Re: [BUG] fatal hang untarring 90GB file, possibly writeback related.

[Jan Kara <jack@suse.cz>]

On Thu 28-04-11 12:36:30, Colin Ian King wrote:
> 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.
  Adding Mel to CC, I guess he'll be interested. Mel, it seems this commit
of yours causes kswapd on non-preempt kernels spin for a *long* time...

								Honza
> 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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-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

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