diff --git a/[refs] b/[refs]
index de394e40da97..a4b3bfbbef4a 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 58ce1fd5805647a58a050bbbbd2252ea5ecb47b3
+refs/heads/master: 4c91c3648c620003cb7b21b8858f36cd6132e168
diff --git a/trunk/lib/radix-tree.c b/trunk/lib/radix-tree.c
index 7cbdada51049..b32efae7688e 100644
--- a/trunk/lib/radix-tree.c
+++ b/trunk/lib/radix-tree.c
@@ -389,8 +389,7 @@ void *radix_tree_tag_set(struct radix_tree_root *root,
 	struct radix_tree_node *slot;
 
 	height = root->height;
-	if (index > radix_tree_maxindex(height))
-		return NULL;
+	BUG_ON(index > radix_tree_maxindex(height));
 
 	slot = root->rnode;
 	shift = (height - 1) * RADIX_TREE_MAP_SHIFT;