diff --git a/ap/os/linux/linux-3.4.x/mm/hugetlb.c b/ap/os/linux/linux-3.4.x/mm/hugetlb.c
new file mode 100644
index 0000000..bc36e28
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/mm/hugetlb.c
@@ -0,0 +1,3216 @@
+/*
+ * Generic hugetlb support.
+ * (C) William Irwin, April 2004
+ */
+#include <linux/list.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/seq_file.h>
+#include <linux/sysctl.h>
+#include <linux/highmem.h>
+#include <linux/mmu_notifier.h>
+#include <linux/nodemask.h>
+#include <linux/pagemap.h>
+#include <linux/mempolicy.h>
+#include <linux/cpuset.h>
+#include <linux/mutex.h>
+#include <linux/bootmem.h>
+#include <linux/sysfs.h>
+#include <linux/slab.h>
+#include <linux/rmap.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <linux/io.h>
+
+#include <linux/hugetlb.h>
+#include <linux/node.h>
+#include "internal.h"
+
+const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
+static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
+unsigned long hugepages_treat_as_movable;
+
+static int max_hstate;
+unsigned int default_hstate_idx;
+struct hstate hstates[HUGE_MAX_HSTATE];
+
+__initdata LIST_HEAD(huge_boot_pages);
+
+/* for command line parsing */
+static struct hstate * __initdata parsed_hstate;
+static unsigned long __initdata default_hstate_max_huge_pages;
+static unsigned long __initdata default_hstate_size;
+
+#define for_each_hstate(h) \
+	for ((h) = hstates; (h) < &hstates[max_hstate]; (h)++)
+
+/*
+ * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
+ */
+static DEFINE_SPINLOCK(hugetlb_lock);
+
+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)
+{
+	return subpool_inode(vma->vm_file->f_dentry->d_inode);
+}
+
+/*
+ * Region tracking -- allows tracking of reservations and instantiated pages
+ *                    across the pages in a mapping.
+ *
+ * The region data structures are protected by a combination of the mmap_sem
+ * and the hugetlb_instantion_mutex.  To access or modify a region the caller
+ * must either hold the mmap_sem for write, or the mmap_sem for read and
+ * the hugetlb_instantiation mutex:
+ *
+ *	down_write(&mm->mmap_sem);
+ * or
+ *	down_read(&mm->mmap_sem);
+ *	mutex_lock(&hugetlb_instantiation_mutex);
+ */
+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;
+
+		/* We overlap with this area, if it extends further than
+		 * us then we must extend ourselves.  Account for its
+		 * existing reservation. */
+		if (rg->to > t) {
+			chg += rg->to - t;
+			t = rg->to;
+		}
+		chg -= rg->to - rg->from;
+	}
+	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;
+}
+
+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) {
+		int seg_from;
+		int seg_to;
+
+		if (rg->to <= f)
+			continue;
+		if (rg->from >= t)
+			break;
+
+		seg_from = max(rg->from, f);
+		seg_to = min(rg->to, t);
+
+		chg += seg_to - seg_from;
+	}
+
+	return chg;
+}
+
+/*
+ * Convert the address within this vma to the page offset within
+ * the mapping, in pagecache page units; huge pages here.
+ */
+static pgoff_t vma_hugecache_offset(struct hstate *h,
+			struct vm_area_struct *vma, unsigned long address)
+{
+	return ((address - vma->vm_start) >> huge_page_shift(h)) +
+			(vma->vm_pgoff >> huge_page_order(h));
+}
+
+pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
+				     unsigned long address)
+{
+	return vma_hugecache_offset(hstate_vma(vma), vma, address);
+}
+
+/*
+ * 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);
+
+	return 1UL << (hstate->order + PAGE_SHIFT);
+}
+EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
+
+/*
+ * Return the page size being used by the MMU to back a VMA. In the majority
+ * of cases, the page size used by the kernel matches the MMU size. On
+ * architectures where it differs, an architecture-specific 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
+
+/*
+ * Flags for MAP_PRIVATE reservations.  These are stored in the bottom
+ * bits of the reservation map pointer, which are always clear due to
+ * alignment.
+ */
+#define HPAGE_RESV_OWNER    (1UL << 0)
+#define HPAGE_RESV_UNMAPPED (1UL << 1)
+#define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
+
+/*
+ * These helpers are used to track how many pages are reserved for
+ * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
+ * is guaranteed to have their future faults succeed.
+ *
+ * With the exception of 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.
+ *
+ * The private mapping reservation is represented in a subtly different
+ * manner to a shared mapping.  A shared mapping has a region map associated
+ * with the underlying file, this region map represents the backing file
+ * pages which have ever had a reservation assigned which this persists even
+ * after the page is instantiated.  A private mapping has a region map
+ * associated with the original mmap which is attached to all VMAs which
+ * reference it, this region map represents those offsets which have consumed
+ * reservation ie. where pages have been instantiated.
+ */
+static unsigned long get_vma_private_data(struct vm_area_struct *vma)
+{
+	return (unsigned long)vma->vm_private_data;
+}
+
+static void set_vma_private_data(struct vm_area_struct *vma,
+							unsigned long value)
+{
+	vma->vm_private_data = (void *)value;
+}
+
+struct resv_map {
+	struct kref refs;
+	struct list_head regions;
+};
+
+static struct resv_map *resv_map_alloc(void)
+{
+	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;
+}
+
+static void resv_map_release(struct kref *ref)
+{
+	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)
+{
+	VM_BUG_ON(!is_vm_hugetlb_page(vma));
+	if (!(vma->vm_flags & VM_MAYSHARE))
+		return (struct resv_map *)(get_vma_private_data(vma) &
+							~HPAGE_RESV_MASK);
+	return NULL;
+}
+
+static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
+{
+	VM_BUG_ON(!is_vm_hugetlb_page(vma));
+	VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
+
+	set_vma_private_data(vma, (get_vma_private_data(vma) &
+				HPAGE_RESV_MASK) | (unsigned long)map);
+}
+
+static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
+{
+	VM_BUG_ON(!is_vm_hugetlb_page(vma));
+	VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
+
+	set_vma_private_data(vma, get_vma_private_data(vma) | flags);
+}
+
+static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
+{
+	VM_BUG_ON(!is_vm_hugetlb_page(vma));
+
+	return (get_vma_private_data(vma) & flag) != 0;
+}
+
+/* Decrement the reserved pages in the hugepage pool by one */
+static void decrement_hugepage_resv_vma(struct hstate *h,
+			struct vm_area_struct *vma)
+{
+	if (vma->vm_flags & VM_NORESERVE)
+		return;
+
+	if (vma->vm_flags & VM_MAYSHARE) {
+		/* Shared mappings always use reserves */
+		h->resv_huge_pages--;
+	} else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
+		/*
+		 * Only the process that called mmap() has reserves for
+		 * private mappings.
+		 */
+		h->resv_huge_pages--;
+	}
+}
+
+/* Reset counters to 0 and clear all HPAGE_RESV_* flags */
+void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
+{
+	VM_BUG_ON(!is_vm_hugetlb_page(vma));
+	if (!(vma->vm_flags & VM_MAYSHARE))
+		vma->vm_private_data = (void *)0;
+}
+
+/* Returns true if the VMA has associated reserve pages */
+static int vma_has_reserves(struct vm_area_struct *vma)
+{
+	if (vma->vm_flags & VM_MAYSHARE)
+		return 1;
+	if (is_vma_resv_set(vma, HPAGE_RESV_OWNER))
+		return 1;
+	return 0;
+}
+
+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);
+	}
+}
+
+static void enqueue_huge_page(struct hstate *h, struct page *page)
+{
+	int nid = page_to_nid(page);
+	list_add(&page->lru, &h->hugepage_freelists[nid]);
+	h->free_huge_pages++;
+	h->free_huge_pages_node[nid]++;
+}
+
+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);
+	list_del(&page->lru);
+	set_page_refcounted(page);
+	h->free_huge_pages--;
+	h->free_huge_pages_node[nid]--;
+	return page;
+}
+
+static struct page *dequeue_huge_page_vma(struct hstate *h,
+				struct vm_area_struct *vma,
+				unsigned long address, int avoid_reserve)
+{
+	struct page *page = NULL;
+	struct mempolicy *mpol;
+	nodemask_t *nodemask;
+	struct zonelist *zonelist;
+	struct zone *zone;
+	struct zoneref *z;
+	unsigned int cpuset_mems_cookie;
+
+retry_cpuset:
+	cpuset_mems_cookie = get_mems_allowed();
+	zonelist = huge_zonelist(vma, address,
+					htlb_alloc_mask, &mpol, &nodemask);
+	/*
+	 * A child process with MAP_PRIVATE mappings created by their parent
+	 * have no page reserves. This check ensures that reservations are
+	 * not "stolen". The child may still get SIGKILLed
+	 */
+	if (!vma_has_reserves(vma) &&
+			h->free_huge_pages - h->resv_huge_pages == 0)
+		goto err;
+
+	/* If reserves cannot be used, ensure enough pages are in the pool */
+	if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
+		goto err;
+
+	for_each_zone_zonelist_nodemask(zone, z, zonelist,
+						MAX_NR_ZONES - 1, nodemask) {
+		if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask)) {
+			page = dequeue_huge_page_node(h, zone_to_nid(zone));
+			if (page) {
+				if (!avoid_reserve)
+					decrement_hugepage_resv_vma(h, vma);
+				break;
+			}
+		}
+	}
+
+	mpol_cond_put(mpol);
+	if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
+		goto retry_cpuset;
+	return page;
+
+err:
+	mpol_cond_put(mpol);
+	return NULL;
+}
+
+static void update_and_free_page(struct hstate *h, struct page *page)
+{
+	int i;
+
+	VM_BUG_ON(h->order >= MAX_ORDER);
+
+	h->nr_huge_pages--;
+	h->nr_huge_pages_node[page_to_nid(page)]--;
+	for (i = 0; i < pages_per_huge_page(h); i++) {
+		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);
+	}
+	set_compound_page_dtor(page, NULL);
+	set_page_refcounted(page);
+	arch_release_hugepage(page);
+	__free_pages(page, huge_page_order(h));
+}
+
+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;
+}
+
+static void free_huge_page(struct page *page)
+{
+	/*
+	 * Can't pass hstate in here because it is called from the
+	 * compound page destructor.
