hugetlb.c 88.6 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/module.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/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 <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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const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
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static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
unsigned long 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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__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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/*
 * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
 */
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DEFINE_SPINLOCK(hugetlb_lock);
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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
	 * remain, free the subpool the subpool remain */
	if (free)
		kfree(spool);
}

struct hugepage_subpool *hugepage_new_subpool(long nr_blocks)
{
	struct hugepage_subpool *spool;

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

	spin_lock_init(&spool->lock);
	spool->count = 1;
	spool->max_hpages = nr_blocks;
	spool->used_hpages = 0;

	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);
}

static int hugepage_subpool_get_pages(struct hugepage_subpool *spool,
				      long delta)
{
	int ret = 0;

	if (!spool)
		return 0;

	spin_lock(&spool->lock);
	if ((spool->used_hpages + delta) <= spool->max_hpages) {
		spool->used_hpages += delta;
	} else {
		ret = -ENOMEM;
	}
	spin_unlock(&spool->lock);

	return ret;
}

static void hugepage_subpool_put_pages(struct hugepage_subpool *spool,
				       long delta)
{
	if (!spool)
		return;

	spin_lock(&spool->lock);
	spool->used_hpages -= delta;
	/* If hugetlbfs_put_super couldn't free spool due to
	* an outstanding quota reference, free it now. */
	unlock_or_release_subpool(spool);
}

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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 *
 * The region data structures are protected by a combination of the mmap_sem
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 * and the hugetlb_instantiation_mutex.  To access or modify a region the caller
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 * must either hold the mmap_sem for write, or the mmap_sem for read and
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 * the hugetlb_instantiation_mutex:
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 *
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 *	down_write(&mm->mmap_sem);
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 * or
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 *	down_read(&mm->mmap_sem);
 *	mutex_lock(&hugetlb_instantiation_mutex);
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 */
struct file_region {
	struct list_head link;
	long from;
	long to;
};

static long region_add(struct list_head *head, long f, long t)
{
	struct file_region *rg, *nrg, *trg;

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

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

	/* 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) {
			list_del(&rg->link);
			kfree(rg);
		}
	}
	nrg->from = f;
	nrg->to = t;
	return 0;
}

static long region_chg(struct list_head *head, long f, long t)
{
	struct file_region *rg, *nrg;
	long chg = 0;

	/* 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) {
		nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
		if (!nrg)
			return -ENOMEM;
		nrg->from = f;
		nrg->to   = f;
		INIT_LIST_HEAD(&nrg->link);
		list_add(&nrg->link, rg->link.prev);

		return t - f;
	}

	/* 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)
			return chg;

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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;
	}
	return chg;
}

static long region_truncate(struct list_head *head, long end)
{
	struct file_region *rg, *trg;
	long chg = 0;

	/* Locate the region we are either in or before. */
	list_for_each_entry(rg, head, link)
		if (end <= rg->to)
			break;
	if (&rg->link == head)
		return 0;

	/* If we are in the middle of a region then adjust it. */
	if (end > rg->from) {
		chg = rg->to - end;
		rg->to = end;
		rg = list_entry(rg->link.next, typeof(*rg), link);
	}

	/* Drop any remaining regions. */
	list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
		if (&rg->link == head)
			break;
		chg += rg->to - rg->from;
		list_del(&rg->link);
		kfree(rg);
	}
	return chg;
}

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static long region_count(struct list_head *head, long f, long t)
{
	struct file_region *rg;
	long chg = 0;

	/* 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;
	}

	return chg;
}

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

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

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/*
 * 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);

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	return 1UL << huge_page_shift(hstate);
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}
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EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
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/*
 * Return the page size being used by the MMU to back a VMA. In the majority
 * of cases, the page size used by the kernel matches the MMU size. On
 * 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

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/*
 * Flags for MAP_PRIVATE reservations.  These are stored in the bottom
 * bits of the reservation map pointer, which are always clear due to
 * alignment.
 */
#define HPAGE_RESV_OWNER    (1UL << 0)
#define HPAGE_RESV_UNMAPPED (1UL << 1)
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#define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
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/*
 * These helpers are used to track how many pages are reserved for
 * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
 * is guaranteed to have their future faults succeed.
 *
 * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
 * the reserve counters are updated with the hugetlb_lock held. It is safe
 * to reset the VMA at fork() time as it is not in use yet and there is no
 * chance of the global counters getting corrupted as a result of the values.
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 *
 * The private mapping reservation is represented in a subtly different
 * manner to a shared mapping.  A shared mapping has a region map associated
 * with the underlying file, this region map represents the backing file
 * pages which have ever had a reservation assigned which this persists even
 * after the page is instantiated.  A private mapping has a region map
 * associated with the original mmap which is attached to all VMAs which
 * reference it, this region map represents those offsets which have consumed
 * reservation ie. where pages have been instantiated.
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 */
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static unsigned long get_vma_private_data(struct vm_area_struct *vma)
{
	return (unsigned long)vma->vm_private_data;
}

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

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struct resv_map {
	struct kref refs;
	struct list_head regions;
};

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static struct resv_map *resv_map_alloc(void)
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{
	struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
	if (!resv_map)
		return NULL;

	kref_init(&resv_map->refs);
	INIT_LIST_HEAD(&resv_map->regions);

	return resv_map;
}

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static void resv_map_release(struct kref *ref)
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{
	struct resv_map *resv_map = container_of(ref, struct resv_map, refs);

	/* Clear out any active regions before we release the map. */
	region_truncate(&resv_map->regions, 0);
	kfree(resv_map);
}

static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
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{
	VM_BUG_ON(!is_vm_hugetlb_page(vma));
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	if (!(vma->vm_flags & VM_MAYSHARE))
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		return (struct resv_map *)(get_vma_private_data(vma) &
							~HPAGE_RESV_MASK);
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	return NULL;
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}

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static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
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{
	VM_BUG_ON(!is_vm_hugetlb_page(vma));
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	VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
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	set_vma_private_data(vma, (get_vma_private_data(vma) &
				HPAGE_RESV_MASK) | (unsigned long)map);
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}

static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
{
	VM_BUG_ON(!is_vm_hugetlb_page(vma));
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	VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
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	set_vma_private_data(vma, get_vma_private_data(vma) | flags);
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}

static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
{
	VM_BUG_ON(!is_vm_hugetlb_page(vma));
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	return (get_vma_private_data(vma) & flag) != 0;
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}

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/* Reset counters to 0 and clear all HPAGE_RESV_* flags */
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void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
{
	VM_BUG_ON(!is_vm_hugetlb_page(vma));
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	if (!(vma->vm_flags & VM_MAYSHARE))
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		vma->vm_private_data = (void *)0;
}

/* Returns true if the VMA has associated reserve pages */
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static int vma_has_reserves(struct vm_area_struct *vma, long chg)
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{
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	if (vma->vm_flags & VM_NORESERVE) {
		/*
		 * This address is already reserved by other process(chg == 0),
		 * so, we should decrement reserved count. Without decrementing,
		 * reserve count remains after releasing inode, because this
		 * allocated page will go into page cache and is regarded as
		 * coming from reserved pool in releasing step.  Currently, we
		 * don't have any other solution to deal with this situation
		 * properly, so add work-around here.
		 */
		if (vma->vm_flags & VM_MAYSHARE && chg == 0)
			return 1;
		else
			return 0;
	}
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	/* Shared mappings always use reserves */
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	if (vma->vm_flags & VM_MAYSHARE)
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		return 1;
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	/*
	 * Only the process that called mmap() has reserves for
	 * private mappings.
	 */
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	if (is_vma_resv_set(vma, HPAGE_RESV_OWNER))
		return 1;
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	return 0;
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}

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static void copy_gigantic_page(struct page *dst, struct page *src)
{
	int i;
	struct hstate *h = page_hstate(src);
	struct page *dst_base = dst;
	struct page *src_base = src;

	for (i = 0; i < pages_per_huge_page(h); ) {
		cond_resched();
		copy_highpage(dst, src);

		i++;
		dst = mem_map_next(dst, dst_base, i);
		src = mem_map_next(src, src_base, i);
	}
}

void copy_huge_page(struct page *dst, struct page *src)
{
	int i;
	struct hstate *h = page_hstate(src);

	if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) {
		copy_gigantic_page(dst, src);
		return;
	}

	might_sleep();
	for (i = 0; i < pages_per_huge_page(h); i++) {
		cond_resched();
		copy_highpage(dst + i, src + i);
	}
}

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static void enqueue_huge_page(struct hstate *h, struct page *page)
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{
	int nid = page_to_nid(page);
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	list_move(&page->lru, &h->hugepage_freelists[nid]);
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	h->free_huge_pages++;
	h->free_huge_pages_node[nid]++;
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}

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

	if (list_empty(&h->hugepage_freelists[nid]))
		return NULL;
	page = list_entry(h->hugepage_freelists[nid].next, struct page, lru);
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	list_move(&page->lru, &h->hugepage_activelist);
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	set_page_refcounted(page);
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	h->free_huge_pages--;
	h->free_huge_pages_node[nid]--;
	return page;
}

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static struct page *dequeue_huge_page_vma(struct hstate *h,
				struct vm_area_struct *vma,
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				unsigned long address, int avoid_reserve,
				long chg)
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{
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	struct page *page = NULL;
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	struct mempolicy *mpol;
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	nodemask_t *nodemask;
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	struct zonelist *zonelist;
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	struct zone *zone;
	struct zoneref *z;
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	unsigned int cpuset_mems_cookie;
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	/*
	 * 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
	 */
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	if (!vma_has_reserves(vma, chg) &&
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			h->free_huge_pages - h->resv_huge_pages == 0)
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		goto err;
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	/* If reserves cannot be used, ensure enough pages are in the pool */
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	if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
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		goto err;
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retry_cpuset:
	cpuset_mems_cookie = get_mems_allowed();
	zonelist = huge_zonelist(vma, address,
					htlb_alloc_mask, &mpol, &nodemask);

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	for_each_zone_zonelist_nodemask(zone, z, zonelist,
						MAX_NR_ZONES - 1, nodemask) {
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		if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask)) {
			page = dequeue_huge_page_node(h, zone_to_nid(zone));
			if (page) {
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				if (avoid_reserve)
					break;
				if (!vma_has_reserves(vma, chg))
					break;

				h->resv_huge_pages--;
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				break;
			}
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		}
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	}
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	mpol_cond_put(mpol);
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	if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
		goto retry_cpuset;
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	return page;
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err:
	return NULL;
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}

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static void update_and_free_page(struct hstate *h, struct page *page)
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{
	int i;
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	VM_BUG_ON(h->order >= MAX_ORDER);

