openwrt/target/linux/generic/patches-3.10/441-block2mtd_probe.patch

--- a/drivers/mtd/devices/block2mtd.c
+++ b/drivers/mtd/devices/block2mtd.c
@@ -234,6 +234,7 @@ static struct block2mtd_dev *add_device(
 		/* We might not have rootfs mounted at this point. Try
 		   to resolve the device name by other means. */
 
+		wait_for_device_probe();
 		dev_t devt = name_to_dev_t(devname);
 		if (devt)
 			bdev = blkdev_get_by_dev(devt, mode, dev);