+	 */
+	struct hstate *h = page_hstate(page);
+	int nid = page_to_nid(page);
+	struct hugepage_subpool *spool =
+		(struct hugepage_subpool *)page_private(page);
+
+	set_page_private(page, 0);
+	page->mapping = NULL;
+	BUG_ON(page_count(page));
+	BUG_ON(page_mapcount(page));
+	INIT_LIST_HEAD(&page->lru);
+
+	spin_lock(&hugetlb_lock);
+	if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) {
+		update_and_free_page(h, page);
+		h->surplus_huge_pages--;
+		h->surplus_huge_pages_node[nid]--;
+	} else {
+		enqueue_huge_page(h, page);
+	}
+	spin_unlock(&hugetlb_lock);
+	hugepage_subpool_put_pages(spool, 1);
+}
+
+static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
+{
+	set_compound_page_dtor(page, free_huge_page);
+	spin_lock(&hugetlb_lock);
+	h->nr_huge_pages++;
+	h->nr_huge_pages_node[nid]++;
+	spin_unlock(&hugetlb_lock);
+	put_page(page); /* free it into the hugepage allocator */
+}
+
+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);
+		set_page_count(p, 0);
+		p->first_page = page;
+	}
+}
+
+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;
+}
+EXPORT_SYMBOL_GPL(PageHuge);
+
+/*
+ * PageHeadHuge() only returns true for hugetlbfs head page, but not for
+ * normal or transparent huge pages.
+ */
+int PageHeadHuge(struct page *page_head)
+{
+	compound_page_dtor *dtor;
+
+	if (!PageHead(page_head))
+		return 0;
+
+	dtor = get_compound_page_dtor(page_head);
+
+	return dtor == free_huge_page;
+}
+EXPORT_SYMBOL_GPL(PageHeadHuge);
+
+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;
+}
+
+static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
+{
+	struct page *page;
+
+	if (h->order >= MAX_ORDER)
+		return NULL;
+
+	page = alloc_pages_exact_node(nid,
+		htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
+						__GFP_REPEAT|__GFP_NOWARN,
+		huge_page_order(h));
+	if (page) {
+		if (arch_prepare_hugepage(page)) {
+			__free_pages(page, huge_page_order(h));
+			return NULL;
+		}
+		prep_new_huge_page(h, page, nid);
+	}
+
+	return page;
+}
+
+/*
+ * common helper functions for hstate_next_node_to_{alloc|free}.
+ * We may have allocated or freed a huge page based on a different
+ * nodes_allowed previously, so h->next_node_to_{alloc|free} might
+ * be outside of *nodes_allowed.  Ensure that we use an allowed
+ * node for alloc or free.
+ */
+static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
+{
+	nid = next_node(nid, *nodes_allowed);
+	if (nid == MAX_NUMNODES)
+		nid = first_node(*nodes_allowed);
+	VM_BUG_ON(nid >= MAX_NUMNODES);
+
+	return nid;
+}
+
+static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
+{
+	if (!node_isset(nid, *nodes_allowed))
+		nid = next_node_allowed(nid, nodes_allowed);
+	return nid;
+}
+
+/*
+ * returns the previously saved node ["this node"] from which to
+ * allocate a persistent huge page for the pool and advance the
+ * next node from which to allocate, handling wrap at end of node
+ * mask.
+ */
+static int hstate_next_node_to_alloc(struct hstate *h,
+					nodemask_t *nodes_allowed)
+{
+	int nid;
+
+	VM_BUG_ON(!nodes_allowed);
+
+	nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed);
+	h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
+
+	return nid;
+}
+
+static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
+{
+	struct page *page;
+	int start_nid;
+	int next_nid;
+	int ret = 0;
+
+	start_nid = hstate_next_node_to_alloc(h, nodes_allowed);
+	next_nid = start_nid;
+
+	do {
+		page = alloc_fresh_huge_page_node(h, next_nid);
+		if (page) {
+			ret = 1;
+			break;
+		}
+		next_nid = hstate_next_node_to_alloc(h, nodes_allowed);
+	} while (next_nid != start_nid);
+
+	if (ret)
+		count_vm_event(HTLB_BUDDY_PGALLOC);
+	else
+		count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
+
+	return ret;
+}
+
+/*
+ * helper for free_pool_huge_page() - return the previously saved
+ * node ["this node"] from which to free a huge page.  Advance the
+ * next node id whether or not we find a free huge page to free so
+ * that the next attempt to free addresses the next node.
+ */
+static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
+{
+	int nid;
+
+	VM_BUG_ON(!nodes_allowed);
+
+	nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
+	h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);
+
+	return nid;
+}
+
+/*
+ * 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.
+ */
+static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
+							 bool acct_surplus)
+{
+	int start_nid;
+	int next_nid;
+	int ret = 0;
+
+	start_nid = hstate_next_node_to_free(h, nodes_allowed);
+	next_nid = start_nid;
+
+	do {
+		/*
+		 * If we're returning unused surplus pages, only examine
+		 * nodes with surplus pages.
+		 */
+		if ((!acct_surplus || h->surplus_huge_pages_node[next_nid]) &&
+		    !list_empty(&h->hugepage_freelists[next_nid])) {
+			struct page *page =
+				list_entry(h->hugepage_freelists[next_nid].next,
+					  struct page, lru);
+			list_del(&page->lru);
+			h->free_huge_pages--;
+			h->free_huge_pages_node[next_nid]--;
+			if (acct_surplus) {
+				h->surplus_huge_pages--;
+				h->surplus_huge_pages_node[next_nid]--;
+			}
+			update_and_free_page(h, page);
+			ret = 1;
+			break;
+		}
+		next_nid = hstate_next_node_to_free(h, nodes_allowed);
+	} while (next_nid != start_nid);
+
+	return ret;
+}
+
+static struct page *alloc_buddy_huge_page(struct hstate *h, int nid)
+{
+	struct page *page;
+	unsigned int r_nid;
+
+	if (h->order >= MAX_ORDER)
+		return NULL;
+
+	/*
+	 * 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);
+	if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
+		spin_unlock(&hugetlb_lock);
+		return NULL;
+	} else {
+		h->nr_huge_pages++;
+		h->surplus_huge_pages++;
+	}
+	spin_unlock(&hugetlb_lock);
+
+	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));
+
+	if (page && arch_prepare_hugepage(page)) {
+		__free_pages(page, huge_page_order(h));
+		page = NULL;
+	}
+
+	spin_lock(&hugetlb_lock);
+	if (page) {
+		r_nid = page_to_nid(page);
+		set_compound_page_dtor(page, free_huge_page);
+		/*
+		 * We incremented the global counters already
+		 */
+		h->nr_huge_pages_node[r_nid]++;
+		h->surplus_huge_pages_node[r_nid]++;
+		__count_vm_event(HTLB_BUDDY_PGALLOC);
+	} else {
+		h->nr_huge_pages--;
+		h->surplus_huge_pages--;
+		__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
+	}
+	spin_unlock(&hugetlb_lock);
+
+	return page;
+}
+
+/*
+ * 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)
+{
+	struct page *page;
+
+	spin_lock(&hugetlb_lock);
+	page = dequeue_huge_page_node(h, nid);
+	spin_unlock(&hugetlb_lock);
+
+	if (!page)
+		page = alloc_buddy_huge_page(h, nid);
+
+	return page;
+}
+
+/*
+ * Increase the hugetlb pool such that it can accommodate a reservation
+ * of size 'delta'.
