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Subject: Re: 2.6.33.5 rt23: machine lockup (nfs/autofs related?)
From: john stultz <johnstul@us.ibm.com>
To: Fernando Lopez-Lezcano <nando@ccrma.Stanford.EDU>
Cc: Thomas Gleixner <tglx@linutronix.de>, LKML <linux-kernel@vger.kernel.org>,
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Date: Fri, 09 Jul 2010 15:57:02 -0700
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On Fri, 2010-07-09 at 15:13 -0700, Fernando Lopez-Lezcano wrote:
> On Fri, 2010-07-09 at 12:54 -0700, john stultz wrote:
> > On Fri, 2010-07-09 at 12:02 -0700, Fernando Lopez-Lezcano wrote:
> > > Ok, I got one! (had to go buy a null modem cable, I thought I had one
> > > but it has disappeared since the last time I did this :-)
> > 
> > Great! Sorry to make you go shopping! But this points out the problem
> > nicely.
> 
> No problem at all, I was sure I had one... anyway, I still need it :-<
> 
> > > Find it below... it keeps spewing stuff every once in a while. Hopefully
> > > this will be enough. No response from the network or the keyboard or
> > > mouse at this point, reset is the only way out. 
> > > 
> > > I can retest if somebody comes up with a patch...
> 
> Sorry, it looks like the patch patched correctly and this is the new
> kernel, but I still get a hang as before. 

So looking over it, I'm not easily seeing what else could be off.

So Lets see if we can cut some of the guess work out of this...

>  [<c04e08e9>] ? d_materialise_unique+0xbf/0x29e

I'm curious exactly where that is in d_materialise_unique. To find out,
can you find the vmlinux image in the base of the directory you built
the kernel you triggered this in?

Then run:
# gdb ./vmlinux

Once gdb loads:
(gdb) list *0xc04e08e9

That should point to exactly where in the function we are trying to
acquire a previously locked lock.

thanks
-john


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