diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index df76291..bb74d7f 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -326,7 +326,7 @@
 	return 0;
 }
 /**
- * ext4_read_block_bitmap()
+ * ext4_read_block_bitmap_nowait()
  * @sb:			super block
  * @block_group:	given block group
  *
@@ -422,6 +422,8 @@
 	struct buffer_head *bh;
 
 	bh = ext4_read_block_bitmap_nowait(sb, block_group);
+	if (!bh)
+		return NULL;
 	if (ext4_wait_block_bitmap(sb, block_group, bh)) {
 		put_bh(bh);
 		return NULL;