2.6.24

 mm

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index eab8c42..db861d8 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -23,12 +23,16 @@
 
 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
 static unsigned long nr_huge_pages, free_huge_pages, resv_huge_pages;
+static unsigned long surplus_huge_pages;
 unsigned long max_huge_pages;
 static struct list_head hugepage_freelists[MAX_NUMNODES];
 static unsigned int nr_huge_pages_node[MAX_NUMNODES];
 static unsigned int free_huge_pages_node[MAX_NUMNODES];
+static unsigned int surplus_huge_pages_node[MAX_NUMNODES];
 static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
 unsigned long hugepages_treat_as_movable;
+unsigned long nr_overcommit_huge_pages;
+static int hugetlb_next_nid;
 
 /*
  * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
@@ -85,6 +89,8 @@ static struct page *dequeue_huge_page(struct vm_area_struct *vma,
          list_del(&page->lru);
          free_huge_pages--;
          free_huge_pages_node[nid]--;
+         if (vma && vma->vm_flags & VM_MAYSHARE)
+            resv_huge_pages--;
          break;
       }
    }
@@ -92,73 +98,352 @@ static struct page *dequeue_huge_page(struct vm_area_struct *vma,
    return page;
 }
 
+static void update_and_free_page(struct page *page)
+{
+   int i;
+   nr_huge_pages--;
+   nr_huge_pages_node[page_to_nid(page)]--;
+   for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); 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);
+   __free_pages(page, HUGETLB_PAGE_ORDER);
+}
+
 static void free_huge_page(struct page *page)
 {
-   BUG_ON(page_count(page));
+   int nid = page_to_nid(page);
+   struct address_space *mapping;
 
+   mapping = (struct address_space *) page_private(page);
+   BUG_ON(page_count(page));
    INIT_LIST_HEAD(&page->lru);
 
    spin_lock(&hugetlb_lock);
-   enqueue_huge_page(page);
+   if (surplus_huge_pages_node[nid]) {
+      update_and_free_page(page);
+      surplus_huge_pages--;
+      surplus_huge_pages_node[nid]--;
+   } else {
+      enqueue_huge_page(page);
+   }
    spin_unlock(&hugetlb_lock);
+   if (mapping)
+      hugetlb_put_quota(mapping, 1);
+   set_page_private(page, 0);
 }
 
-static int alloc_fresh_huge_page(void)
+/*
+ * 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(int delta)
 {
    static int prev_nid;
-   struct page *page;
-   int nid;
+   int nid = prev_nid;
+   int ret = 0;
+
+   VM_BUG_ON(delta != -1 && delta != 1);
+   do {
+      nid = next_node(nid, node_online_map);
+      if (nid == MAX_NUMNODES)
+         nid = first_node(node_online_map);
+
+      /* To shrink on this node, there must be a surplus page */
+      if (delta < 0 && !surplus_huge_pages_node[nid])
+         continue;
+      /* Surplus cannot exceed the total number of pages */
+      if (delta > 0 && surplus_huge_pages_node[nid] >=
+                  nr_huge_pages_node[nid])
+         continue;
+
+      surplus_huge_pages += delta;
+      surplus_huge_pages_node[nid] += delta;
+      ret = 1;
+      break;
+   } while (nid != prev_nid);
 
-   /*
-    * Copy static prev_nid to local nid, work on that, then copy it
-    * back to prev_nid afterwards: otherwise there's a window in which
-    * a racer might pass invalid nid MAX_NUMNODES to alloc_pages_node.
-    * But we don't need to use a spin_lock here: it really doesn't
-    * matter if occasionally a racer chooses the same nid as we do.
-    */
-   nid = next_node(prev_nid, node_online_map);
-   if (nid == MAX_NUMNODES)
-      nid = first_node(node_online_map);
    prev_nid = nid;
+   return ret;
+}
 
-   page = alloc_pages_node(nid, htlb_alloc_mask|__GFP_COMP|__GFP_NOWARN,
-               HUGETLB_PAGE_ORDER);
+static struct page *alloc_fresh_huge_page_node(int nid)
+{
+   struct page *page;
+
+   page = alloc_pages_node(nid,
+      htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|__GFP_NOWARN,
+      HUGETLB_PAGE_ORDER);
    if (page) {
       set_compound_page_dtor(page, free_huge_page);
       spin_lock(&hugetlb_lock);
       nr_huge_pages++;
-      nr_huge_pages_node[page_to_nid(page)]++;
+      nr_huge_pages_node[nid]++;
       spin_unlock(&hugetlb_lock);
       put_page(page); /* free it into the hugepage allocator */
-      return 1;
    }
-   return 0;
+
+   return page;
 }
 
