diff --git a/[refs] b/[refs]
index 0f504491d67f..d53743997d43 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: df66916e71231e9f2377cac9c5c1e2d190f9a427
+refs/heads/master: 4eb3991c5def39bcf553c14ebe2618fcb47b627f
diff --git a/trunk/fs/btrfs/extent_map.c b/trunk/fs/btrfs/extent_map.c
index 2c726b7b9faa..ccbdcb54ec5d 100644
--- a/trunk/fs/btrfs/extent_map.c
+++ b/trunk/fs/btrfs/extent_map.c
@@ -208,7 +208,7 @@ int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len)
 	write_lock(&tree->lock);
 	em = lookup_extent_mapping(tree, start, len);
 
-	WARN_ON(em->start != start || !em);
+	WARN_ON(!em || em->start != start);
 
 	if (!em)
 		goto out;