cgroup: fix memory leak in cgroup_get_sb()

opts.release_agent is not kfree()ed in all necessary places.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 36066d8..947fe3b 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -954,8 +954,11 @@
 	}
 
 	root = kzalloc(sizeof(*root), GFP_KERNEL);
-	if (!root)
+	if (!root) {
+		if (opts.release_agent)
+			kfree(opts.release_agent);
 		return -ENOMEM;
+	}
 
 	init_cgroup_root(root);
 	root->subsys_bits = opts.subsys_bits;