+ */
+static int gather_surplus_pages(struct hstate *h, int delta)
+{
+	struct list_head surplus_list;
+	struct page *page, *tmp;
+	int ret, i;
+	int needed, allocated;
+	bool alloc_ok = true;
+
+	needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
+	if (needed <= 0) {
+		h->resv_huge_pages += delta;
+		return 0;
+	}
+
+	allocated = 0;
+	INIT_LIST_HEAD(&surplus_list);
+
+	ret = -ENOMEM;
+retry:
+	spin_unlock(&hugetlb_lock);
+	for (i = 0; i < needed; i++) {
+		page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
+		if (!page) {
+			alloc_ok = false;
+			break;
+		}
+		list_add(&page->lru, &surplus_list);
+	}
+	allocated += i;
+
+	/*
+	 * After retaking hugetlb_lock, we need to recalculate 'needed'
+	 * because either resv_huge_pages or free_huge_pages may have changed.
+	 */
+	spin_lock(&hugetlb_lock);
+	needed = (h->resv_huge_pages + delta) -
+			(h->free_huge_pages + allocated);
+	if (needed > 0) {
+		if (alloc_ok)
+			goto retry;
+		/*
+		 * We were not able to allocate enough pages to
+		 * satisfy the entire reservation so we free what
+		 * we've allocated so far.
+		 */
+		goto free;
+	}
+	/*
+	 * The surplus_list now contains _at_least_ the number of extra pages
+	 * needed to accommodate the reservation.  Add the appropriate number
+	 * of pages to the hugetlb pool and free the extras back to the buddy
+	 * allocator.  Commit the entire reservation here to prevent another
+	 * process from stealing the pages as they are added to the pool but
+	 * before they are reserved.
+	 */
+	needed += allocated;
+	h->resv_huge_pages += delta;
+	ret = 0;
+
+	/* Free the needed pages to the hugetlb pool */
+	list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
+		if ((--needed) < 0)
+			break;
+		list_del(&page->lru);
+		/*
+		 * 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));
+		enqueue_huge_page(h, page);
+	}
+free:
+	spin_unlock(&hugetlb_lock);
+
+	/* Free unnecessary surplus pages to the buddy allocator */
+	if (!list_empty(&surplus_list)) {
+		list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
+			list_del(&page->lru);
+			put_page(page);
+		}
+	}
+	spin_lock(&hugetlb_lock);
+
+	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.
+ * Called with hugetlb_lock held.
+ */
+static void return_unused_surplus_pages(struct hstate *h,
+					unsigned long unused_resv_pages)
+{
+	unsigned long nr_pages;
+
+	/* Uncommit the reservation */
+	h->resv_huge_pages -= unused_resv_pages;
+
+	/* Cannot return gigantic pages currently */
+	if (h->order >= MAX_ORDER)
+		return;
+
+	nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
+
+	/*
+	 * We want to release as many surplus pages as possible, spread
+	 * evenly across all nodes with memory. Iterate across these nodes
+	 * until we can no longer free unreserved surplus pages. This occurs
+	 * when the nodes with surplus pages have no free pages.
+	 * free_pool_huge_page() will balance the the freed pages across the
+	 * on-line nodes with memory and will handle the hstate accounting.
+	 */
+	while (nr_pages--) {
+		if (!free_pool_huge_page(h, &node_states[N_HIGH_MEMORY], 1))
+			break;
+		cond_resched_lock(&hugetlb_lock);
+	}
+}
+
+/*
+ * Determine if the huge page at addr within the vma has an associated
+ * reservation.  Where it does not we will need to logically increase
+ * 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.
+ */
+static long vma_needs_reservation(struct hstate *h,
+			struct vm_area_struct *vma, unsigned long addr)
+{
+	struct address_space *mapping = vma->vm_file->f_mapping;
+	struct inode *inode = mapping->host;
+
+	if (vma->vm_flags & VM_MAYSHARE) {
+		pgoff_t idx = vma_hugecache_offset(h, vma, addr);
+		return region_chg(&inode->i_mapping->private_list,
+							idx, idx + 1);
+
+	} else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
+		return 1;
+
+	} else  {
+		long err;
+		pgoff_t idx = vma_hugecache_offset(h, vma, addr);
+		struct resv_map *reservations = vma_resv_map(vma);
+
+		err = region_chg(&reservations->regions, idx, idx + 1);
+		if (err < 0)
+			return err;
+		return 0;
+	}
+}
+static void vma_commit_reservation(struct hstate *h,
+			struct vm_area_struct *vma, unsigned long addr)
+{
+	struct address_space *mapping = vma->vm_file->f_mapping;
+	struct inode *inode = mapping->host;
+
+	if (vma->vm_flags & VM_MAYSHARE) {
+		pgoff_t idx = vma_hugecache_offset(h, vma, addr);
+		region_add(&inode->i_mapping->private_list, idx, idx + 1);
+
+	} else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
+		pgoff_t idx = vma_hugecache_offset(h, vma, addr);
+		struct resv_map *reservations = vma_resv_map(vma);
+
+		/* Mark this page used in the map. */
+		region_add(&reservations->regions, idx, idx + 1);
+	}
+}
+
+static struct page *alloc_huge_page(struct vm_area_struct *vma,
+				    unsigned long addr, int avoid_reserve)
+{
+	struct hugepage_subpool *spool = subpool_vma(vma);
+	struct hstate *h = hstate_vma(vma);
+	struct page *page;
+	long chg;
+
+	/*
+	 * 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.
+	 */
+	chg = vma_needs_reservation(h, vma, addr);
+	if (chg < 0)
+		return ERR_PTR(-VM_FAULT_OOM);
+	if (chg)
+		if (hugepage_subpool_get_pages(spool, chg))
+			return ERR_PTR(-VM_FAULT_SIGBUS);
+
+	spin_lock(&hugetlb_lock);
+	page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve);
+	spin_unlock(&hugetlb_lock);
+
+	if (!page) {
+		page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
+		if (!page) {
+			hugepage_subpool_put_pages(spool, chg);
+			return ERR_PTR(-VM_FAULT_SIGBUS);
+		}
+	}
+
+	set_page_private(page, (unsigned long)spool);
+
+	vma_commit_reservation(h, vma, addr);
+
+	return page;
+}
+
+int __weak alloc_bootmem_huge_page(struct hstate *h)
+{
+	struct huge_bootmem_page *m;
+	int nr_nodes = nodes_weight(node_states[N_HIGH_MEMORY]);
+
+	while (nr_nodes) {
+		void *addr;
+
+		addr = __alloc_bootmem_node_nopanic(
+				NODE_DATA(hstate_next_node_to_alloc(h,
+						&node_states[N_HIGH_MEMORY])),
+				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;
+			goto found;
+		}
+		nr_nodes--;
+	}
+	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;
+}
+
+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);
+}
+
+/* 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;
+		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
+		__ClearPageReserved(page);
+		WARN_ON(page_count(page) != 1);
+		prep_compound_huge_page(page, h->order);
+		prep_new_huge_page(h, page, page_to_nid(page));
+		/*
+		 * 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))
+			totalram_pages += 1 << h->order;
+	}
+}
+
+static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
+{
+	unsigned long i;
+
+	for (i = 0; i < h->max_huge_pages; ++i) {
+		if (h->order >= MAX_ORDER) {
+			if (!alloc_bootmem_huge_page(h))
+				break;
+		} else if (!alloc_fresh_huge_page(h,
+					 &node_states[N_HIGH_MEMORY]))
+			break;
+	}
+	h->max_huge_pages = i;
+}
+
+static void __init hugetlb_init_hstates(void)
+{
+	struct hstate *h;
+
+	for_each_hstate(h) {
+		/* oversize hugepages were init'ed in early boot */
+		if (h->order < MAX_ORDER)
+			hugetlb_hstate_alloc_pages(h);
+	}
+}
+
+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;
+}
+
+static void __init report_hugepages(void)
+{
+	struct hstate *h;
+
+	for_each_hstate(h) {
+		char buf[32];
+		printk(KERN_INFO "HugeTLB registered %s page size, "
+				 "pre-allocated %ld pages\n",
+			memfmt(buf, huge_page_size(h)),
+			h->free_huge_pages);
+	}
+}
+
+#ifdef CONFIG_HIGHMEM
+static void try_to_free_low(struct hstate *h, unsigned long count,
+						nodemask_t *nodes_allowed)
+{
+	int i;
+
+	if (h->order >= MAX_ORDER)
+		return;
+
+	for_each_node_mask(i, *nodes_allowed) {
+		struct page *page, *next;
+		struct list_head *freel = &h->hugepage_freelists[i];
+		list_for_each_entry_safe(page, next, freel, lru) {
+			if (count >= h->nr_huge_pages)
+				return;
+			if (PageHighMem(page))
+				continue;
+			list_del(&page->lru);
+			update_and_free_page(h, page);
+			h->free_huge_pages--;
+			h->free_huge_pages_node[page_to_nid(page)]--;
+		}
+	}
+}
+#else
+static inline void try_to_free_low(struct hstate *h, unsigned long count,
+						nodemask_t *nodes_allowed)
+{
+}
+#endif
+
+/*
+ * 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.