-static struct page *alloc_huge_page(struct vm_area_struct *vma,
-                unsigned long addr)
+static int alloc_fresh_huge_page(void)
 {
    struct page *page;
+   int start_nid;
+   int next_nid;
+   int ret = 0;
 
+   start_nid = hugetlb_next_nid;
+
+   do {
+      page = alloc_fresh_huge_page_node(hugetlb_next_nid);
+      if (page)
+         ret = 1;
+      /*
+       * Use a helper variable to find the next node and then
+       * copy it back to hugetlb_next_nid afterwards:
+       * otherwise there's a window in which a racer might
+       * pass invalid nid MAX_NUMNODES to alloc_pages_node.
+       * But we don't need to use a spin_lock here: it really
+       * doesn't matter if occasionally a racer chooses the
+       * same nid as we do.  Move nid forward in the mask even
+       * if we just successfully allocated a hugepage so that
+       * the next caller gets hugepages on the next node.
+       */
+      next_nid = next_node(hugetlb_next_nid, node_online_map);
+      if (next_nid == MAX_NUMNODES)
+         next_nid = first_node(node_online_map);
+      hugetlb_next_nid = next_nid;
+   } while (!page && hugetlb_next_nid != start_nid);
+
+   return ret;
+}
+
+static struct page *alloc_buddy_huge_page(struct vm_area_struct *vma,
+                  unsigned long address)
+{
+   struct page *page;
+   unsigned int nid;
+
+   /*
+    * 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 (vma->vm_flags & VM_MAYSHARE)
-      resv_huge_pages--;
-   else if (free_huge_pages <= resv_huge_pages)
-      goto fail;
+   if (surplus_huge_pages >= nr_overcommit_huge_pages) {
+      spin_unlock(&hugetlb_lock);
+      return NULL;
+   } else {
+      nr_huge_pages++;
+      surplus_huge_pages++;
+   }
+   spin_unlock(&hugetlb_lock);
+
+   page = alloc_pages(htlb_alloc_mask|__GFP_COMP|__GFP_NOWARN,
+               HUGETLB_PAGE_ORDER);
+
+   spin_lock(&hugetlb_lock);
+   if (page) {
+      nid = page_to_nid(page);
+      set_compound_page_dtor(page, free_huge_page);
+      /*
+       * We incremented the global counters already
+       */
+      nr_huge_pages_node[nid]++;
+      surplus_huge_pages_node[nid]++;
+   } else {
+      nr_huge_pages--;
+      surplus_huge_pages--;
+   }
+   spin_unlock(&hugetlb_lock);
+
+   return page;
+}
+
+/*
+ * Increase the hugetlb pool such that it can accomodate a reservation
+ * of size 'delta'.
+ */
+static int gather_surplus_pages(int delta)
+{
+   struct list_head surplus_list;
+   struct page *page, *tmp;
+   int ret, i;
+   int needed, allocated;
+
+   needed = (resv_huge_pages + delta) - free_huge_pages;
+   if (needed <= 0)
+      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(NULL, 0);
+      if (!page) {
+         /*
+          * We were not able to allocate enough pages to
+          * satisfy the entire reservation so we free what
+          * we've allocated so far.
+          */
+         spin_lock(&hugetlb_lock);
+         needed = 0;
+         goto free;
+      }
+
+      list_add(&page->lru, &surplus_list);
+   }
+   allocated += needed;
+
+   /*
+    * 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 = (resv_huge_pages + delta) - (free_huge_pages + allocated);
+   if (needed > 0)
+      goto retry;
+
+   /*
+    * The surplus_list now contains _at_least_ the number of extra pages
+    * needed to accomodate the reservation.  Add the appropriate number
+    * of pages to the hugetlb pool and free the extras back to the buddy
+    * allocator.
+    */
+   needed += allocated;
+   ret = 0;
+free:
+   list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
+      list_del(&page->lru);
+      if ((--needed) >= 0)
+         enqueue_huge_page(page);
+      else {
+         /*
+          * Decrement the refcount and free the page using its
+          * destructor.  This must be done with hugetlb_lock
+          * unlocked which is safe because free_huge_page takes
+          * hugetlb_lock before deciding how to free the page.
+          */
+         spin_unlock(&hugetlb_lock);
+         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.
+ */
+static void return_unused_surplus_pages(unsigned long unused_resv_pages)
+{
+   static int nid = -1;
+   struct page *page;
+   unsigned long nr_pages;
+
+   nr_pages = min(unused_resv_pages, surplus_huge_pages);
+
+   while (nr_pages) {
+      nid = next_node(nid, node_online_map);
+      if (nid == MAX_NUMNODES)
+         nid = first_node(node_online_map);
+
+      if (!surplus_huge_pages_node[nid])
+         continue;
+
+      if (!list_empty(&hugepage_freelists[nid])) {
+         page = list_entry(hugepage_freelists[nid].next,
+                 struct page, lru);
+         list_del(&page->lru);
+         update_and_free_page(page);
+         free_huge_pages--;
+         free_huge_pages_node[nid]--;
+         surplus_huge_pages--;
+         surplus_huge_pages_node[nid]--;
+         nr_pages--;
+      }
+   }
+}
+
+
+static struct page *alloc_huge_page_shared(struct vm_area_struct *vma,
+                  unsigned long addr)
+{
+   struct page *page;
 