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	h->nr_huge_pages--;
	h->nr_huge_pages_node[page_to_nid(page)]--;
	for (i = 0; i < pages_per_huge_page(h); i++) {
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		page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
				1 << PG_referenced | 1 << PG_dirty |
				1 << PG_active | 1 << PG_reserved |
				1 << PG_private | 1 << PG_writeback);
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	}
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	VM_BUG_ON(hugetlb_cgroup_from_page(page));
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	set_compound_page_dtor(page, NULL);
	set_page_refcounted(page);
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	arch_release_hugepage(page);
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	__free_pages(page, huge_page_order(h));
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}

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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;
}

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static void free_huge_page(struct page *page)
{
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	/*
	 * Can't pass hstate in here because it is called from the
	 * compound page destructor.
	 */
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	struct hstate *h = page_hstate(page);
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	int nid = page_to_nid(page);
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	struct hugepage_subpool *spool =
		(struct hugepage_subpool *)page_private(page);
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	set_page_private(page, 0);
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	page->mapping = NULL;
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	BUG_ON(page_count(page));
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	BUG_ON(page_mapcount(page));
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	spin_lock(&hugetlb_lock);
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	hugetlb_cgroup_uncharge_page(hstate_index(h),
				     pages_per_huge_page(h), page);
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	if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) {
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		/* remove the page from active list */
		list_del(&page->lru);
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		update_and_free_page(h, page);
		h->surplus_huge_pages--;
		h->surplus_huge_pages_node[nid]--;
647
	} else {
648
		arch_clear_hugepage_flags(page);
649
		enqueue_huge_page(h, page);
650
	}
651
	spin_unlock(&hugetlb_lock);
652
	hugepage_subpool_put_pages(spool, 1);
653 654
}

655
static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
656
{
657
	INIT_LIST_HEAD(&page->lru);
658 659
	set_compound_page_dtor(page, free_huge_page);
	spin_lock(&hugetlb_lock);
660
	set_hugetlb_cgroup(page, NULL);
661 662
	h->nr_huge_pages++;
	h->nr_huge_pages_node[nid]++;
663 664 665 666
	spin_unlock(&hugetlb_lock);
	put_page(page); /* free it into the hugepage allocator */
}

667 668 669 670 671 672 673 674 675 676 677
static void prep_compound_gigantic_page(struct page *page, unsigned long order)
{
	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);
	__SetPageHead(page);
	for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
		__SetPageTail(p);
678
		set_page_count(p, 0);
679 680 681 682
		p->first_page = page;
	}
}

A
Andrew Morton 已提交
683 684 685 686 687
/*
 * PageHuge() only returns true for hugetlbfs pages, but not for normal or
 * transparent huge pages.  See the PageTransHuge() documentation for more
 * details.
 */
688 689 690 691 692 693 694 695 696 697 698 699
int PageHuge(struct page *page)
{
	compound_page_dtor *dtor;

	if (!PageCompound(page))
		return 0;

	page = compound_head(page);
	dtor = get_compound_page_dtor(page);

	return dtor == free_huge_page;
}
700 701
EXPORT_SYMBOL_GPL(PageHuge);

702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718
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;
}

719
static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
L
Linus Torvalds 已提交
720 721
{
	struct page *page;
722

723 724 725
	if (h->order >= MAX_ORDER)
		return NULL;

726
	page = alloc_pages_exact_node(nid,
727 728
		htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
						__GFP_REPEAT|__GFP_NOWARN,
729
		huge_page_order(h));
L
Linus Torvalds 已提交
730
	if (page) {
731
		if (arch_prepare_hugepage(page)) {
732
			__free_pages(page, huge_page_order(h));
733
			return NULL;
734
		}
735
		prep_new_huge_page(h, page, nid);
L
Linus Torvalds 已提交
736
	}
737 738 739 740

	return page;
}

741
/*
742 743 744 745 746
 * 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.
747
 */
748
static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
749
{
750
	nid = next_node(nid, *nodes_allowed);
751
	if (nid == MAX_NUMNODES)
752
		nid = first_node(*nodes_allowed);
753 754 755 756 757
	VM_BUG_ON(nid >= MAX_NUMNODES);

	return nid;
}

758 759 760 761 762 763 764
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;
}

765
/*
766 767 768 769
 * 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.
770
 */
771 772
static int hstate_next_node_to_alloc(struct hstate *h,
					nodemask_t *nodes_allowed)
773
{
774 775 776 777 778 779
	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);
780 781

	return nid;
782 783
}

784
/*
785 786 787 788
 * 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.
789
 */
790
static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
791
{
792 793 794 795 796 797
	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);
798 799

	return nid;
800 801
}

802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835
#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--)

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;
}

836 837 838 839 840 841
/*
 * 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.
 */
842 843
static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
							 bool acct_surplus)
844
{
845
	int nr_nodes, node;
846 847
	int ret = 0;

848
	for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
849 850 851 852
		/*
		 * If we're returning unused surplus pages, only examine
		 * nodes with surplus pages.
		 */
853 854
		if ((!acct_surplus || h->surplus_huge_pages_node[node]) &&
		    !list_empty(&h->hugepage_freelists[node])) {
855
			struct page *page =
856
				list_entry(h->hugepage_freelists[node].next,
857 858 859
					  struct page, lru);
			list_del(&page->lru);
			h->free_huge_pages--;
860
			h->free_huge_pages_node[node]--;
861 862
			if (acct_surplus) {
				h->surplus_huge_pages--;
863
				h->surplus_huge_pages_node[node]--;
864
			}
865 866
			update_and_free_page(h, page);
			ret = 1;
867
			break;
868
		}
869
	}
870 871 872 873

	return ret;
}

874
static struct page *alloc_buddy_huge_page(struct hstate *h, int nid)
875 876
{
	struct page *page;
877
	unsigned int r_nid;
878

879 880 881
	if (h->order >= MAX_ORDER)
		return NULL;

882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905
	/*
	 * 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);
906
	if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
907 908 909
		spin_unlock(&hugetlb_lock);
		return NULL;
	} else {
910 911
		h->nr_huge_pages++;
		h->surplus_huge_pages++;
912 913 914
	}
	spin_unlock(&hugetlb_lock);

915 916 917 918 919 920 921 922
	if (nid == NUMA_NO_NODE)
		page = alloc_pages(htlb_alloc_mask|__GFP_COMP|
				   __GFP_REPEAT|__GFP_NOWARN,
				   huge_page_order(h));
	else
		page = alloc_pages_exact_node(nid,
			htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
			__GFP_REPEAT|__GFP_NOWARN, huge_page_order(h));
923

924 925
	if (page && arch_prepare_hugepage(page)) {
		__free_pages(page, huge_page_order(h));
926
		page = NULL;
927 928
	}

929
	spin_lock(&hugetlb_lock);
930
	if (page) {
931
		INIT_LIST_HEAD(&page->lru);
932
		r_nid = page_to_nid(page);
933
		set_compound_page_dtor(page, free_huge_page);
934
		set_hugetlb_cgroup(page, NULL);
935 936 937
		/*
		 * We incremented the global counters already
		 */
938 939
		h->nr_huge_pages_node[r_nid]++;
		h->surplus_huge_pages_node[r_nid]++;
940
		__count_vm_event(HTLB_BUDDY_PGALLOC);
941
	} else {
942 943
		h->nr_huge_pages--;
		h->surplus_huge_pages--;
944
		__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
945
	}
946
	spin_unlock(&hugetlb_lock);
947 948 949 950

	return page;
}

951 952 953 954 955 956 957
/*
 * 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)
{
958
	struct page *page = NULL;
959 960

	spin_lock(&hugetlb_lock);
961 962
	if (h->free_huge_pages - h->resv_huge_pages > 0)
		page = dequeue_huge_page_node(h, nid);
963 964
	spin_unlock(&hugetlb_lock);

965
	if (!page)
966 967 968 969 970
		page = alloc_buddy_huge_page(h, nid);

	return page;
}

971
/*
L
Lucas De Marchi 已提交
972
 * Increase the hugetlb pool such that it can accommodate a reservation
973 974
 * of size 'delta'.
 */
975
static int gather_surplus_pages(struct hstate *h, int delta)
976 977 978 979 980
{
	struct list_head surplus_list;
	struct page *page, *tmp;
	int ret, i;
	int needed, allocated;
981
	bool alloc_ok = true;
982

983
	needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
984
	if (needed <= 0) {
985
		h->resv_huge_pages += delta;
986
		return 0;
987
	}
988 989 990 991 992 993 994 995

	allocated = 0;
	INIT_LIST_HEAD(&surplus_list);

	ret = -ENOMEM;
retry:
	spin_unlock(&hugetlb_lock);
	for (i = 0; i < needed; i++) {
996
		page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
997 998 999 1000
		if (!page) {
			alloc_ok = false;
			break;
		}
1001 1002
		list_add(&page->lru, &surplus_list);
	}
1003
	allocated += i;
1004 1005 1006 1007 1008 1009

	/*
	 * 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);
1010 1011
	needed = (h->resv_huge_pages + delta) -
			(h->free_huge_pages + allocated);
1012 1013 1014 1015 1016 1017 1018 1019 1020 1021
	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;
	}
1022 1023
	/*
	 * The surplus_list now contains _at_least_ the number of extra pages
L
Lucas De Marchi 已提交
1024
	 * needed to accommodate the reservation.  Add the appropriate number
1025
	 * of pages to the hugetlb pool and free the extras back to the buddy
1026 1027 1028
	 * 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.
1029 1030
	 */
	needed += allocated;
1031
	h->resv_huge_pages += delta;
1032
	ret = 0;
1033

1034
	/* Free the needed pages to the hugetlb pool */
1035
	list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
1036 1037
		if ((--needed) < 0)
			break;
1038 1039 1040 1041 1042 1043
		/*
		 * This page is now managed by the hugetlb allocator and has
		 * no users -- drop the buddy allocator's reference.
		 */
		put_page_testzero(page);
		VM_BUG_ON(page_count(page));
1044
		enqueue_huge_page(h, page);
1045
	}
1046
free:
1047
	spin_unlock(&hugetlb_lock);
1048 1049

	/* Free unnecessary surplus pages to the buddy allocator */
1050 1051
	list_for_each_entry_safe(page, tmp, &surplus_list, lru)
		put_page(page);
1052
	spin_lock(&hugetlb_lock);
1053 1054 1055 1056 1057 1058 1059 1060

	return ret;
}

/*
 * When releasing a hugetlb pool reservation, any surplus pages that were
 * allocated to satisfy the reservation must be explicitly freed if they were
 * never used.
1061
 * Called with hugetlb_lock held.
1062
 */
1063 1064
static void return_unused_surplus_pages(struct hstate *h,
					unsigned long unused_resv_pages)
1065 1066 1067
{
	unsigned long nr_pages;

