hugetlb.c 125.4 KB
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/*
 * Generic hugetlb support.
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 * (C) Nadia Yvette Chambers, April 2004
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 */
#include <linux/list.h>
#include <linux/init.h>
#include <linux/mm.h>
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#include <linux/seq_file.h>
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#include <linux/sysctl.h>
#include <linux/highmem.h>
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#include <linux/mmu_notifier.h>
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#include <linux/nodemask.h>
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#include <linux/pagemap.h>
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#include <linux/mempolicy.h>
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#include <linux/compiler.h>
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#include <linux/cpuset.h>
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#include <linux/mutex.h>
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#include <linux/bootmem.h>
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#include <linux/sysfs.h>
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#include <linux/slab.h>
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#include <linux/rmap.h>
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#include <linux/swap.h>
#include <linux/swapops.h>
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#include <linux/page-isolation.h>
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#include <linux/jhash.h>
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#include <asm/page.h>
#include <asm/pgtable.h>
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#include <asm/tlb.h>
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#include <linux/io.h>
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#include <linux/hugetlb.h>
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#include <linux/hugetlb_cgroup.h>
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#include <linux/node.h>
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#include "internal.h"
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int hugepages_treat_as_movable;
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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;

179
	if (!spool)
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		return delta;
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	spin_lock(&spool->lock);
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	if (spool->max_hpages != -1)		/* maximum size accounting */
		spool->used_hpages -= delta;

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

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

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

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

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

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

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

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	/*
	 * If no region exists which can be expanded to include the
	 * specified range, the list must have been modified by an
	 * interleving call to region_del().  Pull a region descriptor
	 * from the cache and use it for this range.
	 */
	if (&rg->link == head || t < rg->from) {
		VM_BUG_ON(resv->region_cache_count <= 0);

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

		nrg->from = f;
		nrg->to = t;
		list_add(&nrg->link, rg->link.prev);

		add += t - f;
		goto out_locked;
	}

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

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

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

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/*
 * Examine the existing reserve map and determine how many
 * huge pages in the specified range [f, t) are NOT currently
 * represented.  This routine is called before a subsequent
 * call to region_add that will actually modify the reserve
 * map to add the specified range [f, t).  region_chg does
 * not change the number of huge pages represented by the
 * map.  However, if the existing regions in the map can not
 * be expanded to represent the new range, a new file_region
 * structure is added to the map as a placeholder.  This is
 * so that the subsequent region_add call will have all the
 * regions it needs and will not fail.
 *
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 * Upon entry, region_chg will also examine the cache of region descriptors
 * associated with the map.  If there are not enough descriptors cached, one
 * will be allocated for the in progress add operation.
 *
 * Returns the number of huge pages that need to be added to the existing
 * reservation map for the range [f, t).  This number is greater or equal to
 * zero.  -ENOMEM is returned if a new file_region structure or cache entry
 * is needed and can not be allocated.
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 */
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static long region_chg(struct resv_map *resv, long f, long t)
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{
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	struct list_head *head = &resv->regions;
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	struct file_region *rg, *nrg = NULL;
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	long chg = 0;

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

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

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

		trg = kmalloc(sizeof(*trg), GFP_KERNEL);
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		if (!trg) {
			kfree(nrg);
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			return -ENOMEM;
380
		}
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		spin_lock(&resv->lock);
		list_add(&trg->link, &resv->region_cache);
		resv->region_cache_count++;
		goto retry_locked;
	}

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

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

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

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

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

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

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/*
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 * Delete the specified range [f, t) from the reserve map.  If the
 * t parameter is LONG_MAX, this indicates that ALL regions after f
 * should be deleted.  Locate the regions which intersect [f, t)
 * and either trim, delete or split the existing regions.
 *
 * Returns the number of huge pages deleted from the reserve map.
 * In the normal case, the return value is zero or more.  In the
 * case where a region must be split, a new region descriptor must
 * be allocated.  If the allocation fails, -ENOMEM will be returned.
 * NOTE: If the parameter t == LONG_MAX, then we will never split
 * a region and possibly return -ENOMEM.  Callers specifying
 * t == LONG_MAX do not need to check for -ENOMEM error.
479
 */
480
static long region_del(struct resv_map *resv, long f, long t)
481
{
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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:
488
	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))
498
			continue;
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500
		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.
 */
570
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).
 */
587
static long region_count(struct resv_map *resv, long f, long t)
588
{
589
	struct list_head *head = &resv->regions;
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	struct file_region *rg;
	long chg = 0;

593
	spin_lock(&resv->lock);
594 595
	/* 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)
620
{
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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);
}
630
EXPORT_SYMBOL_GPL(linear_hugepage_index);
631

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

	if (!is_vm_hugetlb_page(vma))
		return PAGE_SIZE;

	hstate = hstate_vma(vma);

645
	return 1UL << huge_page_shift(hstate);
646
}
647
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
 * architectures where it differs, an architecture-specific version of this
 * function is required.
 */
#ifndef vma_mmu_pagesize
unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
{
	return vma_kernel_pagesize(vma);
}
#endif

662 663 664 665 666 667 668
/*
 * 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)
669
#define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
670

671 672 673 674 675 676 677 678 679
/*
 * 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.
680 681 682 683 684 685 686 687 688
 *
 * 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.
689
 */
690 691 692 693 694 695 696 697 698 699 700
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;
}

701
struct resv_map *resv_map_alloc(void)
702 703
{
	struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
704 705 706 707 708
	struct file_region *rg = kmalloc(sizeof(*rg), GFP_KERNEL);

	if (!resv_map || !rg) {
		kfree(resv_map);
		kfree(rg);
709
		return NULL;
710
	}
711 712

	kref_init(&resv_map->refs);
713
	spin_lock_init(&resv_map->lock);
714 715
	INIT_LIST_HEAD(&resv_map->regions);

716 717 718 719 720 721
	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;

722 723 724
	return resv_map;
}

725
void resv_map_release(struct kref *ref)
726 727
{
	struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
728 729
	struct list_head *head = &resv_map->region_cache;
	struct file_region *rg, *trg;
730 731

	/* Clear out any active regions before we release the map. */
732
	region_del(resv_map, 0, LONG_MAX);
733 734 735 736 737 738 739 740 741

	/* ... 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);

742 743 744
	kfree(resv_map);
}

745 746 747 748 749
static inline struct resv_map *inode_resv_map(struct inode *inode)
{
	return inode->i_mapping->private_data;
}

750
static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
751
{
752
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
753 754 755 756 757 758 759
	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 {
760 761
		return (struct resv_map *)(get_vma_private_data(vma) &
							~HPAGE_RESV_MASK);
762
	}
763 764
}

765
static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
766
{
767 768
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
	VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
769

770 771
	set_vma_private_data(vma, (get_vma_private_data(vma) &
				HPAGE_RESV_MASK) | (unsigned long)map);
772 773 774 775
}

static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
{
776 777
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
	VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
778 779

	set_vma_private_data(vma, get_vma_private_data(vma) | flags);
780 781 782 783
}

static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
{
784
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
785 786

	return (get_vma_private_data(vma) & flag) != 0;
787 788
}

789
/* Reset counters to 0 and clear all HPAGE_RESV_* flags */
790 791
void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
{
792
	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
793
	if (!(vma->vm_flags & VM_MAYSHARE))
794 795 796 797
		vma->vm_private_data = (void *)0;
}

/* Returns true if the VMA has associated reserve pages */
798
static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
799
{
800 801 802 803 804 805 806 807 808 809 810
	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)
811
			return true;
812
		else
813
			return false;
814
	}
815 816

	/* Shared mappings always use reserves */
817 818 819 820 821 822 823 824 825 826 827 828 829
	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;
	}
830 831 832 833 834

	/*
	 * Only the process that called mmap() has reserves for
	 * private mappings.
	 */
835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855
	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;
	}
856

857
	return false;
858 859
}

860
static void enqueue_huge_page(struct hstate *h, struct page *page)
L
Linus Torvalds 已提交
861 862
{
	int nid = page_to_nid(page);
863
	list_move(&page->lru, &h->hugepage_freelists[nid]);
864 865
	h->free_huge_pages++;
	h->free_huge_pages_node[nid]++;
L
Linus Torvalds 已提交
866 867
}

868 869 870 871
static struct page *dequeue_huge_page_node(struct hstate *h, int nid)
{
	struct page *page;

872 873 874 875 876 877 878 879
	list_for_each_entry(page, &h->hugepage_freelists[nid], lru)
		if (!is_migrate_isolate_page(page))
			break;
	/*
	 * if 'non-isolated free hugepage' not found on the list,
	 * the allocation fails.
	 */
	if (&h->hugepage_freelists[nid] == &page->lru)
880
		return NULL;
881
	list_move(&page->lru, &h->hugepage_activelist);
882
	set_page_refcounted(page);
883 884 885 886 887
	h->free_huge_pages--;
	h->free_huge_pages_node[nid]--;
	return page;
}

888 889 890
/* Movability of hugepages depends on migration support. */
static inline gfp_t htlb_alloc_mask(struct hstate *h)
{
891
	if (hugepages_treat_as_movable || hugepage_migration_supported(h))
892 893 894 895 896
		return GFP_HIGHUSER_MOVABLE;
	else
		return GFP_HIGHUSER;
}

897 898
static struct page *dequeue_huge_page_vma(struct hstate *h,
				struct vm_area_struct *vma,
899 900
				unsigned long address, int avoid_reserve,
				long chg)
L
Linus Torvalds 已提交
901
{
902
	struct page *page = NULL;
903
	struct mempolicy *mpol;
904
	nodemask_t *nodemask;
905
	struct zonelist *zonelist;
906 907
	struct zone *zone;
	struct zoneref *z;
908
	unsigned int cpuset_mems_cookie;
L
Linus Torvalds 已提交
909

910 911 912 913 914
	/*
	 * 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
	 */
915
	if (!vma_has_reserves(vma, chg) &&
916
			h->free_huge_pages - h->resv_huge_pages == 0)
917
		goto err;
918

919
	/* If reserves cannot be used, ensure enough pages are in the pool */
920
	if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
921
		goto err;
922

923
retry_cpuset:
924
	cpuset_mems_cookie = read_mems_allowed_begin();
925
	zonelist = huge_zonelist(vma, address,
926
					htlb_alloc_mask(h), &mpol, &nodemask);
927

928 929
	for_each_zone_zonelist_nodemask(zone, z, zonelist,
						MAX_NR_ZONES - 1, nodemask) {
930
		if (cpuset_zone_allowed(zone, htlb_alloc_mask(h))) {
931 932
			page = dequeue_huge_page_node(h, zone_to_nid(zone));
			if (page) {
933 934 935 936 937
				if (avoid_reserve)
					break;
				if (!vma_has_reserves(vma, chg))
					break;

938
				SetPagePrivate(page);
939
				h->resv_huge_pages--;
940 941
				break;
			}
A
Andrew Morton 已提交
942
		}
L
Linus Torvalds 已提交
943
	}
944

945
	mpol_cond_put(mpol);
946
	if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
947
		goto retry_cpuset;
L
Linus Torvalds 已提交
948
	return page;
949 950 951

err:
	return NULL;
L
Linus Torvalds 已提交
952 953
}

954 955 956 957 958 959 960 961 962
/*
 * 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)
{
963
	nid = next_node_in(nid, *nodes_allowed);
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 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024
	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--)

1025
#if defined(CONFIG_ARCH_HAS_GIGANTIC_PAGE) && \
1026 1027
	((defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || \
	defined(CONFIG_CMA))
1028
static void destroy_compound_gigantic_page(struct page *page,
1029
					unsigned int order)
1030 1031 1032 1033 1034
{
	int i;
	int nr_pages = 1 << order;
	struct page *p = page + 1;

1035
	atomic_set(compound_mapcount_ptr(page), 0);
1036
	for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
1037
		clear_compound_head(p);
1038 1039 1040 1041 1042 1043 1044
		set_page_refcounted(p);
	}

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

1045
static void free_gigantic_page(struct page *page, unsigned int order)
1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056
{
	free_contig_range(page_to_pfn(page), 1 << order);
}

static int __alloc_gigantic_page(unsigned long start_pfn,
				unsigned long nr_pages)
{
	unsigned long end_pfn = start_pfn + nr_pages;
	return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
}

1057 1058
static bool pfn_range_valid_gigantic(struct zone *z,
			unsigned long start_pfn, unsigned long nr_pages)
1059 1060 1061 1062 1063 1064 1065 1066 1067 1068
{
	unsigned long i, end_pfn = start_pfn + nr_pages;
	struct page *page;

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

		page = pfn_to_page(i);

1069 1070 1071
		if (page_zone(page) != z)
			return false;

1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091
		if (PageReserved(page))
			return false;

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

		if (PageHuge(page))
			return false;
	}

	return true;
}

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

1092
static struct page *alloc_gigantic_page(int nid, unsigned int order)
1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103
{
	unsigned long nr_pages = 1 << order;
	unsigned long ret, pfn, flags;
	struct zone *z;

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

		pfn = ALIGN(z->zone_start_pfn, nr_pages);
		while (zone_spans_last_pfn(z, pfn, nr_pages)) {
1104
			if (pfn_range_valid_gigantic(z, pfn, nr_pages)) {
1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127
				/*
				 * We release the zone lock here because
				 * alloc_contig_range() will also lock the zone
				 * at some point. If there's an allocation
				 * spinning on this lock, it may win the race
				 * and cause alloc_contig_range() to fail...
				 */
				spin_unlock_irqrestore(&z->lock, flags);
				ret = __alloc_gigantic_page(pfn, nr_pages);
				if (!ret)
					return pfn_to_page(pfn);
				spin_lock_irqsave(&z->lock, flags);
			}
			pfn += nr_pages;
		}

