;
		}
		if (!huge_pte_none(pte)) {
4650 4651 4652 4653
			pte_t old_pte;

			old_pte = huge_ptep_modify_prot_start(vma, address, ptep);
			pte = pte_mkhuge(huge_pte_modify(old_pte, newprot));
4654
			pte = arch_make_huge_pte(pte, vma, NULL, 0);
4655
			huge_ptep_modify_prot_commit(vma, address, ptep, old_pte, pte);
4656
			pages++;
4657
		}
4658
		spin_unlock(ptl);
4659
	}
4660
	/*
4661
	 * Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare
4662
	 * may have cleared our pud entry and done put_page on the page table:
4663
	 * once we release i_mmap_rwsem, another task can do the final put_page
4664 4665
	 * and that page table be reused and filled with junk.  If we actually
	 * did unshare a page of pmds, flush the range corresponding to the pud.
4666
	 */
4667
	if (shared_pmd)
4668
		flush_hugetlb_tlb_range(vma, range.start, range.end);
4669 4670
	else
		flush_hugetlb_tlb_range(vma, start, end);
4671 4672 4673 4674
	/*
	 * No need to call mmu_notifier_invalidate_range() we are downgrading
	 * page table protection not changing it to point to a new page.
	 *
4675
	 * See Documentation/vm/mmu_notifier.rst
4676
	 */
4677
	i_mmap_unlock_write(vma->vm_file->f_mapping);
4678
	mmu_notifier_invalidate_range_end(&range);
4679 4680

	return pages << h->order;
4681 4682
}

4683 4684
int hugetlb_reserve_pages(struct inode *inode,
					long from, long to,
4685
					struct vm_area_struct *vma,
4686
					vm_flags_t vm_flags)
4687
{
4688
	long ret, chg;
4689
	struct hstate *h = hstate_inode(inode);
4690
	struct hugepage_subpool *spool = subpool_inode(inode);
4691
	struct resv_map *resv_map;
4692
	long gbl_reserve;
4693

4694 4695 4696 4697 4698 4699
	/* This should never happen */
	if (from > to) {
		VM_WARN(1, "%s called with a negative range\n", __func__);
		return -EINVAL;
	}

4700 4701 4702
	/*
	 * Only apply hugepage reservation if asked. At fault time, an
	 * attempt will be made for VM_NORESERVE to allocate a page
4703
	 * without using reserves
4704
	 */
4705
	if (vm_flags & VM_NORESERVE)
4706 4707
		return 0;

4708 4709 4710 4711 4712 4713
	/*
	 * 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
	 */
4714
	if (!vma || vma->vm_flags & VM_MAYSHARE) {
4715 4716 4717 4718 4719
		/*
		 * resv_map can not be NULL as hugetlb_reserve_pages is only
		 * called for inodes for which resv_maps were created (see
		 * hugetlbfs_get_inode).
		 */
4720
		resv_map = inode_resv_map(inode);
4721

4722
		chg = region_chg(resv_map, from, to);
4723 4724 4725

	} else {
		resv_map = resv_map_alloc();
4726 4727 4728
		if (!resv_map)
			return -ENOMEM;

4729
		chg = to - from;
4730

4731 4732 4733 4734
		set_vma_resv_map(vma, resv_map);
		set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
	}

4735 4736 4737 4738
	if (chg < 0) {
		ret = chg;
		goto out_err;
	}
4739

4740 4741 4742 4743 4744 4745 4746
	/*
	 * 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) {
4747 4748 4749
		ret = -ENOSPC;
		goto out_err;
	}
4750 4751

	/*
4752
	 * Check enough hugepages are available for the reservation.
4753
	 * Hand the pages back to the subpool if there are not
4754
	 */
4755
	ret = hugetlb_acct_memory(h, gbl_reserve);
K
Ken Chen 已提交
4756
	if (ret < 0) {
4757 4758
		/* put back original number of pages, chg */
		(void)hugepage_subpool_put_pages(spool, chg);
4759
		goto out_err;
K
Ken Chen 已提交
4760
	}
4761 4762 4763 4764 4765 4766 4767 4768 4769 4770 4771 4772

