From 44e2aa937e698ea95dd86b2a4fabd734ef2c76db Mon Sep 17 00:00:00 2001
From: Dean Nelson <dnelson@redhat.com>
Date: Tue, 26 Oct 2010 14:22:08 -0700
Subject: [PATCH] mm/hugetlb.c: add missing spin_lock() to hugetlb_cow()

Add missing spin_lock() of the page_table_lock before an error return in
hugetlb_cow(). Callers of hugtelb_cow() expect it to be held upon return.

Signed-off-by: Dean Nelson <dnelson@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/hugetlb.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 96991ded82fe..c4a3558589ab 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2448,8 +2448,11 @@ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
 	 * When the original hugepage is shared one, it does not have
 	 * anon_vma prepared.
 	 */
-	if (unlikely(anon_vma_prepare(vma)))
+	if (unlikely(anon_vma_prepare(vma))) {
+		/* 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);
 	__SetPageUptodate(new_page);