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

	return NULL;
}

static void prep_new_huge_page(struct hstate *h, struct page *page, int nid);
1128
static void prep_compound_gigantic_page(struct page *page, unsigned int order);
1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160

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

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

	return page;
}

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

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

	return 0;
}

static inline bool gigantic_page_supported(void) { return true; }
#else
static inline bool gigantic_page_supported(void) { return false; }
1161
static inline void free_gigantic_page(struct page *page, unsigned int order) { }
1162
static inline void destroy_compound_gigantic_page(struct page *page,
1163
						unsigned int order) { }
1164 1165 1166 1167
static inline int alloc_fresh_gigantic_page(struct hstate *h,
					nodemask_t *nodes_allowed) { return 0; }
#endif

1168
static void update_and_free_page(struct hstate *h, struct page *page)
A
Adam Litke 已提交
1169 1170
{
	int i;
1171

1172 1173
	if (hstate_is_gigantic(h) && !gigantic_page_supported())
		return;
1174

1175 1176 1177
	h->nr_huge_pages--;
	h->nr_huge_pages_node[page_to_nid(page)]--;
	for (i = 0; i < pages_per_huge_page(h); i++) {
1178 1179
		page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
				1 << PG_referenced | 1 << PG_dirty |
1180 1181
				1 << PG_active | 1 << PG_private |
				1 << PG_writeback);
A
Adam Litke 已提交
1182
	}
1183
	VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page);
1184
	set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
A
Adam Litke 已提交
1185
	set_page_refcounted(page);
1186 1187 1188 1189 1190 1191
	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
1192 1193
}

1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204
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;
}

1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229
/*
 * 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]);
}

1230
void free_huge_page(struct page *page)
1231
{
1232 1233 1234 1235
	/*
	 * Can't pass hstate in here because it is called from the
	 * compound page destructor.
	 */
1236
	struct hstate *h = page_hstate(page);
1237
	int nid = page_to_nid(page);
1238 1239
	struct hugepage_subpool *spool =
		(struct hugepage_subpool *)page_private(page);
1240
	bool restore_reserve;
1241

1242
	set_page_private(page, 0);
1243
	page->mapping = NULL;
1244 1245
	VM_BUG_ON_PAGE(page_count(page), page);
	VM_BUG_ON_PAGE(page_mapcount(page), page);
1246
	restore_reserve = PagePrivate(page);
1247
	ClearPagePrivate(page);
1248

1249 1250 1251 1252 1253 1254 1255 1256
	/*
	 * 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;

1257
	spin_lock(&hugetlb_lock);
1258
	clear_page_huge_active(page);
1259 1260
	hugetlb_cgroup_uncharge_page(hstate_index(h),
				     pages_per_huge_page(h), page);
1261 1262 1263
	if (restore_reserve)
		h->resv_huge_pages++;

1264
	if (h->surplus_huge_pages_node[nid]) {
1265 1266
		/* remove the page from active list */
		list_del(&page->lru);
1267 1268 1269
		update_and_free_page(h, page);
		h->surplus_huge_pages--;
		h->surplus_huge_pages_node[nid]--;
1270
	} else {
1271
		arch_clear_hugepage_flags(page);
1272
		enqueue_huge_page(h, page);
1273
	}
1274 1275 1276
	spin_unlock(&hugetlb_lock);
}

1277
static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
1278
{
1279
	INIT_LIST_HEAD(&page->lru);
1280
	set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
1281
	spin_lock(&hugetlb_lock);
1282
	set_hugetlb_cgroup(page, NULL);
1283 1284
	h->nr_huge_pages++;
	h->nr_huge_pages_node[nid]++;
1285 1286 1287 1288
	spin_unlock(&hugetlb_lock);
	put_page(page); /* free it into the hugepage allocator */
}

1289
static void prep_compound_gigantic_page(struct page *page, unsigned int order)
1290 1291 1292 1293 1294 1295 1296
{
	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);
1297
	__ClearPageReserved(page);
1298
	__SetPageHead(page);
1299
	for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312
		/*
		 * 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);
1313
		set_page_count(p, 0);
1314
		set_compound_head(p, page);
1315
	}
1316
	atomic_set(compound_mapcount_ptr(page), -1);
1317 1318
}

A
Andrew Morton 已提交
1319 1320 1321 1322 1323
/*
 * PageHuge() only returns true for hugetlbfs pages, but not for normal or
 * transparent huge pages.  See the PageTransHuge() documentation for more
 * details.
 */
1324 1325 1326 1327 1328 1329
int PageHuge(struct page *page)
{
	if (!PageCompound(page))
		return 0;

	page = compound_head(page);
1330
	return page[1].compound_dtor == HUGETLB_PAGE_DTOR;
1331
}
1332 1333
EXPORT_SYMBOL_GPL(PageHuge);

1334 1335 1336 1337 1338 1339 1340 1341 1342
/*
 * 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;

1343
	return get_compound_page_dtor(page_head) == free_huge_page;
1344 1345
}

1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362
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;
}

1363
static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
L
Linus Torvalds 已提交
1364 1365
{
	struct page *page;
1366

1367
	page = __alloc_pages_node(nid,
1368
		htlb_alloc_mask(h)|__GFP_COMP|__GFP_THISNODE|
1369
						__GFP_REPEAT|__GFP_NOWARN,
1370
		huge_page_order(h));
L
Linus Torvalds 已提交
1371
	if (page) {
1372
		prep_new_huge_page(h, page, nid);
L
Linus Torvalds 已提交
1373
	}
1374 1375 1376 1377

	return page;
}

1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399
static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
{
	struct page *page;
	int nr_nodes, node;
	int ret = 0;

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

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

	return ret;
}

1400 1401 1402 1403 1404 1405
/*
 * 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.
 */
1406 1407
static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
							 bool acct_surplus)
1408
{
1409
	int nr_nodes, node;
1410 1411
	int ret = 0;

1412
	for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
1413 1414 1415 1416
		/*
		 * If we're returning unused surplus pages, only examine
		 * nodes with surplus pages.
		 */
1417 1418
		if ((!acct_surplus || h->surplus_huge_pages_node[node]) &&
		    !list_empty(&h->hugepage_freelists[node])) {
1419
			struct page *page =
1420
				list_entry(h->hugepage_freelists[node].next,
1421 1422 1423
					  struct page, lru);
			list_del(&page->lru);
			h->free_huge_pages--;
1424
			h->free_huge_pages_node[node]--;
1425 1426
			if (acct_surplus) {
				h->surplus_huge_pages--;
1427
				h->surplus_huge_pages_node[node]--;
1428
			}
1429 1430
			update_and_free_page(h, page);
			ret = 1;
1431
			break;
1432
		}
1433
	}
1434 1435 1436 1437

	return ret;
}

1438 1439
/*
 * Dissolve a given free hugepage into free buddy pages. This function does
1440 1441 1442
 * nothing for in-use (including surplus) hugepages. Returns -EBUSY if the
 * number of free hugepages would be reduced below the number of reserved
 * hugepages.
1443
 */
1444
static int dissolve_free_huge_page(struct page *page)
1445
{
1446 1447
	int rc = 0;

1448 1449
	spin_lock(&hugetlb_lock);
	if (PageHuge(page) && !page_count(page)) {
1450 1451 1452
		struct page *head = compound_head(page);
		struct hstate *h = page_hstate(head);
		int nid = page_to_nid(head);
1453 1454 1455 1456
		if (h->free_huge_pages - h->resv_huge_pages == 0) {
			rc = -EBUSY;
			goto out;
		}
1457
		list_del(&head->lru);
1458 1459
		h->free_huge_pages--;
		h->free_huge_pages_node[nid]--;
1460
		h->max_huge_pages--;
1461
		update_and_free_page(h, head);
1462
	}
1463
out:
1464
	spin_unlock(&hugetlb_lock);
1465
	return rc;
1466 1467 1468 1469 1470
}

/*
 * Dissolve free hugepages in a given pfn range. Used by memory hotplug to
 * make specified memory blocks removable from the system.
1471 1472
 * Note that this will dissolve a free gigantic hugepage completely, if any
 * part of it lies within the given range.
1473 1474
 * Also note that if dissolve_free_huge_page() returns with an error, all
 * free hugepages that were dissolved before that error are lost.
1475
 */
1476
int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
1477 1478
{
	unsigned long pfn;
1479
	struct page *page;
1480
	int rc = 0;
1481

1482
	if (!hugepages_supported())
1483
		return rc;
1484

1485 1486 1487 1488 1489 1490 1491 1492
	for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order) {
		page = pfn_to_page(pfn);
		if (PageHuge(page) && !page_count(page)) {
			rc = dissolve_free_huge_page(page);
			if (rc)
				break;
		}
	}
1493 1494

	return rc;
1495 1496
}

1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514
/*
 * There are 3 ways this can get called:
 * 1. With vma+addr: we use the VMA's memory policy
 * 2. With !vma, but nid=NUMA_NO_NODE:  We try to allocate a huge
 *    page from any node, and let the buddy allocator itself figure
 *    it out.
 * 3. With !vma, but nid!=NUMA_NO_NODE.  We allocate a huge page
 *    strictly from 'nid'
 */
static struct page *__hugetlb_alloc_buddy_huge_page(struct hstate *h,
		struct vm_area_struct *vma, unsigned long addr, int nid)
{
	int order = huge_page_order(h);
	gfp_t gfp = htlb_alloc_mask(h)|__GFP_COMP|__GFP_REPEAT|__GFP_NOWARN;
	unsigned int cpuset_mems_cookie;

	/*
	 * We need a VMA to get a memory policy.  If we do not
D
Dave Hansen 已提交
1515 1516 1517 1518 1519 1520
	 * have one, we use the 'nid' argument.
	 *
	 * The mempolicy stuff below has some non-inlined bits
	 * and calls ->vm_ops.  That makes it hard to optimize at
	 * compile-time, even when NUMA is off and it does
	 * nothing.  This helps the compiler optimize it out.
1521
	 */
D
Dave Hansen 已提交
1522
	if (!IS_ENABLED(CONFIG_NUMA) || !vma) {
1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538
		/*
		 * If a specific node is requested, make sure to
		 * get memory from there, but only when a node
		 * is explicitly specified.
		 */
		if (nid != NUMA_NO_NODE)
			gfp |= __GFP_THISNODE;
		/*
		 * Make sure to call something that can handle
		 * nid=NUMA_NO_NODE
		 */
		return alloc_pages_node(nid, gfp, order);
	}

	/*
	 * OK, so we have a VMA.  Fetch the mempolicy and try to
D
Dave Hansen 已提交
1539 1540
	 * allocate a huge page with it.  We will only reach this
	 * when CONFIG_NUMA=y.
1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572
	 */
	do {
		struct page *page;
		struct mempolicy *mpol;
		struct zonelist *zl;
		nodemask_t *nodemask;

		cpuset_mems_cookie = read_mems_allowed_begin();
		zl = huge_zonelist(vma, addr, gfp, &mpol, &nodemask);
		mpol_cond_put(mpol);
		page = __alloc_pages_nodemask(gfp, order, zl, nodemask);
		if (page)
			return page;
	} while (read_mems_allowed_retry(cpuset_mems_cookie));

	return NULL;
}

/*
 * There are two ways to allocate a huge page:
 * 1. When you have a VMA and an address (like a fault)
 * 2. When you have no VMA (like when setting /proc/.../nr_hugepages)
 *
 * 'vma' and 'addr' are only for (1).  'nid' is always NUMA_NO_NODE in
 * this case which signifies that the allocation should be done with
 * respect for the VMA's memory policy.
 *
 * For (2), we ignore 'vma' and 'addr' and use 'nid' exclusively. This
 * implies that memory policies will not be taken in to account.
 */
static struct page *__alloc_buddy_huge_page(struct hstate *h,
		struct vm_area_struct *vma, unsigned long addr, int nid)
1573 1574
{
	struct page *page;
1575
	unsigned int r_nid;
1576

1577
	if (hstate_is_gigantic(h))
1578 1579
		return NULL;

1580 1581 1582 1583 1584 1585
	/*
	 * Make sure that anyone specifying 'nid' is not also specifying a VMA.
	 * This makes sure the caller is picking _one_ of the modes with which
	 * we can call this function, not both.
	 */
	if (vma || (addr != -1)) {
D
Dave Hansen 已提交
1586 1587
		VM_WARN_ON_ONCE(addr == -1);
		VM_WARN_ON_ONCE(nid != NUMA_NO_NODE);
1588
	}
1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612
	/*
	 * Assume we will successfully allocate the surplus page to
	 * prevent racing processes from causing the surplus to exceed
	 * overcommit
	 *
	 * This however introduces a different race, where a process B
	 * tries to grow the static hugepage pool while alloc_pages() is
	 * called by process A. B will only examine the per-node
	 * counters in determining if surplus huge pages can be
	 * converted to normal huge pages in adjust_pool_surplus(). A
	 * won't be able to increment the per-node counter, until the
	 * lock is dropped by B, but B doesn't drop hugetlb_lock until
	 * no more huge pages can be converted from surplus to normal
	 * state (and doesn't try to convert again). Thus, we have a
	 * case where a surplus huge page exists, the pool is grown, and
	 * the surplus huge page still exists after, even though it
	 * should just have been converted to a normal huge page. This
	 * does not leak memory, though, as the hugepage will be freed
	 * once it is out of use. It also does not allow the counters to
	 * go out of whack in adjust_pool_surplus() as we don't modify
	 * the node values until we've gotten the hugepage and only the
	 * per-node value is checked there.
	 */
	spin_lock(&hugetlb_lock);
1613
	if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
1614 1615 1616
		spin_unlock(&hugetlb_lock);
		return NULL;
	} else {
1617 1618
		h->nr_huge_pages++;
		h->surplus_huge_pages++;
1619 1620 1621
	}
	spin_unlock(&hugetlb_lock);

1622
	page = __hugetlb_alloc_buddy_huge_page(h, vma, addr, nid);
1623 1624

	spin_lock(&hugetlb_lock);
1625
	if (page) {
1626
		INIT_LIST_HEAD(&page->lru);
1627
		r_nid = page_to_nid(page);
1628
		set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
1629
		set_hugetlb_cgroup(page, NULL);
1630 1631 1632
		/*
		 * We incremented the global counters already
		 */
1633 1634
		h->nr_huge_pages_node[r_nid]++;
		h->surplus_huge_pages_node[r_nid]++;
1635
		__count_vm_event(HTLB_BUDDY_PGALLOC);
1636
	} else {
1637 1638
		h->nr_huge_pages--;
		h->surplus_huge_pages--;
1639
		__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
1640
	}
1641
	spin_unlock(&hugetlb_lock);
1642 1643 1644 1645

	return page;
}

1646 1647 1648 1649 1650
/*
 * Allocate a huge page from 'nid'.  Note, 'nid' may be
 * NUMA_NO_NODE, which means that it may be allocated
 * anywhere.
 */
D
Dave Hansen 已提交
1651
static
1652 1653 1654 1655 1656 1657 1658 1659 1660 1661
struct page *__alloc_buddy_huge_page_no_mpol(struct hstate *h, int nid)
{
	unsigned long addr = -1;

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

/*
 * Use the VMA's mpolicy to allocate a huge page from the buddy.
 */
D
Dave Hansen 已提交
1662
static
1663 1664 1665 1666 1667 1668
struct page *__alloc_buddy_huge_page_with_mpol(struct hstate *h,
		struct vm_area_struct *vma, unsigned long addr)
{
	return __alloc_buddy_huge_page(h, vma, addr, NUMA_NO_NODE);
}

1669 1670 1671 1672 1673 1674 1675
/*
 * This allocation function is useful in the context where vma is irrelevant.
 * E.g. soft-offlining uses this function because it only cares physical
 * address of error page.
 */
struct page *alloc_huge_page_node(struct hstate *h, int nid)
{
1676
	struct page *page = NULL;
1677 1678

	spin_lock(&hugetlb_lock);
1679 1680
	if (h->free_huge_pages - h->resv_huge_pages > 0)
		page = dequeue_huge_page_node(h, nid);
1681 1682
	spin_unlock(&hugetlb_lock);

1683
	if (!page)
1684
		page = __alloc_buddy_huge_page_no_mpol(h, nid);
1685 1686 1687 1688

	return page;
}

1689
/*
L
Lucas De Marchi 已提交
1690
 * Increase the hugetlb pool such that it can accommodate a reservation
1691 1692
 * of size 'delta'.
 */
1693
static int gather_surplus_pages(struct hstate *h, int delta)
1694 1695 1696 1697 1698
{
	struct list_head surplus_list;
	struct page *page, *tmp;
	int ret, i;
	int needed, allocated;
1699
	bool alloc_ok = true;
1700

1701
	needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
1702
	if (needed <= 0) {
1703
		h->resv_huge_pages += delta;
1704
		return 0;
1705
	}
1706 1707 1708 1709 1710 1711 1712 1713

	allocated = 0;
	INIT_LIST_HEAD(&surplus_list);

	ret = -ENOMEM;
retry:
	spin_unlock(&hugetlb_lock);
	for (i = 0; i < needed; i++) {
1714
		page = __alloc_buddy_huge_page_no_mpol(h, NUMA_NO_NODE);
1715 1716 1717 1718
		if (!page) {
			alloc_ok = false;
			break;
		}
1719 1720
		list_add(&page->lru, &surplus_list);
	}
1721
	allocated += i;
1722 1723 1724 1725 1726 1727

	/*
	 * 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);
1728 1729
	needed = (h->resv_huge_pages + delta) -
			(h->free_huge_pages + allocated);
1730 1731 1732 1733 1734 1735 1736 1737 1738 1739
	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;
	}
1740 1741
	/*
	 * The surplus_list now contains _at_least_ the number of extra pages
L
Lucas De Marchi 已提交
1742
	 * needed to accommodate the reservation.  Add the appropriate number
1743
	 * of pages to the hugetlb pool and free the extras back to the buddy
1744 1745 1746
	 * 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.
1747 1748
	 */
	needed += allocated;
1749
	h->resv_huge_pages += delta;
1750
	ret = 0;
1751

1752
	/* Free the needed pages to the hugetlb pool */
1753
	list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
1754 1755
		if ((--needed) < 0)
			break;
1756 1757 1758 1759 1760
		/*
		 * This page is now managed by the hugetlb allocator and has
		 * no users -- drop the buddy allocator's reference.
		 */
		put_page_testzero(page);
1761
		VM_BUG_ON_PAGE(page_count(page), page);
1762
		enqueue_huge_page(h, page);
1763
	}
1764
free:
1765
	spin_unlock(&hugetlb_lock);
1766 1767

	/* Free unnecessary surplus pages to the buddy allocator */
1768 1769
	list_for_each_entry_safe(page, tmp, &surplus_list, lru)
		put_page(page);
1770
	spin_lock(&hugetlb_lock);
1771 1772 1773 1774 1775

	return ret;
}

/*
1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787
 * 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.
1788
 */
1789 1790
static void return_unused_surplus_pages(struct hstate *h,
					unsigned long unused_resv_pages)
1791 1792 1793
{
	unsigned long nr_pages;

1794
	/* Cannot return gigantic pages currently */
1795
	if (hstate_is_gigantic(h))
1796
		goto out;
1797

1798 1799 1800 1801
	/*
	 * Part (or even all) of the reservation could have been backed
	 * by pre-allocated pages. Only free surplus pages.
	 */
1802
	nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
1803

1804 1805
	/*
	 * We want to release as many surplus pages as possible, spread
1806 1807 1808 1809 1810
	 * 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.
1811 1812 1813 1814
	 *
	 * 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.
1815 1816
	 */
	while (nr_pages--) {
1817 1818
		h->resv_huge_pages--;
		unused_resv_pages--;
1819
		if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1))
1820
			goto out;
1821
		cond_resched_lock(&hugetlb_lock);
1822
	}
1823 1824 1825 1826

out:
	/* Fully uncommit the reservation */
	h->resv_huge_pages -= unused_resv_pages;
1827 1828
}

1829

1830
/*
1831
 * vma_needs_reservation, vma_commit_reservation and vma_end_reservation
1832
 * are used by the huge page allocation routines to manage reservations.
1833 1834 1835 1836 1837 1838
 *
 * 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
1839 1840 1841
 * 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.
1842 1843 1844 1845 1846 1847
 *
 * 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.
1848 1849 1850 1851 1852
 *
 * 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.
1853
 */
1854 1855 1856
enum vma_resv_mode {
	VMA_NEEDS_RESV,
	VMA_COMMIT_RESV,
1857
	VMA_END_RESV,
1858
	VMA_ADD_RESV,
1859
};
1860 1861
static long __vma_reservation_common(struct hstate *h,
				struct vm_area_struct *vma, unsigned long addr,
1862
				enum vma_resv_mode mode)
1863
{
1864 1865
	struct resv_map *resv;
	pgoff_t idx;
1866
	long ret;
1867

1868 1869
	resv = vma_resv_map(vma);
	if (!resv)
1870
		return 1;
1871

1872
	idx = vma_hugecache_offset(h, vma, addr);
1873 1874
	switch (mode) {
	case VMA_NEEDS_RESV:
1875
		ret = region_chg(resv, idx, idx + 1);
1876 1877 1878 1879
		break;
	case VMA_COMMIT_RESV:
		ret = region_add(resv, idx, idx + 1);
		break;
1880
	case VMA_END_RESV:
1881 1882 1883
		region_abort(resv, idx, idx + 1);
		ret = 0;
		break;
1884 1885 1886 1887 1888 1889 1890 1891
	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;
1892 1893 1894
	default:
		BUG();
	}
1895

1896
	if (vma->vm_flags & VM_MAYSHARE)
1897
		return ret;
1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916
	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;
	}
1917
	else
1918
		return ret < 0 ? ret : 0;
1919
}
1920 1921

static long vma_needs_reservation(struct hstate *h,
1922
			struct vm_area_struct *vma, unsigned long addr)
1923
{
1924
	return __vma_reservation_common(h, vma, addr, VMA_NEEDS_RESV);
1925
}
1926

1927 1928 1929
static long vma_commit_reservation(struct hstate *h,
			struct vm_area_struct *vma, unsigned long addr)
{
1930 1931 1932
	return __vma_reservation_common(h, vma, addr, VMA_COMMIT_RESV);
}

1933
static void vma_end_reservation(struct hstate *h,
1934 1935
			struct vm_area_struct *vma, unsigned long addr)
{
1936
	(void)__vma_reservation_common(h, vma, addr, VMA_END_RESV);
1937 1938
}

1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988
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);
	}
}

1989
struct page *alloc_huge_page(struct vm_area_struct *vma,
1990
				    unsigned long addr, int avoid_reserve)
L
Linus Torvalds 已提交
1991
{
1992
	struct hugepage_subpool *spool = subpool_vma(vma);
1993
	struct hstate *h = hstate_vma(vma);
1994
	struct page *page;
1995 1996
	long map_chg, map_commit;
	long gbl_chg;
1997 1998
	int ret, idx;
	struct hugetlb_cgroup *h_cg;
1999

2000
	idx = hstate_index(h);
2001
	/*
2002 2003 2004
	 * 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).
2005
	 */
2006 2007
	map_chg = gbl_chg = vma_needs_reservation(h, vma, addr);
	if (map_chg < 0)
2008
		return ERR_PTR(-ENOMEM);
2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

	/*
	 * 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) {
2020
			vma_end_reservation(h, vma, addr);
2021
			return ERR_PTR(-ENOSPC);
2022
		}
L
Linus Torvalds 已提交
2023

2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035
		/*
		 * 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;
	}

2036
	ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
2037 2038 2039
	if (ret)
		goto out_subpool_put;

L
Linus Torvalds 已提交
2040
	spin_lock(&hugetlb_lock);
2041 2042 2043 2044 2045 2046
	/*
	 * 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);
2047
	if (!page) {
2048
		spin_unlock(&hugetlb_lock);
2049
		page = __alloc_buddy_huge_page_with_mpol(h, vma, addr);
2050 2051
		if (!page)
			goto out_uncharge_cgroup;
2052 2053 2054 2055
		if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
			SetPagePrivate(page);
			h->resv_huge_pages--;
		}
2056 2057
		spin_lock(&hugetlb_lock);
		list_move(&page->lru, &h->hugepage_activelist);
2058
		/* Fall through */
K
Ken Chen 已提交
2059
	}
2060 2061
	hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
	spin_unlock(&hugetlb_lock);
2062

2063
	set_page_private(page, (unsigned long)spool);
2064

2065 2066
	map_commit = vma_commit_reservation(h, vma, addr);
	if (unlikely(map_chg > map_commit)) {
2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080
		/*
		 * 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);
	}
2081
	return page;
2082 2083 2084 2085

out_uncharge_cgroup:
	hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
out_subpool_put:
2086
	if (map_chg || avoid_reserve)
2087
		hugepage_subpool_put_pages(spool, 1);
2088
	vma_end_reservation(h, vma, addr);
2089
	return ERR_PTR(-ENOSPC);
2090 2091
}

2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105
/*
 * alloc_huge_page()'s wrapper which simply returns the page if allocation
 * succeeds, otherwise NULL. This function is called from new_vma_page(),
 * where no ERR_VALUE is expected to be returned.
 */
struct page *alloc_huge_page_noerr(struct vm_area_struct *vma,
				unsigned long addr, int avoid_reserve)
{
	struct page *page = alloc_huge_page(vma, addr, avoid_reserve);
	if (IS_ERR(page))
		page = NULL;
	return page;
}

2106
int __weak alloc_bootmem_huge_page(struct hstate *h)
2107 2108
{
	struct huge_bootmem_page *m;
2109
	int nr_nodes, node;
2110

2111
	for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) {
2112 2113
		void *addr;

2114 2115 2116
		addr = memblock_virt_alloc_try_nid_nopanic(
				huge_page_size(h), huge_page_size(h),
				0, BOOTMEM_ALLOC_ACCESSIBLE, node);
2117 2118 2119 2120 2121 2122 2123
		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;
2124
			goto found;
2125 2126 2127 2128 2129
		}
	}
	return 0;

found:
2130
	BUG_ON(!IS_ALIGNED(virt_to_phys(m), huge_page_size(h)));
2131 2132 2133 2134 2135 2136
	/* Put them into a private list first because mem_map is not up yet */
	list_add(&m->list, &huge_boot_pages);
	m->hstate = h;
	return 1;
}

2137 2138
static void __init prep_compound_huge_page(struct page *page,
		unsigned int order)
2139 2140 2141 2142 2143 2144 2145
{
	if (unlikely(order > (MAX_ORDER - 1)))
		prep_compound_gigantic_page(page, order);
	else
		prep_compound_page(page, order);
}

2146 2147 2148 2149 2150 2151 2152
/* Put bootmem huge pages into the standard lists after mem_map is up */
static void __init gather_bootmem_prealloc(void)
{
	struct huge_bootmem_page *m;

	list_for_each_entry(m, &huge_boot_pages, list) {
		struct hstate *h = m->hstate;
2153 2154 2155 2156
		struct page *page;

