Re: OOPS at mount

From: David Woodhouse <dwmw2@infradead.org>
To: joakim.tjernlund@transmode.se
Cc: linux-mtd@lists.infradead.org
Subject: Re: OOPS at mount
Date: Thu, 26 Apr 2007 09:29:55 +0100	[thread overview]
Message-ID: <1177576195.2755.286.camel@pmac.infradead.org> (raw)
In-Reply-To: <1177575617.28488.17.camel@gentoo-jocke.transmode.se>

On Thu, 2007-04-26 at 10:20 +0200, Joakim Tjernlund wrote:
> No this is a matter of installing a number of new execuables/libs in
> the FS and moving a few symlinks. Then a reboot.
> I suspect that the it is only one of these printout that actually
> makes the system crash, the other ones has problaby been there for a
> while. Does that make sense?

Yes. Only one of those was a complaint with "but the old size was 0",
which will have led to a NULL frag_last() since there were no frags.

> No, none acutally.

Hmmm.

> > 
> > This is with JFFS2 from 2.6.20, right? Not a bug in the read_inode code
> > I just committed a couple of days ago?
> 
> Plain 2.6.20 with my optimized scan you just commited.

By 'optimised scan' you just mean the fix to make it not crash, right?

Not the _real_ optimisation I committed before that, which rewrites the
entire read_inode() code path?

> > 
> > > Wonder how the lab manged to get that many corrupted nodes?
> > > One thing that is rather new in our system is that we trigger GC by
> > > sending HUP to the GC thread from a script in user space at startup
> > > and then every 24 hours.
> > 
> > That shouldn't make any difference. 
> 
> I know, but thats the only thing that I can think of that is somewhat
> unique to our system.

Hm. I'm trying to think how it could trigger the problem -- even if we
didn't block SIGHUP when we were in the GC routines, I still don't see
how we could lose old nodes of a file without writing out new ones.

You can reproduce this at will by mounting a _clean_ filesystem, then
"installing a number of new executables and moving a few symlinks" and
then rebooting?

Can you do that all with CONFIG_JFFS2_FS_DEBUG=1 and log it? I'll then
see where _all_ the nodes for these problematics files are on the first
boot, I'll see what happens when you make changes, and I'll see what we
find on the second boot.

If you kill the GC thread (or hack the kernel not to start it) that'll
make the dump a bit less noisy.

-- 
dwmw2