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

[Marcus]

Dang, I was hoping some ground was being made on this.

On Wed, Apr 2, 2014 at 11:05 AM, Marcin Gibuła <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
>
>
>