#ifdef CONFIG_HIGHMEM
		page = pfn_to_page(m->phys >> PAGE_SHIFT);
2157 2158
		memblock_free_late(__pa(m),
				   sizeof(struct huge_bootmem_page));
2159 2160 2161
#else
		page = virt_to_page(m);
#endif
2162
		WARN_ON(page_count(page) != 1);
2163
		prep_compound_huge_page(page, h->order);
2164
		WARN_ON(PageReserved(page));
2165
		prep_new_huge_page(h, page, page_to_nid(page));
2166 2167 2168 2169 2170 2171
		/*
		 * 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.
		 */
2172
		if (hstate_is_gigantic(h))
2173
			adjust_managed_page_count(page, 1 << h->order);
2174 2175 2176
	}
}

2177
static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
L
Linus Torvalds 已提交
2178 2179
{
	unsigned long i;
2180

2181
	for (i = 0; i < h->max_huge_pages; ++i) {
2182
		if (hstate_is_gigantic(h)) {
2183 2184
			if (!alloc_bootmem_huge_page(h))
				break;
2185
		} else if (!alloc_fresh_huge_page(h,
2186
					 &node_states[N_MEMORY]))
L
Linus Torvalds 已提交
2187 2188
			break;
	}
2189
	h->max_huge_pages = i;
2190 2191 2192 2193 2194 2195 2196
}

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

	for_each_hstate(h) {
2197 2198 2199
		if (minimum_order > huge_page_order(h))
			minimum_order = huge_page_order(h);

2200
		/* oversize hugepages were init'ed in early boot */
2201
		if (!hstate_is_gigantic(h))
2202
			hugetlb_hstate_alloc_pages(h);
2203
	}
2204
	VM_BUG_ON(minimum_order == UINT_MAX);
2205 2206
}

A
Andi Kleen 已提交
2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217
static char * __init memfmt(char *buf, unsigned long n)
{
	if (n >= (1UL << 30))
		sprintf(buf, "%lu GB", n >> 30);
	else if (n >= (1UL << 20))
		sprintf(buf, "%lu MB", n >> 20);
	else
		sprintf(buf, "%lu KB", n >> 10);
	return buf;
}

2218 2219 2220 2221 2222
static void __init report_hugepages(void)
{
	struct hstate *h;

	for_each_hstate(h) {
A
Andi Kleen 已提交
2223
		char buf[32];
2224
		pr_info("HugeTLB registered %s page size, pre-allocated %ld pages\n",
A
Andi Kleen 已提交
2225 2226
			memfmt(buf, huge_page_size(h)),
			h->free_huge_pages);
2227 2228 2229
	}
}

L
Linus Torvalds 已提交
2230
#ifdef CONFIG_HIGHMEM
2231 2232
static void try_to_free_low(struct hstate *h, unsigned long count,
						nodemask_t *nodes_allowed)
L
Linus Torvalds 已提交
2233
{
2234 2235
	int i;

2236
	if (hstate_is_gigantic(h))
2237 2238
		return;

2239
	for_each_node_mask(i, *nodes_allowed) {
L
Linus Torvalds 已提交
2240
		struct page *page, *next;
2241 2242 2243
		struct list_head *freel = &h->hugepage_freelists[i];
		list_for_each_entry_safe(page, next, freel, lru) {
			if (count >= h->nr_huge_pages)
2244
				return;
L
Linus Torvalds 已提交
2245 2246 2247
			if (PageHighMem(page))
				continue;
			list_del(&page->lru);
2248
			update_and_free_page(h, page);
2249 2250
			h->free_huge_pages--;
			h->free_huge_pages_node[page_to_nid(page)]--;
L
Linus Torvalds 已提交
2251 2252 2253 2254
		}
	}
}
#else
2255 2256
static inline void try_to_free_low(struct hstate *h, unsigned long count,
						nodemask_t *nodes_allowed)
L
Linus Torvalds 已提交
2257 2258 2259 2260
{
}
#endif

2261 2262 2263 2264 2265
/*
 * 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.
 */
2266 2267
static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
				int delta)
2268
{
2269
	int nr_nodes, node;
2270 2271 2272

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

2273 2274 2275 2276
	if (delta < 0) {
		for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
			if (h->surplus_huge_pages_node[node])
				goto found;
2277
		}
2278 2279 2280 2281 2282
	} 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;
2283
		}
2284 2285
	}
	return 0;
2286

2287 2288 2289 2290
found:
	h->surplus_huge_pages += delta;
	h->surplus_huge_pages_node[node] += delta;
	return 1;
2291 2292
}

2293
#define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
2294 2295
static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
						nodemask_t *nodes_allowed)
L
Linus Torvalds 已提交
2296
{
2297
	unsigned long min_count, ret;
L
Linus Torvalds 已提交
2298

2299
	if (hstate_is_gigantic(h) && !gigantic_page_supported())
2300 2301
		return h->max_huge_pages;

2302 2303 2304 2305
	/*
	 * Increase the pool size
	 * First take pages out of surplus state.  Then make up the
	 * remaining difference by allocating fresh huge pages.
2306
	 *
N
Naoya Horiguchi 已提交
2307
	 * We might race with __alloc_buddy_huge_page() here and be unable
2308 2309 2310 2311
	 * 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.
2312
	 */
L
Linus Torvalds 已提交
2313
	spin_lock(&hugetlb_lock);
2314
	while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
2315
		if (!adjust_pool_surplus(h, nodes_allowed, -1))
2316 2317 2318
			break;
	}

2319
	while (count > persistent_huge_pages(h)) {
2320 2321 2322 2323 2324 2325
		/*
		 * 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);
2326 2327 2328 2329

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

2330 2331 2332 2333
		if (hstate_is_gigantic(h))
			ret = alloc_fresh_gigantic_page(h, nodes_allowed);
		else
			ret = alloc_fresh_huge_page(h, nodes_allowed);
2334 2335 2336 2337
		spin_lock(&hugetlb_lock);
		if (!ret)
			goto out;

2338 2339 2340
		/* Bail for signals. Probably ctrl-c from user */
		if (signal_pending(current))
			goto out;
2341 2342 2343 2344 2345 2346 2347 2348
	}

	/*
	 * 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.
2349 2350 2351 2352
	 *
	 * By placing pages into the surplus state independent of the
	 * overcommit value, we are allowing the surplus pool size to
	 * exceed overcommit. There are few sane options here. Since
N
Naoya Horiguchi 已提交
2353
	 * __alloc_buddy_huge_page() is checking the global counter,
2354 2355 2356
	 * 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.
2357
	 */
2358
	min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
2359
	min_count = max(count, min_count);
2360
	try_to_free_low(h, min_count, nodes_allowed);
2361
	while (min_count < persistent_huge_pages(h)) {
2362
		if (!free_pool_huge_page(h, nodes_allowed, 0))
L
Linus Torvalds 已提交
2363
			break;
2364
		cond_resched_lock(&hugetlb_lock);
L
Linus Torvalds 已提交
2365
	}
2366
	while (count < persistent_huge_pages(h)) {
2367
		if (!adjust_pool_surplus(h, nodes_allowed, 1))
2368 2369 2370
			break;
	}
out:
2371
	ret = persistent_huge_pages(h);
L
Linus Torvalds 已提交
2372
	spin_unlock(&hugetlb_lock);
2373
	return ret;
L
Linus Torvalds 已提交
2374 2375
}

2376 2377 2378 2379 2380 2381 2382 2383 2384 2385
#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];

2386 2387 2388
static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);

static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
2389 2390
{
	int i;
2391

2392
	for (i = 0; i < HUGE_MAX_HSTATE; i++)
2393 2394 2395
		if (hstate_kobjs[i] == kobj) {
			if (nidp)
				*nidp = NUMA_NO_NODE;
2396
			return &hstates[i];
2397 2398 2399
		}

	return kobj_to_node_hstate(kobj, nidp);
2400 2401
}

2402
static ssize_t nr_hugepages_show_common(struct kobject *kobj,
2403 2404
					struct kobj_attribute *attr, char *buf)
{
2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415
	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);
2416
}
2417

2418 2419 2420
static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
					   struct hstate *h, int nid,
					   unsigned long count, size_t len)
2421 2422
{
	int err;
2423
	NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
2424

2425
	if (hstate_is_gigantic(h) && !gigantic_page_supported()) {
2426 2427 2428 2429
		err = -EINVAL;
		goto out;
	}

2430 2431 2432 2433 2434 2435 2436
	if (nid == NUMA_NO_NODE) {
		/*
		 * global hstate attribute
		 */
		if (!(obey_mempolicy &&
				init_nodemask_of_mempolicy(nodes_allowed))) {
			NODEMASK_FREE(nodes_allowed);
2437
			nodes_allowed = &node_states[N_MEMORY];
2438 2439 2440 2441 2442 2443 2444 2445 2446
		}
	} else if (nodes_allowed) {
		/*
		 * per node hstate attribute: adjust count to global,
		 * but restrict alloc/free to the specified node.
		 */
		count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
		init_nodemask_of_node(nodes_allowed, nid);
	} else
2447
		nodes_allowed = &node_states[N_MEMORY];
2448

2449
	h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
2450

2451
	if (nodes_allowed != &node_states[N_MEMORY])
2452 2453 2454
		NODEMASK_FREE(nodes_allowed);

	return len;
2455 2456 2457
out:
	NODEMASK_FREE(nodes_allowed);
	return err;
2458 2459
}

2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476
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);
}

2477 2478 2479 2480 2481 2482 2483 2484 2485
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)
{
2486
	return nr_hugepages_store_common(false, kobj, buf, len);
2487 2488 2489
}
HSTATE_ATTR(nr_hugepages);

2490 2491 2492 2493 2494 2495 2496 2497 2498 2499 2500 2501 2502 2503 2504
#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)
{
2505
	return nr_hugepages_store_common(true, kobj, buf, len);
2506 2507 2508 2509 2510
}
HSTATE_ATTR(nr_hugepages_mempolicy);
#endif


2511 2512 2513
static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
					struct kobj_attribute *attr, char *buf)
{
2514
	struct hstate *h = kobj_to_hstate(kobj, NULL);
2515 2516
	return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
}
2517

2518 2519 2520 2521 2522
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;
2523
	struct hstate *h = kobj_to_hstate(kobj, NULL);
2524

2525
	if (hstate_is_gigantic(h))
2526 2527
		return -EINVAL;

2528
	err = kstrtoul(buf, 10, &input);
2529
	if (err)
2530
		return err;
2531 2532 2533 2534 2535 2536 2537 2538 2539 2540 2541 2542

	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)
{
2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553
	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);
2554 2555 2556 2557 2558 2559
}
HSTATE_ATTR_RO(free_hugepages);

static ssize_t resv_hugepages_show(struct kobject *kobj,
					struct kobj_attribute *attr, char *buf)
{
2560
	struct hstate *h = kobj_to_hstate(kobj, NULL);
2561 2562 2563 2564 2565 2566 2567
	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)
{
2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578
	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);
2579 2580 2581 2582 2583 2584 2585 2586 2587
}
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,
2588 2589 2590
#ifdef CONFIG_NUMA
	&nr_hugepages_mempolicy_attr.attr,
#endif
2591 2592 2593 2594 2595 2596 2597
	NULL,
};

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

J
Jeff Mahoney 已提交
2598 2599 2600
static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
				    struct kobject **hstate_kobjs,
				    struct attribute_group *hstate_attr_group)
2601 2602
{
	int retval;
2603
	int hi = hstate_index(h);
2604

2605 2606
	hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
	if (!hstate_kobjs[hi])
2607 2608
		return -ENOMEM;

2609
	retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
2610
	if (retval)
2611
		kobject_put(hstate_kobjs[hi]);
2612 2613 2614 2615 2616 2617 2618 2619 2620 2621 2622 2623 2624 2625

	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) {
2626 2627
		err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
					 hstate_kobjs, &hstate_attr_group);
2628
		if (err)
2629
			pr_err("Hugetlb: Unable to add hstate %s", h->name);
2630 2631 2632
	}
}

2633 2634 2635 2636
#ifdef CONFIG_NUMA

/*
 * node_hstate/s - associate per node hstate attributes, via their kobjects,
2637 2638 2639
 * 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
2640 2641 2642 2643 2644 2645
 * the base kernel, on the hugetlb module.
 */
struct node_hstate {
	struct kobject		*hugepages_kobj;
	struct kobject		*hstate_kobjs[HUGE_MAX_HSTATE];
};
2646
static struct node_hstate node_hstates[MAX_NUMNODES];
2647 2648

/*
2649
 * A subset of global hstate attributes for node devices
2650 2651 2652 2653 2654 2655 2656 2657 2658 2659 2660 2661 2662
 */
static struct attribute *per_node_hstate_attrs[] = {
	&nr_hugepages_attr.attr,
	&free_hugepages_attr.attr,
	&surplus_hugepages_attr.attr,
	NULL,
};

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

/*
2663
 * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
2664 2665 2666 2667 2668 2669 2670 2671 2672 2673 2674 2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685
 * 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;
}

/*
2686
 * Unregister hstate attributes from a single node device.
2687 2688
 * No-op if no hstate attributes attached.
 */
2689
static void hugetlb_unregister_node(struct node *node)
2690 2691
{
	struct hstate *h;
2692
	struct node_hstate *nhs = &node_hstates[node->dev.id];
2693 2694

	if (!nhs->hugepages_kobj)
2695
		return;		/* no hstate attributes */
2696

2697 2698 2699 2700 2701
	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;
2702
		}
2703
	}
2704 2705 2706 2707 2708 2709 2710

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


/*
2711
 * Register hstate attributes for a single node device.
2712 2713
 * No-op if attributes already registered.
 */
2714
static void hugetlb_register_node(struct node *node)
2715 2716
{
	struct hstate *h;
2717
	struct node_hstate *nhs = &node_hstates[node->dev.id];
2718 2719 2720 2721 2722 2723
	int err;