1068
	/* Uncommit the reservation */
1069
	h->resv_huge_pages -= unused_resv_pages;
1070

1071 1072 1073 1074
	/* Cannot return gigantic pages currently */
	if (h->order >= MAX_ORDER)
		return;

1075
	nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
1076

1077 1078
	/*
	 * We want to release as many surplus pages as possible, spread
1079 1080 1081 1082 1083
	 * 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.
1084 1085
	 */
	while (nr_pages--) {
1086
		if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1))
1087
			break;
1088 1089 1090
	}
}

1091 1092 1093
/*
 * Determine if the huge page at addr within the vma has an associated
 * reservation.  Where it does not we will need to logically increase
1094 1095 1096 1097 1098 1099
 * reservation and actually increase subpool usage before an allocation
 * can occur.  Where any new reservation would be required the
 * reservation change is prepared, but not committed.  Once the page
 * has been allocated from the subpool and instantiated the change should
 * be committed via vma_commit_reservation.  No action is required on
 * failure.
1100
 */
1101
static long vma_needs_reservation(struct hstate *h,
1102
			struct vm_area_struct *vma, unsigned long addr)
1103 1104 1105 1106
{
	struct address_space *mapping = vma->vm_file->f_mapping;
	struct inode *inode = mapping->host;

1107
	if (vma->vm_flags & VM_MAYSHARE) {
1108
		pgoff_t idx = vma_hugecache_offset(h, vma, addr);
1109 1110 1111
		return region_chg(&inode->i_mapping->private_list,
							idx, idx + 1);

1112 1113
	} else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
		return 1;
1114

1115
	} else  {
1116
		long err;
1117
		pgoff_t idx = vma_hugecache_offset(h, vma, addr);
1118
		struct resv_map *resv = vma_resv_map(vma);
1119

1120
		err = region_chg(&resv->regions, idx, idx + 1);
1121 1122 1123 1124
		if (err < 0)
			return err;
		return 0;
	}
1125
}
1126 1127
static void vma_commit_reservation(struct hstate *h,
			struct vm_area_struct *vma, unsigned long addr)
1128 1129 1130 1131
{
	struct address_space *mapping = vma->vm_file->f_mapping;
	struct inode *inode = mapping->host;

1132
	if (vma->vm_flags & VM_MAYSHARE) {
1133
		pgoff_t idx = vma_hugecache_offset(h, vma, addr);
1134
		region_add(&inode->i_mapping->private_list, idx, idx + 1);
1135 1136

	} else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
1137
		pgoff_t idx = vma_hugecache_offset(h, vma, addr);
1138
		struct resv_map *resv = vma_resv_map(vma);
1139 1140

		/* Mark this page used in the map. */
1141
		region_add(&resv->regions, idx, idx + 1);
1142 1143 1144
	}
}

1145
static struct page *alloc_huge_page(struct vm_area_struct *vma,
1146
				    unsigned long addr, int avoid_reserve)
L
Linus Torvalds 已提交
1147
{
1148
	struct hugepage_subpool *spool = subpool_vma(vma);
1149
	struct hstate *h = hstate_vma(vma);
1150
	struct page *page;
1151
	long chg;
1152 1153
	int ret, idx;
	struct hugetlb_cgroup *h_cg;
1154

1155
	idx = hstate_index(h);
1156
	/*
1157 1158 1159 1160 1161 1162
	 * Processes that did not create the mapping will have no
	 * reserves and will not have accounted against subpool
	 * limit. Check that the subpool limit can be made before
	 * satisfying the allocation MAP_NORESERVE mappings may also
	 * need pages and subpool limit allocated allocated if no reserve
	 * mapping overlaps.
1163
	 */
1164
	chg = vma_needs_reservation(h, vma, addr);
1165
	if (chg < 0)
1166
		return ERR_PTR(-ENOMEM);
1167 1168
	if (chg || avoid_reserve)
		if (hugepage_subpool_get_pages(spool, 1))
1169
			return ERR_PTR(-ENOSPC);
L
Linus Torvalds 已提交
1170

1171 1172
	ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
	if (ret) {
1173 1174
		if (chg || avoid_reserve)
			hugepage_subpool_put_pages(spool, 1);
1175 1176
		return ERR_PTR(-ENOSPC);
	}
L
Linus Torvalds 已提交
1177
	spin_lock(&hugetlb_lock);
1178
	page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, chg);
1179
	if (!page) {
1180
		spin_unlock(&hugetlb_lock);
1181
		page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
K
Ken Chen 已提交
1182
		if (!page) {
1183 1184 1185
			hugetlb_cgroup_uncharge_cgroup(idx,
						       pages_per_huge_page(h),
						       h_cg);
1186 1187
			if (chg || avoid_reserve)
				hugepage_subpool_put_pages(spool, 1);
1188
			return ERR_PTR(-ENOSPC);
K
Ken Chen 已提交
1189
		}
1190 1191
		spin_lock(&hugetlb_lock);
		list_move(&page->lru, &h->hugepage_activelist);
1192
		/* Fall through */
K
Ken Chen 已提交
1193
	}
1194 1195
	hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
	spin_unlock(&hugetlb_lock);
1196

1197
	set_page_private(page, (unsigned long)spool);
1198

1199
	vma_commit_reservation(h, vma, addr);
1200
	return page;
1201 1202
}

1203
int __weak alloc_bootmem_huge_page(struct hstate *h)
1204 1205
{
	struct huge_bootmem_page *m;
1206
	int nr_nodes, node;
1207

1208
	for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) {
1209 1210
		void *addr;

1211
		addr = __alloc_bootmem_node_nopanic(NODE_DATA(node),
1212 1213 1214 1215 1216 1217 1218 1219 1220
				huge_page_size(h), huge_page_size(h), 0);

		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;
1221
			goto found;
1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233
		}
	}
	return 0;

found:
	BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1));
	/* 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;
}

1234 1235 1236 1237 1238 1239 1240 1241
static void prep_compound_huge_page(struct page *page, int order)
{
	if (unlikely(order > (MAX_ORDER - 1)))
		prep_compound_gigantic_page(page, order);
	else
		prep_compound_page(page, order);
}

1242 1243 1244 1245 1246 1247 1248
/* 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;
1249 1250 1251 1252 1253 1254 1255 1256 1257
		struct page *page;

#ifdef CONFIG_HIGHMEM
		page = pfn_to_page(m->phys >> PAGE_SHIFT);
		free_bootmem_late((unsigned long)m,
				  sizeof(struct huge_bootmem_page));
#else
		page = virt_to_page(m);
#endif
1258 1259
		__ClearPageReserved(page);
		WARN_ON(page_count(page) != 1);
1260
		prep_compound_huge_page(page, h->order);
1261
		prep_new_huge_page(h, page, page_to_nid(page));
1262 1263 1264 1265 1266 1267 1268
		/*
		 * 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.
		 */
		if (h->order > (MAX_ORDER - 1))
1269
			adjust_managed_page_count(page, 1 << h->order);
1270 1271 1272
	}
}

1273
static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
L
Linus Torvalds 已提交
1274 1275
{
	unsigned long i;
1276

1277
	for (i = 0; i < h->max_huge_pages; ++i) {
1278 1279 1280
		if (h->order >= MAX_ORDER) {
			if (!alloc_bootmem_huge_page(h))
				break;
1281
		} else if (!alloc_fresh_huge_page(h,
1282
					 &node_states[N_MEMORY]))
L
Linus Torvalds 已提交
1283 1284
			break;
	}
1285
	h->max_huge_pages = i;
1286 1287 1288 1289 1290 1291 1292
}

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

	for_each_hstate(h) {
1293 1294 1295
		/* oversize hugepages were init'ed in early boot */
		if (h->order < MAX_ORDER)
			hugetlb_hstate_alloc_pages(h);
1296 1297 1298
	}
}

A
Andi Kleen 已提交
1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309
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;
}

1310 1311 1312 1313 1314
static void __init report_hugepages(void)
{
	struct hstate *h;

	for_each_hstate(h) {
A
Andi Kleen 已提交
1315
		char buf[32];
1316
		pr_info("HugeTLB registered %s page size, pre-allocated %ld pages\n",
A
Andi Kleen 已提交
1317 1318
			memfmt(buf, huge_page_size(h)),
			h->free_huge_pages);
1319 1320 1321
	}
}

L
Linus Torvalds 已提交
1322
#ifdef CONFIG_HIGHMEM
1323 1324
static void try_to_free_low(struct hstate *h, unsigned long count,
						nodemask_t *nodes_allowed)
L
Linus Torvalds 已提交
1325
{
1326 1327
	int i;

1328 1329 1330
	if (h->order >= MAX_ORDER)
		return;

1331
	for_each_node_mask(i, *nodes_allowed) {
L
Linus Torvalds 已提交
1332
		struct page *page, *next;
1333 1334 1335
		struct list_head *freel = &h->hugepage_freelists[i];
		list_for_each_entry_safe(page, next, freel, lru) {
			if (count >= h->nr_huge_pages)
1336
				return;
L
Linus Torvalds 已提交
1337 1338 1339
			if (PageHighMem(page))
				continue;
			list_del(&page->lru);
1340
			update_and_free_page(h, page);
1341 1342
			h->free_huge_pages--;
			h->free_huge_pages_node[page_to_nid(page)]--;
L
Linus Torvalds 已提交
1343 1344 1345 1346
		}
	}
}
#else
1347 1348
static inline void try_to_free_low(struct hstate *h, unsigned long count,
						nodemask_t *nodes_allowed)
L
Linus Torvalds 已提交
1349 1350 1351 1352
{
}
#endif

1353 1354 1355 1356 1357
/*
 * 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.
 */
1358 1359
static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
				int delta)
1360
{
1361
	int nr_nodes, node;
1362 1363 1364

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

1365 1366 1367 1368
	if (delta < 0) {
		for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
			if (h->surplus_huge_pages_node[node])
				goto found;
1369
		}
1370 1371 1372 1373 1374
	} 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;
1375
		}
1376 1377
	}
	return 0;
1378

1379 1380 1381 1382
found:
	h->surplus_huge_pages += delta;
	h->surplus_huge_pages_node[node] += delta;
	return 1;
1383 1384
}

1385
#define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
1386 1387
static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
						nodemask_t *nodes_allowed)
L
Linus Torvalds 已提交
1388
{
1389
	unsigned long min_count, ret;
L
Linus Torvalds 已提交
1390

1391 1392 1393
	if (h->order >= MAX_ORDER)
		return h->max_huge_pages;

1394 1395 1396 1397
	/*
	 * Increase the pool size
	 * First take pages out of surplus state.  Then make up the
	 * remaining difference by allocating fresh huge pages.
1398 1399 1400 1401 1402 1403
	 *
	 * We might race with alloc_buddy_huge_page() here and be unable
	 * 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.
1404
	 */
L
Linus Torvalds 已提交
1405
	spin_lock(&hugetlb_lock);
1406
	while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
1407
		if (!adjust_pool_surplus(h, nodes_allowed, -1))
1408 1409 1410
			break;
	}