+ */
+static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
+				int delta)
+{
+	int start_nid, next_nid;
+	int ret = 0;
+
+	VM_BUG_ON(delta != -1 && delta != 1);
+
+	if (delta < 0)
+		start_nid = hstate_next_node_to_alloc(h, nodes_allowed);
+	else
+		start_nid = hstate_next_node_to_free(h, nodes_allowed);
+	next_nid = start_nid;
+
+	do {
+		int nid = next_nid;
+		if (delta < 0)  {
+			/*
+			 * To shrink on this node, there must be a surplus page
+			 */
+			if (!h->surplus_huge_pages_node[nid]) {
+				next_nid = hstate_next_node_to_alloc(h,
+								nodes_allowed);
+				continue;
+			}
+		}
+		if (delta > 0) {
+			/*
+			 * Surplus cannot exceed the total number of pages
+			 */
+			if (h->surplus_huge_pages_node[nid] >=
+						h->nr_huge_pages_node[nid]) {
+				next_nid = hstate_next_node_to_free(h,
+								nodes_allowed);
+				continue;
+			}
+		}
+
+		h->surplus_huge_pages += delta;
+		h->surplus_huge_pages_node[nid] += delta;
+		ret = 1;
+		break;
+	} while (next_nid != start_nid);
+
+	return ret;
+}
+
+#define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
+static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
+						nodemask_t *nodes_allowed)
+{
+	unsigned long min_count, ret;
+
+	if (h->order >= MAX_ORDER)
+		return h->max_huge_pages;
+
+	/*
+	 * Increase the pool size
+	 * First take pages out of surplus state.  Then make up the
+	 * remaining difference by allocating fresh huge pages.
+	 *
+	 * 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.
+	 */
+	spin_lock(&hugetlb_lock);
+	while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
+		if (!adjust_pool_surplus(h, nodes_allowed, -1))
+			break;
+	}
+
+	while (count > persistent_huge_pages(h)) {
+		/*
+		 * 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);
+		ret = alloc_fresh_huge_page(h, nodes_allowed);
+		spin_lock(&hugetlb_lock);
+		if (!ret)
+			goto out;
+
+		/* Bail for signals. Probably ctrl-c from user */
+		if (signal_pending(current))
+			goto out;
+	}
+
+	/*
+	 * 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.
+	 *
+	 * 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.
+	 */
+	min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
+	min_count = max(count, min_count);
+	try_to_free_low(h, min_count, nodes_allowed);
+	while (min_count < persistent_huge_pages(h)) {
+		if (!free_pool_huge_page(h, nodes_allowed, 0))
+			break;
+		cond_resched_lock(&hugetlb_lock);
+	}
+	while (count < persistent_huge_pages(h)) {
+		if (!adjust_pool_surplus(h, nodes_allowed, 1))
+			break;
+	}
+out:
+	ret = persistent_huge_pages(h);
+	spin_unlock(&hugetlb_lock);
+	return ret;
+}
+
+#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];
+
+static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
+
+static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
+{
+	int i;
+
+	for (i = 0; i < HUGE_MAX_HSTATE; i++)
+		if (hstate_kobjs[i] == kobj) {
+			if (nidp)
+				*nidp = NUMA_NO_NODE;
+			return &hstates[i];
+		}
+
+	return kobj_to_node_hstate(kobj, nidp);
+}
+
+static ssize_t nr_hugepages_show_common(struct kobject *kobj,
+					struct kobj_attribute *attr, char *buf)
+{
+	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);
+}
+
+static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
+			struct kobject *kobj, struct kobj_attribute *attr,
+			const char *buf, size_t len)
+{
+	int err;
+	int nid;
+	unsigned long count;
+	struct hstate *h;
+	NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
+
+	err = strict_strtoul(buf, 10, &count);
+	if (err)
+		goto out;
+
+	h = kobj_to_hstate(kobj, &nid);
+	if (h->order >= MAX_ORDER) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	if (nid == NUMA_NO_NODE) {
+		/*
+		 * global hstate attribute
+		 */
+		if (!(obey_mempolicy &&
+				init_nodemask_of_mempolicy(nodes_allowed))) {
+			NODEMASK_FREE(nodes_allowed);
+			nodes_allowed = &node_states[N_HIGH_MEMORY];
+		}
+	} 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
+		nodes_allowed = &node_states[N_HIGH_MEMORY];
+
+	h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
+
+	if (nodes_allowed != &node_states[N_HIGH_MEMORY])
+		NODEMASK_FREE(nodes_allowed);
+
+	return len;
+out:
+	NODEMASK_FREE(nodes_allowed);
+	return err;
+}
+
+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);
+}
+HSTATE_ATTR(nr_hugepages);
+
+#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
+
+
+static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
+					struct kobj_attribute *attr, char *buf)
+{
+	struct hstate *h = kobj_to_hstate(kobj, NULL);
+	return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
+}
+
+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;
+	struct hstate *h = kobj_to_hstate(kobj, NULL);
+
+	if (h->order >= MAX_ORDER)
+		return -EINVAL;
+
+	err = strict_strtoul(buf, 10, &input);
+	if (err)
+		return err;
+
+	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)
+{
+	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);
+}
+HSTATE_ATTR_RO(free_hugepages);
+
+static ssize_t resv_hugepages_show(struct kobject *kobj,
+					struct kobj_attribute *attr, char *buf)
+{
+	struct hstate *h = kobj_to_hstate(kobj, NULL);
+	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)
+{
+	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);
+}
+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,
+#ifdef CONFIG_NUMA
+	&nr_hugepages_mempolicy_attr.attr,
+#endif
+	NULL,
+};
+
+static struct attribute_group hstate_attr_group = {
+	.attrs = hstate_attrs,
+};
+
+static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
+				    struct kobject **hstate_kobjs,
+				    struct attribute_group *hstate_attr_group)
+{
+	int retval;
+	int hi = h - hstates;
+
+	hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
+	if (!hstate_kobjs[hi])
+		return -ENOMEM;
+
+	retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
+	if (retval)
+		kobject_put(hstate_kobjs[hi]);
+
+	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) {
+		err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
+					 hstate_kobjs, &hstate_attr_group);
+		if (err)
+			printk(KERN_ERR "Hugetlb: Unable to add hstate %s",
+								h->name);
+	}
+}
+
+#ifdef CONFIG_NUMA
+
+/*
+ * node_hstate/s - associate per node hstate attributes, via their kobjects,
+ * 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
+ * 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];
+
+/*
+ * A subset of global hstate attributes for node devices
+ */
+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,
+};
+
+/*
+ * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
+ * 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;
+}
+
+/*
+ * Unregister hstate attributes from a single node device.
+ * No-op if no hstate attributes attached.
+ */
+void hugetlb_unregister_node(struct node *node)
+{
+	struct hstate *h;
+	struct node_hstate *nhs = &node_hstates[node->dev.id];
+
+	if (!nhs->hugepages_kobj)
+		return;		/* no hstate attributes */
+
+	for_each_hstate(h)
+		if (nhs->hstate_kobjs[h - hstates]) {
+			kobject_put(nhs->hstate_kobjs[h - hstates]);
+			nhs->hstate_kobjs[h - hstates] = NULL;
+		}
+
+	kobject_put(nhs->hugepages_kobj);
+	nhs->hugepages_kobj = NULL;
+}
+
+/*
+ * hugetlb module exit:  unregister hstate attributes from node devices
+ * that have them.
+ */
+static void hugetlb_unregister_all_nodes(void)
+{
+	int nid;
+
+	/*
+	 * disable node device registrations.
+	 */
+	register_hugetlbfs_with_node(NULL, NULL);
+
+	/*
+	 * remove hstate attributes from any nodes that have them.
+	 */
+	for (nid = 0; nid < nr_node_ids; nid++)
+		hugetlb_unregister_node(&node_devices[nid]);
+}
+
+/*
+ * Register hstate attributes for a single node device.
