diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index d9481640b3e116b2ac4077ece7e94bca1c36c42e..541454b4f479ca5e8b2f24ce76d8188e5f989b95 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -393,8 +393,13 @@ STORE(bch_cached_dev)
 	if (attr == &sysfs_writeback_running)
 		bch_writeback_queue(dc);
 
+	/*
+	 * Only set BCACHE_DEV_WB_RUNNING when cached device attached to
+	 * a cache set, otherwise it doesn't make sense.
+	 */
 	if (attr == &sysfs_writeback_percent)
-		if (!test_and_set_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags))
+		if ((dc->disk.c != NULL) &&
+		    (!test_and_set_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags)))
 			schedule_delayed_work(&dc->writeback_rate_update,
 				      dc->writeback_rate_update_seconds * HZ);