	/*
	 * 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
	 */
4773 4774 4775 4776 4777 4778 4779 4780 4781 4782 4783 4784 4785 4786 4787 4788 4789 4790
	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);
		}
	}
4791
	return 0;
4792
out_err:
4793
	if (!vma || vma->vm_flags & VM_MAYSHARE)
4794 4795 4796
		/* Don't call region_abort if region_chg failed */
		if (chg >= 0)
			region_abort(resv_map, from, to);
J
Joonsoo Kim 已提交
4797 4798
	if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
		kref_put(&resv_map->refs, resv_map_release);
4799
	return ret;
4800 4801
}

4802 4803
long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
								long freed)
4804
{
4805
	struct hstate *h = hstate_inode(inode);
4806
	struct resv_map *resv_map = inode_resv_map(inode);
4807
	long chg = 0;
4808
	struct hugepage_subpool *spool = subpool_inode(inode);
4809
	long gbl_reserve;
K
Ken Chen 已提交
4810

4811 4812 4813 4814
	/*
	 * Since this routine can be called in the evict inode path for all
	 * hugetlbfs inodes, resv_map could be NULL.
	 */
4815 4816 4817 4818 4819 4820 4821 4822 4823 4824 4825
	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
4826
	spin_lock(&inode->i_lock);
4827
	inode->i_blocks -= (blocks_per_huge_page(h) * freed);
K
Ken Chen 已提交
4828 4829
	spin_unlock(&inode->i_lock);

4830 4831 4832 4833 4834 4835
	/*
	 * 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);
4836 4837

	return 0;
4838
}
4839

4840 4841 4842 4843 4844 4845 4846 4847 4848 4849 4850
#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
4851 4852
	unsigned long vm_flags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
	unsigned long svm_flags = svma->vm_flags & VM_LOCKED_CLEAR_MASK;
4853 4854 4855 4856 4857 4858 4859 4860 4861 4862 4863 4864 4865

	/*
	 * 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;
}

4866
static bool vma_shareable(struct vm_area_struct *vma, unsigned long addr)
4867 4868 4869 4870 4871 4872 4873
{
	unsigned long base = addr & PUD_MASK;
	unsigned long end = base + PUD_SIZE;

	/*
	 * check on proper vm_flags and page table alignment
	 */
4874
	if (vma->vm_flags & VM_MAYSHARE && range_in_vma(vma, base, end))
4875 4876
		return true;
	return false;
4877 4878
}

4879 4880 4881 4882 4883 4884 4885 4886 4887 4888 4889 4890 4891 4892 4893 4894 4895 4896 4897 4898 4899 4900 4901 4902 4903 4904 4905 4906 4907
/*
 * Determine if start,end range within vma could be mapped by shared pmd.
 * If yes, adjust start and end to cover range associated with possible
 * shared pmd mappings.
 */
void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma,
				unsigned long *start, unsigned long *end)
{
	unsigned long check_addr = *start;

	if (!(vma->vm_flags & VM_MAYSHARE))
		return;

	for (check_addr = *start; check_addr < *end; check_addr += PUD_SIZE) {
		unsigned long a_start = check_addr & PUD_MASK;
		unsigned long a_end = a_start + PUD_SIZE;

		/*
		 * If sharing is possible, adjust start/end if necessary.
		 */
		if (range_in_vma(vma, a_start, a_end)) {
			if (a_start < *start)
				*start = a_start;
			if (a_end > *end)
				*end = a_end;
		}
	}
}

4908 4909 4910 4911
/*
 * 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
4912 4913 4914 4915 4916 4917
 * code much cleaner.
 *
 * This routine must be called with i_mmap_rwsem held in at least read mode.
 * For hugetlbfs, this prevents removal of any page table entries associated
 * with the address space.  This is important as we are setting up sharing
 * based on existing page table entries (mappings).
4918 4919 4920 4921 4922 4923 4924 4925 4926 4927 4928
 */
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;
4929
	spinlock_t *ptl;
4930 4931 4932 4933 4934 4935 4936 4937 4938 4939

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

	vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) {
		if (svma == vma)
			continue;

		saddr = page_table_shareable(svma, vma, addr, idx);
		if (saddr) {
4940 4941
			spte = huge_pte_offset(svma->vm_mm, saddr,
					       vma_mmu_pagesize(svma));
4942 4943 4944 4945 4946 4947 4948 4949 4950 4951
			if (spte) {
				get_page(virt_to_page(spte));
				break;
			}
		}
	}

	if (!spte)
		goto out;