+ * No-op if attributes already registered.
+ */
+void hugetlb_register_node(struct node *node)
+{
+	struct hstate *h;
+	struct node_hstate *nhs = &node_hstates[node->dev.id];
+	int err;
+
+	if (nhs->hugepages_kobj)
+		return;		/* already allocated */
+
+	nhs->hugepages_kobj = kobject_create_and_add("hugepages",
+							&node->dev.kobj);
+	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) {
+			printk(KERN_ERR "Hugetlb: Unable to add hstate %s"
+					" for node %d\n",
+						h->name, node->dev.id);
+			hugetlb_unregister_node(node);
+			break;
+		}
+	}
+}
+
+/*
+ * hugetlb init time:  register hstate attributes for all registered node
+ * devices of nodes that have memory.  All on-line nodes should have
+ * registered their associated device by this time.
+ */
+static void hugetlb_register_all_nodes(void)
+{
+	int nid;
+
+	for_each_node_state(nid, N_HIGH_MEMORY) {
+		struct node *node = &node_devices[nid];
+		if (node->dev.id == nid)
+			hugetlb_register_node(node);
+	}
+
+	/*
+	 * Let the node device driver know we're here so it can
+	 * [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
+
+static void __exit hugetlb_exit(void)
+{
+	struct hstate *h;
+
+	hugetlb_unregister_all_nodes();
+
+	for_each_hstate(h) {
+		kobject_put(hstate_kobjs[h - hstates]);
+	}
+
+	kobject_put(hugepages_kobj);
+}
+module_exit(hugetlb_exit);
+
+static int __init hugetlb_init(void)
+{
+	/* 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;
+
+	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);
+	}
+	default_hstate_idx = size_to_hstate(default_hstate_size) - hstates;
+	if (default_hstate_max_huge_pages)
+		default_hstate.max_huge_pages = default_hstate_max_huge_pages;
+
+	hugetlb_init_hstates();
+
+	gather_bootmem_prealloc();
+
+	report_hugepages();
+
+	hugetlb_sysfs_init();
+
+	hugetlb_register_all_nodes();
+
+	return 0;
+}
+module_init(hugetlb_init);
+
+/* Should be called on processing a hugepagesz=... option */
+void __init hugetlb_add_hstate(unsigned order)
+{
+	struct hstate *h;
+	unsigned long i;
+
+	if (size_to_hstate(PAGE_SIZE << order)) {
+		printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n");
+		return;
+	}
+	BUG_ON(max_hstate >= HUGE_MAX_HSTATE);
+	BUG_ON(order == 0);
+	h = &hstates[max_hstate++];
+	h->order = order;
+	h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
+	h->nr_huge_pages = 0;
+	h->free_huge_pages = 0;
+	for (i = 0; i < MAX_NUMNODES; ++i)
+		INIT_LIST_HEAD(&h->hugepage_freelists[i]);
+	h->next_nid_to_alloc = first_node(node_states[N_HIGH_MEMORY]);
+	h->next_nid_to_free = first_node(node_states[N_HIGH_MEMORY]);
+	snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
+					huge_page_size(h)/1024);
+
+	parsed_hstate = h;
+}
+
+static int __init hugetlb_nrpages_setup(char *s)
+{
+	unsigned long *mhp;
+	static unsigned long *last_mhp;
+
+	/*
+	 * !max_hstate means we haven't parsed a hugepagesz= parameter yet,
+	 * so this hugepages= parameter goes to the "default hstate".
+	 */
+	if (!max_hstate)
+		mhp = &default_hstate_max_huge_pages;
+	else
+		mhp = &parsed_hstate->max_huge_pages;
+
+	if (mhp == last_mhp) {
+		printk(KERN_WARNING "hugepages= specified twice without "
+			"interleaving hugepagesz=, ignoring\n");
+		return 1;
+	}
+
+	if (sscanf(s, "%lu", mhp) <= 0)
+		*mhp = 0;
+
+	/*
+	 * 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.
+	 */
+	if (max_hstate && parsed_hstate->order >= MAX_ORDER)
+		hugetlb_hstate_alloc_pages(parsed_hstate);
+
+	last_mhp = mhp;
+
+	return 1;
+}
+__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);
+
+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
+static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
+			 struct ctl_table *table, int write,
+			 void __user *buffer, size_t *length, loff_t *ppos)
+{
+	struct hstate *h = &default_hstate;
+	unsigned long tmp;
+	int ret;
+
+	tmp = h->max_huge_pages;
+
+	if (write && h->order >= MAX_ORDER)
+		return -EINVAL;
+
+	table->data = &tmp;
+	table->maxlen = sizeof(unsigned long);
+	ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
+	if (ret)
+		goto out;
+
+	if (write) {
+		NODEMASK_ALLOC(nodemask_t, nodes_allowed,
+						GFP_KERNEL | __GFP_NORETRY);
+		if (!(obey_mempolicy &&
+			       init_nodemask_of_mempolicy(nodes_allowed))) {
+			NODEMASK_FREE(nodes_allowed);
+			nodes_allowed = &node_states[N_HIGH_MEMORY];
+		}
+		h->max_huge_pages = set_max_huge_pages(h, tmp, nodes_allowed);
+
+		if (nodes_allowed != &node_states[N_HIGH_MEMORY])
+			NODEMASK_FREE(nodes_allowed);
+	}
+out:
+	return ret;
+}
+
+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 */
+
+int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
+			void __user *buffer,
+			size_t *length, loff_t *ppos)
+{
+	proc_dointvec(table, write, buffer, length, ppos);
+	if (hugepages_treat_as_movable)
+		htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
+	else
+		htlb_alloc_mask = GFP_HIGHUSER;
+	return 0;
+}
+
+int hugetlb_overcommit_handler(struct ctl_table *table, int write,
+			void __user *buffer,
+			size_t *length, loff_t *ppos)
+{
+	struct hstate *h = &default_hstate;
+	unsigned long tmp;
+	int ret;
+
+	tmp = h->nr_overcommit_huge_pages;
+
+	if (write && h->order >= MAX_ORDER)
+		return -EINVAL;
+
+	table->data = &tmp;
+	table->maxlen = sizeof(unsigned long);
+	ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
+	if (ret)
+		goto out;
+
+	if (write) {
+		spin_lock(&hugetlb_lock);
+		h->nr_overcommit_huge_pages = tmp;
+		spin_unlock(&hugetlb_lock);
+	}
+out:
+	return ret;
+}
+
+#endif /* CONFIG_SYSCTL */
+
+void hugetlb_report_meminfo(struct seq_file *m)
+{
+	struct hstate *h = &default_hstate;
+	seq_printf(m,
+			"HugePages_Total:   %5lu\n"
+			"HugePages_Free:    %5lu\n"
+			"HugePages_Rsvd:    %5lu\n"
+			"HugePages_Surp:    %5lu\n"
+			"Hugepagesize:   %8lu kB\n",
+			h->nr_huge_pages,
+			h->free_huge_pages,
+			h->resv_huge_pages,
+			h->surplus_huge_pages,
+			1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
+}
+
+int hugetlb_report_node_meminfo(int nid, char *buf)
+{
+	struct hstate *h = &default_hstate;
+	return sprintf(buf,
+		"Node %d HugePages_Total: %5u\n"
+		"Node %d HugePages_Free:  %5u\n"
+		"Node %d HugePages_Surp:  %5u\n",
+		nid, h->nr_huge_pages_node[nid],
+		nid, h->free_huge_pages_node[nid],
+		nid, h->surplus_huge_pages_node[nid]);
+}
+
+/* Return the number pages of memory we physically have, in PAGE_SIZE units. */
+unsigned long hugetlb_total_pages(void)
+{
+	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;
+}
+
+static int hugetlb_acct_memory(struct hstate *h, long delta)
+{
+	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) {
+		if (gather_surplus_pages(h, delta) < 0)
+			goto out;
+
+		if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
+			return_unused_surplus_pages(h, delta);
+			goto out;
+		}
+	}
+
+	ret = 0;
+	if (delta < 0)
+		return_unused_surplus_pages(h, (unsigned long) -delta);
+
+out:
+	spin_unlock(&hugetlb_lock);
+	return ret;
+}
+
+static void hugetlb_vm_op_open(struct vm_area_struct *vma)
+{
+	struct resv_map *reservations = vma_resv_map(vma);
+
+	/*
+	 * 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
+	 * has a reference to the reservation map it cannot disappear until
+	 * after this open call completes.  It is therefore safe to take a
+	 * new reference here without additional locking.
