Re: 2.6.33.5 rt23: machine lockup (nfs/autofs related?)

[Fernando Lopez-Lezcano <nando@ccrma.Stanford.EDU>]

On Thu, 2010-07-08 at 15:33 -0700, john stultz wrote:
> On Thu, 2010-07-08 at 10:19 -0700, Fernando Lopez-Lezcano wrote:
> > We are having problems with 2.6.33.5+rt23, at least in our configuration
> > while accessing an nfs automounted directory. This causes a complete
> > machine lockup (press reset to exit as the only option). 
> > 
> > I simply use the Nautilus file manager (in Fedora 12) to navigate to an
> > autofs mounted directory and the process monitor goes to 100% on one
> > core (or maybe two), the mouse jerks a bit and the whole thing goes
> > catatonic almost immediately. 
> > 
> > I get this in any open terminal at the time of the crash:
> > 
> > --------
> > Message from syslogd@localhost at Jul  8 10:13:54 ...
> >  kernel:------------[ cut here ]------------
> > 
> > Message from syslogd@localhost at Jul  8 10:13:54 ...
> >  kernel:invalid opcode: 0000 [#1] PREEMPT SMP 
> > 
> > Message from syslogd@localhost at Jul  8 10:13:54 ...
> >  kernel:last sysfs
> > file: /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
> > 
> > Message from syslogd@localhost at Jul  8 10:13:54 ...
> >  kernel:Process nautilus (pid: 2874, ti=f0204000 task=f17dd1f0
> > task.ti=f0204000)
> > 
> > Message from syslogd@localhost at Jul  8 10:13:54 ...
> >  kernel:Stack:
> > 
> > Message from syslogd@localhost at Jul  8 10:13:54 ...
> >  kernel:Call Trace:
> > 
> > Message from syslogd@localhost at Jul  8 10:13:54 ...
> >  kernel:Code: 7b 08 00 89 45 b8 75 12 8d 43 04 89 43 04 89 43 08 8d 43
> > 0c 89 43 0c 89 43 10 8b 43 14 64 8b 15 2c d1 a5 c0 83 e0 fc 39 c2 75 04
> > <0f> 0b eb fe 8b 3a 81 ff 08 01 00 00 74 0a 83 ff 02 b8 04 00 00 
> > 
> > Message from syslogd@localhost at Jul  8 10:13:54 ...
> >  kernel:EIP: [<c0792c0f>] rt_spin_lock_slowlock+0x43/0x1bb SS:ESP
> > 0068:f0205cbc
> > --------
> > 
> > And that's it... nothing else in the logs. 
> 
> Hrm. Not too much to go on there, but thanks for the report.
> 
> 
> > For now we are booting into the normal Fedora kernel (this is on Fedora
> > 12) as this makes the rt kernel not usable in our setup. 
> > 
> > Let me know if there is anything else I can do to help debug this...
> 
> Had you done any testing with earlier 2.6.33-rt kernels where this
> didn't occur? If so what version?

I have been working with the whole series but my main usage case does
not use nfs/autofs (see next paragraphs). 

I have noticed that the problem does not appear to happen when I cd into
an nfs automounted directory directly. It appears to happen only when
listing the contents of a mount point (ie: when "/whatever/" is an
autofs mount point where several directories are mounted, not
necessarily from the same server). 

Before switching to Fedora 12 users were normally running 2.6.29 rt and
I had been running 2.6.31.x and 2.6.33.x rt, but I don't think it ever
happened to me personally (I'm always using the command line - this is
completely reproducible with nautilus). After the switch it started
happening almost immediately to regular users (using nautilus mostly). 

How could I try to get more debugging information?
-- Fernando