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Date: Sat, 30 Aug 2008 14:14:31 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Matthias Urlichs <matthias@urlichs.de>, linux-kernel@vger.kernel.org,
       Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [Regression] sshd hangs on close
Message-Id: <20080830141431.7bb34048.akpm@linux-foundation.org>
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	<200808302228.58255.rjw@sisk.pl>
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On Sat, 30 Aug 2008 22:28:57 +0200 "Rafael J. Wysocki" <rjw@sisk.pl> wrote:

> [Adding CCs]
> 
> On Saturday, 30 of August 2008, Matthias Urlichs wrote:
> > "top" sees multiple instances of:
> > 
> >  6008 root      20 3184 D    0   0:00.06 flush_cpu sshd: root@pts/13            
> > 
> > This is 2.6.27rc5, preemption and tickless turned on, on a 4-CPU machine.
> > (OK, two hyperthreaded ones :-P) strace() shows that this happens on the
> > last close of its /dev/ptmx file descriptor, which hangs.
> > 
> > I'll do a bisect early next week unless somebody else identifies a likely
> > suspect.
> > 

Please do `echo w > /proc/sysrq-trigger', send the resulting trace.