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

	nhs->hugepages_kobj = kobject_create_and_add("hugepages",
2724
							&node->dev.kobj);
2725 2726 2727 2728 2729 2730 2731 2732
	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) {
2733 2734
			pr_err("Hugetlb: Unable to add hstate %s for node %d\n",
				h->name, node->dev.id);
2735 2736 2737 2738 2739 2740 2741
			hugetlb_unregister_node(node);
			break;
		}
	}
}

/*
2742
 * hugetlb init time:  register hstate attributes for all registered node
2743 2744
 * devices of nodes that have memory.  All on-line nodes should have
 * registered their associated device by this time.
2745
 */
2746
static void __init hugetlb_register_all_nodes(void)
2747 2748 2749
{
	int nid;

2750
	for_each_node_state(nid, N_MEMORY) {
2751
		struct node *node = node_devices[nid];
2752
		if (node->dev.id == nid)
2753 2754 2755 2756
			hugetlb_register_node(node);
	}

	/*
2757
	 * Let the node device driver know we're here so it can
2758 2759 2760 2761 2762 2763 2764 2765 2766 2767 2768 2769 2770 2771 2772 2773 2774 2775 2776
	 * [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

2777 2778
static int __init hugetlb_init(void)
{
2779 2780
	int i;

2781
	if (!hugepages_supported())
2782
		return 0;
2783

2784 2785 2786 2787
	if (!size_to_hstate(default_hstate_size)) {
		default_hstate_size = HPAGE_SIZE;
		if (!size_to_hstate(default_hstate_size))
			hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
2788
	}
2789
	default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
2790 2791 2792 2793
	if (default_hstate_max_huge_pages) {
		if (!default_hstate.max_huge_pages)
			default_hstate.max_huge_pages = default_hstate_max_huge_pages;
	}
2794 2795

	hugetlb_init_hstates();
2796
	gather_bootmem_prealloc();
2797 2798 2799
	report_hugepages();

	hugetlb_sysfs_init();
2800
	hugetlb_register_all_nodes();
2801
	hugetlb_cgroup_file_init();
2802

2803 2804 2805 2806 2807
#ifdef CONFIG_SMP
	num_fault_mutexes = roundup_pow_of_two(8 * num_possible_cpus());
#else
	num_fault_mutexes = 1;
#endif
2808
	hugetlb_fault_mutex_table =
2809
		kmalloc(sizeof(struct mutex) * num_fault_mutexes, GFP_KERNEL);
2810
	BUG_ON(!hugetlb_fault_mutex_table);
2811 2812

	for (i = 0; i < num_fault_mutexes; i++)
2813
		mutex_init(&hugetlb_fault_mutex_table[i]);
2814 2815
	return 0;
}
2816
subsys_initcall(hugetlb_init);
2817 2818

/* Should be called on processing a hugepagesz=... option */
2819 2820 2821 2822 2823
void __init hugetlb_bad_size(void)
{
	parsed_valid_hugepagesz = false;
}

2824
void __init hugetlb_add_hstate(unsigned int order)
2825 2826
{
	struct hstate *h;
2827 2828
	unsigned long i;

2829
	if (size_to_hstate(PAGE_SIZE << order)) {
J
Joe Perches 已提交
2830
		pr_warn("hugepagesz= specified twice, ignoring\n");
2831 2832
		return;
	}
2833
	BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
2834
	BUG_ON(order == 0);
2835
	h = &hstates[hugetlb_max_hstate++];
2836 2837
	h->order = order;
	h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
2838 2839 2840 2841
	h->nr_huge_pages = 0;
	h->free_huge_pages = 0;
	for (i = 0; i < MAX_NUMNODES; ++i)
		INIT_LIST_HEAD(&h->hugepage_freelists[i]);
2842
	INIT_LIST_HEAD(&h->hugepage_activelist);
2843 2844
	h->next_nid_to_alloc = first_memory_node;
	h->next_nid_to_free = first_memory_node;
2845 2846
	snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
					huge_page_size(h)/1024);
2847

2848 2849 2850
	parsed_hstate = h;
}

2851
static int __init hugetlb_nrpages_setup(char *s)
2852 2853
{
	unsigned long *mhp;
2854
	static unsigned long *last_mhp;
2855

2856 2857 2858 2859 2860 2861
	if (!parsed_valid_hugepagesz) {
		pr_warn("hugepages = %s preceded by "
			"an unsupported hugepagesz, ignoring\n", s);
		parsed_valid_hugepagesz = true;
		return 1;
	}
2862
	/*
2863
	 * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
2864 2865
	 * so this hugepages= parameter goes to the "default hstate".
	 */
2866
	else if (!hugetlb_max_hstate)
2867 2868 2869 2870
		mhp = &default_hstate_max_huge_pages;
	else
		mhp = &parsed_hstate->max_huge_pages;

2871
	if (mhp == last_mhp) {
J
Joe Perches 已提交
2872
		pr_warn("hugepages= specified twice without interleaving hugepagesz=, ignoring\n");
2873 2874 2875
		return 1;
	}

2876 2877 2878
	if (sscanf(s, "%lu", mhp) <= 0)
		*mhp = 0;

2879 2880 2881 2882 2883
	/*
	 * 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.
	 */
2884
	if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER)
2885 2886 2887 2888
		hugetlb_hstate_alloc_pages(parsed_hstate);

	last_mhp = mhp;

2889 2890
	return 1;
}
2891 2892 2893 2894 2895 2896 2897 2898
__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);
2899

2900 2901 2902 2903 2904 2905 2906 2907 2908 2909 2910 2911
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
2912 2913 2914
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
2915
{
2916
	struct hstate *h = &default_hstate;
2917
	unsigned long tmp = h->max_huge_pages;
2918
	int ret;
2919

2920
	if (!hugepages_supported())
2921
		return -EOPNOTSUPP;
2922

2923 2924
	table->data = &tmp;
	table->maxlen = sizeof(unsigned long);
2925 2926 2927
	ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
	if (ret)
		goto out;
2928

2929 2930 2931
	if (write)
		ret = __nr_hugepages_store_common(obey_mempolicy, h,
						  NUMA_NO_NODE, tmp, *length);
2932 2933
out:
	return ret;
L
Linus Torvalds 已提交
2934
}
2935

2936 2937 2938 2939 2940 2941 2942 2943 2944 2945 2946 2947 2948 2949 2950 2951 2952
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 */

2953
int hugetlb_overcommit_handler(struct ctl_table *table, int write,
2954
			void __user *buffer,
2955 2956
			size_t *length, loff_t *ppos)
{
2957
	struct hstate *h = &default_hstate;
2958
	unsigned long tmp;
2959
	int ret;
2960

2961
	if (!hugepages_supported())
2962
		return -EOPNOTSUPP;
2963

2964
	tmp = h->nr_overcommit_huge_pages;
2965

2966
	if (write && hstate_is_gigantic(h))
2967 2968
		return -EINVAL;

2969 2970
	table->data = &tmp;
	table->maxlen = sizeof(unsigned long);
2971 2972 2973
	ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
	if (ret)
		goto out;
2974 2975 2976 2977 2978 2979

	if (write) {
		spin_lock(&hugetlb_lock);
		h->nr_overcommit_huge_pages = tmp;
		spin_unlock(&hugetlb_lock);
	}
2980 2981
out:
	return ret;
2982 2983
}

L
Linus Torvalds 已提交
2984 2985
#endif /* CONFIG_SYSCTL */

2986
void hugetlb_report_meminfo(struct seq_file *m)
L
Linus Torvalds 已提交
2987
{
2988
	struct hstate *h = &default_hstate;
2989 2990
	if (!hugepages_supported())
		return;
2991
	seq_printf(m,
2992 2993 2994 2995 2996
			"HugePages_Total:   %5lu\n"
			"HugePages_Free:    %5lu\n"
			"HugePages_Rsvd:    %5lu\n"
			"HugePages_Surp:    %5lu\n"
			"Hugepagesize:   %8lu kB\n",
2997 2998 2999 3000 3001
			h->nr_huge_pages,
			h->free_huge_pages,
			h->resv_huge_pages,
			h->surplus_huge_pages,
			1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
L
Linus Torvalds 已提交
3002 3003 3004 3005
}

int hugetlb_report_node_meminfo(int nid, char *buf)
{
3006
	struct hstate *h = &default_hstate;
3007 3008
	if (!hugepages_supported())
		return 0;
L
Linus Torvalds 已提交
3009 3010
	return sprintf(buf,
		"Node %d HugePages_Total: %5u\n"
3011 3012
		"Node %d HugePages_Free:  %5u\n"
		"Node %d HugePages_Surp:  %5u\n",
3013 3014 3015
		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
3016 3017
}

3018 3019 3020 3021 3022
void hugetlb_show_meminfo(void)
{
	struct hstate *h;
	int nid;

3023 3024 3025
	if (!hugepages_supported())
		return;

3026 3027 3028 3029 3030 3031 3032 3033 3034 3035
	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));
}

3036 3037 3038 3039 3040 3041
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
3042 3043 3044
/* Return the number pages of memory we physically have, in PAGE_SIZE units. */
unsigned long hugetlb_total_pages(void)
{
3045 3046 3047 3048 3049 3050
	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
3051 3052
}

3053
static int hugetlb_acct_memory(struct hstate *h, long delta)
M
Mel Gorman 已提交
3054 3055 3056 3057 3058 3059 3060 3061 3062 3063 3064 3065 3066 3067 3068 3069 3070 3071 3072 3073 3074 3075
{
	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) {
3076
		if (gather_surplus_pages(h, delta) < 0)
M
Mel Gorman 已提交
3077 3078
			goto out;

3079 3080
		if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
			return_unused_surplus_pages(h, delta);
M
Mel Gorman 已提交
3081 3082 3083 3084 3085 3086
			goto out;
		}
	}

	ret = 0;
	if (delta < 0)
3087
		return_unused_surplus_pages(h, (unsigned long) -delta);
M
Mel Gorman 已提交
3088 3089 3090 3091 3092 3093

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

3094 3095
static void hugetlb_vm_op_open(struct vm_area_struct *vma)
{
3096
	struct resv_map *resv = vma_resv_map(vma);
3097 3098 3099 3100 3101

	/*
	 * 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
3102
	 * has a reference to the reservation map it cannot disappear until
3103 3104 3105
	 * after this open call completes.  It is therefore safe to take a
	 * new reference here without additional locking.
	 */
3106
	if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
3107
		kref_get(&resv->refs);
3108 3109
}

3110 3111
static void hugetlb_vm_op_close(struct vm_area_struct *vma)
{
3112
	struct hstate *h = hstate_vma(vma);
3113
	struct resv_map *resv = vma_resv_map(vma);
3114
	struct hugepage_subpool *spool = subpool_vma(vma);
3115
	unsigned long reserve, start, end;
3116
	long gbl_reserve;
3117

3118 3119
	if (!resv || !is_vma_resv_set(vma, HPAGE_RESV_OWNER))
		return;
3120

3121 3122
	start = vma_hugecache_offset(h, vma, vma->vm_start);
	end = vma_hugecache_offset(h, vma, vma->vm_end);
3123

3124
	reserve = (end - start) - region_count(resv, start, end);
3125

3126 3127 3128
	kref_put(&resv->refs, resv_map_release);

	if (reserve) {
3129 3130 3131 3132 3133 3134
		/*
		 * 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);
3135
	}
3136 3137
}

L
Linus Torvalds 已提交
3138 3139 3140 3141 3142 3143
/*
 * 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.
 */
N
Nick Piggin 已提交
3144
static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
L
Linus Torvalds 已提交
3145 3146
{
	BUG();
N
Nick Piggin 已提交
3147
	return 0;
L
Linus Torvalds 已提交
3148 3149
}

3150
const struct vm_operations_struct hugetlb_vm_ops = {
N
Nick Piggin 已提交
3151
	.fault = hugetlb_vm_op_fault,
3152
	.open = hugetlb_vm_op_open,
3153
	.close = hugetlb_vm_op_close,
L
Linus Torvalds 已提交
3154 3155
};

3156 3157
static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
				int writable)
D
David Gibson 已提交
3158 3159 3160
{
	pte_t entry;

3161
	if (writable) {
3162 3163
		entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page,
					 vma->vm_page_prot)));
D
David Gibson 已提交
3164
	} else {
3165 3166
		entry = huge_pte_wrprotect(mk_huge_pte(page,
					   vma->vm_page_prot));
D
David Gibson 已提交
3167 3168 3169
	}
	entry = pte_mkyoung(entry);
	entry = pte_mkhuge(entry);
3170
	entry = arch_make_huge_pte(entry, vma, page, writable);
D
David Gibson 已提交
3171 3172 3173 3174

	return entry;
}

3175 3176 3177 3178 3179
static void set_huge_ptep_writable(struct vm_area_struct *vma,
				   unsigned long address, pte_t *ptep)
{
	pte_t entry;

3180
	entry = huge_pte_mkwrite(huge_pte_mkdirty(huge_ptep_get(ptep)));
3181
	if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
3182
		update_mmu_cache(vma, address, ptep);
3183 3184
}

3185 3186 3187 3188 3189 3190 3191 3192 3193 3194 3195 3196 3197 3198 3199 3200 3201 3202 3203 3204 3205 3206 3207 3208 3209
static int is_hugetlb_entry_migration(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_migration_entry(swp))
		return 1;
	else
		return 0;
}

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;
}
3210

D
David Gibson 已提交
3211 3212 3213 3214 3215
int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
			    struct vm_area_struct *vma)
{
	pte_t *src_pte, *dst_pte, entry;
	struct page *ptepage;
3216
	unsigned long addr;
3217
	int cow;
3218 3219
	struct hstate *h = hstate_vma(vma);
	unsigned long sz = huge_page_size(h);
3220 3221 3222
	unsigned long mmun_start;	/* For mmu_notifiers */
	unsigned long mmun_end;		/* For mmu_notifiers */
	int ret = 0;
3223 3224

	cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
D
David Gibson 已提交
3225

3226 3227 3228 3229 3230
	mmun_start = vma->vm_start;
	mmun_end = vma->vm_end;
	if (cow)
		mmu_notifier_invalidate_range_start(src, mmun_start, mmun_end);

