From: Mike Galbraith <efault@gmx.de>
To: Milton Miller <miltonm@bga.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Peter Zijlstra <peterz@infradead.org>,
akpm@linux-foundation.org, Anton Blanchard <anton@samba.org>,
xiaoguangrong@cn.fujitsu.com, mingo@elte.hu, jaxboe@fusionio.com,
npiggin@gmail.com, JBeulich@novell.com, rusty@rustcorp.com.au,
torvalds@linux-foundation.org, benh@kernel.crashing.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3 v2] call_function_many: fix list delete vs add race
Date: Wed, 02 Feb 2011 07:22:01 +0100 [thread overview]
Message-ID: <1296627721.7858.3.camel@marge.simson.net> (raw)
In-Reply-To: <ipi-paul-reply@mdm.bga.com>
On Tue, 2011-02-01 at 14:00 -0800, Milton Miller wrote:
> On Tue, 1 Feb 2011 about 14:00:26 -0800, "Paul E. McKenney" wrote:
> > Starting with smp_call_function_many():
> >
> > o The check for refs is redundant:
> >
> > /* some callers might race with other cpus changing the mask */
> > if (unlikely(!refs)) {
> > csd_unlock(&data->csd);
> > return;
> > }
> >
> > The memory barriers and atomic functions in
> > generic_smp_call_function_interrupt() prevent the callback from
> > being reused before the cpumask bits have all been cleared, right?
>
> The issue is not the cpumask in the csd, but the mask passed in from the
> caller. If other cpus clear the mask between the cpumask_first and and
> cpumask_next above (where we established there were at least two cpus not
> ourself) and the cpumask_copy, then this can happen. Both Mike Galbraith
> and Jan Beulich saw this in practice (Mikes case was mm_cpumask(mm)).
Mine (and Jan's) is a flavor of one hit and fixed via copy in ia64.
http://git2.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=75c1c91cb92806f960fcd6e53d2a0c21f343081c
-Mike
next prev parent reply other threads:[~2011-02-02 6:22 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-12 4:07 [PATCH] smp_call_function_many SMP race Anton Blanchard
2011-01-17 18:17 ` Peter Zijlstra
2011-01-18 21:05 ` Milton Miller
2011-01-18 21:06 ` [PATCH 2/2] consolidate writes in smp_call_funtion_interrupt Milton Miller
2011-01-27 16:22 ` Peter Zijlstra
2011-01-27 21:59 ` Milton Miller
2011-01-29 0:20 ` call_function_many: fix list delete vs add race Milton Miller
2011-01-31 7:21 ` Mike Galbraith
2011-01-31 20:26 ` [PATCH] smp_call_function_many: handle concurrent clearing of mask Milton Miller
2011-02-01 3:15 ` Mike Galbraith
2011-01-31 10:27 ` call_function_many: fix list delete vs add race Peter Zijlstra
2011-01-31 20:26 ` Milton Miller
2011-01-31 20:39 ` Peter Zijlstra
2011-01-31 21:17 ` Peter Zijlstra
2011-01-31 21:36 ` Milton Miller
2011-02-01 0:22 ` Benjamin Herrenschmidt
2011-02-01 1:39 ` Linus Torvalds
2011-02-01 2:18 ` Paul E. McKenney
2011-02-01 2:43 ` Linus Torvalds
2011-02-01 4:45 ` Paul E. McKenney
2011-02-01 5:46 ` Linus Torvalds
2011-02-01 6:18 ` Benjamin Herrenschmidt
2011-02-01 14:13 ` Paul E. McKenney
2011-02-01 6:16 ` Benjamin Herrenschmidt
[not found] ` <ipi-list-reply@mdm.bga.com>
2011-02-01 7:12 ` [PATCH 1/3 v2] " Milton Miller
2011-02-01 22:00 ` Paul E. McKenney
2011-02-01 22:00 ` Milton Miller
2011-02-02 4:17 ` Paul E. McKenney
2011-02-06 23:51 ` Paul E. McKenney
2011-03-15 19:27 ` [PATCH 0/4 v3] smp_call_function_many issues from review Milton Miller
2011-03-15 20:22 ` Luck, Tony
2011-03-15 20:32 ` Dimitri Sivanich
2011-03-15 20:39 ` Peter Zijlstra
2011-03-16 17:55 ` Linus Torvalds
2011-03-16 18:13 ` Peter Zijlstra
2011-03-17 3:15 ` Mike Galbraith
2011-02-07 8:12 ` [PATCH 1/3 v2] call_function_many: fix list delete vs add race Mike Galbraith
2011-02-08 19:36 ` Paul E. McKenney
2011-08-21 6:17 ` Mike Galbraith
2011-02-02 6:22 ` Mike Galbraith [this message]
2011-02-01 7:12 ` [PATCH 2/3 v2] smp_call_function_many: handle concurrent clearing of mask Milton Miller
2011-03-15 19:27 ` [PATCH 1/4 v3] call_function_many: fix list delete vs add race Milton Miller
2011-03-15 19:27 ` [PATCH 2/4 v3] call_function_many: add missing ordering Milton Miller
2011-03-16 12:06 ` Paul E. McKenney
2011-03-15 19:27 ` [PATCH 3/4 v3] smp_call_function_many: handle concurrent clearing of mask Milton Miller
2011-03-15 22:32 ` Catalin Marinas
2011-03-16 7:52 ` Jan Beulich
2011-03-15 19:27 ` [PATCH 4/4 v3] smp_call_function_interrupt: use typedef and %pf Milton Miller
2011-01-18 21:07 ` [PATCH 1/2] smp_call_function_many SMP race Milton Miller
2011-01-20 0:41 ` Andrew Morton
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