Re: [Qemu-block] forward of qemu bug regarding random qemu hangs at shutdown

[Kevin Wolf]

Am 06.09.2018 um 21:29 hat Christian Borntraeger geschrieben:
> Kevin,
> 
> for reference, it seems that his bug report somehow got lost.
> https://bugs.launchpad.net/qemu/+bug/1788582

That looks... interesting. The reproducer doesn't even seem to use a
block device, and the backtrace shows a QEMU that is just sitting in the
main loop waiting for events, not somewhere in the shutdown process
after exiting the main loop where bdrv_drain_all() would be called. I
fail to even come up with a theory about any connection between this and
commit 0f12264e7.

I think we need more information there. Can you set a breakpoint on
bdrv_drain_all_begin() to see where it's even called? When I start a
qemu instance without a block device, the first time this is called is
during shutdown after the mainloop (i.e. after the place where you're
seeing a hang).

Maybe bisect within the commit that seems to cause the bug, by
selectively disabling some hunks in it?

Kevin