+	 */
+	if (reservations)
+		kref_get(&reservations->refs);
+}
+
+static void resv_map_put(struct vm_area_struct *vma)
+{
+	struct resv_map *reservations = vma_resv_map(vma);
+
+	if (!reservations)
+		return;
+	kref_put(&reservations->refs, resv_map_release);
+}
+
+static void hugetlb_vm_op_close(struct vm_area_struct *vma)
+{
+	struct hstate *h = hstate_vma(vma);
+	struct resv_map *reservations = vma_resv_map(vma);
+	struct hugepage_subpool *spool = subpool_vma(vma);
+	unsigned long reserve;
+	unsigned long start;
+	unsigned long end;
+
+	if (reservations) {
+		start = vma_hugecache_offset(h, vma, vma->vm_start);
+		end = vma_hugecache_offset(h, vma, vma->vm_end);
+
+		reserve = (end - start) -
+			region_count(&reservations->regions, start, end);
+
+		resv_map_put(vma);
+
+		if (reserve) {
+			hugetlb_acct_memory(h, -reserve);
+			hugepage_subpool_put_pages(spool, reserve);
+		}
+	}
+}
+
+/*
+ * 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.
+ */
+static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	BUG();
+	return 0;
+}
+
+const struct vm_operations_struct hugetlb_vm_ops = {
+	.fault = hugetlb_vm_op_fault,
+	.open = hugetlb_vm_op_open,
+	.close = hugetlb_vm_op_close,
+};
+
+static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
+				int writable)
+{
+	pte_t entry;
+
+	if (writable) {
+		entry =
+		    pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
+	} else {
+		entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
+	}
+	entry = pte_mkyoung(entry);
+	entry = pte_mkhuge(entry);
+
+	return entry;
+}
+
+static void set_huge_ptep_writable(struct vm_area_struct *vma,
+				   unsigned long address, pte_t *ptep)
+{
+	pte_t entry;
+
+	entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
+	if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
+		update_mmu_cache(vma, address, ptep);
+}
+
+static int is_hugetlb_entry_migration(pte_t pte)
+{
+	swp_entry_t swp;
+
+	if (huge_pte_none(pte) || pte_present(pte))
+		return 0;
+	swp = pte_to_swp_entry(pte);
+	if (non_swap_entry(swp) && is_migration_entry(swp))
+		return 1;
+	else
+		return 0;
+}
+
+static int is_hugetlb_entry_hwpoisoned(pte_t pte)
+{
+	swp_entry_t swp;
+
+	if (huge_pte_none(pte) || pte_present(pte))
+		return 0;
+	swp = pte_to_swp_entry(pte);
+	if (non_swap_entry(swp) && is_hwpoison_entry(swp))
+		return 1;
+	else
+		return 0;
+}
+
+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;
+	unsigned long addr;
+	int cow;
+	struct hstate *h = hstate_vma(vma);
+	unsigned long sz = huge_page_size(h);
+
+	cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
+
+	for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
+		src_pte = huge_pte_offset(src, addr);
+		if (!src_pte)
+			continue;
+		dst_pte = huge_pte_alloc(dst, addr, sz);
+		if (!dst_pte)
+			goto nomem;
+
+		/* If the pagetables are shared don't copy or take references */
+		if (dst_pte == src_pte)
+			continue;
+
+		spin_lock(&dst->page_table_lock);
+		spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING);
+		entry = huge_ptep_get(src_pte);
+		if (huge_pte_none(entry)) { /* skip none entry */
+			;
+		} else if (unlikely(is_hugetlb_entry_migration(entry) ||
+				    is_hugetlb_entry_hwpoisoned(entry))) {
+			swp_entry_t swp_entry = pte_to_swp_entry(entry);
+
+			if (is_write_migration_entry(swp_entry) && cow) {
+				/*
+				 * COW mappings require pages in both
+				 * parent and child to be set to read.
+				 */
+				make_migration_entry_read(&swp_entry);
+				entry = swp_entry_to_pte(swp_entry);
+				set_huge_pte_at(src, addr, src_pte, entry);
+			}
+			set_huge_pte_at(dst, addr, dst_pte, entry);
+		} else {
+			if (cow)
+				huge_ptep_set_wrprotect(src, addr, src_pte);
+			entry = huge_ptep_get(src_pte);
+			ptepage = pte_page(entry);
+			get_page(ptepage);
+			page_dup_rmap(ptepage);
+			set_huge_pte_at(dst, addr, dst_pte, entry);
+		}
+		spin_unlock(&src->page_table_lock);
+		spin_unlock(&dst->page_table_lock);
+	}
+	return 0;
+
+nomem:
+	return -ENOMEM;
+}
+
+void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
+			    unsigned long end, struct page *ref_page)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	unsigned long address;
+	pte_t *ptep;
+	pte_t pte;
+	struct page *page;
+	struct page *tmp;
+	struct hstate *h = hstate_vma(vma);
+	unsigned long sz = huge_page_size(h);
+
+	/*
+	 * A page gathering list, protected by per file i_mmap_mutex. The
+	 * lock is used to avoid list corruption from multiple unmapping
+	 * of the same page since we are using page->lru.
+	 */
+	LIST_HEAD(page_list);
+
+	WARN_ON(!is_vm_hugetlb_page(vma));
+	BUG_ON(start & ~huge_page_mask(h));
+	BUG_ON(end & ~huge_page_mask(h));
+
+	mmu_notifier_invalidate_range_start(mm, start, end);
+	spin_lock(&mm->page_table_lock);
+	for (address = start; address < end; address += sz) {
+		ptep = huge_pte_offset(mm, address);
+		if (!ptep)
+			continue;
+
+		if (huge_pmd_unshare(mm, &address, ptep))
+			continue;
+
+		pte = huge_ptep_get(ptep);
+		if (huge_pte_none(pte))
+			continue;
+
+		/*
+		 * Migrating hugepage or HWPoisoned hugepage is already
+		 * unmapped and its refcount is dropped
+		 */
+		if (unlikely(!pte_present(pte)))
+			continue;
+
+		page = pte_page(pte);
+		/*
+		 * 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);
+		}
+
+		pte = huge_ptep_get_and_clear(mm, address, ptep);
+		if (pte_dirty(pte))
+			set_page_dirty(page);
+		list_add(&page->lru, &page_list);
+
+		/* Bail out after unmapping reference page if supplied */
+		if (ref_page)
+			break;
+	}
+	flush_tlb_range(vma, start, end);
+	spin_unlock(&mm->page_table_lock);
+	mmu_notifier_invalidate_range_end(mm, start, end);
+	list_for_each_entry_safe(page, tmp, &page_list, lru) {
+		page_remove_rmap(page);
+		list_del(&page->lru);
+		put_page(page);
+	}
+}
+
+void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
+			  unsigned long end, struct page *ref_page)
+{
+	mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
+	__unmap_hugepage_range(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 below.
+	 *
+	 * This works because in the contexts this is called, the VMA is
+	 * going to be destroyed. It is not vunerable to madvise(DONTNEED)
+	 * because madvise is not supported on hugetlbfs. The same applies
+	 * for direct IO. unmap_hugepage_range() is only being called just
+	 * before free_pgtables() so clearing VM_MAYSHARE will not cause
+	 * surprises later.
+	 */
+	vma->vm_flags &= ~VM_MAYSHARE;
+	mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
+}
+
+/*
+ * 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.
+ */
+static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
+				struct page *page, unsigned long address)
+{
+	struct hstate *h = hstate_vma(vma);
+	struct vm_area_struct *iter_vma;
+	struct address_space *mapping;
+	struct prio_tree_iter iter;
+	pgoff_t pgoff;
+
+	/*
+	 * vm_pgoff is in PAGE_SIZE units, hence the different calculation
+	 * from page cache lookup which is in HPAGE_SIZE units.
+	 */
+	address = address & huge_page_mask(h);
+	pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
+			vma->vm_pgoff;
+	mapping = vma->vm_file->f_dentry->d_inode->i_mapping;
+
+	/*
+	 * 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
+	 */
+	mutex_lock(&mapping->i_mmap_mutex);
+	vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
+		/* 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))
+			__unmap_hugepage_range(iter_vma,
+				address, address + huge_page_size(h),
+				page);
+	}
+	mutex_unlock(&mapping->i_mmap_mutex);
+
+	return 1;
+}
+
+/*
+ * Hugetlb_cow() should be called with page lock of the original hugepage held.
+ * 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.
+ */
+static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
+			unsigned long address, pte_t *ptep, pte_t pte,
+			struct page *pagecache_page)
+{
+	struct hstate *h = hstate_vma(vma);
+	struct page *old_page, *new_page;
+	int avoidcopy;
+	int outside_reserve = 0;
+
+	old_page = pte_page(pte);
+
+retry_avoidcopy:
+	/* If no-one else is actually using this page, avoid the copy
+	 * and just make the page writable */
+	avoidcopy = (page_mapcount(old_page) == 1);
+	if (avoidcopy) {
+		if (PageAnon(old_page))
+			page_move_anon_rmap(old_page, vma, address);
+		set_huge_ptep_writable(vma, address, ptep);
+		return 0;
+	}
+
+	/*
+	 * 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.