+   spin_lock(&hugetlb_lock);
    page = dequeue_huge_page(vma, addr);
-   if (!page)
-      goto fail;
+   spin_unlock(&hugetlb_lock);
+   return page ? page : ERR_PTR(-VM_FAULT_OOM);
+}
 
+static struct page *alloc_huge_page_private(struct vm_area_struct *vma,
+                  unsigned long addr)
+{
+   struct page *page = NULL;
+
+   if (hugetlb_get_quota(vma->vm_file->f_mapping, 1))
+      return ERR_PTR(-VM_FAULT_SIGBUS);
+
+   spin_lock(&hugetlb_lock);
+   if (free_huge_pages > resv_huge_pages)
+      page = dequeue_huge_page(vma, addr);
    spin_unlock(&hugetlb_lock);
-   set_page_refcounted(page);
+   if (!page) {
+      page = alloc_buddy_huge_page(vma, addr);
+      if (!page) {
+         hugetlb_put_quota(vma->vm_file->f_mapping, 1);
+         return ERR_PTR(-VM_FAULT_OOM);
+      }
+   }
    return page;
+}
+
+static struct page *alloc_huge_page(struct vm_area_struct *vma,
+                unsigned long addr)
+{
+   struct page *page;
+   struct address_space *mapping = vma->vm_file->f_mapping;
 
-fail:
    if (vma->vm_flags & VM_MAYSHARE)
-      resv_huge_pages++;
-   spin_unlock(&hugetlb_lock);
-   return NULL;
+      page = alloc_huge_page_shared(vma, addr);
+   else
+      page = alloc_huge_page_private(vma, addr);
+
+   if (!IS_ERR(page)) {
+      set_page_refcounted(page);
+      set_page_private(page, (unsigned long) mapping);
+   }
+   return page;
 }
 
 static int __init hugetlb_init(void)
@@ -171,6 +456,8 @@ static int __init hugetlb_init(void)
    for (i = 0; i < MAX_NUMNODES; ++i)
       INIT_LIST_HEAD(&hugepage_freelists[i]);
 
+   hugetlb_next_nid = first_node(node_online_map);
+
    for (i = 0; i < max_huge_pages; ++i) {
       if (!alloc_fresh_huge_page())
          break;
@@ -201,21 +488,6 @@ static unsigned int cpuset_mems_nr(unsigned int *array)
 }
 
 #ifdef CONFIG_SYSCTL
-static void update_and_free_page(struct page *page)
-{
-   int i;
-   nr_huge_pages--;
-   nr_huge_pages_node[page_to_nid(page)]--;
-   for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); 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);
-   __free_pages(page, HUGETLB_PAGE_ORDER);
-}
-
 #ifdef CONFIG_HIGHMEM
 static void try_to_free_low(unsigned long count)
 {
@@ -224,14 +496,14 @@ static void try_to_free_low(unsigned long count)
    for (i = 0; i < MAX_NUMNODES; ++i) {
       struct page *page, *next;
       list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
+         if (count >= nr_huge_pages)
+            return;
          if (PageHighMem(page))
             continue;
          list_del(&page->lru);
          update_and_free_page(page);
          free_huge_pages--;
          free_huge_pages_node[page_to_nid(page)]--;
-         if (count >= nr_huge_pages)
-            return;
       }
    }
 }
@@ -241,26 +513,75 @@ static inline void try_to_free_low(unsigned long count)
 }
 #endif
 
