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authorDean Nelson <dnelson@redhat.com>2010-12-02 14:31:12 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2010-12-02 14:51:14 -0800
commit1f64d69c7ad2e48e697493e45590679f7a69b7b2 (patch)
tree62e6c3d1dd31e1f87992710cde6b0b905f482606
parent94c35de9a918665d9354efe2bafc29ba4b37497a (diff)
downloadlinux-1f64d69c7ad2e48e697493e45590679f7a69b7b2.tar.gz
mm/hugetlb.c: avoid double unlock_page() in hugetlb_fault()
Have hugetlb_fault() call unlock_page(page) only if it had previously
called lock_page(page).

Setting CONFIG_DEBUG_VM=y and then running the libhugetlbfs test suite,
resulted in the tripping of VM_BUG_ON(!PageLocked(page)) in
unlock_page() having been called by hugetlb_fault() when page ==
pagecache_page.  This patch remedied the problem.

Signed-off-by: Dean Nelson <dnelson@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/hugetlb.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index c4a3558589ab..85855240933d 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2738,7 +2738,8 @@ out_page_table_lock:
 		unlock_page(pagecache_page);
 		put_page(pagecache_page);
 	}
-	unlock_page(page);
+	if (page != pagecache_page)
+		unlock_page(page);
 
 out_mutex:
 	mutex_unlock(&hugetlb_instantiation_mutex);