+	 */
+	if (!(vma->vm_flags & VM_MAYSHARE) &&
+			is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
+			old_page != pagecache_page)
+		outside_reserve = 1;
+
+	page_cache_get(old_page);
+
+	/* Drop page_table_lock as buddy allocator may be called */
+	spin_unlock(&mm->page_table_lock);
+	new_page = alloc_huge_page(vma, address, outside_reserve);
+
+	if (IS_ERR(new_page)) {
+		page_cache_release(old_page);
+
+		/*
+		 * 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));
+				spin_lock(&mm->page_table_lock);
+				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;
+			}
+			WARN_ON_ONCE(1);
+		}
+
+		/* Caller expects lock to be held */
+		spin_lock(&mm->page_table_lock);
+		return -PTR_ERR(new_page);
+	}
+
+	/*
+	 * When the original hugepage is shared one, it does not have
+	 * anon_vma prepared.
+	 */
+	if (unlikely(anon_vma_prepare(vma))) {
+		page_cache_release(new_page);
+		page_cache_release(old_page);
+		/* Caller expects lock to be held */
+		spin_lock(&mm->page_table_lock);
+		return VM_FAULT_OOM;
+	}
+
+	copy_user_huge_page(new_page, old_page, address, vma,
+			    pages_per_huge_page(h));
+	__SetPageUptodate(new_page);
+
+	/*
+	 * Retake the page_table_lock to check for racing updates
+	 * before the page tables are altered
+	 */
+	spin_lock(&mm->page_table_lock);
+	ptep = huge_pte_offset(mm, address & huge_page_mask(h));
+	if (likely(pte_same(huge_ptep_get(ptep), pte))) {
+		/* Break COW */
+		mmu_notifier_invalidate_range_start(mm,
+			address & huge_page_mask(h),
+			(address & huge_page_mask(h)) + huge_page_size(h));
+		huge_ptep_clear_flush(vma, address, ptep);
+		set_huge_pte_at(mm, address, ptep,
+				make_huge_pte(vma, new_page, 1));
+		page_remove_rmap(old_page);
+		hugepage_add_new_anon_rmap(new_page, vma, address);
+		/* Make the old page be freed below */
+		new_page = old_page;
+		mmu_notifier_invalidate_range_end(mm,
+			address & huge_page_mask(h),
+			(address & huge_page_mask(h)) + huge_page_size(h));
+	}
+	page_cache_release(new_page);
+	page_cache_release(old_page);
+	return 0;
+}
+
+/* Return the pagecache page at a given address within a VMA */
+static struct page *hugetlbfs_pagecache_page(struct hstate *h,
+			struct vm_area_struct *vma, unsigned long address)
+{
+	struct address_space *mapping;
+	pgoff_t idx;
+
+	mapping = vma->vm_file->f_mapping;
+	idx = vma_hugecache_offset(h, vma, address);
+
+	return find_lock_page(mapping, idx);
+}
+
+/*
+ * 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,
+			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;
+}
+
+static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
+			unsigned long address, pte_t *ptep, unsigned int flags)
+{
+	struct hstate *h = hstate_vma(vma);
+	int ret = VM_FAULT_SIGBUS;
+	int anon_rmap = 0;
+	pgoff_t idx;
+	unsigned long size;
+	struct page *page;
+	struct address_space *mapping;
+	pte_t new_pte;
+
+	/*
+	 * Currently, we are forced to kill the process in the event the
+	 * original mapper has unmapped pages from the child due to a failed
+	 * COW. Warn that such a situation has occurred as it may not be obvious
+	 */
+	if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
+		printk(KERN_WARNING
+			"PID %d killed due to inadequate hugepage pool\n",
+			current->pid);
+		return ret;
+	}
+
+	mapping = vma->vm_file->f_mapping;
+	idx = vma_hugecache_offset(h, vma, address);
+
+	/*
+	 * Use page lock to guard against racing truncation
+	 * before we get page_table_lock.
+	 */
+retry:
+	page = find_lock_page(mapping, idx);
+	if (!page) {
+		size = i_size_read(mapping->host) >> huge_page_shift(h);
+		if (idx >= size)
+			goto out;
+		page = alloc_huge_page(vma, address, 0);
+		if (IS_ERR(page)) {
+			ret = -PTR_ERR(page);
+			goto out;
+		}
+		clear_huge_page(page, address, pages_per_huge_page(h));
+		__SetPageUptodate(page);
+
+		if (vma->vm_flags & VM_MAYSHARE) {
+			int err;
+			struct inode *inode = mapping->host;
+
+			err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
+			if (err) {
+				put_page(page);
+				if (err == -EEXIST)
+					goto retry;
+				goto out;
+			}
+
+			spin_lock(&inode->i_lock);
+			inode->i_blocks += blocks_per_huge_page(h);
+			spin_unlock(&inode->i_lock);
+		} else {
+			lock_page(page);
+			if (unlikely(anon_vma_prepare(vma))) {
+				ret = VM_FAULT_OOM;
+				goto backout_unlocked;
+			}
+			anon_rmap = 1;
+		}
+	} else {
+		/*
+		 * 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))) {
+			ret = VM_FAULT_HWPOISON |
+			      VM_FAULT_SET_HINDEX(h - hstates);
+			goto backout_unlocked;
+		}
+	}
+
+	/*
+	 * 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.
+	 */
+	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
+		if (vma_needs_reservation(h, vma, address) < 0) {
+			ret = VM_FAULT_OOM;
+			goto backout_unlocked;
+		}
+
+	spin_lock(&mm->page_table_lock);
+	size = i_size_read(mapping->host) >> huge_page_shift(h);
+	if (idx >= size)
+		goto backout;
+
+	ret = 0;
+	if (!huge_pte_none(huge_ptep_get(ptep)))
+		goto backout;
+
+	if (anon_rmap)
+		hugepage_add_new_anon_rmap(page, vma, address);
+	else
+		page_dup_rmap(page);
+	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);
+
+	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
+		/* Optimization, do the COW without a second fault */
+		ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page);
+	}
+
+	spin_unlock(&mm->page_table_lock);
+	unlock_page(page);
+out:
+	return ret;
+
+backout:
+	spin_unlock(&mm->page_table_lock);
+backout_unlocked:
+	unlock_page(page);
+	put_page(page);
+	goto out;
+}
+
+int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
+			unsigned long address, unsigned int flags)
+{
+	pte_t *ptep;
+	pte_t entry;
+	int ret;
+	struct page *page = NULL;
+	struct page *pagecache_page = NULL;
+	static DEFINE_MUTEX(hugetlb_instantiation_mutex);
+	struct hstate *h = hstate_vma(vma);
+	int need_wait_lock = 0;
+
+	address &= huge_page_mask(h);
+
+	ptep = huge_pte_offset(mm, address);
+	if (ptep) {
+		entry = huge_ptep_get(ptep);
+		if (unlikely(is_hugetlb_entry_migration(entry))) {
+			migration_entry_wait_huge(mm, ptep);
+			return 0;
+		} else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
+			return VM_FAULT_HWPOISON_LARGE |
+			       VM_FAULT_SET_HINDEX(h - hstates);
+	}
+
+	ptep = huge_pte_alloc(mm, address, huge_page_size(h));
+	if (!ptep)
+		return VM_FAULT_OOM;
+
+	/*
+	 * 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);
+	entry = huge_ptep_get(ptep);
+	if (huge_pte_none(entry)) {
+		ret = hugetlb_no_page(mm, vma, address, ptep, flags);
+		goto out_mutex;
+	}
+
+	ret = 0;
+
+	/*
+	 * entry could be a migration/hwpoison entry at this point, so this
+	 * check prevents the kernel from going below assuming that we have
+	 * a active hugepage in pagecache. This goto expects the 2nd page fault,
+	 * and is_hugetlb_entry_(migration|hwpoisoned) check will properly
+	 * handle it.
+	 */
+	if (!pte_present(entry))
+		goto out_mutex;
+
+	/*
+	 * 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.
+	 */
+	if ((flags & FAULT_FLAG_WRITE) && !pte_write(entry)) {
+		if (vma_needs_reservation(h, vma, address) < 0) {
+			ret = VM_FAULT_OOM;
+			goto out_mutex;
+		}
+
+		if (!(vma->vm_flags & VM_MAYSHARE))
+			pagecache_page = hugetlbfs_pagecache_page(h,
+								vma, address);
+	}
+
+	spin_lock(&mm->page_table_lock);
+
+	/* Check for a racing update before calling hugetlb_cow */
+	if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
+		goto out_page_table_lock;
+
+	/*
+	 * hugetlb_cow() requires page locks of pte_page(entry) and
+	 * pagecache_page, so here we need take the former one
+	 * when page != pagecache_page or !pagecache_page.
