disk missing in the guest contingently when hotplug several virtio scsi disks consecutively

Hi, I found a bug that disk missing (not all disks missing ) in the guest contingently when hotplug several virtio scsi disks consecutively.  After rebooting the guest,the missing disks appear again.

The guest is centos7.3 running on a centos7.3 host and the scsi controllers are configed with iothread.  The scsi controller xml is below:

    <controller type='scsi' index='0' model='virtio-scsi'>
      <driver iothread='26'/>
      <alias name='scsi0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
    </controller>


If the scsi controllers are configed without iothread,  disks are all can be seen in the guest when hotplug several virtio scsi disks consecutively.

I think the biggest difference between them is that scsi controllers with iothread call virtio_notify_irqfd to notify guest and scsi controllers without

iothread call virtio_notify instead.  What make it difference? Will  interrupts are lost when call virtio_notify_irqfd  due to  race condition for some unknow reasons? Maybe guys more familiar with scsi dataplane can help. Thanks for your reply!