1411
	while (count > persistent_huge_pages(h)) {
1412 1413 1414 1415 1416 1417
		/*
		 * 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);
1418
		ret = alloc_fresh_huge_page(h, nodes_allowed);
1419 1420 1421 1422
		spin_lock(&hugetlb_lock);
		if (!ret)
			goto out;

1423 1424 1425
		/* Bail for signals. Probably ctrl-c from user */
		if (signal_pending(current))
			goto out;
1426 1427 1428 1429 1430 1431 1432 1433
	}

	/*
	 * 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.
1434 1435 1436 1437 1438 1439 1440 1441
	 *
	 * 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
	 * alloc_buddy_huge_page() is checking the global counter,
	 * 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.
1442
	 */
1443
	min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
1444
	min_count = max(count, min_count);
1445
	try_to_free_low(h, min_count, nodes_allowed);
1446
	while (min_count < persistent_huge_pages(h)) {
1447
		if (!free_pool_huge_page(h, nodes_allowed, 0))
L
Linus Torvalds 已提交
1448 1449
			break;
	}
1450
	while (count < persistent_huge_pages(h)) {
1451
		if (!adjust_pool_surplus(h, nodes_allowed, 1))
1452 1453 1454
			break;
	}
out:
1455
	ret = persistent_huge_pages(h);
L
Linus Torvalds 已提交
1456
	spin_unlock(&hugetlb_lock);
1457
	return ret;
L
Linus Torvalds 已提交
1458 1459
}

1460 1461 1462 1463 1464 1465 1466 1467 1468 1469
#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];

1470 1471 1472
static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);

static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
1473 1474
{
	int i;
1475

1476
	for (i = 0; i < HUGE_MAX_HSTATE; i++)
1477 1478 1479
		if (hstate_kobjs[i] == kobj) {
			if (nidp)
				*nidp = NUMA_NO_NODE;
1480
			return &hstates[i];
1481 1482 1483
		}

	return kobj_to_node_hstate(kobj, nidp);
1484 1485
}

1486
static ssize_t nr_hugepages_show_common(struct kobject *kobj,
1487 1488
					struct kobj_attribute *attr, char *buf)
{
1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499
	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);
1500
}
1501

1502 1503 1504
static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
			struct kobject *kobj, struct kobj_attribute *attr,
			const char *buf, size_t len)
1505 1506
{
	int err;
1507
	int nid;
1508
	unsigned long count;
1509
	struct hstate *h;
1510
	NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
1511

1512
	err = kstrtoul(buf, 10, &count);
1513
	if (err)
1514
		goto out;
1515

1516
	h = kobj_to_hstate(kobj, &nid);
1517 1518 1519 1520 1521
	if (h->order >= MAX_ORDER) {
		err = -EINVAL;
		goto out;
	}

1522 1523 1524 1525 1526 1527 1528
	if (nid == NUMA_NO_NODE) {
		/*
		 * global hstate attribute
		 */
		if (!(obey_mempolicy &&
				init_nodemask_of_mempolicy(nodes_allowed))) {
			NODEMASK_FREE(nodes_allowed);
1529
			nodes_allowed = &node_states[N_MEMORY];
1530 1531 1532 1533 1534 1535 1536 1537 1538
		}
	} 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
1539
		nodes_allowed = &node_states[N_MEMORY];
1540

1541
	h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
1542

1543
	if (nodes_allowed != &node_states[N_MEMORY])
1544 1545 1546
		NODEMASK_FREE(nodes_allowed);

	return len;
1547 1548 1549
out:
	NODEMASK_FREE(nodes_allowed);
	return err;
1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561
}

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)
{
	return nr_hugepages_store_common(false, kobj, attr, buf, len);
1562 1563 1564
}
HSTATE_ATTR(nr_hugepages);

1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585
#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)
{
	return nr_hugepages_store_common(true, kobj, attr, buf, len);
}
HSTATE_ATTR(nr_hugepages_mempolicy);
#endif


1586 1587 1588
static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
					struct kobj_attribute *attr, char *buf)
{
1589
	struct hstate *h = kobj_to_hstate(kobj, NULL);
1590 1591
	return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
}
1592

1593 1594 1595 1596 1597
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;
1598
	struct hstate *h = kobj_to_hstate(kobj, NULL);
1599

1600 1601 1602
	if (h->order >= MAX_ORDER)
		return -EINVAL;

1603
	err = kstrtoul(buf, 10, &input);
1604
	if (err)
1605
		return err;
1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617

	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)
{
1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628
	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);
1629 1630 1631 1632 1633 1634
}
HSTATE_ATTR_RO(free_hugepages);

static ssize_t resv_hugepages_show(struct kobject *kobj,
					struct kobj_attribute *attr, char *buf)
{
1635
	struct hstate *h = kobj_to_hstate(kobj, NULL);
1636 1637 1638 1639 1640 1641 1642
	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)
{
1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653
	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);
1654 1655 1656 1657 1658 1659 1660 1661 1662
}
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,
1663 1664 1665
#ifdef CONFIG_NUMA
	&nr_hugepages_mempolicy_attr.attr,
#endif
1666 1667 1668 1669 1670 1671 1672
	NULL,
};

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

J
Jeff Mahoney 已提交
1673 1674 1675
static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
				    struct kobject **hstate_kobjs,
				    struct attribute_group *hstate_attr_group)
1676 1677
{
	int retval;
1678
	int hi = hstate_index(h);
1679

1680 1681
	hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
	if (!hstate_kobjs[hi])
1682 1683
		return -ENOMEM;

1684
	retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
1685
	if (retval)
1686
		kobject_put(hstate_kobjs[hi]);
1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700

	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) {
1701 1702
		err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
					 hstate_kobjs, &hstate_attr_group);
1703
		if (err)
1704
			pr_err("Hugetlb: Unable to add hstate %s", h->name);
1705 1706 1707
	}
}

1708 1709 1710 1711
#ifdef CONFIG_NUMA

/*
 * node_hstate/s - associate per node hstate attributes, via their kobjects,
1712 1713 1714
 * 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
1715 1716 1717 1718 1719 1720 1721 1722 1723
 * the base kernel, on the hugetlb module.
 */
struct node_hstate {
	struct kobject		*hugepages_kobj;
	struct kobject		*hstate_kobjs[HUGE_MAX_HSTATE];
};
struct node_hstate node_hstates[MAX_NUMNODES];

/*
1724
 * A subset of global hstate attributes for node devices
1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737
 */
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,
};

/*
1738
 * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760
 * 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;
}

/*
1761
 * Unregister hstate attributes from a single node device.
1762 1763
 * No-op if no hstate attributes attached.
 */
1764
static void hugetlb_unregister_node(struct node *node)
1765 1766
{
	struct hstate *h;
1767
	struct node_hstate *nhs = &node_hstates[node->dev.id];
1768 1769

	if (!nhs->hugepages_kobj)
1770
		return;		/* no hstate attributes */
1771

1772 1773 1774 1775 1776
	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;
1777
		}
1778
	}
1779 1780 1781 1782 1783 1784

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

/*
1785
 * hugetlb module exit:  unregister hstate attributes from node devices
1786 1787 1788 1789 1790 1791 1792
 * that have them.
 */
static void hugetlb_unregister_all_nodes(void)
{
	int nid;

	/*
1793
	 * disable node device registrations.
1794 1795 1796 1797 1798 1799 1800
	 */
	register_hugetlbfs_with_node(NULL, NULL);

	/*
	 * remove hstate attributes from any nodes that have them.
	 */
	for (nid = 0; nid < nr_node_ids; nid++)
1801
		hugetlb_unregister_node(node_devices[nid]);
1802 1803 1804
}

/*
1805
 * Register hstate attributes for a single node device.
1806 1807
 * No-op if attributes already registered.
 */
1808
static void hugetlb_register_node(struct node *node)
1809 1810
{
	struct hstate *h;
1811
	struct node_hstate *nhs = &node_hstates[node->dev.id];
1812 1813 1814 1815 1816 1817
	int err;

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

	nhs->hugepages_kobj = kobject_create_and_add("hugepages",
1818
							&node->dev.kobj);
1819 1820 1821 1822 1823 1824 1825 1826
	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) {
1827 1828
			pr_err("Hugetlb: Unable to add hstate %s for node %d\n",
				h->name, node->dev.id);
1829 1830 1831 1832 1833 1834 1835
			hugetlb_unregister_node(node);
			break;
		}
	}
}

/*
1836
 * hugetlb init time:  register hstate attributes for all registered node
1837 1838
 * devices of nodes that have memory.  All on-line nodes should have
 * registered their associated device by this time.
1839 1840 1841 1842 1843
 */
static void hugetlb_register_all_nodes(void)
{
	int nid;

1844
	for_each_node_state(nid, N_MEMORY) {
1845
		struct node *node = node_devices[nid];
1846
		if (node->dev.id == nid)
1847 1848 1849 1850
			hugetlb_register_node(node);
	}

	/*
1851
	 * Let the node device driver know we're here so it can
1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872
	 * [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_unregister_all_nodes(void) { }

static void hugetlb_register_all_nodes(void) { }

#endif

1873 1874 1875 1876
static void __exit hugetlb_exit(void)
{
	struct hstate *h;

1877 1878
	hugetlb_unregister_all_nodes();

1879
	for_each_hstate(h) {
1880
		kobject_put(hstate_kobjs[hstate_index(h)]);
1881 1882 1883 1884 1885 1886 1887 1888
	}

	kobject_put(hugepages_kobj);
}
module_exit(hugetlb_exit);

static int __init hugetlb_init(void)
{
1889 1890 1891 1892 1893 1894
	/* Some platform decide whether they support huge pages at boot
	 * time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when
	 * there is no such support
	 */
	if (HPAGE_SHIFT == 0)
		return 0;
1895

1896 1897 1898 1899
	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);
1900
	}
1901
	default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
1902 1903
	if (default_hstate_max_huge_pages)
		default_hstate.max_huge_pages = default_hstate_max_huge_pages;
1904 1905

	hugetlb_init_hstates();
1906
	gather_bootmem_prealloc();
1907 1908 1909
	report_hugepages();

	hugetlb_sysfs_init();
1910
	hugetlb_register_all_nodes();
1911
	hugetlb_cgroup_file_init();
1912

1913 1914 1915 1916 1917 1918 1919 1920
	return 0;
}
module_init(hugetlb_init);

/* Should be called on processing a hugepagesz=... option */
void __init hugetlb_add_hstate(unsigned order)
{
	struct hstate *h;
1921 1922
	unsigned long i;

