On Fri, Sep 07, 2018 at 11:34 AM +0200, Kevin Wolf <[email protected]> wrote: > 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).
I can try that. > > Maybe bisect within the commit that seems to cause the bug, by > selectively disabling some hunks in it? If I remove the line(s) /* Execute pending BHs first (may modify the graph) and check everything * else only after the BHs have executed. */ while (aio_poll(qemu_get_aio_context(), false)); in the function 'bdrv_drain_all_poll', then it works. > > Kevin > -- Kind regards / Beste Grüße Marc Hartmayer IBM Deutschland Research & Development GmbH Vorsitzende des Aufsichtsrats: Martina Koederitz Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen Registergericht: Amtsgericht Stuttgart, HRB 243294
