[Bug 1859418] Re: disk driver with iothread setting hangs live migrations

[Launchpad Bug Tracker]

[Expired for QEMU because there has been no activity for 60 days.]

** Changed in: qemu
       Status: Incomplete => Expired

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1859418

Title:
  disk driver with iothread setting hangs live migrations

Status in QEMU:
  Expired

Bug description:
  Per report raised at
  https://bugzilla.redhat.com/show_bug.cgi?id=1790093

  Description of problem:

  A disk driver definition using iothread parameter causes live
  migration with copy storage to hang during or just before the final
  ram sync stage.

  Interestingly, having the scsi controller as a separate iothread does
  not trigger the issue.

  Version-Release number of selected component (if applicable):

  I can reproduce this on centos7 with qemu-ev and with centos 8:

  qemu-kvm-ev-2.12.0-33.1.el7_7.4.x86_64
  qemu-kvm-2.12.0-65.module_el8.0.0+189+f9babebb.5.x86_64

  Steps to Reproduce:
  1. Create a definition with 1 iothread on the disk image:

        <driver name='qemu' type='qcow2' iothread='1' />

  2. Issue a live migrate request like: virsh migrate --live --copy-storage-all 
vm qemu+tcp://remote/system
  3. Live migrate on source copies storage and then hangs at 80-99%, I guess 
during the ram copy phase.

  Keeping exactly the same config but without the iothread on the disk
  driver has successful migrations every time.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1859418/+subscriptions