4952
	ptl = huge_pte_lock(hstate_vma(vma), mm, spte);
4953
	if (pud_none(*pud)) {
4954 4955
		pud_populate(mm, pud,
				(pmd_t *)((unsigned long)spte & PAGE_MASK));
4956
		mm_inc_nr_pmds(mm);
4957
	} else {
4958
		put_page(virt_to_page(spte));
4959
	}
4960
	spin_unlock(ptl);
4961 4962 4963 4964 4965 4966 4967 4968 4969 4970 4971 4972
out:
	pte = (pte_t *)pmd_alloc(mm, pud, addr);
	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.
 *
4973
 * Called with page table lock held and i_mmap_rwsem held in write mode.
4974 4975 4976 4977 4978 4979 4980
 *
 * 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);
4981 4982
	p4d_t *p4d = p4d_offset(pgd, *addr);
	pud_t *pud = pud_offset(p4d, *addr);
4983 4984 4985 4986 4987 4988 4989

	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));
4990
	mm_dec_nr_pmds(mm);
4991 4992 4993
	*addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
	return 1;
}
4994 4995 4996 4997 4998 4999
#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;
}
5000 5001 5002 5003 5004

int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
{
	return 0;
}
5005 5006 5007 5008 5009

void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma,
				unsigned long *start, unsigned long *end)
{
}
5010
#define want_pmd_share()	(0)
5011 5012
#endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */

5013 5014 5015 5016 5017
#ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
pte_t *huge_pte_alloc(struct mm_struct *mm,
			unsigned long addr, unsigned long sz)
{
	pgd_t *pgd;
5018
	p4d_t *p4d;
5019 5020 5021 5022
	pud_t *pud;
	pte_t *pte = NULL;

	pgd = pgd_offset(mm, addr);
5023 5024 5025
	p4d = p4d_alloc(mm, pgd, addr);
	if (!p4d)
		return NULL;
5026
	pud = pud_alloc(mm, p4d, addr);
5027 5028 5029 5030 5031 5032 5033 5034 5035 5036 5037
	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);
		}
	}
5038
	BUG_ON(pte && pte_present(*pte) && !pte_huge(*pte));
5039 5040 5041 5042

	return pte;
}

5043 5044 5045 5046 5047 5048 5049 5050 5051
/*
 * huge_pte_offset() - Walk the page table to resolve the hugepage
 * entry at address @addr
 *
 * Return: Pointer to page table or swap entry (PUD or PMD) for
 * address @addr, or NULL if a p*d_none() entry is encountered and the
 * size @sz doesn't match the hugepage size at this level of the page
 * table.
 */
5052 5053
pte_t *huge_pte_offset(struct mm_struct *mm,
		       unsigned long addr, unsigned long sz)
5054 5055
{
	pgd_t *pgd;
5056
	p4d_t *p4d;
5057
	pud_t *pud;
5058
	pmd_t *pmd;
5059 5060

	pgd = pgd_offset(mm, addr);
5061 5062 5063 5064 5065
	if (!pgd_present(*pgd))
		return NULL;
	p4d = p4d_offset(pgd, addr);
	if (!p4d_present(*p4d))
		return NULL;
5066

5067
	pud = pud_offset(p4d, addr);
5068
	if (sz != PUD_SIZE && pud_none(*pud))
5069
		return NULL;
5070 5071
	/* hugepage or swap? */
	if (pud_huge(*pud) || !pud_present(*pud))
5072
		return (pte_t *)pud;
5073

5074
	pmd = pmd_offset(pud, addr);
5075 5076 5077 5078 5079 5080 5081
	if (sz != PMD_SIZE && pmd_none(*pmd))
		return NULL;
	/* hugepage or swap? */
	if (pmd_huge(*pmd) || !pmd_present(*pmd))
		return (pte_t *)pmd;

	return NULL;
5082 5083
}

5084 5085 5086 5087 5088 5089 5090 5091 5092 5093 5094 5095 5096
#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);
}

5097 5098 5099 5100 5101 5102 5103 5104
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;
}

5105
struct page * __weak
5106
follow_huge_pmd(struct mm_struct *mm, unsigned long address,
5107
		pmd_t *pmd, int flags)
5108
{
5109 5110
	struct page *page = NULL;
	spinlock_t *ptl;
5111
	pte_t pte;
J
John Hubbard 已提交
5112 5113 5114 5115 5116 5117

