[Qemu-devel] QEMU refusing to die on FreeBSD host

[Qemu-devel] QEMU refusing to die on FreeBSD host

[Jake Myers]

Hello,

On FreeBSD 7-STABLE, qemu refuses to exit even after the window is 
closed. It is stuck so badly that even kill -9 fails to stop it. I 
looked in top to see what it was doing that would cause it to lock so badly:

PID USERNAME    THR PRI NICE   SIZE    RES STATE    TIME   WCPU COMMAND
34859 root          1  -8   20   433M   416M devdrn   9:49  0.00% qemu

I believe the problem is that qemu for some reason refuses to stop 
trying to use the kqemu device.

I am running the latest qemu (0.9.1). I can provide a backtrace on 
request (I'm really busy right now with other things, so I didn't have 
time to attach one).

Regards
Jacob Myers

Re: [Qemu-devel] QEMU refusing to die on FreeBSD host

[Juergen Lock]

On Sun, Apr 06, 2008 at 12:55:39AM -0400, Jake Myers wrote:
> Hello,
> 
> On FreeBSD 7-STABLE, qemu refuses to exit even after the window is closed. 
> It is stuck so badly that even kill -9 fails to stop it. I looked in top to 
> see what it was doing that would cause it to lock so badly:
> 
> PID USERNAME    THR PRI NICE   SIZE    RES STATE    TIME   WCPU COMMAND
> 34859 root          1  -8   20   433M   416M devdrn   9:49  0.00% qemu
> 
> I believe the problem is that qemu for some reason refuses to stop trying 
> to use the kqemu device.
> 
> I am running the latest qemu (0.9.1). I can provide a backtrace on request 
> (I'm really busy right now with other things, so I didn't have time to 
> attach one).

Yeah this looks like its the same FreeBSD 7.x/SMP issue that I already
got reports of (refcount problem, similar to what has already been fixed
once, only this time it seems to be a race...)

 If it is, you should be able to work around it by using an uniprocessor
host kernel until a fix is known.

 Sorry...
	Juergen

Re: [Qemu-devel] QEMU refusing to die on FreeBSD host

[M. Warner Losh]

In message: <20080406163440.GA47504@saturn.kn-bremen.de>
            Juergen Lock <nox@jelal.kn-bremen.de> writes:
: On Sun, Apr 06, 2008 at 12:55:39AM -0400, Jake Myers wrote:
: > Hello,
: > 
: > On FreeBSD 7-STABLE, qemu refuses to exit even after the window is closed. 
: > It is stuck so badly that even kill -9 fails to stop it. I looked in top to 
: > see what it was doing that would cause it to lock so badly:
: > 
: > PID USERNAME    THR PRI NICE   SIZE    RES STATE    TIME   WCPU COMMAND
: > 34859 root          1  -8   20   433M   416M devdrn   9:49  0.00% qemu
: > 
: > I believe the problem is that qemu for some reason refuses to stop trying 
: > to use the kqemu device.
: > 
: > I am running the latest qemu (0.9.1). I can provide a backtrace on request 
: > (I'm really busy right now with other things, so I didn't have time to 
: > attach one).
: 
: Yeah this looks like its the same FreeBSD 7.x/SMP issue that I already
: got reports of (refcount problem, similar to what has already been fixed
: once, only this time it seems to be a race...)
: 
:  If it is, you should be able to work around it by using an uniprocessor
: host kernel until a fix is known.

Well, reboot also works, since qemu that gets stuck will slowly be
paged out to the swap partition...  it isn't a huge deal from a
practical perspective...  Of course, this is just until the bug is
fixed...

Warner

Re: [Qemu-devel] QEMU refusing to die on FreeBSD host

[Jake Myers]

Juergen Lock wrote:
> On Sun, Apr 06, 2008 at 12:55:39AM -0400, Jake Myers wrote:
>   
>> Hello,
>>
>> On FreeBSD 7-STABLE, qemu refuses to exit even after the window is closed. 
>> It is stuck so badly that even kill -9 fails to stop it. I looked in top to 
>> see what it was doing that would cause it to lock so badly:
>>
>> PID USERNAME    THR PRI NICE   SIZE    RES STATE    TIME   WCPU COMMAND
>> 34859 root          1  -8   20   433M   416M devdrn   9:49  0.00% qemu
>>
>> I believe the problem is that qemu for some reason refuses to stop trying 
>> to use the kqemu device.
>>
>> I am running the latest qemu (0.9.1). I can provide a backtrace on request 
>> (I'm really busy right now with other things, so I didn't have time to 
>> attach one).
>>     
>
> Yeah this looks like its the same FreeBSD 7.x/SMP issue that I already
> got reports of (refcount problem, similar to what has already been fixed
> once, only this time it seems to be a race...)
>
>  If it is, you should be able to work around it by using an uniprocessor
> host kernel until a fix is known.
>
>  Sorry...
> 	Juergen
>
>
>
>   
I disabled SMP in my kernel, rebuilt the kqemu module, and tried to run 
it again. The same issue occurs.

