--- zzzz-none-000/linux-4.4.60/drivers/block/loop.c	2017-04-08 07:53:53.000000000 +0000
+++ scorpion-7490-727/linux-4.4.60/drivers/block/loop.c	2021-02-04 17:41:59.000000000 +0000
@@ -1569,9 +1569,8 @@
 	return err;
 }
 
-static void lo_release(struct gendisk *disk, fmode_t mode)
+static void __lo_release(struct loop_device *lo)
 {
-	struct loop_device *lo = disk->private_data;
 	int err;
 
 	if (atomic_dec_return(&lo->lo_refcnt))
@@ -1597,6 +1596,13 @@
 	mutex_unlock(&lo->lo_ctl_mutex);
 }
 
+static void lo_release(struct gendisk *disk, fmode_t mode)
+{
+	mutex_lock(&loop_index_mutex);
+	__lo_release(disk->private_data);
+	mutex_unlock(&loop_index_mutex);
+}
+
 static const struct block_device_operations lo_fops = {
 	.owner =	THIS_MODULE,
 	.open =		lo_open,