3231
	for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
3232
		spinlock_t *src_ptl, *dst_ptl;
H
Hugh Dickins 已提交
3233 3234 3235
		src_pte = huge_pte_offset(src, addr);
		if (!src_pte)
			continue;
3236
		dst_pte = huge_pte_alloc(dst, addr, sz);
3237 3238 3239 3240
		if (!dst_pte) {
			ret = -ENOMEM;
			break;
		}
3241 3242 3243 3244 3245

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

3246 3247 3248
		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);
3249 3250 3251 3252 3253 3254 3255 3256 3257 3258 3259 3260 3261 3262 3263 3264 3265 3266
		entry = huge_ptep_get(src_pte);
		if (huge_pte_none(entry)) { /* skip none entry */
			;
		} else if (unlikely(is_hugetlb_entry_migration(entry) ||
				    is_hugetlb_entry_hwpoisoned(entry))) {
			swp_entry_t swp_entry = pte_to_swp_entry(entry);

			if (is_write_migration_entry(swp_entry) && cow) {
				/*
				 * COW mappings require pages in both
				 * parent and child to be set to read.
				 */
				make_migration_entry_read(&swp_entry);
				entry = swp_entry_to_pte(swp_entry);
				set_huge_pte_at(src, addr, src_pte, entry);
			}
			set_huge_pte_at(dst, addr, dst_pte, entry);
		} else {
3267
			if (cow) {
3268
				huge_ptep_set_wrprotect(src, addr, src_pte);
3269 3270 3271
				mmu_notifier_invalidate_range(src, mmun_start,
								   mmun_end);
			}
3272
			entry = huge_ptep_get(src_pte);
3273 3274
			ptepage = pte_page(entry);
			get_page(ptepage);
3275
			page_dup_rmap(ptepage, true);
3276
			set_huge_pte_at(dst, addr, dst_pte, entry);
3277
			hugetlb_count_add(pages_per_huge_page(h), dst);
3278
		}
3279 3280
		spin_unlock(src_ptl);
		spin_unlock(dst_ptl);
D
David Gibson 已提交
3281 3282
	}

3283 3284 3285 3286
	if (cow)
		mmu_notifier_invalidate_range_end(src, mmun_start, mmun_end);

	return ret;
D
David Gibson 已提交
3287 3288
}

3289 3290 3291
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
3292 3293 3294
{
	struct mm_struct *mm = vma->vm_mm;
	unsigned long address;
3295
	pte_t *ptep;
D
David Gibson 已提交
3296
	pte_t pte;
3297
	spinlock_t *ptl;
D
David Gibson 已提交
3298
	struct page *page;
3299 3300
	struct hstate *h = hstate_vma(vma);
	unsigned long sz = huge_page_size(h);
3301 3302
	const unsigned long mmun_start = start;	/* For mmu_notifiers */
	const unsigned long mmun_end   = end;	/* For mmu_notifiers */
3303

D
David Gibson 已提交
3304
	WARN_ON(!is_vm_hugetlb_page(vma));
3305 3306
	BUG_ON(start & ~huge_page_mask(h));
	BUG_ON(end & ~huge_page_mask(h));
D
David Gibson 已提交
3307

3308 3309 3310 3311 3312
	/*
	 * This is a hugetlb vma, all the pte entries should point
	 * to huge page.
	 */
	tlb_remove_check_page_size_change(tlb, sz);
3313
	tlb_start_vma(tlb, vma);
3314
	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
3315 3316
	address = start;
	for (; address < end; address += sz) {
3317
		ptep = huge_pte_offset(mm, address);
A
Adam Litke 已提交
3318
		if (!ptep)
3319 3320
			continue;

3321
		ptl = huge_pte_lock(h, mm, ptep);
3322 3323 3324 3325
		if (huge_pmd_unshare(mm, &address, ptep)) {
			spin_unlock(ptl);
			continue;
		}
3326

3327
		pte = huge_ptep_get(ptep);
3328 3329 3330 3331
		if (huge_pte_none(pte)) {
			spin_unlock(ptl);
			continue;
		}
3332 3333

		/*
3334 3335
		 * Migrating hugepage or HWPoisoned hugepage is already
		 * unmapped and its refcount is dropped, so just clear pte here.
3336
		 */
3337
		if (unlikely(!pte_present(pte))) {
3338
			huge_pte_clear(mm, address, ptep);
3339 3340
			spin_unlock(ptl);
			continue;
3341
		}
3342 3343

		page = pte_page(pte);
3344 3345 3346 3347 3348 3349
		/*
		 * 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) {
3350 3351 3352 3353
			if (page != ref_page) {
				spin_unlock(ptl);
				continue;
			}
3354 3355 3356 3357 3358 3359 3360 3361
			/*
			 * 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);
		}

3362
		pte = huge_ptep_get_and_clear(mm, address, ptep);
3363
		tlb_remove_huge_tlb_entry(h, tlb, ptep, address);
3364
		if (huge_pte_dirty(pte))
3365
			set_page_dirty(page);
3366

3367
		hugetlb_count_sub(pages_per_huge_page(h), mm);
3368
		page_remove_rmap(page, true);
3369

3370
		spin_unlock(ptl);
3371
		tlb_remove_page_size(tlb, page, huge_page_size(h));
3372 3373 3374 3375 3376
		/*
		 * Bail out after unmapping reference page if supplied
		 */
		if (ref_page)
			break;
3377
	}
3378
	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
3379
	tlb_end_vma(tlb, vma);
L
Linus Torvalds 已提交
3380
}
D
David Gibson 已提交
3381

3382 3383 3384 3385 3386 3387 3388 3389 3390 3391 3392 3393
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
3394
	 * is to clear it before releasing the i_mmap_rwsem. This works
3395
	 * because in the context this is called, the VMA is about to be
3396
	 * destroyed and the i_mmap_rwsem is held.
3397 3398 3399 3400
	 */
	vma->vm_flags &= ~VM_MAYSHARE;
}

3401
void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
3402
			  unsigned long end, struct page *ref_page)
3403
{
3404 3405 3406 3407 3408
	struct mm_struct *mm;
	struct mmu_gather tlb;

	mm = vma->vm_mm;

3409
	tlb_gather_mmu(&tlb, mm, start, end);
3410 3411
	__unmap_hugepage_range(&tlb, vma, start, end, ref_page);
	tlb_finish_mmu(&tlb, start, end);
3412 3413
}

3414 3415 3416 3417 3418 3419
/*
 * 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.
 */
3420 3421
static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
			      struct page *page, unsigned long address)
3422
{
3423
	struct hstate *h = hstate_vma(vma);
3424 3425 3426 3427 3428 3429 3430 3431
	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.
	 */
3432
	address = address & huge_page_mask(h);
3433 3434
	pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
			vma->vm_pgoff;
3435
	mapping = vma->vm_file->f_mapping;
3436

3437 3438 3439 3440 3441
	/*
	 * 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
	 */
3442
	i_mmap_lock_write(mapping);
3443
	vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) {
3444 3445 3446 3447
		/* Do not unmap the current VMA */
		if (iter_vma == vma)
			continue;

3448 3449 3450 3451 3452 3453 3454 3455
		/*
		 * 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;

3456 3457 3458 3459 3460 3461 3462 3463
		/*
		 * 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))
3464 3465
			unmap_hugepage_range(iter_vma, address,
					     address + huge_page_size(h), page);
3466
	}
3467
	i_mmap_unlock_write(mapping);
3468 3469
}

3470 3471
/*
 * Hugetlb_cow() should be called with page lock of the original hugepage held.
3472 3473 3474
 * 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.
3475
 */
3476
static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
3477 3478
		       unsigned long address, pte_t *ptep,
		       struct page *pagecache_page, spinlock_t *ptl)
3479
{
3480
	pte_t pte;
3481
	struct hstate *h = hstate_vma(vma);
3482
	struct page *old_page, *new_page;
3483
	int ret = 0, outside_reserve = 0;
3484 3485
	unsigned long mmun_start;	/* For mmu_notifiers */
	unsigned long mmun_end;		/* For mmu_notifiers */
3486

3487
	pte = huge_ptep_get(ptep);
3488 3489
	old_page = pte_page(pte);

3490
retry_avoidcopy:
3491 3492
	/* If no-one else is actually using this page, avoid the copy
	 * and just make the page writable */
3493
	if (page_mapcount(old_page) == 1 && PageAnon(old_page)) {
3494
		page_move_anon_rmap(old_page, vma);
3495
		set_huge_ptep_writable(vma, address, ptep);
N
Nick Piggin 已提交
3496
		return 0;
3497 3498
	}

3499 3500 3501 3502 3503 3504 3505 3506 3507
	/*
	 * 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.
	 */
3508
	if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
3509 3510 3511
			old_page != pagecache_page)
		outside_reserve = 1;

3512
	get_page(old_page);
3513

3514 3515 3516 3517
	/*
	 * Drop page table lock as buddy allocator may be called. It will
	 * be acquired again before returning to the caller, as expected.
	 */
3518
	spin_unlock(ptl);
3519
	new_page = alloc_huge_page(vma, address, outside_reserve);
3520

3521
	if (IS_ERR(new_page)) {
3522 3523 3524 3525 3526 3527 3528 3529
		/*
		 * 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) {
3530
			put_page(old_page);
3531
			BUG_ON(huge_pte_none(pte));
3532 3533 3534 3535 3536 3537 3538 3539 3540 3541 3542 3543
			unmap_ref_private(mm, vma, old_page, address);
			BUG_ON(huge_pte_none(pte));
			spin_lock(ptl);
			ptep = huge_pte_offset(mm, address & huge_page_mask(h));
			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;
3544 3545
		}

3546 3547 3548
		ret = (PTR_ERR(new_page) == -ENOMEM) ?
			VM_FAULT_OOM : VM_FAULT_SIGBUS;
		goto out_release_old;
3549 3550
	}

3551 3552 3553 3554
	/*
	 * When the original hugepage is shared one, it does not have
	 * anon_vma prepared.
	 */
3555
	if (unlikely(anon_vma_prepare(vma))) {
3556 3557
		ret = VM_FAULT_OOM;
		goto out_release_all;
3558
	}
3559

A
Andrea Arcangeli 已提交
3560 3561
	copy_user_huge_page(new_page, old_page, address, vma,
			    pages_per_huge_page(h));
N
Nick Piggin 已提交
3562
	__SetPageUptodate(new_page);
3563
	set_page_huge_active(new_page);
3564

3565 3566 3567
	mmun_start = address & huge_page_mask(h);
	mmun_end = mmun_start + huge_page_size(h);
	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
3568

3569
	/*
3570
	 * Retake the page table lock to check for racing updates
3571 3572
	 * before the page tables are altered
	 */
3573
	spin_lock(ptl);
3574
	ptep = huge_pte_offset(mm, address & huge_page_mask(h));
3575
	if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) {
3576 3577
		ClearPagePrivate(new_page);

3578
		/* Break COW */
3579
		huge_ptep_clear_flush(vma, address, ptep);
3580
		mmu_notifier_invalidate_range(mm, mmun_start, mmun_end);
3581 3582
		set_huge_pte_at(mm, address, ptep,
				make_huge_pte(vma, new_page, 1));
3583
		page_remove_rmap(old_page, true);
3584
		hugepage_add_new_anon_rmap(new_page, vma, address);
3585 3586 3587
		/* Make the old page be freed below */
		new_page = old_page;
	}
3588
	spin_unlock(ptl);
3589
	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
3590
out_release_all:
3591
	restore_reserve_on_error(h, vma, address, new_page);
3592
	put_page(new_page);
3593
out_release_old:
3594
	put_page(old_page);
3595

3596 3597
	spin_lock(ptl); /* Caller expects lock to be held */
	return ret;
3598 3599
}

3600
/* Return the pagecache page at a given address within a VMA */
3601 3602
static struct page *hugetlbfs_pagecache_page(struct hstate *h,
			struct vm_area_struct *vma, unsigned long address)
3603 3604
{
	struct address_space *mapping;
3605
	pgoff_t idx;
3606 3607

	mapping = vma->vm_file->f_mapping;
3608
	idx = vma_hugecache_offset(h, vma, address);
3609 3610 3611 3612

	return find_lock_page(mapping, idx);
}

H
Hugh Dickins 已提交
3613 3614 3615 3616 3617
/*
 * 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
3618 3619 3620 3621 3622 3623 3624 3625 3626 3627 3628 3629 3630 3631 3632
			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;
}

3633 3634 3635 3636 3637 3638 3639 3640 3641 3642 3643 3644 3645 3646 3647 3648 3649
int huge_add_to_page_cache(struct page *page, struct address_space *mapping,
			   pgoff_t idx)
{
	struct inode *inode = mapping->host;
	struct hstate *h = hstate_inode(inode);
	int err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);

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

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

3650
static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
3651 3652
			   struct address_space *mapping, pgoff_t idx,
			   unsigned long address, pte_t *ptep, unsigned int flags)
3653
{
3654
	struct hstate *h = hstate_vma(vma);
3655
	int ret = VM_FAULT_SIGBUS;
3656
	int anon_rmap = 0;
A
Adam Litke 已提交
3657 3658
	unsigned long size;
	struct page *page;
3659
	pte_t new_pte;
3660
	spinlock_t *ptl;
A
Adam Litke 已提交
3661

3662 3663 3664
	/*
	 * 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
3665
	 * COW. Warn that such a situation has occurred as it may not be obvious
3666 3667
	 */
	if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
3668
		pr_warn_ratelimited("PID %d killed due to inadequate hugepage pool\n",
3669
			   current->pid);
3670 3671 3672
		return ret;
	}