+#define persistent_huge_pages (nr_huge_pages - surplus_huge_pages)
 static unsigned long set_max_huge_pages(unsigned long count)
 {
-   while (count > nr_huge_pages) {
-      if (!alloc_fresh_huge_page())
-         return nr_huge_pages;
-   }
-   if (count >= nr_huge_pages)
-      return nr_huge_pages;
+   unsigned long min_count, ret;
 
+   /*
+    * 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);
-   count = max(count, resv_huge_pages);
-   try_to_free_low(count);
-   while (count < nr_huge_pages) {
+   while (surplus_huge_pages && count > persistent_huge_pages) {
+      if (!adjust_pool_surplus(-1))
+         break;
+   }
+
+   while (count > persistent_huge_pages) {
+      int ret;
+      /*
+       * 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();
+      spin_lock(&hugetlb_lock);
+      if (!ret)
+         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 = resv_huge_pages + nr_huge_pages - free_huge_pages;
+   min_count = max(count, min_count);
+   try_to_free_low(min_count);
+   while (min_count < persistent_huge_pages) {
       struct page *page = dequeue_huge_page(NULL, 0);
       if (!page)
          break;
       update_and_free_page(page);
    }
+   while (count < persistent_huge_pages) {
+      if (!adjust_pool_surplus(1))
+         break;
+   }
+out:
+   ret = persistent_huge_pages;
    spin_unlock(&hugetlb_lock);
-   return nr_huge_pages;
+   return ret;
 }
 
 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
@@ -292,10 +613,12 @@ int hugetlb_report_meminfo(char *buf)
          "HugePages_Total: %5lu\n"
          "HugePages_Free:  %5lu\n"
          "HugePages_Rsvd:  %5lu\n"
+         "HugePages_Surp:  %5lu\n"
          "Hugepagesize:    %5lu kB\n",
          nr_huge_pages,
          free_huge_pages,
          resv_huge_pages,
+         surplus_huge_pages,
          HPAGE_SIZE/1024);
 }
 
@@ -355,7 +678,6 @@ static void set_huge_ptep_writable(struct vm_area_struct *vma,
    entry = pte_mkwrite(pte_mkdirty(*ptep));
    if (ptep_set_access_flags(vma, address, ptep, entry, 1)) {
       update_mmu_cache(vma, address, entry);
-      lazy_mmu_prot_update(entry);
    }
 }
 
@@ -377,6 +699,11 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
       dst_pte = huge_pte_alloc(dst, addr);
       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(&src->page_table_lock);
       if (!pte_none(*src_pte)) {
@@ -479,9 +806,9 @@ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
    page_cache_get(old_page);
    new_page = alloc_huge_page(vma, address);
 
-   if (!new_page) {
+   if (IS_ERR(new_page)) {
       page_cache_release(old_page);
-      return VM_FAULT_OOM;
+      return -PTR_ERR(new_page);
    }
 
    spin_unlock(&mm->page_table_lock);
@@ -525,27 +852,28 @@ retry:
       size = i_size_read(mapping->host) >> HPAGE_SHIFT;
       if (idx >= size)
          goto out;
-      if (hugetlb_get_quota(mapping))
-         goto out;
       page = alloc_huge_page(vma, address);
-      if (!page) {
-         hugetlb_put_quota(mapping);
-         ret = VM_FAULT_OOM;
+      if (IS_ERR(page)) {
+         ret = -PTR_ERR(page);
          goto out;
       }
       clear_huge_page(page, address);
 
       if (vma->vm_flags & VM_SHARED) {
          int err;
+         struct inode *inode = mapping->host;
 
          err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
          if (err) {
             put_page(page);
-            hugetlb_put_quota(mapping);
             if (err == -EEXIST)
                goto retry;
             goto out;
          }
+
+         spin_lock(&inode->i_lock);
+         inode->i_blocks += BLOCKS_PER_HUGEPAGE;
+         spin_unlock(&inode->i_lock);
       } else
          lock_page(page);
    }
@@ -575,7 +903,6 @@ out:
 
 backout:
    spin_unlock(&mm->page_table_lock);
-   hugetlb_put_quota(mapping);
    unlock_page(page);
    put_page(page);
    goto out;
@@ -621,7 +948,8 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 
 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 long *position, int *length, int i,
+         int write)
 {
    unsigned long pfn_offset;
    unsigned long vaddr = *position;
@@ -639,11 +967,11 @@ int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
        */
       pte = huge_pte_offset(mm, vaddr & HPAGE_MASK);
 
