Re: [PATCH v4 4/6] iotests: 194: test also migration of dirty bitmap

[Vladimir Sementsov-Ogievskiy]

04.06.2020 10:21, Thomas Huth wrote:
> On 03/06/2020 10.06, Vladimir Sementsov-Ogievskiy wrote:
> > 03.06.2020 10:52, Thomas Huth wrote:
> > > On 22/05/2020 00.06, Vladimir Sementsov-Ogievskiy wrote:
> > > > Test that dirty bitmap migration works when we deal with mirror.
> > > >
> > > > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> > > > Reviewed-by: Eric Blake <eblake@redhat.com>
> > > > ---
> > > >    tests/qemu-iotests/194     | 14 ++++++++++----
> > > >    tests/qemu-iotests/194.out |  6 ++++++
> > > >    2 files changed, 16 insertions(+), 4 deletions(-)
> > >
> > >    Hi!
> > >
> > > This test broke the iotest in the gitlab CI:
> > >
> > >    https://gitlab.com/huth/qemu/-/jobs/578520599#L3780
> > >
> > > it works again when I revert this commit.
> > >
> > > Could the test be reworked so that it works in CI pipelines, too?
> > > Otherwise, I think it's best if we disable it in the .gitlab-ci.yml
> > > file...
> [...]
> > - Qemu aborted. Not good. Definitely is better to fix it than just
> > exclude the test.. I can't reproduce. Could you provide backtrace from
> > coredump?
>
> It aborted in block/dirty-bitmap.c, line 295, that's the
> "assert(!bdrv_dirty_bitmap_busy(bitmap));" if I got it right.
>
> Full backtrace here:
>
>   https://gitlab.com/huth/qemu/-/jobs/580553686#L3638

Aha, missed it, thanks.

Hm. in 194 iotest we wait for migration finish on source, but not on target. I 
can assume, that in your setup target shutdown occurs earlier than migration 
finish, so we have busy bitmap on shutdown.
It's known bug (at least for me :), patch is in list:
[PATCH v2 00/22] Fix error handling during bitmap postcopy
  [..]
  [PATCH v2 10/22] migration/block-dirty-bitmap: cancel migration on shutdown  
(https://lists.gnu.org/archive/html/qemu-devel/2020-02/msg04288.html)
     If target is turned of prior to postcopy finished, target crashes
     because busy bitmaps are found at shutdown.
     Canceling incoming migration helps, as it removes all unfinished (and
     therefore busy) bitmaps.
  [..]


Still, of course iotest 194 should be fixed too, to wait for migration finish 
on target too, I'll send a patch.

--
Best regards,
Vladimir