diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 2c7a0f4..7104ac8 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -948,6 +948,11 @@
 	unsigned int major, minor;
 
 	cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
+	if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
+		sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
+		cfqg->blkg.dev = MKDEV(major, minor);
+		goto done;
+	}
 	if (cfqg || !create)
 		goto done;