--- x/fs/super.c
+++ y/fs/super.c
@@ -1624,9 +1624,9 @@ struct dentry *mount_bdev(struct file_sy
 		 */
 		super_unlock_excl(s);
 		error = setup_bdev_super(s, flags, NULL);
-		__super_lock_excl(s);
 		if (!error)
 			error = fill_super(s, data, flags & SB_SILENT ? 1 : 0);
+		__super_lock_excl(s);
 		if (error) {
 			deactivate_locked_super(s);
 			return ERR_PTR(error);