From: Colin Ian King <colin.king.lkml@gmail.com>
Subject: Re: [BUG] fatal hang untarring 90GB file, possibly writeback
 related.
Date: Thu, 28 Apr 2011 12:36:30 +0100
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Cc: Chris Mason <chris.mason@oracle.com>, linux-fsdevel
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To: James Bottomley <James.Bottomley@suse.de>
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One more data point to add, I've been looking at an identical issue when
copying large amounts of data.  I bisected this - and the lockups occur
with commit 
3e7d344970673c5334cf7b5bb27c8c0942b06126 - before that I don't see the
issue. With this commit, my file copy test locks up after ~8-10
iterations, before this commit I can copy > 100 times and don't see the
lockup.

On Wed, 2011-04-27 at 15:05 -0500, James Bottomley wrote:
> On Wed, 2011-04-27 at 12:50 -0500, James Bottomley wrote:
> > To test the theory, Chris asked me to try with data=ordered.
> > Unfortunately, the deadlock still shows up.  This is what I get.
> 
> As another data point: I'm trying the same kernel with CONFIG_PREEMPT
> enabled.  This time the deadlock doesn't happen.  Instead, kswapd0 gets
> pegged at 99% CPU for much of the untar, but it does eventually
> complete.
> 
> James
> 
> 
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