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Date: Tue, 11 Nov 2008 09:28:02 -0800
From: Frank Mayhar <fmayhar@...gle.com>
To: Ingo Molnar <mingo@...e.hu>
Cc: Oleg Nesterov <oleg@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Peter Zijlstra <peterz@...radead.org>, adobriyan@...il.com,
Doug Chapman <doug.chapman@...com>,
Roland McGrath <roland@...hat.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] for account_group_exec_runtime(), make sure ->signal
can't be freed under rq->lock
On Tue, 2008-11-11 at 18:16 +0100, Ingo Molnar wrote:
> * Frank Mayhar <fmayhar@...gle.com> wrote:
>
> > On Tue, 2008-11-11 at 11:35 +0100, Ingo Molnar wrote:
> > > * Oleg Nesterov <oleg@...hat.com> wrote:
> > > > The patch is ugly, but I don't see the better fix for now. Needs the
> > > > review from Peter/Ingo.
> > > this is indeed too ugly, and if we do it we'll get both this ugliness
> > > and the CPU loop upstream forever. Frank, if you dont have time to fix
> > > this code, then i guess the best thing is to do the full revert that
> > > Peter sent.
> >
> > Well, at the moment I'm up to my armpits in alligators. That said,
> > we're going to have to pull in this code regardless, ugliness and
> > all, since we're guaranteed to run into the soft lockup bug
> > otherwise. This means that I'll have strong incentive to come back
> > and readdress the fix to remove the ugliness and address Peter's
> > concerns. I have no idea when that will be, however.
>
> well, we wont leave buggy code in there for .28 - it could trigger
> anytime on any SMP box, no matter how narrow the race is.
Sorry, by "we" I meant where I work, not the Linux kernel folks; I guess
it's as true for you guys as it is for us but I'm certainly not in a
position to speak for you.
> I've picked up the spin-wait fix from Oleg, because it fixes the bug.
> But we should really fix the fundamental issues here too.
Agreed, in spades. In fact I plan to track this internally so it
doesn't fall off my radar.
--
Frank Mayhar <fmayhar@...gle.com>
Google, Inc.
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