1923
	if (size_to_hstate(PAGE_SIZE << order)) {
1924
		pr_warning("hugepagesz= specified twice, ignoring\n");
1925 1926
		return;
	}
1927
	BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
1928
	BUG_ON(order == 0);
1929
	h = &hstates[hugetlb_max_hstate++];
1930 1931
	h->order = order;
	h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
1932 1933 1934 1935
	h->nr_huge_pages = 0;
	h->free_huge_pages = 0;
	for (i = 0; i < MAX_NUMNODES; ++i)
		INIT_LIST_HEAD(&h->hugepage_freelists[i]);
1936
	INIT_LIST_HEAD(&h->hugepage_activelist);
1937 1938
	h->next_nid_to_alloc = first_node(node_states[N_MEMORY]);
	h->next_nid_to_free = first_node(node_states[N_MEMORY]);
1939 1940
	snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
					huge_page_size(h)/1024);
1941

1942 1943 1944
	parsed_hstate = h;
}

1945
static int __init hugetlb_nrpages_setup(char *s)
1946 1947
{
	unsigned long *mhp;
1948
	static unsigned long *last_mhp;
1949 1950

	/*
1951
	 * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
1952 1953
	 * so this hugepages= parameter goes to the "default hstate".
	 */
1954
	if (!hugetlb_max_hstate)
1955 1956 1957 1958
		mhp = &default_hstate_max_huge_pages;
	else
		mhp = &parsed_hstate->max_huge_pages;

1959
	if (mhp == last_mhp) {
1960 1961
		pr_warning("hugepages= specified twice without "
			   "interleaving hugepagesz=, ignoring\n");
1962 1963 1964
		return 1;
	}

1965 1966 1967
	if (sscanf(s, "%lu", mhp) <= 0)
		*mhp = 0;

1968 1969 1970 1971 1972
	/*
	 * 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.
	 */
1973
	if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER)
1974 1975 1976 1977
		hugetlb_hstate_alloc_pages(parsed_hstate);

	last_mhp = mhp;

1978 1979
	return 1;
}
1980 1981 1982 1983 1984 1985 1986 1987
__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);
1988

1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000
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
2001 2002 2003
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
2004
{
2005 2006
	struct hstate *h = &default_hstate;
	unsigned long tmp;
2007
	int ret;
2008

2009
	tmp = h->max_huge_pages;
2010

2011 2012 2013
	if (write && h->order >= MAX_ORDER)
		return -EINVAL;

2014 2015
	table->data = &tmp;
	table->maxlen = sizeof(unsigned long);
2016 2017 2018
	ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
	if (ret)
		goto out;
2019

2020
	if (write) {
2021 2022
		NODEMASK_ALLOC(nodemask_t, nodes_allowed,
						GFP_KERNEL | __GFP_NORETRY);
2023 2024 2025
		if (!(obey_mempolicy &&
			       init_nodemask_of_mempolicy(nodes_allowed))) {
			NODEMASK_FREE(nodes_allowed);
2026
			nodes_allowed = &node_states[N_MEMORY];
2027 2028 2029
		}
		h->max_huge_pages = set_max_huge_pages(h, tmp, nodes_allowed);

2030
		if (nodes_allowed != &node_states[N_MEMORY])
2031 2032
			NODEMASK_FREE(nodes_allowed);
	}
2033 2034
out:
	return ret;
L
Linus Torvalds 已提交
2035
}
2036

2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053
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 */

2054
int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
2055
			void __user *buffer,
2056 2057
			size_t *length, loff_t *ppos)
{
2058
	proc_dointvec(table, write, buffer, length, ppos);
2059 2060 2061 2062 2063 2064 2065
	if (hugepages_treat_as_movable)
		htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
	else
		htlb_alloc_mask = GFP_HIGHUSER;
	return 0;
}

2066
int hugetlb_overcommit_handler(struct ctl_table *table, int write,
2067
			void __user *buffer,
2068 2069
			size_t *length, loff_t *ppos)
{
2070
	struct hstate *h = &default_hstate;
2071
	unsigned long tmp;
2072
	int ret;
2073

2074
	tmp = h->nr_overcommit_huge_pages;
2075

2076 2077 2078
	if (write && h->order >= MAX_ORDER)
		return -EINVAL;

2079 2080
	table->data = &tmp;
	table->maxlen = sizeof(unsigned long);
2081 2082 2083
	ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
	if (ret)
		goto out;
2084 2085 2086 2087 2088 2089

	if (write) {
		spin_lock(&hugetlb_lock);
		h->nr_overcommit_huge_pages = tmp;
		spin_unlock(&hugetlb_lock);
	}
2090 2091
out:
	return ret;
2092 2093
}

L
Linus Torvalds 已提交
2094 2095
#endif /* CONFIG_SYSCTL */

2096
void hugetlb_report_meminfo(struct seq_file *m)
L
Linus Torvalds 已提交
2097
{
2098
	struct hstate *h = &default_hstate;
2099
	seq_printf(m,
2100 2101 2102 2103 2104
			"HugePages_Total:   %5lu\n"
			"HugePages_Free:    %5lu\n"
			"HugePages_Rsvd:    %5lu\n"
			"HugePages_Surp:    %5lu\n"
			"Hugepagesize:   %8lu kB\n",
2105 2106 2107 2108 2109
			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
2110 2111 2112 2113
}

int hugetlb_report_node_meminfo(int nid, char *buf)
{
2114
	struct hstate *h = &default_hstate;
L
Linus Torvalds 已提交
2115 2116
	return sprintf(buf,
		"Node %d HugePages_Total: %5u\n"
2117 2118
		"Node %d HugePages_Free:  %5u\n"
		"Node %d HugePages_Surp:  %5u\n",
2119 2120 2121
		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
2122 2123
}

2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138
void hugetlb_show_meminfo(void)
{
	struct hstate *h;
	int nid;

	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));
}

L
Linus Torvalds 已提交
2139 2140 2141
/* Return the number pages of memory we physically have, in PAGE_SIZE units. */
unsigned long hugetlb_total_pages(void)
{
2142 2143 2144 2145 2146 2147
	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
2148 2149
}

2150
static int hugetlb_acct_memory(struct hstate *h, long delta)
M
Mel Gorman 已提交
2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172
{
	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) {
2173
		if (gather_surplus_pages(h, delta) < 0)
M
Mel Gorman 已提交
2174 2175
			goto out;

2176 2177
		if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
			return_unused_surplus_pages(h, delta);
M
Mel Gorman 已提交
2178 2179 2180 2181 2182 2183
			goto out;
		}
	}

	ret = 0;
	if (delta < 0)
2184
		return_unused_surplus_pages(h, (unsigned long) -delta);
M
Mel Gorman 已提交
2185 2186 2187 2188 2189 2190

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

2191 2192
static void hugetlb_vm_op_open(struct vm_area_struct *vma)
{
2193
	struct resv_map *resv = vma_resv_map(vma);
2194 2195 2196 2197 2198

	/*
	 * 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
2199
	 * has a reference to the reservation map it cannot disappear until
2200 2201 2202
	 * after this open call completes.  It is therefore safe to take a
	 * new reference here without additional locking.
	 */
2203 2204
	if (resv)
		kref_get(&resv->refs);
2205 2206
}

2207 2208
static void resv_map_put(struct vm_area_struct *vma)
{
2209
	struct resv_map *resv = vma_resv_map(vma);
2210

2211
	if (!resv)
2212
		return;
2213
	kref_put(&resv->refs, resv_map_release);
2214 2215
}

2216 2217
static void hugetlb_vm_op_close(struct vm_area_struct *vma)
{
2218
	struct hstate *h = hstate_vma(vma);
2219
	struct resv_map *resv = vma_resv_map(vma);
2220
	struct hugepage_subpool *spool = subpool_vma(vma);
2221 2222 2223 2224
	unsigned long reserve;
	unsigned long start;
	unsigned long end;

2225
	if (resv) {
2226 2227
		start = vma_hugecache_offset(h, vma, vma->vm_start);
		end = vma_hugecache_offset(h, vma, vma->vm_end);
2228 2229

		reserve = (end - start) -
2230
			region_count(&resv->regions, start, end);
2231

2232
		resv_map_put(vma);
2233

2234
		if (reserve) {
2235
			hugetlb_acct_memory(h, -reserve);
2236
			hugepage_subpool_put_pages(spool, reserve);
2237
		}
2238
	}
2239 2240
}

L
Linus Torvalds 已提交
2241 2242 2243 2244 2245 2246
/*
 * 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
2247
static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
L
Linus Torvalds 已提交
2248 2249
{
	BUG();
N
Nick Piggin 已提交
2250
	return 0;
L
Linus Torvalds 已提交
2251 2252
}

2253
const struct vm_operations_struct hugetlb_vm_ops = {
N
Nick Piggin 已提交
2254
	.fault = hugetlb_vm_op_fault,
2255
	.open = hugetlb_vm_op_open,
2256
	.close = hugetlb_vm_op_close,
L
Linus Torvalds 已提交
2257 2258
};

2259 2260
static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
				int writable)
D
David Gibson 已提交
2261 2262 2263
{
	pte_t entry;

2264
	if (writable) {
2265 2266
		entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page,
					 vma->vm_page_prot)));
D
David Gibson 已提交
2267
	} else {
2268 2269
		entry = huge_pte_wrprotect(mk_huge_pte(page,
					   vma->vm_page_prot));
D
David Gibson 已提交
2270 2271 2272
	}
	entry = pte_mkyoung(entry);
	entry = pte_mkhuge(entry);
2273
	entry = arch_make_huge_pte(entry, vma, page, writable);
D
David Gibson 已提交
2274 2275 2276 2277

	return entry;
}

2278 2279 2280 2281 2282
static void set_huge_ptep_writable(struct vm_area_struct *vma,
				   unsigned long address, pte_t *ptep)
{
	pte_t entry;

2283
	entry = huge_pte_mkwrite(huge_pte_mkdirty(huge_ptep_get(ptep)));
2284
	if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
2285
		update_mmu_cache(vma, address, ptep);
2286 2287 2288
}


D
David Gibson 已提交
2289 2290 2291 2292 2293
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;
2294
	unsigned long addr;
2295
	int cow;
2296 2297
	struct hstate *h = hstate_vma(vma);
	unsigned long sz = huge_page_size(h);
2298 2299

	cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
D
David Gibson 已提交
2300

2301
	for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
H
Hugh Dickins 已提交
2302 2303 2304
		src_pte = huge_pte_offset(src, addr);
		if (!src_pte)
			continue;
2305
		dst_pte = huge_pte_alloc(dst, addr, sz);
D
David Gibson 已提交
2306 2307
		if (!dst_pte)
			goto nomem;
2308 2309 2310 2311 2312