	/* FOLL_GET and FOLL_PIN are mutually exclusive. */
	if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
			 (FOLL_PIN | FOLL_GET)))
		return NULL;

5118 5119 5120 5121 5122 5123 5124 5125 5126
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;
5127 5128
	pte = huge_ptep_get((pte_t *)pmd);
	if (pte_present(pte)) {
5129
		page = pmd_page(*pmd) + ((address & ~PMD_MASK) >> PAGE_SHIFT);
J
John Hubbard 已提交
5130 5131 5132 5133 5134 5135 5136 5137 5138 5139 5140 5141
		/*
		 * try_grab_page() should always succeed here, because: a) we
		 * hold the pmd (ptl) lock, and b) we've just checked that the
		 * huge pmd (head) page is present in the page tables. The ptl
		 * prevents the head page and tail pages from being rearranged
		 * in any way. So this page must be available at this point,
		 * unless the page refcount overflowed:
		 */
		if (WARN_ON_ONCE(!try_grab_page(page, flags))) {
			page = NULL;
			goto out;
		}
5142
	} else {
5143
		if (is_hugetlb_entry_migration(pte)) {
5144 5145 5146 5147 5148 5149 5150 5151 5152 5153 5154
			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);
5155 5156 5157
	return page;
}

5158
struct page * __weak
5159
follow_huge_pud(struct mm_struct *mm, unsigned long address,
5160
		pud_t *pud, int flags)
5161
{
J
John Hubbard 已提交
5162
	if (flags & (FOLL_GET | FOLL_PIN))
5163
		return NULL;
5164

5165
	return pte_page(*(pte_t *)pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT);
5166 5167
}

5168 5169 5170
struct page * __weak
follow_huge_pgd(struct mm_struct *mm, unsigned long address, pgd_t *pgd, int flags)
{
J
John Hubbard 已提交
5171
	if (flags & (FOLL_GET | FOLL_PIN))
5172 5173 5174 5175 5176
		return NULL;

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

5177 5178
bool isolate_huge_page(struct page *page, struct list_head *list)
{
5179 5180
	bool ret = true;

5181
	VM_BUG_ON_PAGE(!PageHead(page), page);
5182
	spin_lock(&hugetlb_lock);
5183 5184 5185 5186 5187
	if (!page_huge_active(page) || !get_page_unless_zero(page)) {
		ret = false;
		goto unlock;
	}
	clear_page_huge_active(page);
5188
	list_move_tail(&page->lru, list);
5189
unlock:
5190
	spin_unlock(&hugetlb_lock);
5191
	return ret;
5192 5193 5194 5195
}

void putback_active_hugepage(struct page *page)
{
5196
	VM_BUG_ON_PAGE(!PageHead(page), page);
5197
	spin_lock(&hugetlb_lock);
5198
	set_page_huge_active(page);
5199 5200 5201 5202
	list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
	spin_unlock(&hugetlb_lock);
	put_page(page);
}
5203 5204 5205 5206 5207 5208 5209 5210 5211 5212 5213 5214 5215 5216 5217 5218 5219 5220 5221 5222 5223 5224 5225 5226 5227 5228 5229 5230 5231 5232 5233 5234 5235

void move_hugetlb_state(struct page *oldpage, struct page *newpage, int reason)
{
	struct hstate *h = page_hstate(oldpage);

	hugetlb_cgroup_migrate(oldpage, newpage);
	set_page_owner_migrate_reason(newpage, reason);

	/*
	 * transfer temporary state of the new huge page. This is
	 * reverse to other transitions because the newpage is going to
	 * be final while the old one will be freed so it takes over
	 * the temporary status.
	 *
	 * Also note that we have to transfer the per-node surplus state
	 * here as well otherwise the global surplus count will not match
	 * the per-node's.
	 */
	if (PageHugeTemporary(newpage)) {
		int old_nid = page_to_nid(oldpage);
		int new_nid = page_to_nid(newpage);

		SetPageHugeTemporary(oldpage);
		ClearPageHugeTemporary(newpage);

		spin_lock(&hugetlb_lock);
		if (h->surplus_huge_pages_node[old_nid]) {
			h->surplus_huge_pages_node[old_nid]--;
			h->surplus_huge_pages_node[new_nid]++;
		}
		spin_unlock(&hugetlb_lock);
	}
}