Re: qemu-kvm-1.0.1 - unable to exit if vcpu is in infinite loop

[Peter Lieven <pl@dlhnet.de>]

On 08/21/12 10:23, Stefan Hajnoczi wrote:
> On Tue, Aug 21, 2012 at 8:21 AM, Jan Kiszka<jan.kiszka@siemens.com>  wrote:
>> On 2012-08-19 11:42, Avi Kivity wrote:
>>> On 08/17/2012 06:04 PM, Jan Kiszka wrote:
>>>>>> Can anyone imagine that such a barrier may actually be required? If it
>>>>>> is currently possible that env->stop is evaluated before we called into
>>>>>> sigtimedwait in qemu_kvm_eat_signals, then we could actually eat the
>>>>>> signal without properly processing its reason (stop).
>>>> Should not be required (TM): Both signal eating / stop checking and stop
>>>> setting / signal generation happens under the BQL, thus the ordering
>>>> must not make a difference here.
>>> Agree.
>>>
>>>
>>>> Don't see where we could lose a signal. Maybe due to a subtle memory
>>>> corruption that sets thread_kicked to non-zero, preventing the kicking
>>>> this way.
>>> Cannot be ruled out, yet too much of a coincidence.
>>>
>>> Could be a kernel bug (either in kvm or elsewhere), we've had several
>>> before in this area.
>>>
>>> Is this reproducible?
>> Not for me. Peter only hit it very rarely, Peter obviously more easily.
> I have only hit this once and was not able to reproduce it.
For me it was very reproducible, but my issue was fixed by:

http://www.mail-archive.com/kvm@vger.kernel.org/msg70908.html

Never seen this since then,
Peter

> Stefan