linux-kernel - Re: hanging aio process

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Message-ID: <alpine.LFD.2.11.1405211552350.1579@denkbrett>
Date:	Wed, 21 May 2014 16:12:19 +0200 (CEST)
From:	Sebastian Ott <sebott@...ux.vnet.ibm.com>
To:	Benjamin LaHaise <bcrl@...ck.org>
cc:	Anatol Pomozov <anatol.pomozov@...il.com>, linux-aio@...ck.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: hanging aio process

Hi,

On Wed, 21 May 2014, Benjamin LaHaise wrote:
> On Wed, May 21, 2014 at 10:48:55AM +0200, Sebastian Ott wrote:
> > > 
> > > I already did that and it didn't change, always 1 + (1UL << 31) in all
> > > cases, before and after percpu_ref_kill(&ctx->reqs). I'm not really
> > > familiar with this percpu_ref stuff but it looks like the initial
> > > reference is dropped asynchronous.
> > 
> > 
> > cat /sys/kernel/debug/tracing/trace
> 
> Your trace still isn't monitoring aio_complete().  You need to check if 
> aio_complete() is getting called in order to determine if the bug is in 
> the core aio code or not.

Yes, sry about that there were just too many of them. But I was able to
reproduce the problem with fio writing a little less data. Sadly it's
still much tracing data - a compressed archive is attached.

The number of aio_complete invocations is the same for the good and the
bad case:

for T in trace.bad trace.good  ;do wc $T ;done
  49156  294920 3735651 trace.bad
  49159  294939 3735901 trace.good

for T in trace.bad trace.good  ;do grep aio_complete $T | wc ;done
  49120  294720 3733120
  49120  294720 3733120

Regards,
Sebastian
Download attachment "traces.tar.xz" of type "APPLICATION/x-xz" (295128 bytes)