+	 */
+	page = pte_page(entry);
+	if (page != pagecache_page)
+		if (!trylock_page(page)) {
+			need_wait_lock = 1;
+			goto out_page_table_lock;
+	}
+
+	get_page(page);
+
+
+	if (flags & FAULT_FLAG_WRITE) {
+		if (!pte_write(entry)) {
+			ret = hugetlb_cow(mm, vma, address, ptep, entry,
+							pagecache_page);
+			goto out_put_page;
+		}
+		entry = pte_mkdirty(entry);
+	}
+	entry = pte_mkyoung(entry);
+	if (huge_ptep_set_access_flags(vma, address, ptep, entry,
+						flags & FAULT_FLAG_WRITE))
+		update_mmu_cache(vma, address, ptep);
+
+out_put_page:
+	if (page != pagecache_page)
+		unlock_page(page);
+	put_page(page);
+out_page_table_lock:
+	spin_unlock(&mm->page_table_lock);
+
+	if (pagecache_page) {
+		unlock_page(pagecache_page);
+		put_page(pagecache_page);
+	}
+	if (page != pagecache_page)
+		unlock_page(page);
+	put_page(page);
+
+out_mutex:
+	mutex_unlock(&hugetlb_instantiation_mutex);
+
+	return ret;
+}
+
+/* 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;
+}
+
+int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
+			struct page **pages, struct vm_area_struct **vmas,
+			unsigned long *position, int *length, int i,
+			unsigned int flags)
+{
+	unsigned long pfn_offset;
+	unsigned long vaddr = *position;
+	int remainder = *length;
+	struct hstate *h = hstate_vma(vma);
+
+	spin_lock(&mm->page_table_lock);
+	while (vaddr < vma->vm_end && remainder) {
+		pte_t *pte;
+		int absent;
+		struct page *page;
+
+		/*
+		 * Some archs (sparc64, sh*) have multiple pte_ts to
+		 * each hugepage.  We have to make sure we get the
+		 * first, for the page indexing below to work.
+		 */
+		pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
+		absent = !pte || huge_pte_none(huge_ptep_get(pte));
+
+		/*
+		 * When coredumping, it suits get_dump_page if we just return
+		 * 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.
+		 */
+		if (absent && (flags & FOLL_DUMP) &&
+		    !hugetlbfs_pagecache_present(h, vma, vaddr)) {
+			remainder = 0;
+			break;
+		}
+
+		/*
+		 * 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)) ||
+		    ((flags & FOLL_WRITE) && !pte_write(huge_ptep_get(pte)))) {
+			int ret;
+
+			spin_unlock(&mm->page_table_lock);
+			ret = hugetlb_fault(mm, vma, vaddr,
+				(flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
+			spin_lock(&mm->page_table_lock);
+			if (!(ret & VM_FAULT_ERROR))
+				continue;
+
+			remainder = 0;
+			break;
+		}
+
+		pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
+		page = pte_page(huge_ptep_get(pte));
+same_page:
+		if (pages) {
+			pages[i] = mem_map_offset(page, pfn_offset);
+			get_page(pages[i]);
+		}
+
+		if (vmas)
+			vmas[i] = vma;
+
+		vaddr += PAGE_SIZE;
+		++pfn_offset;
+		--remainder;
+		++i;
+		if (vaddr < vma->vm_end && remainder &&
+				pfn_offset < pages_per_huge_page(h)) {
+			/*
+			 * We use pfn_offset to avoid touching the pageframes
+			 * of this compound page.
+			 */
+			goto same_page;
+		}
+	}
+	spin_unlock(&mm->page_table_lock);
+	*length = remainder;
+	*position = vaddr;
+
+	return i ? i : -EFAULT;
+}
+
+void hugetlb_change_protection(struct vm_area_struct *vma,
+		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;
+	struct hstate *h = hstate_vma(vma);
+
+	BUG_ON(address >= end);
+	flush_cache_range(vma, address, end);
+
+	mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
+	spin_lock(&mm->page_table_lock);
+	for (; address < end; address += huge_page_size(h)) {
+		ptep = huge_pte_offset(mm, address);
+		if (!ptep)
+			continue;
+		if (huge_pmd_unshare(mm, &address, ptep))
+			continue;
+		pte = huge_ptep_get(ptep);
+		if (unlikely(is_hugetlb_entry_hwpoisoned(pte)))
+			continue;
+		if (unlikely(is_hugetlb_entry_migration(pte))) {
+			swp_entry_t entry = pte_to_swp_entry(pte);
+
+			if (is_write_migration_entry(entry)) {
+				pte_t newpte;
+
+				make_migration_entry_read(&entry);
+				newpte = swp_entry_to_pte(entry);
+				set_huge_pte_at(mm, address, ptep, newpte);
+			}
+			continue;
+		}
+		if (!huge_pte_none(pte)) {
+			pte = huge_ptep_get_and_clear(mm, address, ptep);
+			pte = pte_mkhuge(pte_modify(pte, newprot));
+			set_huge_pte_at(mm, address, ptep, pte);
+		}
+	}
+	spin_unlock(&mm->page_table_lock);
+	/*
+	 * 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.
+	 */
+	flush_tlb_range(vma, start, end);
+	mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
+}
+
+int hugetlb_reserve_pages(struct inode *inode,
+					long from, long to,
+					struct vm_area_struct *vma,
+					vm_flags_t vm_flags)
+{
+	long ret, chg;
+	struct hstate *h = hstate_inode(inode);
+	struct hugepage_subpool *spool = subpool_inode(inode);
+
+	/*
+	 * Only apply hugepage reservation if asked. At fault time, an
+	 * attempt will be made for VM_NORESERVE to allocate a page
+	 * without using reserves
+	 */
+	if (vm_flags & VM_NORESERVE)
+		return 0;
+
+	/*
+	 * 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
+	 */
+	if (!vma || vma->vm_flags & VM_MAYSHARE)
+		chg = region_chg(&inode->i_mapping->private_list, from, to);
+	else {
+		struct resv_map *resv_map = resv_map_alloc();
+		if (!resv_map)
+			return -ENOMEM;
+
+		chg = to - from;
+
+		set_vma_resv_map(vma, resv_map);
+		set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
+	}
+
+	if (chg < 0) {
+		ret = chg;
+		goto out_err;
+	}
+
+	/* There must be enough pages in the subpool for the mapping */
+	if (hugepage_subpool_get_pages(spool, chg)) {
+		ret = -ENOSPC;
+		goto out_err;
+	}
+
+	/*
+	 * Check enough hugepages are available for the reservation.
+	 * Hand the pages back to the subpool if there are not
+	 */
+	ret = hugetlb_acct_memory(h, chg);
+	if (ret < 0) {
+		hugepage_subpool_put_pages(spool, chg);
+		goto out_err;
+	}
+
+	/*
+	 * 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
+	 */
+	if (!vma || vma->vm_flags & VM_MAYSHARE)
+		region_add(&inode->i_mapping->private_list, from, to);
+	return 0;
+out_err:
+	if (vma)
+		resv_map_put(vma);
+	return ret;
+}
+
+void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
+{
+	struct hstate *h = hstate_inode(inode);
+	long chg = region_truncate(&inode->i_mapping->private_list, offset);
+	struct hugepage_subpool *spool = subpool_inode(inode);
+
+	spin_lock(&inode->i_lock);
+	inode->i_blocks -= (blocks_per_huge_page(h) * freed);
+	spin_unlock(&inode->i_lock);
+
+	hugepage_subpool_put_pages(spool, (chg - freed));
+	hugetlb_acct_memory(h, -(chg - freed));
+}
+
+#ifdef CONFIG_MEMORY_FAILURE
+
+/* 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;
+}
+
+/*
+ * This function is called from memory failure code.
+ * Assume the caller holds page lock of the head page.
+ */
+int dequeue_hwpoisoned_huge_page(struct page *hpage)
+{
+	struct hstate *h = page_hstate(hpage);
+	int nid = page_to_nid(hpage);
+	int ret = -EBUSY;
+
+	spin_lock(&hugetlb_lock);
+	if (is_hugepage_on_freelist(hpage)) {
+		list_del(&hpage->lru);
+		set_page_refcounted(hpage);
+		h->free_huge_pages--;
+		h->free_huge_pages_node[nid]--;
+		ret = 0;
+	}
+	spin_unlock(&hugetlb_lock);
+	return ret;
+}
+#endif