Re: [Qemu-devel] [PULL 10/40] migration: Delay start of migration main routines

[Kevin Wolf]

Am 18.05.2018 um 14:14 hat Kevin Wolf geschrieben:
> Am 18.05.2018 um 12:34 hat Dr. David Alan Gilbert geschrieben:
> > * Kevin Wolf (address@hidden) wrote:
> > > Am 16.05.2018 um 01:39 hat Juan Quintela geschrieben:
> > > > We need to make sure that we have started all the multifd threads.
> > > > 
> > > > Signed-off-by: Juan Quintela <address@hidden>
> > > > Reviewed-by: Daniel P. Berrangé <address@hidden>
> > > 
> > > This commit makes qemu-iotests 091 hang for me. Either it breaks
> > > backward compatibility intentionally and we need to update the test
> > > case, or there is a bug somewhere.
> > 
> > It's not an intentional break.
> > And the avocado tcp and exec migrations pass OK, so hmm.
> 
> In case it helps, 169 fails as well and I got a core dump of an aborting
> QEMU process:
> 
> (gdb) bt
> #0  0x00007ff079f779fb in raise () at /lib64/libc.so.6
> #1  0x00007ff079f79800 in abort () at /lib64/libc.so.6
> #2  0x00007ff079f700da in __assert_fail_base () at /lib64/libc.so.6
> #3  0x00007ff079f70152 in  () at /lib64/libc.so.6
> #4  0x000055c2126f067b in bdrv_close_all () at block.c:3375
> #5  0x000055c2123c54a6 in main (argc=<optimized out>, argv=<optimized out>, 
> envp=<optimized out>) at vl.c:4682
> 
> If I understand correctly, that assertion failure means that someone is
> still holding a reference to a block device after all user-owned
> references have been closed. I suppose this was the source qemu and
> the migration hasn't been completed properly, though I haven't looked at
> the code yet and this idea might be completely wrong.
> 
> Anyway, 091 is certainly the simpler test case to play with, but maybe
> this gives you another hint.

Any news on this? This is starting to become really annoying as a
hanging test suite impacts my ability to properly test block layer
patches.

If there is no hope of quickly getting a proper fix for this, we may
have to revert something for now to fight the symptoms at least.

Kevin