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

H
Hugh Dickins 已提交
2313
		spin_lock(&dst->page_table_lock);
N
Nick Piggin 已提交
2314
		spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING);
2315
		if (!huge_pte_none(huge_ptep_get(src_pte))) {
2316
			if (cow)
2317 2318
				huge_ptep_set_wrprotect(src, addr, src_pte);
			entry = huge_ptep_get(src_pte);
2319 2320
			ptepage = pte_page(entry);
			get_page(ptepage);
2321
			page_dup_rmap(ptepage);
2322 2323 2324
			set_huge_pte_at(dst, addr, dst_pte, entry);
		}
		spin_unlock(&src->page_table_lock);
H
Hugh Dickins 已提交
2325
		spin_unlock(&dst->page_table_lock);
D
David Gibson 已提交
2326 2327 2328 2329 2330 2331 2332
	}
	return 0;

nomem:
	return -ENOMEM;
}

N
Naoya Horiguchi 已提交
2333 2334 2335 2336 2337 2338 2339
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);
2340
	if (non_swap_entry(swp) && is_migration_entry(swp))
N
Naoya Horiguchi 已提交
2341
		return 1;
2342
	else
N
Naoya Horiguchi 已提交
2343 2344 2345
		return 0;
}

2346 2347 2348 2349 2350 2351 2352
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);
2353
	if (non_swap_entry(swp) && is_hwpoison_entry(swp))
2354
		return 1;
2355
	else
2356 2357 2358
		return 0;
}

2359 2360 2361
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
2362
{
2363
	int force_flush = 0;
D
David Gibson 已提交
2364 2365
	struct mm_struct *mm = vma->vm_mm;
	unsigned long address;
2366
	pte_t *ptep;
D
David Gibson 已提交
2367 2368
	pte_t pte;
	struct page *page;
2369 2370
	struct hstate *h = hstate_vma(vma);
	unsigned long sz = huge_page_size(h);
2371 2372
	const unsigned long mmun_start = start;	/* For mmu_notifiers */
	const unsigned long mmun_end   = end;	/* For mmu_notifiers */
2373

D
David Gibson 已提交
2374
	WARN_ON(!is_vm_hugetlb_page(vma));
2375 2376
	BUG_ON(start & ~huge_page_mask(h));
	BUG_ON(end & ~huge_page_mask(h));
D
David Gibson 已提交
2377

2378
	tlb_start_vma(tlb, vma);
2379
	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2380
again:
2381
	spin_lock(&mm->page_table_lock);
2382
	for (address = start; address < end; address += sz) {
2383
		ptep = huge_pte_offset(mm, address);
A
Adam Litke 已提交
2384
		if (!ptep)
2385 2386
			continue;

2387 2388 2389
		if (huge_pmd_unshare(mm, &address, ptep))
			continue;

2390 2391 2392 2393 2394 2395 2396
		pte = huge_ptep_get(ptep);
		if (huge_pte_none(pte))
			continue;

		/*
		 * HWPoisoned hugepage is already unmapped and dropped reference
		 */
2397
		if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) {
2398
			huge_pte_clear(mm, address, ptep);
2399
			continue;
2400
		}
2401 2402

		page = pte_page(pte);
2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419
		/*
		 * 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) {
			if (page != ref_page)
				continue;

			/*
			 * 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);
		}

2420
		pte = huge_ptep_get_and_clear(mm, address, ptep);
2421
		tlb_remove_tlb_entry(tlb, ptep, address);
2422
		if (huge_pte_dirty(pte))
2423
			set_page_dirty(page);
2424

2425 2426 2427 2428
		page_remove_rmap(page);
		force_flush = !__tlb_remove_page(tlb, page);
		if (force_flush)
			break;
2429 2430 2431
		/* Bail out after unmapping reference page if supplied */
		if (ref_page)
			break;
D
David Gibson 已提交
2432
	}
2433
	spin_unlock(&mm->page_table_lock);
2434 2435 2436 2437 2438 2439 2440 2441 2442 2443
	/*
	 * mmu_gather ran out of room to batch pages, we break out of
	 * the PTE lock to avoid doing the potential expensive TLB invalidate
	 * and page-free while holding it.
	 */
	if (force_flush) {
		force_flush = 0;
		tlb_flush_mmu(tlb);
		if (address < end && !ref_page)
			goto again;
2444
	}
2445
	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2446
	tlb_end_vma(tlb, vma);
L
Linus Torvalds 已提交
2447
}
D
David Gibson 已提交
2448

2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467
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
	 * is to clear it before releasing the i_mmap_mutex. This works
	 * because in the context this is called, the VMA is about to be
	 * destroyed and the i_mmap_mutex is held.
	 */
	vma->vm_flags &= ~VM_MAYSHARE;
}

2468
void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
2469
			  unsigned long end, struct page *ref_page)
2470
{
2471 2472 2473 2474 2475
	struct mm_struct *mm;
	struct mmu_gather tlb;

	mm = vma->vm_mm;

2476
	tlb_gather_mmu(&tlb, mm, start, end);
2477 2478
	__unmap_hugepage_range(&tlb, vma, start, end, ref_page);
	tlb_finish_mmu(&tlb, start, end);
2479 2480
}

2481 2482 2483 2484 2485 2486
/*
 * 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.
 */
2487 2488
static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
				struct page *page, unsigned long address)
2489
{
2490
	struct hstate *h = hstate_vma(vma);
2491 2492 2493 2494 2495 2496 2497 2498
	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.
	 */
2499
	address = address & huge_page_mask(h);
2500 2501
	pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
			vma->vm_pgoff;
A
Al Viro 已提交
2502
	mapping = file_inode(vma->vm_file)->i_mapping;
2503

2504 2505 2506 2507 2508
	/*
	 * 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
	 */
2509
	mutex_lock(&mapping->i_mmap_mutex);
2510
	vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) {
2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521 2522
		/* Do not unmap the current VMA */
		if (iter_vma == vma)
			continue;

		/*
		 * 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))
2523 2524
			unmap_hugepage_range(iter_vma, address,
					     address + huge_page_size(h), page);
2525
	}
2526
	mutex_unlock(&mapping->i_mmap_mutex);
2527 2528 2529 2530

	return 1;
}

2531 2532
/*
 * Hugetlb_cow() should be called with page lock of the original hugepage held.
2533 2534 2535
 * 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.
2536
 */
2537
static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
2538 2539
			unsigned long address, pte_t *ptep, pte_t pte,
			struct page *pagecache_page)
2540
{
2541
	struct hstate *h = hstate_vma(vma);
2542
	struct page *old_page, *new_page;
2543
	int outside_reserve = 0;
2544 2545
	unsigned long mmun_start;	/* For mmu_notifiers */
	unsigned long mmun_end;		/* For mmu_notifiers */
2546 2547 2548

	old_page = pte_page(pte);

2549
retry_avoidcopy:
2550 2551
	/* If no-one else is actually using this page, avoid the copy
	 * and just make the page writable */
2552 2553
	if (page_mapcount(old_page) == 1 && PageAnon(old_page)) {
		page_move_anon_rmap(old_page, vma, address);
2554
		set_huge_ptep_writable(vma, address, ptep);
N
Nick Piggin 已提交
2555
		return 0;
2556 2557
	}

2558 2559 2560 2561 2562 2563 2564 2565 2566
	/*
	 * 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.
	 */
2567
	if (!(vma->vm_flags & VM_MAYSHARE) &&
2568 2569 2570 2571
			is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
			old_page != pagecache_page)
		outside_reserve = 1;

2572
	page_cache_get(old_page);
2573 2574 2575

	/* Drop page_table_lock as buddy allocator may be called */
	spin_unlock(&mm->page_table_lock);
2576
	new_page = alloc_huge_page(vma, address, outside_reserve);
2577

2578
	if (IS_ERR(new_page)) {
2579
		long err = PTR_ERR(new_page);
2580
		page_cache_release(old_page);
2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592

		/*
		 * 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) {
			BUG_ON(huge_pte_none(pte));
			if (unmap_ref_private(mm, vma, old_page, address)) {
				BUG_ON(huge_pte_none(pte));
2593
				spin_lock(&mm->page_table_lock);
2594 2595 2596 2597 2598 2599 2600 2601
				ptep = huge_pte_offset(mm, address & huge_page_mask(h));
				if (likely(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;
2602 2603 2604 2605
			}
			WARN_ON_ONCE(1);
		}

2606 2607
		/* Caller expects lock to be held */
		spin_lock(&mm->page_table_lock);
2608 2609 2610 2611
		if (err == -ENOMEM)
			return VM_FAULT_OOM;
		else
			return VM_FAULT_SIGBUS;
2612 2613
	}

2614 2615 2616 2617
	/*
	 * When the original hugepage is shared one, it does not have
	 * anon_vma prepared.
	 */
2618
	if (unlikely(anon_vma_prepare(vma))) {
2619 2620
		page_cache_release(new_page);
		page_cache_release(old_page);
2621 2622
		/* Caller expects lock to be held */
		spin_lock(&mm->page_table_lock);
2623
		return VM_FAULT_OOM;
2624
	}
2625

A
Andrea Arcangeli 已提交
2626 2627
	copy_user_huge_page(new_page, old_page, address, vma,
			    pages_per_huge_page(h));
N
Nick Piggin 已提交
2628
	__SetPageUptodate(new_page);
2629

2630 2631 2632
	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);
2633 2634 2635 2636 2637
	/*
	 * Retake the page_table_lock to check for racing updates
	 * before the page tables are altered
	 */
	spin_lock(&mm->page_table_lock);
2638
	ptep = huge_pte_offset(mm, address & huge_page_mask(h));
2639
	if (likely(pte_same(huge_ptep_get(ptep), pte))) {
2640
		/* Break COW */
2641
		huge_ptep_clear_flush(vma, address, ptep);
2642 2643
		set_huge_pte_at(mm, address, ptep,
				make_huge_pte(vma, new_page, 1));
2644
		page_remove_rmap(old_page);
2645
		hugepage_add_new_anon_rmap(new_page, vma, address);
2646 2647 2648
		/* Make the old page be freed below */
		new_page = old_page;
	}
2649 2650 2651 2652
	spin_unlock(&mm->page_table_lock);
	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
	/* Caller expects lock to be held */
	spin_lock(&mm->page_table_lock);
2653 2654
	page_cache_release(new_page);
	page_cache_release(old_page);
N
Nick Piggin 已提交
2655
	return 0;
2656 2657
}

