linux-ext4 - Re: pagefault in generic_file_buffered

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Date:	Wed, 15 Nov 2006 15:39:52 -0500
From:	Chris Mason <chris.mason@...cle.com>
To:	Andrew Morton <akpm@...l.org>
Cc:	Badari Pulavarty <pbadari@...ibm.com>,
	linux-mm <linux-mm@...ck.org>, ext4 <linux-ext4@...r.kernel.org>,
	lkml <linux-kernel@...r.kernel.org>, npiggin@...e.de
Subject: Re: pagefault in generic_file_buffered_write() causing deadlock

On Wed, Nov 15, 2006 at 11:29:57AM -0800, Andrew Morton wrote:
> Oh well.  If it's a deadlock (this is not clear from your description) then
> please gather backtraces of all affected tasks.
> 
> There is an ab/ba deadlock with journal_start() and lock_page(), iirc. 
> Chris and I had a look at that a while back and collapsed in exhaustion -
> it isn't pretty.  

This should be the page fault/journal lock inversion stuff Nick was
working on.  His patchset had a pretty good description of the problems,
Badari can also dig through the novell/ltc bugzillas for vmmstress.
Should be LTC9358.

Hopefully Nick's patches will address all of this.  sles9 had a partial
solution for the mmap deadlock, I think it was to dirty the inode at a
later time.  For some reason, I thought this workload was passing in
later kernels...

-chris
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