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Subject: Re: 2.6.33.5 rt23: machine lockup (nfs/autofs related?)
From: Fernando Lopez-Lezcano <nando@ccrma.Stanford.EDU>
To: john stultz <johnstul@us.ibm.com>
Cc: nando@ccrma.Stanford.EDU, Thomas Gleixner <tglx@linutronix.de>,
        LKML <linux-kernel@vger.kernel.org>,
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Date: Wed, 14 Jul 2010 15:02:12 -0700
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On Wed, 2010-07-14 at 14:36 -0700, john stultz wrote:
> On Wed, 2010-07-14 at 14:32 -0700, Fernando Lopez-Lezcano wrote:
> > On Mon, 2010-07-12 at 20:06 -0700, Fernando Lopez-Lezcano wrote:
> > > > > --------
> > > > > BUG: unable to handle kernel NULL pointer dereference at 0000008c
> > > > > IP: [<c045e50a>] rt_spin_lock_fastunlock.clone.2+0x6/0x3e
> > > > ...
> > > > > Pid: 2855, comm: nautilus Not tainted
> > > > > 2.6.33.6-147.rt23.3.fc12.ccrma.i686.rt #3 P5K/EPU/P5K/EPU
> > > > > EIP: 0060:[<c045e50a>] EFLAGS: 00210246 CPU: 0
> > > > > EIP is at rt_spin_lock_fastunlock.clone.2+0x6/0x3e
> > > > > EAX: 00000078 EBX: ef45393c ECX: 00000000 EDX: 00000078
> > > > > ESI: ef716edc EDI: 00000000 EBP: f1977c8c ESP: f1977c88
> > > > >  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 preempt:00000000
> > > > > Process nautilus (pid: 2855, ti=f1976000 task=f2347130 task.ti=f1976000)
> > > > > Stack:
> > > > >  ef45393c f1977c94 c0781206 f1977cc8 c04d842e 00000000 ef703e54 faadd5bc
> > > > > <0> f1977cdc 126bc87a ef703ddc 00000000 ef45393c ef716edc ef6f5494
> > > > > faafdc6c
> > > > > <0> f1977df8 faad9041 c3604b5c faafdc6c ef452bfc 00007e7f f5eb41e8
> > > > > 00000007
> > > > > Call Trace:
> > > > >  [<c0781206>] ? rt_spin_unlock+0x8/0xa
> > > > >  [<c04d842e>] ? d_materialise_unique+0x210/0x2aa
> > > > 
> > > > Can you gdb list *0xc04d842e ?
> > > 
> > > (gdb) list *0xc04d842e
> > > 0xc04d842e is in d_materialise_unique (fs/dcache.c:2073).
> > > 2068	out_unalias:
> > > 2069		d_move_locked(alias, dentry);
> > > 2070		ret = alias;
> > > 2071	out_err:
> > > 2072		spin_unlock(&inode->i_lock);
> > > 2073		if (m2)
> > > 2074			mutex_unlock(m2);
> > > 2075		if (m1)
> > > 2076			mutex_unlock(m1);
> > > 2077		return ret;
> > > 
> > > > Thanks again for all the testing here! Its really appreciated!
> > 
> > I just tried building 2.6.33.6 rt26 (saw it this morning on the site)
> > and it does not exhibit this problem. Woohoo!
> 
> Yea. The vfs-scalability patches were dropped. Sort of a bummer, but I'm
> glad that fixes it for you.
> 
> We may run into the issue again when the patches can get beaten back
> into shape, but I'll try to hunt down the issue from your log output
> prior to that.

Ok, let me know if you need me to test again. I have the serial cable
now! :-)

> Thanks again for the testing and great feedback!

Sure.
-- Fernando


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