A
Adam Litke 已提交
3673 3674 3675 3676
	/*
	 * Use page lock to guard against racing truncation
	 * before we get page_table_lock.
	 */
3677 3678 3679
retry:
	page = find_lock_page(mapping, idx);
	if (!page) {
3680
		size = i_size_read(mapping->host) >> huge_page_shift(h);
3681 3682
		if (idx >= size)
			goto out;
3683
		page = alloc_huge_page(vma, address, 0);
3684
		if (IS_ERR(page)) {
3685 3686 3687 3688 3689
			ret = PTR_ERR(page);
			if (ret == -ENOMEM)
				ret = VM_FAULT_OOM;
			else
				ret = VM_FAULT_SIGBUS;
3690 3691
			goto out;
		}
A
Andrea Arcangeli 已提交
3692
		clear_huge_page(page, address, pages_per_huge_page(h));
N
Nick Piggin 已提交
3693
		__SetPageUptodate(page);
3694
		set_page_huge_active(page);
3695

3696
		if (vma->vm_flags & VM_MAYSHARE) {
3697
			int err = huge_add_to_page_cache(page, mapping, idx);
3698 3699 3700 3701 3702 3703
			if (err) {
				put_page(page);
				if (err == -EEXIST)
					goto retry;
				goto out;
			}
3704
		} else {
3705
			lock_page(page);
3706 3707 3708 3709
			if (unlikely(anon_vma_prepare(vma))) {
				ret = VM_FAULT_OOM;
				goto backout_unlocked;
			}
3710
			anon_rmap = 1;
3711
		}
3712
	} else {
3713 3714 3715 3716 3717 3718
		/*
		 * 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))) {
3719
			ret = VM_FAULT_HWPOISON |
3720
				VM_FAULT_SET_HINDEX(hstate_index(h));
3721 3722
			goto backout_unlocked;
		}
3723
	}
3724

3725 3726 3727 3728 3729 3730
	/*
	 * 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.
	 */
3731
	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3732 3733 3734 3735
		if (vma_needs_reservation(h, vma, address) < 0) {
			ret = VM_FAULT_OOM;
			goto backout_unlocked;
		}
3736
		/* Just decrements count, does not deallocate */
3737
		vma_end_reservation(h, vma, address);
3738
	}
3739

3740
	ptl = huge_pte_lock(h, mm, ptep);
3741
	size = i_size_read(mapping->host) >> huge_page_shift(h);
A
Adam Litke 已提交
3742 3743 3744
	if (idx >= size)
		goto backout;

N
Nick Piggin 已提交
3745
	ret = 0;
3746
	if (!huge_pte_none(huge_ptep_get(ptep)))
A
Adam Litke 已提交
3747 3748
		goto backout;

3749 3750
	if (anon_rmap) {
		ClearPagePrivate(page);
3751
		hugepage_add_new_anon_rmap(page, vma, address);
3752
	} else
3753
		page_dup_rmap(page, true);
3754 3755 3756 3757
	new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
				&& (vma->vm_flags & VM_SHARED)));
	set_huge_pte_at(mm, address, ptep, new_pte);

3758
	hugetlb_count_add(pages_per_huge_page(h), mm);
3759
	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3760
		/* Optimization, do the COW without a second fault */
3761
		ret = hugetlb_cow(mm, vma, address, ptep, page, ptl);
3762 3763
	}

3764
	spin_unlock(ptl);
A
Adam Litke 已提交
3765 3766
	unlock_page(page);
out:
3767
	return ret;
A
Adam Litke 已提交
3768 3769

backout:
3770
	spin_unlock(ptl);
3771
backout_unlocked:
A
Adam Litke 已提交
3772
	unlock_page(page);
3773
	restore_reserve_on_error(h, vma, address, page);
A
Adam Litke 已提交
3774 3775
	put_page(page);
	goto out;
3776 3777
}

3778
#ifdef CONFIG_SMP
3779
u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
3780 3781 3782 3783 3784 3785 3786 3787 3788 3789 3790 3791 3792 3793 3794 3795 3796 3797 3798 3799 3800 3801 3802 3803
			    struct vm_area_struct *vma,
			    struct address_space *mapping,
			    pgoff_t idx, unsigned long address)
{
	unsigned long key[2];
	u32 hash;

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

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

	return hash & (num_fault_mutexes - 1);
}
#else
/*
 * For uniprocesor systems we always use a single mutex, so just
 * return 0 and avoid the hashing overhead.
 */
3804
u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
3805 3806 3807 3808 3809 3810 3811 3812
			    struct vm_area_struct *vma,
			    struct address_space *mapping,
			    pgoff_t idx, unsigned long address)
{
	return 0;
}
#endif

3813
int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3814
			unsigned long address, unsigned int flags)
3815
{
3816
	pte_t *ptep, entry;
3817
	spinlock_t *ptl;
3818
	int ret;
3819 3820
	u32 hash;
	pgoff_t idx;
3821
	struct page *page = NULL;
3822
	struct page *pagecache_page = NULL;
3823
	struct hstate *h = hstate_vma(vma);
3824
	struct address_space *mapping;
3825
	int need_wait_lock = 0;
3826

3827 3828
	address &= huge_page_mask(h);

3829 3830 3831
	ptep = huge_pte_offset(mm, address);
	if (ptep) {
		entry = huge_ptep_get(ptep);
N
Naoya Horiguchi 已提交
3832
		if (unlikely(is_hugetlb_entry_migration(entry))) {
3833
			migration_entry_wait_huge(vma, mm, ptep);
N
Naoya Horiguchi 已提交
3834 3835
			return 0;
		} else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
3836
			return VM_FAULT_HWPOISON_LARGE |
3837
				VM_FAULT_SET_HINDEX(hstate_index(h));
3838 3839 3840 3841
	} else {
		ptep = huge_pte_alloc(mm, address, huge_page_size(h));
		if (!ptep)
			return VM_FAULT_OOM;
3842 3843
	}

3844 3845 3846
	mapping = vma->vm_file->f_mapping;
	idx = vma_hugecache_offset(h, vma, address);

3847 3848 3849 3850 3851
	/*
	 * 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.
	 */
3852 3853
	hash = hugetlb_fault_mutex_hash(h, mm, vma, mapping, idx, address);
	mutex_lock(&hugetlb_fault_mutex_table[hash]);
3854

3855 3856
	entry = huge_ptep_get(ptep);
	if (huge_pte_none(entry)) {
3857
		ret = hugetlb_no_page(mm, vma, mapping, idx, address, ptep, flags);
3858
		goto out_mutex;
3859
	}
3860

N
Nick Piggin 已提交
3861
	ret = 0;
3862

3863 3864 3865 3866 3867 3868 3869 3870 3871 3872
	/*
	 * 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;

3873 3874 3875 3876 3877 3878 3879 3880
	/*
	 * 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.
	 */
3881
	if ((flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) {
3882 3883
		if (vma_needs_reservation(h, vma, address) < 0) {
			ret = VM_FAULT_OOM;
3884
			goto out_mutex;
3885
		}
3886
		/* Just decrements count, does not deallocate */
3887
		vma_end_reservation(h, vma, address);
3888

3889
		if (!(vma->vm_flags & VM_MAYSHARE))
3890 3891 3892 3893
			pagecache_page = hugetlbfs_pagecache_page(h,
								vma, address);
	}

3894 3895 3896 3897 3898 3899
	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;

3900 3901 3902 3903 3904 3905 3906
	/*
	 * 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)
3907 3908 3909 3910
		if (!trylock_page(page)) {
			need_wait_lock = 1;
			goto out_ptl;
		}
3911

3912
	get_page(page);
3913

3914
	if (flags & FAULT_FLAG_WRITE) {
3915
		if (!huge_pte_write(entry)) {
3916 3917
			ret = hugetlb_cow(mm, vma, address, ptep,
					  pagecache_page, ptl);
3918
			goto out_put_page;
3919
		}
3920
		entry = huge_pte_mkdirty(entry);
3921 3922
	}
	entry = pte_mkyoung(entry);
3923 3924
	if (huge_ptep_set_access_flags(vma, address, ptep, entry,
						flags & FAULT_FLAG_WRITE))
3925
		update_mmu_cache(vma, address, ptep);
3926 3927 3928 3929
out_put_page:
	if (page != pagecache_page)
		unlock_page(page);
	put_page(page);
3930 3931
out_ptl:
	spin_unlock(ptl);
3932 3933 3934 3935 3936

	if (pagecache_page) {
		unlock_page(pagecache_page);
		put_page(pagecache_page);
	}
3937
out_mutex:
3938
	mutex_unlock(&hugetlb_fault_mutex_table[hash]);
3939 3940 3941 3942 3943 3944 3945 3946 3947
	/*
	 * 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);
3948
	return ret;
3949 3950
}

3951 3952 3953 3954 3955 3956 3957 3958 3959 3960 3961 3962 3963 3964 3965 3966 3967 3968 3969 3970 3971 3972 3973 3974 3975 3976 3977 3978 3979 3980 3981 3982 3983 3984 3985 3986 3987 3988 3989 3990 3991 3992 3993 3994 3995 3996 3997 3998 3999 4000 4001 4002 4003 4004 4005 4006 4007 4008 4009 4010 4011 4012 4013 4014 4015 4016 4017 4018 4019 4020 4021 4022 4023 4024 4025 4026 4027 4028 4029 4030 4031
/*
 * 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)
{
	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,
						pages_per_huge_page(h));

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

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

	ptl = huge_pte_lockptr(h, dst_mm, dst_pte);
	spin_lock(ptl);

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

	ClearPagePrivate(page);
	hugepage_add_new_anon_rmap(page, dst_vma, dst_addr);

	_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);
	ret = 0;
out:
	return ret;
out_release_unlock:
	spin_unlock(ptl);
	put_page(page);
	goto out;
}

4032 4033 4034 4035
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,
			 long i, unsigned int flags)
D
David Gibson 已提交
4036
{
4037 4038
	unsigned long pfn_offset;
	unsigned long vaddr = *position;
4039
	unsigned long remainder = *nr_pages;
4040
	struct hstate *h = hstate_vma(vma);
D
David Gibson 已提交
4041 4042

	while (vaddr < vma->vm_end && remainder) {
A
Adam Litke 已提交
4043
		pte_t *pte;
4044
		spinlock_t *ptl = NULL;
H
Hugh Dickins 已提交
4045
		int absent;
A
Adam Litke 已提交
4046
		struct page *page;
D
David Gibson 已提交
4047

4048 4049 4050 4051 4052 4053 4054 4055 4056
		/*
		 * If we have a pending SIGKILL, don't keep faulting pages and
		 * potentially allocating memory.
		 */
		if (unlikely(fatal_signal_pending(current))) {
			remainder = 0;
			break;
		}

A
Adam Litke 已提交
4057 4058
		/*
		 * Some archs (sparc64, sh*) have multiple pte_ts to
H
Hugh Dickins 已提交
4059
		 * each hugepage.  We have to make sure we get the
A
Adam Litke 已提交
4060
		 * first, for the page indexing below to work.
4061 4062
		 *
		 * Note that page table lock is not held when pte is null.
A
Adam Litke 已提交
4063
		 */
4064
		pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
4065 4066
		if (pte)
			ptl = huge_pte_lock(h, mm, pte);
H
Hugh Dickins 已提交
4067 4068 4069 4070
		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
4071 4072 4073 4074
		 * 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
4075
		 */
H
Hugh Dickins 已提交
4076 4077
		if (absent && (flags & FOLL_DUMP) &&
		    !hugetlbfs_pagecache_present(h, vma, vaddr)) {
4078 4079
			if (pte)
				spin_unlock(ptl);
H
Hugh Dickins 已提交
4080 4081 4082
			remainder = 0;
			break;
		}
D
David Gibson 已提交
4083

4084 4085 4086 4087 4088 4089 4090 4091 4092 4093 4094
		/*
		 * 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)) ||
4095 4096
		    ((flags & FOLL_WRITE) &&
		      !huge_pte_write(huge_ptep_get(pte)))) {
A
Adam Litke 已提交
4097
			int ret;
D
David Gibson 已提交
4098

4099 4100
			if (pte)
				spin_unlock(ptl);
H
Hugh Dickins 已提交
4101 4102
			ret = hugetlb_fault(mm, vma, vaddr,
				(flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
4103
			if (!(ret & VM_FAULT_ERROR))
A
Adam Litke 已提交
4104
				continue;
D
David Gibson 已提交
4105

A
Adam Litke 已提交
4106 4107 4108 4109
			remainder = 0;
			break;
		}

4110
		pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
4111
		page = pte_page(huge_ptep_get(pte));
4112
same_page:
4113
		if (pages) {
H
Hugh Dickins 已提交
4114
			pages[i] = mem_map_offset(page, pfn_offset);
4115
			get_page(pages[i]);
4116
		}
D
David Gibson 已提交
4117 4118 4119 4120 4121

		if (vmas)
			vmas[i] = vma;

		vaddr += PAGE_SIZE;
4122
		++pfn_offset;
D
David Gibson 已提交
4123 4124
		--remainder;
		++i;
4125
		if (vaddr < vma->vm_end && remainder &&
4126
				pfn_offset < pages_per_huge_page(h)) {
4127 4128 4129 4130 4131 4132
			/*
			 * We use pfn_offset to avoid touching the pageframes
			 * of this compound page.
			 */
			goto same_page;
		}
4133
		spin_unlock(ptl);
D
David Gibson 已提交
4134
	}
4135
	*nr_pages = remainder;
D
David Gibson 已提交
4136 4137
	*position = vaddr;

