Re: [Qemu-devel] Unresponsive linux guest once migrated

[Dr. David Alan Gilbert]

* Marcus (address@hidden) wrote:
> Dang, I was hoping some ground was being made on this.

Can you answer the same questions I asked Marcin?
What's the latest version of QEMU you've seen this on, what CPU are you
using, what guest OS and what's your QEMU command line?

Dave

> 
> On Wed, Apr 2, 2014 at 11:05 AM, Marcin Gibu??a <address@hidden> wrote:
> >>> Yes, that's where it gets weird. I've never seen this on fresh VM.
> >>> It needs to be idle for couple of hours at least. And even then it
> >>> doesn't always hang.
> >>
> >>
> >> So your OS is just sitting at a text console, running nothing special?
> >> When you reboot after the migration what's the last thing you see
> >> in the guests logs? Is there anything from after the migration?
> >
> >
> > Yes, it's completely idle. After reboot there is nothing in logs. I've
> > dumped memory of one of hanged test VMs and found kernel message buffer. The
> > last entries were:
> >
> >
> > init: failsafe main process (659) killed by TERM signal
> > init: plymouth-upstart-bridge main process (651) killed by TERM signal
> >
> > <migration goes here, guest hangs>
> >
> > Clocksource tsc unstable (delta = 470666274 ns)
> >
> > <inject-nmi to test>
> >
> > Uhhuh. NMI received for unknown reason 30 on CPU 0.
> > Do you have a strange power saving mode enabled?I:
> >
> > Dazed and confused, but trying to continue
> > Uhhuh. NMI received for unknown reason 20 on CPU 0.
> > Do you have a strange power saving mode enabled?I:
> >
> > Dazed and confused, but trying to continue
> > <0>Dazed and confused, but trying to continue
> >
> >
> >
> > I've tried to disassemble where VM kernel (3.8.something from Ubuntu) is
> > spinning (using qemu-monitor, registers info and symbols from guest kernel)
> > and it was loop inside __run_timers function from kernel/timer.c:
> >
> > while (time_after_eq(jiffies, base->timer_jiffies)) {
> >   ...
> > }
> >
> > However my disassembly and qemu debugging skills are limited, would it help
> > if I dump memory of broken VM and send it you somehow?
> >
> > --
> > mg
> >
> >
> >
> 
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK