[Bug 1763649] Re: qemu segfaults after re-attaching ceph volume to instance

[Crazik]

I was confused by your "versions on Bionic/Queens are good" statement.

Openstack was upgraded to Queens, it's correct, I am using cloud archive
repositories for OpenStack packages, while base system is still based on
Xenial.

So final summary is correct,

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https://bugs.launchpad.net/bugs/1763649

Title:
  qemu segfaults after re-attaching ceph volume to instance

Status in Ubuntu Cloud Archive:
  New
Status in qemu package in Ubuntu:
  Fix Released
Status in qemu source package in Xenial:
  Incomplete
Status in qemu source package in Artful:
  Incomplete

Bug description:
  I have OpenStack compute nodes with qemu-system-x86. Using Ceph as
  storage backend for base disks and volumes (no local storage).

  When I create a new volume on ceph and attach to instance - it's working.
  When I detach volume, and re-attach again, with limited number of repeats I am able to crash my instance. Sometimes it's just in second try, sometimes 6, 9. In most cases it won't survive 10 cycles.

  Steps to reproduce:

  - create instance
  - create volume in ceph

  define volume in disk.xml: http://paste.openstack.org/show/719130/

  now try a loop:

  while true; do
    virsh attach-device instance-0xxx disk.xml;
    sleep 5;
    virsh detach-disk  instance-000022e8 vdb --live;
    sleep 5;
  done

  After few iterations, instance is crashed.

  Logs:

  kernel: [3866704.245319] traps: qemu-system-x86[23382] general
  protection ip:558690860750 sp:7faaf36f6ea8 error:0 in qemu-system-
  x86_64[5586902a7000+842000]

  or

  kernel: [7252748.718834] qemu-system-x86[30720]: segfault at 100 ip
  000056258ba78144 sp 00007fca010c1eb0 error 4 in qemu-system-
  x86_64[56258b47a000+842000]

  Ubuntu Xenial 16.04.3 with cloud-archive at Ocata repositories
  kernel: 4.4.0-109-generic
  qemu-system-x86 1:2.8+dfsg-3ubuntu2.9~cloud1
  libvirt-bin 2.5.0-3ubuntu5.6~cloud0
  ceph/rados: 10.2.10-1xenial

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