linux-kernel - Re: [3.6.6] panic on reboot / khungtaskd blocked? (WARNING: at arch/x86/kernel/smp.c:123 native_smp_send

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Date:	Wed, 14 Nov 2012 22:10:46 +0100
From:	Paweł Sikora <pawel.sikora@...k.net>
To:	Michael Wang <wangyun@...ux.vnet.ibm.com>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	torvalds@...ux-foundation.org, arekm@...-linux.org,
	baggins@...-linux.org
Subject: Re: [3.6.6] panic on reboot / khungtaskd blocked? (WARNING: at arch/x86/kernel/smp.c:123 native_smp_send_reschedule)

On Wednesday 14 of November 2012 10:32:41 Michael Wang wrote:
> On 11/13/2012 05:40 PM, Paweł Sikora wrote:
> > On Monday 12 of November 2012 13:33:39 Paweł Sikora wrote:
> >> On Monday 12 of November 2012 11:22:47 Paweł Sikora wrote:
> >>> On Monday 12 of November 2012 15:40:31 Michael Wang wrote:
> >>>> On 11/12/2012 03:16 PM, Paweł Sikora wrote:
> >>>>> On Monday 12 of November 2012 11:04:12 Michael Wang wrote:
> >>>>>> On 11/09/2012 09:48 PM, Paweł Sikora wrote:
> >>>>>>> Hi,
> >>>>>>>
> >>>>>>> during playing with new ups i've caught an nice oops on reboot:
> >>>>>>>
> >>>>>>> http://imgbin.org/index.php?page=image&id=10253
> >>>>>>>
> >>>>>>> probably the upstream is also affected.
> >>>>>>
> >>>>>> Hi, Paweł
> >>>>>>
> >>>>>> Are you using a clean 3.6.6 without any modify?
> >>>>>
> >>>>> yes, pure 3.6.6 form git tree with modular config.
> >>>>>
> >>>>>> Looks like some threads has set itself to be UNINTERRUPTIBLE with out
> >>>>>> any design on switch itself back later(or the time is too long), are you
> >>>>>> accidentally using some bad designed module?
> >>>>>
> >>>>> hmm, hard to say. mostly all modules are loaded automatically by kernel.
> >>>>
> >>>> Could you please provide the whole dmesg in text? your picture lost the
> >>>> print info of the hung task.
> >>>
> >>> i've grabbed the console via rs232 but there's no more info (see attached txt).
> >>
> >> hmm, i have one observation.
> >>
> >> during rc.shutdown there're messages on console like this: Cannot stat file /proc/$pid/fd/1: Connection timed out
> >> afaics this file descriptor points to vnc log file on a remote machine, e.g.:
> >>
> >> # ps aux|grep xfwm4
> >> eda       1748  0.0  0.0 320220 11224 ?        S    13:08   0:00 xfwm4 
> >>
> >> # readlink -m /proc/1748/fd/1
> >> /remote/dragon/ahome/eda/.vnc/odra:11.log
> >>
> >> # mount|grep ahome
> >> dragon:/home/users/ on /remote/dragon/ahome type nfs (rw,relatime,vers=3,rsize=262144,wsize=262144,namlen=255,soft,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=10.0.2.121,mountvers=3,mountport=45251,mountproto=udp,local_lock=none,addr=10.0.2.121)
> >>
> >>
> >> so, probably during `killall5 -TERM/-KILL` on shutdown stage something sometimes go wrong
> >> and these processes (xfce4/vncserver) survive the signal and hang on the nfs i/o.
> >>
> > 
> > ok, now i have full sysrq+w backtraces from shutdown process. i hope i'll help you.
> 
> This can only tell us what's the task in UNINTERRUPTABLE state, but with
> out time info, we can't find out which one is the hung task...

attaching backtraces reported by khungtaskd during reboot sequence.

View attachment "dmesg.txt" of type "text/plain" (36467 bytes)