[Qemu-devel] latest rc: virtio-blk hangs forever after migration

[Andrey Korolyov]

Hello,

the issue is not specific to the iothread code because generic
virtio-blk also hangs up:

Given code set like in the
http://www.mail-archive.com/address@hidden/msg246164.html,
launch a VM with virtio-blk disk and writeback rbd backend, fire up
fio, migrate once with libvirt:

time virsh migrate vm27842 qemu+tcp://10.6.0.10/system --live
--persistent --undefinesource --timeout 60


real    1m2.969s
user    0m0.016s
sys     0m0.008s

For ones who are unfamiliar with libvirt syntax this means that the
live migration was failed to complete over sixty seconds, VM was
frozen, moved and re-launched at the destination. After this, I/O gets
stuck forever. Any diagnostic information is available upon request if
there will be difficulties repeating the issue.