From: Andrew Morton <akpm@linux-foundation.org>
To: Milton Miller <miltonm@bga.com>
Cc: Anton Blanchard <anton@samba.org>,
Peter Zijlstra <peterz@infradead.org>,
xiaoguangrong@cn.fujitsu.com, mingo@elte.hu, jaxboe@fusionio.com,
npiggin@gmail.com, rusty@rustcorp.com.au,
torvalds@linux-foundation.org, paulmck@linux.vnet.ibm.com,
benh@kernel.crashing.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] smp_call_function_many SMP race
Date: Wed, 19 Jan 2011 16:41:59 -0800 [thread overview]
Message-ID: <20110119164159.2ff499c8.akpm@linux-foundation.org> (raw)
In-Reply-To: <smp-call-function-simplified@mdm.bga.com>
On Tue, 18 Jan 2011 15:07:25 -0600
Milton Miller <miltonm@bga.com> wrote:
> I noticed a failure where we hit the following WARN_ON in
> generic_smp_call_function_interrupt:
>
> if (!cpumask_test_and_clear_cpu(cpu, data->cpumask))
> continue;
>
> data->csd.func(data->csd.info);
>
> refs = atomic_dec_return(&data->refs);
> WARN_ON(refs < 0); <-------------------------
>
> We atomically tested and cleared our bit in the cpumask, and yet the
> number of cpus left (ie refs) was 0. How can this be?
>
> It turns out commit 54fdade1c3332391948ec43530c02c4794a38172
> (generic-ipi: make struct call_function_data lockless)
> is at fault. It removes locking from smp_call_function_many and in
> doing so creates a rather complicated race.
I've been waving https://bugzilla.kernel.org/show_bug.cgi?id=23042 at
the x86 guys for a while now, to no avail. Do you think you just fixed
it?
prev parent reply other threads:[~2011-01-20 0:43 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
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 [this message]
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