diff --git a/[refs] b/[refs]
index 230201d9f8ea..e0a8a113562a 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 5b760e64a64c8940cdccd0ba6fce19a9bd010d20
+refs/heads/master: db36a46113e101a8aa2d6ede41e78f2eaabed3f1
diff --git a/trunk/mm/sparse.c b/trunk/mm/sparse.c
index fa933f43b2c9..42ca0ea9af1b 100644
--- a/trunk/mm/sparse.c
+++ b/trunk/mm/sparse.c
@@ -130,6 +130,8 @@ int __section_nr(struct mem_section* ms)
 		     break;
 	}
 
+	VM_BUG_ON(root_nr == NR_SECTION_ROOTS);
+
 	return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
 }