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Date: Fri, 6 Apr 2007 18:39:27 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Michal Piotrowski <michal.k.k.piotrowski@gmail.com>
Cc: Nick Piggin <npiggin@suse.de>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       "Eric W. Biederman" <ebiederm@xmission.com>,
       Thomas Gleixner <tglx@linutronix.de>,
       Nick Piggin <nickpiggin@yahoo.com.au>, Mingming Cao <cmm@us.ibm.com>,
       Adrian Bunk <bunk@stusta.de>, Andrew Morton <akpm@linux-foundation.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Mariusz Kozlowski <m.kozlowski@tuxland.pl>,
       Oliver Pinter <oliver.pntr@gmail.com>,
       Sid Boyce <g3vbv@blueyonder.co.uk>, Jens Axboe <jens.axboe@oracle.com>
Subject: Re: [patch] hrtimers debug patch
Message-ID: <20070406163927.GA27031@elte.hu>
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* Michal Piotrowski <michal.k.k.piotrowski@gmail.com> wrote:

> > thanks! I have stared at hrtimer.c a few more hours and the good 
> > news is that i found a narrow SMP race. The bad news is that i dont 
> > think it could explain your bug symptoms: the worst-case effect of 
> > the race should be an incorrect timeout on the current CPU - not a 
> > KTIME_MAX thing like your logs show.
> >
> > But maybe i didnt think through the effects of the bug well enough, 
> > and your box has a HT CPU, with HT CPUs being pretty good at 
> > triggering narrow SMP races - so maybe we are lucky? Fix attached 
> > below. Patch is build and boot-tested.
> 
> I didn't see this weird hang for 12 days. I think that this patch 
> solves this issue.

cool :)

> Huge thans!

huge thanks to you for testing it!

	Ingo