1 files changed, 35 insertions, 9 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 92155db888b9..4c97c174e2e1 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1942,6 +1942,15 @@ retry:
                         lock_page(page);
         }
 
+        /*
+         * 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 (write_access && !(vma->vm_flags & VM_SHARED))
+                vma_needs_reservation(h, vma, address);
+
         spin_lock(&mm->page_table_lock);
         size = i_size_read(mapping->host) >> huge_page_shift(h);
         if (idx >= size)
@@ -1978,6 +1987,7 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
         pte_t *ptep;
         pte_t entry;
         int ret;
+        struct page *pagecache_page = NULL;
         static DEFINE_MUTEX(hugetlb_instantiation_mutex);
         struct hstate *h = hstate_vma(vma);
 
@@ -2000,19 +2010,35 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 
         ret = 0;
 
+        /*
+         * 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 (write_access && !pte_write(entry)) {
+                vma_needs_reservation(h, vma, address);
+
+                if (!(vma->vm_flags & VM_SHARED))
+                        pagecache_page = hugetlbfs_pagecache_page(h,
+                                                                vma, address);
+        }
+
         spin_lock(&mm->page_table_lock);
         /* Check for a racing update before calling hugetlb_cow */
         if (likely(pte_same(entry, huge_ptep_get(ptep))))
-                if (write_access && !pte_write(entry)) {
-                        struct page *page;
-                        page = hugetlbfs_pagecache_page(h, vma, address);
-                        ret = hugetlb_cow(mm, vma, address, ptep, entry, page);
-                        if (page) {
-                                unlock_page(page);
-                                put_page(page);
-                        }
-                }
+                if (write_access && !pte_write(entry))
+                        ret = hugetlb_cow(mm, vma, address, ptep, entry,
+                                                        pagecache_page);
         spin_unlock(&mm->page_table_lock);
+
+        if (pagecache_page) {
+                unlock_page(pagecache_page);
+                put_page(pagecache_page);
+        }
+
         mutex_unlock(&hugetlb_instantiation_mutex);
 
         return ret;