Subject: Re: futexes: Still infinite loop in get_futex_key() in 2.6.31-rc4
From: Jens Rosenboom <jens@mcbone.net>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Sonny Rao <sonnyrao@us.ibm.com>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>
In-Reply-To: <1248701812.6987.1637.camel@twins>
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	 <1248701812.6987.1637.camel@twins>
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Date: Wed, 29 Jul 2009 08:22:48 +0200
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On Mon, 2009-07-27 at 15:36 +0200, Peter Zijlstra wrote:
[...]
> Bugger.. how easy it is to reproduce?

Okay, my colleague found the right combination of scripts, take the two
attached, run them both a couple of times in parallel for some hours,
and get a stuck ps. This happens both on an old 2.6.29.1 I happened to
still have on one machine as with 2.6.31-rc4. Both of them dual-core
Opterons as the original one. If you want further tracebacks or other
information, let me know.

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#!/usr/bin/perl -w
use strict;

my $a = 'a';
while (1) {
 $0 = "null_".$a++;
}

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Content-Disposition: attachment; filename="pees.pl"
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#!/usr/bin/perl -w
use strict;

while (1) {
 my @a = grep (/ SOMETHING: /, `ps ax 2>/dev/null`);
}

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