2658
/* Return the pagecache page at a given address within a VMA */
2659 2660
static struct page *hugetlbfs_pagecache_page(struct hstate *h,
			struct vm_area_struct *vma, unsigned long address)
2661 2662
{
	struct address_space *mapping;
2663
	pgoff_t idx;
2664 2665

	mapping = vma->vm_file->f_mapping;
2666
	idx = vma_hugecache_offset(h, vma, address);
2667 2668 2669 2670

	return find_lock_page(mapping, idx);
}

H
Hugh Dickins 已提交
2671 2672 2673 2674 2675
/*
 * 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
2676 2677 2678 2679 2680 2681 2682 2683 2684 2685 2686 2687 2688 2689 2690
			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;
}

2691
static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
2692
			unsigned long address, pte_t *ptep, unsigned int flags)
2693
{
2694
	struct hstate *h = hstate_vma(vma);
2695
	int ret = VM_FAULT_SIGBUS;
2696
	int anon_rmap = 0;
2697
	pgoff_t idx;
A
Adam Litke 已提交
2698 2699 2700
	unsigned long size;
	struct page *page;
	struct address_space *mapping;
2701
	pte_t new_pte;
A
Adam Litke 已提交
2702

2703 2704 2705
	/*
	 * 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
2706
	 * COW. Warn that such a situation has occurred as it may not be obvious
2707 2708
	 */
	if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
2709 2710
		pr_warning("PID %d killed due to inadequate hugepage pool\n",
			   current->pid);
2711 2712 2713
		return ret;
	}

A
Adam Litke 已提交
2714
	mapping = vma->vm_file->f_mapping;
2715
	idx = vma_hugecache_offset(h, vma, address);
A
Adam Litke 已提交
2716 2717 2718 2719 2720

	/*
	 * Use page lock to guard against racing truncation
	 * before we get page_table_lock.
	 */
2721 2722 2723
retry:
	page = find_lock_page(mapping, idx);
	if (!page) {
2724
		size = i_size_read(mapping->host) >> huge_page_shift(h);
2725 2726
		if (idx >= size)
			goto out;
2727
		page = alloc_huge_page(vma, address, 0);
2728
		if (IS_ERR(page)) {
2729 2730 2731 2732 2733
			ret = PTR_ERR(page);
			if (ret == -ENOMEM)
				ret = VM_FAULT_OOM;
			else
				ret = VM_FAULT_SIGBUS;
2734 2735
			goto out;
		}
A
Andrea Arcangeli 已提交
2736
		clear_huge_page(page, address, pages_per_huge_page(h));
N
Nick Piggin 已提交
2737
		__SetPageUptodate(page);
2738

2739
		if (vma->vm_flags & VM_MAYSHARE) {
2740
			int err;
K
Ken Chen 已提交
2741
			struct inode *inode = mapping->host;
2742 2743 2744 2745 2746 2747 2748 2749

			err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
			if (err) {
				put_page(page);
				if (err == -EEXIST)
					goto retry;
				goto out;
			}
K
Ken Chen 已提交
2750 2751

			spin_lock(&inode->i_lock);
2752
			inode->i_blocks += blocks_per_huge_page(h);
K
Ken Chen 已提交
2753
			spin_unlock(&inode->i_lock);
2754
		} else {
2755
			lock_page(page);
2756 2757 2758 2759
			if (unlikely(anon_vma_prepare(vma))) {
				ret = VM_FAULT_OOM;
				goto backout_unlocked;
			}
2760
			anon_rmap = 1;
2761
		}
2762
	} else {
2763 2764 2765 2766 2767 2768
		/*
		 * 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))) {
2769
			ret = VM_FAULT_HWPOISON |
2770
				VM_FAULT_SET_HINDEX(hstate_index(h));
2771 2772
			goto backout_unlocked;
		}
2773
	}
2774

2775 2776 2777 2778 2779 2780
	/*
	 * 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.
	 */
2781
	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
2782 2783 2784 2785
		if (vma_needs_reservation(h, vma, address) < 0) {
			ret = VM_FAULT_OOM;
			goto backout_unlocked;
		}
2786

2787
	spin_lock(&mm->page_table_lock);
2788
	size = i_size_read(mapping->host) >> huge_page_shift(h);
A
Adam Litke 已提交
2789 2790 2791
	if (idx >= size)
		goto backout;

N
Nick Piggin 已提交
2792
	ret = 0;
2793
	if (!huge_pte_none(huge_ptep_get(ptep)))
A
Adam Litke 已提交
2794 2795
		goto backout;

2796 2797 2798 2799
	if (anon_rmap)
		hugepage_add_new_anon_rmap(page, vma, address);
	else
		page_dup_rmap(page);
2800 2801 2802 2803
	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);

2804
	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
2805
		/* Optimization, do the COW without a second fault */
2806
		ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page);
2807 2808
	}

2809
	spin_unlock(&mm->page_table_lock);
A
Adam Litke 已提交
2810 2811
	unlock_page(page);
out:
2812
	return ret;
A
Adam Litke 已提交
2813 2814 2815

backout:
	spin_unlock(&mm->page_table_lock);
2816
backout_unlocked:
A
Adam Litke 已提交
2817 2818 2819
	unlock_page(page);
	put_page(page);
	goto out;
2820 2821
}

2822
int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2823
			unsigned long address, unsigned int flags)
2824 2825 2826
{
	pte_t *ptep;
	pte_t entry;
2827
	int ret;
2828
	struct page *page = NULL;
2829
	struct page *pagecache_page = NULL;
2830
	static DEFINE_MUTEX(hugetlb_instantiation_mutex);
2831
	struct hstate *h = hstate_vma(vma);
2832

2833 2834
	address &= huge_page_mask(h);

2835 2836 2837
	ptep = huge_pte_offset(mm, address);
	if (ptep) {
		entry = huge_ptep_get(ptep);
N
Naoya Horiguchi 已提交
2838
		if (unlikely(is_hugetlb_entry_migration(entry))) {
2839
			migration_entry_wait_huge(mm, ptep);
N
Naoya Horiguchi 已提交
2840 2841
			return 0;
		} else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
2842
			return VM_FAULT_HWPOISON_LARGE |
2843
				VM_FAULT_SET_HINDEX(hstate_index(h));
2844 2845
	}

2846
	ptep = huge_pte_alloc(mm, address, huge_page_size(h));
2847 2848 2849
	if (!ptep)
		return VM_FAULT_OOM;

2850 2851 2852 2853 2854 2855
	/*
	 * 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.
	 */
	mutex_lock(&hugetlb_instantiation_mutex);
2856 2857
	entry = huge_ptep_get(ptep);
	if (huge_pte_none(entry)) {
2858
		ret = hugetlb_no_page(mm, vma, address, ptep, flags);
2859
		goto out_mutex;
2860
	}
2861

N
Nick Piggin 已提交
2862
	ret = 0;
2863

2864 2865 2866 2867 2868 2869 2870 2871
	/*
	 * 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.
	 */
2872
	if ((flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) {
2873 2874
		if (vma_needs_reservation(h, vma, address) < 0) {
			ret = VM_FAULT_OOM;
2875
			goto out_mutex;
2876
		}
2877

2878
		if (!(vma->vm_flags & VM_MAYSHARE))
2879 2880 2881 2882
			pagecache_page = hugetlbfs_pagecache_page(h,
								vma, address);
	}

2883 2884 2885 2886 2887 2888 2889 2890
	/*
	 * 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.
	 * Note that locking order is always pagecache_page -> page,
	 * so no worry about deadlock.
	 */
	page = pte_page(entry);
2891
	get_page(page);
2892
	if (page != pagecache_page)
2893 2894
		lock_page(page);

2895 2896
	spin_lock(&mm->page_table_lock);
	/* Check for a racing update before calling hugetlb_cow */
2897 2898 2899 2900
	if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
		goto out_page_table_lock;


2901
	if (flags & FAULT_FLAG_WRITE) {
2902
		if (!huge_pte_write(entry)) {
2903 2904
			ret = hugetlb_cow(mm, vma, address, ptep, entry,
							pagecache_page);
2905 2906
			goto out_page_table_lock;
		}
2907
		entry = huge_pte_mkdirty(entry);
2908 2909
	}
	entry = pte_mkyoung(entry);
2910 2911
	if (huge_ptep_set_access_flags(vma, address, ptep, entry,
						flags & FAULT_FLAG_WRITE))
2912
		update_mmu_cache(vma, address, ptep);
2913 2914

out_page_table_lock:
2915
	spin_unlock(&mm->page_table_lock);
2916 2917 2918 2919 2920

	if (pagecache_page) {
		unlock_page(pagecache_page);
		put_page(pagecache_page);
	}
2921 2922
	if (page != pagecache_page)
		unlock_page(page);
2923
	put_page(page);
2924

2925
out_mutex:
2926
	mutex_unlock(&hugetlb_instantiation_mutex);
2927 2928

	return ret;
2929 2930
}

2931 2932 2933 2934
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
2935
{
2936 2937
	unsigned long pfn_offset;
	unsigned long vaddr = *position;
2938
	unsigned long remainder = *nr_pages;
2939
	struct hstate *h = hstate_vma(vma);
D
David Gibson 已提交
2940

2941
	spin_lock(&mm->page_table_lock);
D
David Gibson 已提交
2942
	while (vaddr < vma->vm_end && remainder) {
A
Adam Litke 已提交
2943
		pte_t *pte;
H
Hugh Dickins 已提交
2944
		int absent;
A
Adam Litke 已提交
2945
		struct page *page;
D
David Gibson 已提交
2946

A
Adam Litke 已提交
2947 2948
		/*
		 * Some archs (sparc64, sh*) have multiple pte_ts to
H
Hugh Dickins 已提交
2949
		 * each hugepage.  We have to make sure we get the
A
Adam Litke 已提交
2950 2951
		 * first, for the page indexing below to work.
		 */
2952
		pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
H
Hugh Dickins 已提交
2953 2954 2955 2956
		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
2957 2958 2959 2960
		 * 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
2961
		 */
H
Hugh Dickins 已提交
2962 2963
		if (absent && (flags & FOLL_DUMP) &&
		    !hugetlbfs_pagecache_present(h, vma, vaddr)) {
H
Hugh Dickins 已提交
2964 2965 2966
			remainder = 0;
			break;
		}
D
David Gibson 已提交
2967

2968 2969 2970 2971 2972 2973 2974 2975 2976 2977 2978
		/*
		 * 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)) ||
2979 2980
		    ((flags & FOLL_WRITE) &&
		      !huge_pte_write(huge_ptep_get(pte)))) {
A
Adam Litke 已提交
2981
			int ret;
D
David Gibson 已提交
2982

A
Adam Litke 已提交
2983
			spin_unlock(&mm->page_table_lock);
H
Hugh Dickins 已提交
2984 2985
			ret = hugetlb_fault(mm, vma, vaddr,
				(flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
A
Adam Litke 已提交
2986
			spin_lock(&mm->page_table_lock);
2987
			if (!(ret & VM_FAULT_ERROR))
A
Adam Litke 已提交
2988
				continue;
D
David Gibson 已提交
2989