Regards
Jacob Myers

Re: [Qemu-devel] QEMU refusing to die on FreeBSD host

[Juergen Lock]

In article <47F99FB4.7050403@gmail.com> you write:
>Juergen Lock wrote:
>> On Sun, Apr 06, 2008 at 12:55:39AM -0400, Jake Myers wrote:
>>   
>>> Hello,
>>>
>>> On FreeBSD 7-STABLE, qemu refuses to exit even after the window is closed. 
>>> It is stuck so badly that even kill -9 fails to stop it. I looked in top to 
>>> see what it was doing that would cause it to lock so badly:
>>>
>>> PID USERNAME    THR PRI NICE   SIZE    RES STATE    TIME   WCPU COMMAND
>>> 34859 root          1  -8   20   433M   416M devdrn   9:49  0.00% qemu
>>>
>>> I believe the problem is that qemu for some reason refuses to stop trying 
>>> to use the kqemu device.
>>>
>>> I am running the latest qemu (0.9.1). I can provide a backtrace on request 
>>> (I'm really busy right now with other things, so I didn't have time to 
>>> attach one).
>>>     
>>
>> Yeah this looks like its the same FreeBSD 7.x/SMP issue that I already
>> got reports of (refcount problem, similar to what has already been fixed
>> once, only this time it seems to be a race...)
>>
>>  If it is, you should be able to work around it by using an uniprocessor
>> host kernel until a fix is known.
>>
>>  Sorry...
>> 	Juergen
>>
>>
>>
>>   
>I disabled SMP in my kernel, rebuilt the kqemu module, and tried to run 
>it again. The same issue occurs.

Hmm okay, then its not an SMP issue, thanks for the information!
I guess then you can only do what Warner Losh suggested for the moment,
leave the hanging process(es) until reboot...  (You should at least be
able to run qemu again from another terminal, maybe use screen for this.)

 Sorry again...
	Juergen

Re: [Qemu-devel] QEMU refusing to die on FreeBSD host

[Juergen Lock]

On Mon, Apr 07, 2008 at 09:14:20PM +0200, Juergen Lock wrote:
> In article <47F99FB4.7050403@gmail.com> you write:
> >Juergen Lock wrote:
> >> On Sun, Apr 06, 2008 at 12:55:39AM -0400, Jake Myers wrote:
> >>   
> >>> Hello,
> >>>
> >>> On FreeBSD 7-STABLE, qemu refuses to exit even after the window is closed. 
> >>> It is stuck so badly that even kill -9 fails to stop it. I looked in top to 
> >>> see what it was doing that would cause it to lock so badly:
> >>>
> >>> PID USERNAME    THR PRI NICE   SIZE    RES STATE    TIME   WCPU COMMAND
> >>> 34859 root          1  -8   20   433M   416M devdrn   9:49  0.00% qemu
> >>>
> >>> I believe the problem is that qemu for some reason refuses to stop trying 
> >>> to use the kqemu device.
> >>>
> >>> I am running the latest qemu (0.9.1). I can provide a backtrace on request 
> >>> (I'm really busy right now with other things, so I didn't have time to 
> >>> attach one).
> >>>     
> >>
> >> Yeah this looks like its the same FreeBSD 7.x/SMP issue that I already
> >> got reports of (refcount problem, similar to what has already been fixed
> >> once, only this time it seems to be a race...)
> >>
> >>  If it is, you should be able to work around it by using an uniprocessor
> >> host kernel until a fix is known.
> >>
> >>  Sorry...
> >> 	Juergen
> >>
> >>
> >>
> >>   
> >I disabled SMP in my kernel, rebuilt the kqemu module, and tried to run 
> >it again. The same issue occurs.
> 
> Hmm okay, then its not an SMP issue, thanks for the information!
> [...]

OK, I just committed a fix, please try updating your kqemu port and
tell me if it works for you then.

 Thanx,
	Juergen

Re: [Qemu-devel] QEMU refusing to die on FreeBSD host

[Jake Myers]

Juergen Lock wrote:
> On Mon, Apr 07, 2008 at 09:14:20PM +0200, Juergen Lock wrote:
>   
>> In article <47F99FB4.7050403@gmail.com> you write:
>>     
>>> Juergen Lock wrote:
>>>       
>>>> On Sun, Apr 06, 2008 at 12:55:39AM -0400, Jake Myers wrote:
>>>>   
>>>>         
>>>>> Hello,
>>>>>
>>>>> On FreeBSD 7-STABLE, qemu refuses to exit even after the window is closed. 
>>>>> It is stuck so badly that even kill -9 fails to stop it. I looked in top to 
>>>>> see what it was doing that would cause it to lock so badly:
>>>>>
>>>>> PID USERNAME    THR PRI NICE   SIZE    RES STATE    TIME   WCPU COMMAND
>>>>> 34859 root          1  -8   20   433M   416M devdrn   9:49  0.00% qemu
>>>>>
>>>>> I believe the problem is that qemu for some reason refuses to stop trying 
>>>>> to use the kqemu device.
>>>>>
>>>>> I am running the latest qemu (0.9.1). I can provide a backtrace on request 
>>>>> (I'm really busy right now with other things, so I didn't have time to 
>>>>> attach one).
>>>>>     
>>>>>           
>>>> Yeah this looks like its the same FreeBSD 7.x/SMP issue that I already
>>>> got reports of (refcount problem, similar to what has already been fixed
>>>> once, only this time it seems to be a race...)
>>>>
>>>>  If it is, you should be able to work around it by using an uniprocessor
>>>> host kernel until a fix is known.
>>>>
>>>>  Sorry...
>>>> 	Juergen
>>>>
>>>>
>>>>
>>>>   
>>>>         
>>> I disabled SMP in my kernel, rebuilt the kqemu module, and tried to run 
>>> it again. The same issue occurs.
>>>       
>> Hmm okay, then its not an SMP issue, thanks for the information!
>> [...]
>>     
>
> OK, I just committed a fix, please try updating your kqemu port and
> tell me if it works for you then.
>
>  Thanx,
> 	Juergen
>
>   
Sorry for my very belated paste, I was away on vacation. It all works 
flawlessly now, thank you very much :-).

Regards
Jacob Myers