-      if (!pte || pte_none(*pte)) {
+      if (!pte || pte_none(*pte) || (write && !pte_write(*pte))) {
          int ret;
 
          spin_unlock(&mm->page_table_lock);
-         ret = hugetlb_fault(mm, vma, vaddr, 0);
+         ret = hugetlb_fault(mm, vma, vaddr, write);
          spin_lock(&mm->page_table_lock);
          if (!(ret & VM_FAULT_ERROR))
             continue;
@@ -708,7 +1036,6 @@ void hugetlb_change_protection(struct vm_area_struct *vma,
          pte = huge_ptep_get_and_clear(mm, address, ptep);
          pte = pte_mkhuge(pte_modify(pte, newprot));
          set_huge_pte_at(mm, address, ptep, pte);
-         lazy_mmu_prot_update(pte);
       }
    }
    spin_unlock(&mm->page_table_lock);
@@ -771,10 +1098,10 @@ static long region_chg(struct list_head *head, long f, long t)
 
    /* 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 guarentee to record the reservation. */
+    * 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 == 0)
+      if (!nrg)
          return -ENOMEM;
       nrg->from = f;
       nrg->to   = f;
@@ -843,21 +1170,6 @@ static int hugetlb_acct_memory(long delta)
    int ret = -ENOMEM;
 
    spin_lock(&hugetlb_lock);
-   if ((delta + resv_huge_pages) <= free_huge_pages) {
-      resv_huge_pages += delta;
-      ret = 0;
-   }
-   spin_unlock(&hugetlb_lock);
-   return ret;
-}
-
-int hugetlb_reserve_pages(struct inode *inode, long from, long to)
-{
-   long ret, chg;
-
-   chg = region_chg(&inode->i_mapping->private_list, from, to);
-   if (chg < 0)
-      return chg;
    /*
     * When cpuset is configured, it breaks the strict hugetlb page
     * reservation as the accounting is done on a global variable. Such
@@ -875,12 +1187,39 @@ int hugetlb_reserve_pages(struct inode *inode, long from, long to)
     * a best attempt and hopefully to minimize the impact of changing
     * semantics that cpuset has.
     */
-   if (chg > cpuset_mems_nr(free_huge_pages_node))
-      return -ENOMEM;
+   if (delta > 0) {
+      if (gather_surplus_pages(delta) < 0)
+         goto out;
+
+      if (delta > cpuset_mems_nr(free_huge_pages_node))
+         goto out;
+   }
+
+   ret = 0;
+   resv_huge_pages += delta;
+   if (delta < 0)
+      return_unused_surplus_pages((unsigned long) -delta);
+
+out:
+   spin_unlock(&hugetlb_lock);
+   return ret;
+}
+
+int hugetlb_reserve_pages(struct inode *inode, long from, long to)
+{
+   long ret, chg;
 
+   chg = region_chg(&inode->i_mapping->private_list, from, to);
+   if (chg < 0)
+      return chg;
+
+   if (hugetlb_get_quota(inode->i_mapping, chg))
+      return -ENOSPC;
    ret = hugetlb_acct_memory(chg);
-   if (ret < 0)
+   if (ret < 0) {
+      hugetlb_put_quota(inode->i_mapping, chg);
       return ret;
+   }
    region_add(&inode->i_mapping->private_list, from, to);
    return 0;
 }
@@ -888,5 +1227,11 @@ int hugetlb_reserve_pages(struct inode *inode, long from, long to)
 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
 {
    long chg = region_truncate(&inode->i_mapping->private_list, offset);
-   hugetlb_acct_memory(freed - chg);
+
+   spin_lock(&inode->i_lock);
+   inode->i_blocks -= BLOCKS_PER_HUGEPAGE * freed;
+   spin_unlock(&inode->i_lock);
+
+   hugetlb_put_quota(inode->i_mapping, (chg - freed));
+   hugetlb_acct_memory(-(chg - freed));
 }