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

["Paweł Sikora" <pawel.sikora@agmk.net>]

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.

BR,
Paweł.