H
Hugh Dickins 已提交
4138
	return i ? i : -EFAULT;
D
David Gibson 已提交
4139
}
4140

4141 4142 4143 4144 4145 4146 4147 4148
#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

4149
unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
4150 4151 4152 4153 4154 4155
		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;
4156
	struct hstate *h = hstate_vma(vma);
4157
	unsigned long pages = 0;
4158 4159 4160 4161

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

4162
	mmu_notifier_invalidate_range_start(mm, start, end);
4163
	i_mmap_lock_write(vma->vm_file->f_mapping);
4164
	for (; address < end; address += huge_page_size(h)) {
4165
		spinlock_t *ptl;
4166 4167 4168
		ptep = huge_pte_offset(mm, address);
		if (!ptep)
			continue;
4169
		ptl = huge_pte_lock(h, mm, ptep);
4170 4171
		if (huge_pmd_unshare(mm, &address, ptep)) {
			pages++;
4172
			spin_unlock(ptl);
4173
			continue;
4174
		}
4175 4176 4177 4178 4179 4180 4181 4182 4183 4184 4185 4186 4187 4188 4189 4190 4191 4192 4193 4194
		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);
				set_huge_pte_at(mm, address, ptep, newpte);
				pages++;
			}
			spin_unlock(ptl);
			continue;
		}
		if (!huge_pte_none(pte)) {
4195
			pte = huge_ptep_get_and_clear(mm, address, ptep);
4196
			pte = pte_mkhuge(huge_pte_modify(pte, newprot));
4197
			pte = arch_make_huge_pte(pte, vma, NULL, 0);
4198
			set_huge_pte_at(mm, address, ptep, pte);
4199
			pages++;
4200
		}
4201
		spin_unlock(ptl);
4202
	}
4203
	/*
4204
	 * Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare
4205
	 * may have cleared our pud entry and done put_page on the page table:
4206
	 * once we release i_mmap_rwsem, another task can do the final put_page
4207 4208
	 * and that page table be reused and filled with junk.
	 */
4209
	flush_hugetlb_tlb_range(vma, start, end);
4210
	mmu_notifier_invalidate_range(mm, start, end);
4211
	i_mmap_unlock_write(vma->vm_file->f_mapping);
4212
	mmu_notifier_invalidate_range_end(mm, start, end);
4213 4214

	return pages << h->order;
4215 4216
}

4217 4218
int hugetlb_reserve_pages(struct inode *inode,
					long from, long to,
4219
					struct vm_area_struct *vma,
4220
					vm_flags_t vm_flags)
4221
{
4222
	long ret, chg;
4223
	struct hstate *h = hstate_inode(inode);
4224
	struct hugepage_subpool *spool = subpool_inode(inode);
4225
	struct resv_map *resv_map;
4226
	long gbl_reserve;
4227

4228 4229 4230
	/*
	 * Only apply hugepage reservation if asked. At fault time, an
	 * attempt will be made for VM_NORESERVE to allocate a page
4231
	 * without using reserves
4232
	 */
4233
	if (vm_flags & VM_NORESERVE)
4234 4235
		return 0;

4236 4237 4238 4239 4240 4241
	/*
	 * 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
	 */
4242
	if (!vma || vma->vm_flags & VM_MAYSHARE) {
4243
		resv_map = inode_resv_map(inode);
4244

4245
		chg = region_chg(resv_map, from, to);
4246 4247 4248

	} else {
		resv_map = resv_map_alloc();
4249 4250 4251
		if (!resv_map)
			return -ENOMEM;

4252
		chg = to - from;
4253

4254 4255 4256 4257
		set_vma_resv_map(vma, resv_map);
		set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
	}

4258 4259 4260 4261
	if (chg < 0) {
		ret = chg;
		goto out_err;
	}
4262

4263 4264 4265 4266 4267 4268 4269
	/*
	 * 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) {
4270 4271 4272
		ret = -ENOSPC;
		goto out_err;
	}
4273 4274

	/*
4275
	 * Check enough hugepages are available for the reservation.
4276
	 * Hand the pages back to the subpool if there are not
4277
	 */
4278
	ret = hugetlb_acct_memory(h, gbl_reserve);
K
Ken Chen 已提交
4279
	if (ret < 0) {
4280 4281
		/* put back original number of pages, chg */
		(void)hugepage_subpool_put_pages(spool, chg);
4282
		goto out_err;
K
Ken Chen 已提交
4283
	}
4284 4285 4286 4287 4288 4289 4290 4291 4292 4293 4294 4295

	/*
	 * 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
	 */
4296 4297 4298 4299 4300 4301 4302 4303 4304 4305 4306 4307 4308 4309 4310 4311 4312 4313
	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);
		}
	}
4314
	return 0;
4315
out_err:
4316 4317
	if (!vma || vma->vm_flags & VM_MAYSHARE)
		region_abort(resv_map, from, to);
J
Joonsoo Kim 已提交
4318 4319
	if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
		kref_put(&resv_map->refs, resv_map_release);
4320
	return ret;
4321 4322
}

4323 4324
long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
								long freed)
4325
{
4326
	struct hstate *h = hstate_inode(inode);
4327
	struct resv_map *resv_map = inode_resv_map(inode);
4328
	long chg = 0;
4329
	struct hugepage_subpool *spool = subpool_inode(inode);
4330
	long gbl_reserve;
K
Ken Chen 已提交
4331

4332 4333 4334 4335 4336 4337 4338 4339 4340 4341 4342
	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
4343
	spin_lock(&inode->i_lock);
4344
	inode->i_blocks -= (blocks_per_huge_page(h) * freed);
K
Ken Chen 已提交
4345 4346
	spin_unlock(&inode->i_lock);

4347 4348 4349 4350 4351 4352
	/*
	 * 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);
4353 4354

	return 0;
4355
}
4356

4357 4358 4359 4360 4361 4362 4363 4364 4365 4366 4367
#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
4368 4369
	unsigned long vm_flags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
	unsigned long svm_flags = svma->vm_flags & VM_LOCKED_CLEAR_MASK;
4370 4371 4372 4373 4374 4375 4376 4377 4378 4379 4380 4381 4382

	/*
	 * 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;
}

4383
static bool vma_shareable(struct vm_area_struct *vma, unsigned long addr)
4384 4385 4386 4387 4388 4389 4390 4391 4392
{
	unsigned long base = addr & PUD_MASK;
	unsigned long end = base + PUD_SIZE;

	/*
	 * check on proper vm_flags and page table alignment
	 */
	if (vma->vm_flags & VM_MAYSHARE &&
	    vma->vm_start <= base && end <= vma->vm_end)
4393 4394
		return true;
	return false;
4395 4396 4397 4398 4399 4400 4401
}

/*
 * Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc()
 * and returns the corresponding pte. While this is not necessary for the
 * !shared pmd case because we can allocate the pmd later as well, it makes the
 * code much cleaner. pmd allocation is essential for the shared case because
4402
 * pud has to be populated inside the same i_mmap_rwsem section - otherwise
4403 4404 4405 4406 4407 4408 4409 4410 4411 4412 4413 4414 4415
 * racing tasks could either miss the sharing (see huge_pte_offset) or select a
 * bad pmd for sharing.
 */
pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
{
	struct vm_area_struct *vma = find_vma(mm, addr);
	struct address_space *mapping = vma->vm_file->f_mapping;
	pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
			vma->vm_pgoff;
	struct vm_area_struct *svma;
	unsigned long saddr;
	pte_t *spte = NULL;
	pte_t *pte;
4416
	spinlock_t *ptl;
4417 4418 4419 4420

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

4421
	i_mmap_lock_write(mapping);
4422 4423 4424 4425 4426 4427 4428 4429 4430 4431 4432 4433 4434 4435 4436 4437 4438
	vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) {
		if (svma == vma)
			continue;

		saddr = page_table_shareable(svma, vma, addr, idx);
		if (saddr) {
			spte = huge_pte_offset(svma->vm_mm, saddr);
			if (spte) {
				get_page(virt_to_page(spte));
				break;
			}
		}
	}

	if (!spte)
		goto out;

4439
	ptl = huge_pte_lock(hstate_vma(vma), mm, spte);
4440
	if (pud_none(*pud)) {
4441 4442
		pud_populate(mm, pud,
				(pmd_t *)((unsigned long)spte & PAGE_MASK));
4443
		mm_inc_nr_pmds(mm);
4444
	} else {
4445
		put_page(virt_to_page(spte));
4446
	}
4447
	spin_unlock(ptl);
4448 4449
out:
	pte = (pte_t *)pmd_alloc(mm, pud, addr);
4450
	i_mmap_unlock_write(mapping);
4451 4452 4453 4454 4455 4456 4457 4458 4459 4460
	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.
 *
4461
 * called with page table lock held.
4462 4463 4464 4465 4466 4467 4468 4469 4470 4471 4472 4473 4474 4475 4476
 *
 * 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);
	pud_t *pud = pud_offset(pgd, *addr);

	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));
4477
	mm_dec_nr_pmds(mm);
4478 4479 4480
	*addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
	return 1;
}
4481 4482 4483 4484 4485 4486
#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;
}
4487 4488 4489 4490 4491

int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
{
	return 0;
}
4492
#define want_pmd_share()	(0)
4493 4494
#endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */

4495 4496 4497 4498 4499 4500 4501 4502 4503 4504 4505 4506 4507 4508 4509 4510 4511 4512 4513 4514 4515
#ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
pte_t *huge_pte_alloc(struct mm_struct *mm,
			unsigned long addr, unsigned long sz)
{
	pgd_t *pgd;
	pud_t *pud;
	pte_t *pte = NULL;

	pgd = pgd_offset(mm, addr);
	pud = pud_alloc(mm, pgd, addr);
	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);
		}
	}
4516
	BUG_ON(pte && pte_present(*pte) && !pte_huge(*pte));
4517 4518 4519 4520 4521 4522 4523 4524 4525 4526 4527 4528 4529 4530 4531 4532 4533 4534 4535 4536 4537 4538

	return pte;
}

pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd = NULL;

	pgd = pgd_offset(mm, addr);
	if (pgd_present(*pgd)) {
		pud = pud_offset(pgd, addr);
		if (pud_present(*pud)) {
			if (pud_huge(*pud))
				return (pte_t *)pud;
			pmd = pmd_offset(pud, addr);
		}
	}
	return (pte_t *) pmd;
}

4539 4540 4541 4542 4543 4544 4545 4546 4547 4548 4549 4550 4551 4552
#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);
}

struct page * __weak
4553
follow_huge_pmd(struct mm_struct *mm, unsigned long address,
4554
		pmd_t *pmd, int flags)
4555
{
4556 4557 4558 4559 4560 4561 4562 4563 4564 4565 4566 4567
	struct page *page = NULL;
	spinlock_t *ptl;
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;
	if (pmd_present(*pmd)) {
4568
		page = pmd_page(*pmd) + ((address & ~PMD_MASK) >> PAGE_SHIFT);
4569 4570 4571 4572 4573 4574 4575 4576 4577 4578 4579 4580 4581 4582 4583
		if (flags & FOLL_GET)
			get_page(page);
	} else {
		if (is_hugetlb_entry_migration(huge_ptep_get((pte_t *)pmd))) {
			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);
4584 4585 4586
	return page;
}

4587
struct page * __weak
4588
follow_huge_pud(struct mm_struct *mm, unsigned long address,
4589
		pud_t *pud, int flags)
4590
{
4591 4592
	if (flags & FOLL_GET)
		return NULL;
4593

4594
	return pte_page(*(pte_t *)pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT);
4595 4596
}

4597 4598
#ifdef CONFIG_MEMORY_FAILURE

4599 4600 4601
/*
 * This function is called from memory failure code.
 */
4602
int dequeue_hwpoisoned_huge_page(struct page *hpage)
4603 4604 4605
{
	struct hstate *h = page_hstate(hpage);
	int nid = page_to_nid(hpage);
4606
	int ret = -EBUSY;
4607 4608

	spin_lock(&hugetlb_lock);
4609 4610 4611 4612 4613
	/*
	 * Just checking !page_huge_active is not enough, because that could be
	 * an isolated/hwpoisoned hugepage (which have >0 refcount).
	 */
	if (!page_huge_active(hpage) && !page_count(hpage)) {
4614 4615 4616 4617 4618 4619 4620
		/*
		 * Hwpoisoned hugepage isn't linked to activelist or freelist,
		 * but dangling hpage->lru can trigger list-debug warnings
		 * (this happens when we call unpoison_memory() on it),
		 * so let it point to itself with list_del_init().
		 */
		list_del_init(&hpage->lru);
4621
		set_page_refcounted(hpage);
4622 4623 4624 4625
		h->free_huge_pages--;
		h->free_huge_pages_node[nid]--;
		ret = 0;
	}
4626
	spin_unlock(&hugetlb_lock);
4627
	return ret;
4628
}
4629
#endif
4630 4631 4632

bool isolate_huge_page(struct page *page, struct list_head *list)
{
4633 4634
	bool ret = true;

4635
	VM_BUG_ON_PAGE(!PageHead(page), page);
4636
	spin_lock(&hugetlb_lock);
4637 4638 4639 4640 4641
	if (!page_huge_active(page) || !get_page_unless_zero(page)) {
		ret = false;
		goto unlock;
	}
	clear_page_huge_active(page);
4642
	list_move_tail(&page->lru, list);
4643
unlock:
4644
	spin_unlock(&hugetlb_lock);
4645
	return ret;
4646 4647 4648 4649
}

void putback_active_hugepage(struct page *page)
{
4650
	VM_BUG_ON_PAGE(!PageHead(page), page);
4651
	spin_lock(&hugetlb_lock);
4652
	set_page_huge_active(page);
4653 4654 4655 4656
	list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
	spin_unlock(&hugetlb_lock);
	put_page(page);
}