A
Adam Litke 已提交
2990 2991 2992 2993
			remainder = 0;
			break;
		}

2994
		pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
2995
		page = pte_page(huge_ptep_get(pte));
2996
same_page:
2997
		if (pages) {
H
Hugh Dickins 已提交
2998
			pages[i] = mem_map_offset(page, pfn_offset);
K
KOSAKI Motohiro 已提交
2999
			get_page(pages[i]);
3000
		}
D
David Gibson 已提交
3001 3002 3003 3004 3005

		if (vmas)
			vmas[i] = vma;

		vaddr += PAGE_SIZE;
3006
		++pfn_offset;
D
David Gibson 已提交
3007 3008
		--remainder;
		++i;
3009
		if (vaddr < vma->vm_end && remainder &&
3010
				pfn_offset < pages_per_huge_page(h)) {
3011 3012 3013 3014 3015 3016
			/*
			 * We use pfn_offset to avoid touching the pageframes
			 * of this compound page.
			 */
			goto same_page;
		}
D
David Gibson 已提交
3017
	}
3018
	spin_unlock(&mm->page_table_lock);
3019
	*nr_pages = remainder;
D
David Gibson 已提交
3020 3021
	*position = vaddr;

H
Hugh Dickins 已提交
3022
	return i ? i : -EFAULT;
D
David Gibson 已提交
3023
}
3024

3025
unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
3026 3027 3028 3029 3030 3031
		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;
3032
	struct hstate *h = hstate_vma(vma);
3033
	unsigned long pages = 0;
3034 3035 3036 3037

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

3038
	mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
3039
	spin_lock(&mm->page_table_lock);
3040
	for (; address < end; address += huge_page_size(h)) {
3041 3042 3043
		ptep = huge_pte_offset(mm, address);
		if (!ptep)
			continue;
3044 3045
		if (huge_pmd_unshare(mm, &address, ptep)) {
			pages++;
3046
			continue;
3047
		}
3048
		if (!huge_pte_none(huge_ptep_get(ptep))) {
3049
			pte = huge_ptep_get_and_clear(mm, address, ptep);
3050
			pte = pte_mkhuge(huge_pte_modify(pte, newprot));
3051
			pte = arch_make_huge_pte(pte, vma, NULL, 0);
3052
			set_huge_pte_at(mm, address, ptep, pte);
3053
			pages++;
3054 3055 3056
		}
	}
	spin_unlock(&mm->page_table_lock);
3057 3058 3059 3060 3061 3062
	/*
	 * Must flush TLB before releasing i_mmap_mutex: x86's huge_pmd_unshare
	 * may have cleared our pud entry and done put_page on the page table:
	 * once we release i_mmap_mutex, another task can do the final put_page
	 * and that page table be reused and filled with junk.
	 */
3063
	flush_tlb_range(vma, start, end);
3064
	mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
3065 3066

	return pages << h->order;
3067 3068
}

3069 3070
int hugetlb_reserve_pages(struct inode *inode,
					long from, long to,
3071
					struct vm_area_struct *vma,
3072
					vm_flags_t vm_flags)
3073
{
3074
	long ret, chg;
3075
	struct hstate *h = hstate_inode(inode);
3076
	struct hugepage_subpool *spool = subpool_inode(inode);
3077

3078 3079 3080
	/*
	 * Only apply hugepage reservation if asked. At fault time, an
	 * attempt will be made for VM_NORESERVE to allocate a page
3081
	 * without using reserves
3082
	 */
3083
	if (vm_flags & VM_NORESERVE)
3084 3085
		return 0;

3086 3087 3088 3089 3090 3091
	/*
	 * 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
	 */
3092
	if (!vma || vma->vm_flags & VM_MAYSHARE)
3093
		chg = region_chg(&inode->i_mapping->private_list, from, to);
3094 3095 3096 3097 3098
	else {
		struct resv_map *resv_map = resv_map_alloc();
		if (!resv_map)
			return -ENOMEM;

3099
		chg = to - from;
3100

3101 3102 3103 3104
		set_vma_resv_map(vma, resv_map);
		set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
	}

3105 3106 3107 3108
	if (chg < 0) {
		ret = chg;
		goto out_err;
	}
3109

3110
	/* There must be enough pages in the subpool for the mapping */
3111 3112 3113 3114
	if (hugepage_subpool_get_pages(spool, chg)) {
		ret = -ENOSPC;
		goto out_err;
	}
3115 3116

	/*
3117
	 * Check enough hugepages are available for the reservation.
3118
	 * Hand the pages back to the subpool if there are not
3119
	 */
3120
	ret = hugetlb_acct_memory(h, chg);
K
Ken Chen 已提交
3121
	if (ret < 0) {
3122
		hugepage_subpool_put_pages(spool, chg);
3123
		goto out_err;
K
Ken Chen 已提交
3124
	}
3125 3126 3127 3128 3129 3130 3131 3132 3133 3134 3135 3136

	/*
	 * 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
	 */
3137
	if (!vma || vma->vm_flags & VM_MAYSHARE)
3138
		region_add(&inode->i_mapping->private_list, from, to);
3139
	return 0;
3140
out_err:
3141 3142
	if (vma)
		resv_map_put(vma);
3143
	return ret;
3144 3145 3146 3147
}

void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
{
3148
	struct hstate *h = hstate_inode(inode);
3149
	long chg = region_truncate(&inode->i_mapping->private_list, offset);
3150
	struct hugepage_subpool *spool = subpool_inode(inode);
K
Ken Chen 已提交
3151 3152

	spin_lock(&inode->i_lock);
3153
	inode->i_blocks -= (blocks_per_huge_page(h) * freed);
K
Ken Chen 已提交
3154 3155
	spin_unlock(&inode->i_lock);

3156
	hugepage_subpool_put_pages(spool, (chg - freed));
3157
	hugetlb_acct_memory(h, -(chg - freed));
3158
}
3159

3160 3161 3162 3163 3164 3165 3166 3167 3168 3169 3170 3171 3172 3173 3174 3175 3176 3177 3178 3179 3180 3181 3182 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 3210 3211 3212 3213 3214 3215 3216 3217 3218 3219 3220 3221 3222 3223 3224 3225 3226 3227 3228 3229 3230 3231 3232 3233 3234 3235 3236 3237 3238 3239 3240 3241 3242 3243 3244 3245 3246 3247 3248 3249 3250 3251 3252 3253 3254 3255 3256 3257 3258 3259 3260 3261 3262 3263 3264 3265 3266 3267 3268 3269 3270 3271 3272 3273 3274 3275 3276 3277 3278 3279
#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 */
	unsigned long vm_flags = vma->vm_flags & ~VM_LOCKED;
	unsigned long svm_flags = svma->vm_flags & ~VM_LOCKED;

	/*
	 * 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;
}

static int vma_shareable(struct vm_area_struct *vma, unsigned long addr)
{
	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)
		return 1;
	return 0;
}

/*
 * 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
 * pud has to be populated inside the same i_mmap_mutex section - otherwise
 * 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;

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

	mutex_lock(&mapping->i_mmap_mutex);
	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;

	spin_lock(&mm->page_table_lock);
	if (pud_none(*pud))
		pud_populate(mm, pud,
				(pmd_t *)((unsigned long)spte & PAGE_MASK));
	else
		put_page(virt_to_page(spte));
	spin_unlock(&mm->page_table_lock);
out:
	pte = (pte_t *)pmd_alloc(mm, pud, addr);
	mutex_unlock(&mapping->i_mmap_mutex);
	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.
 *
 * called with vma->vm_mm->page_table_lock held.
 *
 * 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));
	*addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
	return 1;
}
3280 3281 3282 3283 3284 3285 3286
#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;
}
#define want_pmd_share()	(0)
3287 3288
#endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */

3289 3290 3291 3292 3293 3294 3295 3296 3297 3298 3299 3300 3301 3302 3303 3304 3305 3306 3307 3308 3309 3310 3311 3312 3313 3314 3315 3316 3317 3318 3319 3320 3321 3322 3323 3324 3325 3326 3327 3328 3329 3330 3331 3332 3333 3334 3335 3336 3337 3338 3339 3340 3341 3342 3343 3344 3345 3346 3347 3348 3349 3350 3351 3352 3353 3354 3355 3356 3357 3358 3359 3360 3361 3362 3363 3364 3365 3366 3367 3368 3369
#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);
		}
	}
	BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte));

	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;
}

struct page *
follow_huge_pmd(struct mm_struct *mm, unsigned long address,
		pmd_t *pmd, int write)
{
	struct page *page;

	page = pte_page(*(pte_t *)pmd);
	if (page)
		page += ((address & ~PMD_MASK) >> PAGE_SHIFT);
	return page;
}

struct page *
follow_huge_pud(struct mm_struct *mm, unsigned long address,
		pud_t *pud, int write)
{
	struct page *page;

	page = pte_page(*(pte_t *)pud);
	if (page)
		page += ((address & ~PUD_MASK) >> PAGE_SHIFT);
	return page;
}

#else /* !CONFIG_ARCH_WANT_GENERAL_HUGETLB */

/* Can be overriden by architectures */
__attribute__((weak)) struct page *
follow_huge_pud(struct mm_struct *mm, unsigned long address,
	       pud_t *pud, int write)
{
	BUG();
	return NULL;
}

#endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */

3370 3371
#ifdef CONFIG_MEMORY_FAILURE

3372 3373 3374 3375 3376 3377 3378 3379 3380 3381 3382 3383 3384 3385
/* Should be called in hugetlb_lock */
static int is_hugepage_on_freelist(struct page *hpage)
{
	struct page *page;
	struct page *tmp;
	struct hstate *h = page_hstate(hpage);
	int nid = page_to_nid(hpage);

	list_for_each_entry_safe(page, tmp, &h->hugepage_freelists[nid], lru)
		if (page == hpage)
			return 1;
	return 0;
}

3386 3387 3388 3389
/*
 * This function is called from memory failure code.
 * Assume the caller holds page lock of the head page.
 */
3390
int dequeue_hwpoisoned_huge_page(struct page *hpage)
3391 3392 3393
{
	struct hstate *h = page_hstate(hpage);
	int nid = page_to_nid(hpage);
3394
	int ret = -EBUSY;
3395 3396

	spin_lock(&hugetlb_lock);
3397
	if (is_hugepage_on_freelist(hpage)) {
3398 3399 3400 3401 3402 3403 3404
		/*
		 * 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);
3405
		set_page_refcounted(hpage);
3406 3407 3408 3409
		h->free_huge_pages--;
		h->free_huge_pages_node[nid]--;
		ret = 0;
	}
3410
	spin_unlock(&hugetlb_lock);
3411
	return ret;
3412
}
3413
#endif