Comment 13 for bug 1856871

It then might be a problem with "/dev/loop-control" device node. Which dynamically find or allocate a free device, but also add and remove loop devices from the running system.

# drivers/block/loop.c

   2090 static void loop_remove(struct loop_device *lo)
   2091 {
   2092 del_gendisk(lo->lo_disk);
   2093 blk_cleanup_queue(lo->lo_queue);
   2094 blk_mq_free_tag_set(&lo->tag_set);
   2095 put_disk(lo->lo_disk);
   2096 kfree(lo);
   2097 }

   2177 case LOOP_CTL_REMOVE:
   2178 ret = loop_lookup(&lo, parm);
   2179 if (ret < 0)
   2180 break;
   2181 if (lo->lo_state != Lo_unbound) {
   2182 ret = -EBUSY;
   2183 break;
   2184 }
   2185 if (atomic_read(&lo->lo_refcnt) > 0) {
   2186 ret = -EBUSY;
   2187 break;
   2188 }
   2189 lo->lo_disk->private_data = NULL;
   2190 idr_remove(&loop_index_idr, lo->lo_number);
   2191 loop_remove(lo);
   2192 break;