Re: [Xen-devel] [xen-unstable test] 110009: regressions - FAIL

[Julien Grall <julien.grall@xxxxxxx>]

Hi Jan,

On 12/06/2017 15:57, Jan Beulich wrote:
> > > > On 12.06.17 at 16:30, <julien.grall@xxxxxxx> wrote:
> > On 09/06/17 09:19, Jan Beulich wrote:
> > > > > > On 07.06.17 at 10:12, <JBeulich@xxxxxxxx> wrote:
> > > > > > > On 06.06.17 at 21:19, <sstabellini@xxxxxxxxxx> wrote:
> > > > > On Tue, 6 Jun 2017, Jan Beulich wrote:
> > > > > > > > > On 06.06.17 at 16:00, <ian.jackson@xxxxxxxxxxxxx> wrote:
> > > > > > > Looking at the serial logs for that and comparing them with 10009,
> > > > > > > it's not terribly easy to see what's going on because the kernel
> > > > > > > versions are different and so produce different messages about xenbr0
> > > > > > > (and I think may have a different bridge port management algorithm).
> > > > > > >
> > > > > > > But the messages about promiscuous mode seem the same, and of course
> > > > > > > promiscuous mode is controlled by userspace, rather than by the kernel
> > > > > > > (so should be the same in both).
> > > > > > >
> > > > > > > However, in the failed test we see extra messages about promis:
> > > > > > >
> > > > > > >   Jun  5 13:37:08.353656 [ 2191.652079] device vif7.0-emu left promiscuous
> > > > > > > mode
> > > > > > >   ...
> > > > > > >   Jun  5 13:37:08.377571 [ 2191.675298] device vif7.0 left promiscuous mode
> > > > > > Wouldn't those be another result of the guest shutting down /
> > > > > > being shut down?
> > > > > >
> > > > > > > Also, the qemu log for the guest in the failure case says this:
> > > > > > >
> > > > > > >   Log-dirty command enable
> > > > > > >   Log-dirty: no command yet.
> > > > > > >   reset requested in cpu_handle_ioreq.
> > > > > > So this would seem to call for instrumentation on the qemu side
> > > > > > then, as the only path via which this can be initiated is - afaics -
> > > > > > qemu_system_reset_request(), which doesn't have very many
> > > > > > callers that could possibly be of interest here. Adding Stefano ...
> > > > > I am pretty sure that those messages come from qemu traditional: "reset
> > > > > requested in cpu_handle_ioreq" is not printed by qemu-xen.
> > > > Oh, indeed - I didn't pay attention to this being a *-qemut-*
> > > > test. I'm sorry.
> > > >
> > > > > In any case, the request comes from qemu_system_reset_request, which is
> > > > > called by hw/acpi.c:pm_ioport_writew. It looks like the guest OS
> > > > > initiated the reset (or resume)?
> > > > Right, this and hw/pckbd.c look to be the only possible
> > > > sources. Yet then it's still unclear what makes the guest go
> > > > down.
> > > So with all of the above in mind I wonder whether we shouldn't
> > > revert 933f966bcd then - that debugging code is unlikely to help
> > > with any further analysis of the issue, as reaching that code
> > > for a dying domain is only a symptom as far as we understand it
> > > now, not anywhere near the cause.
> > Are you suggesting to revert on Xen 4.9?
> Yes, if we revert now, then I'd say on both master and 4.9.
I would be ok with that.

Cheers,

--
Julien Grall

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