From: Avi Kivity <avi@redhat.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tejun Heo <tj@kernel.org>,
linux-kernel@vger.kernel.org, jeff@garzik.org, mingo@elte.hu,
akpm@linux-foundation.org, jens.axboe@oracle.com,
rusty@rustcorp.com.au, cl@linux-foundation.org,
dhowells@redhat.com, arjan@linux.intel.com,
torvalds@linux-foundation.org, peterz@infradead.org,
andi@firstfloor.org, Andi Kleen <ak@linux.intel.com>,
Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH 01/21] workqueue: fix race condition in schedule_on_each_cpu()
Date: Tue, 17 Nov 2009 09:04:56 +0200 [thread overview]
Message-ID: <4B024B18.40604@redhat.com> (raw)
In-Reply-To: <20091116230427.GD5293@nowhere>
On 11/17/2009 01:04 AM, Frederic Weisbecker wrote:
> On Tue, Nov 17, 2009 at 02:15:06AM +0900, Tejun Heo wrote:
>
>> Commit 65a64464349883891e21e74af16c05d6e1eeb4e9 which allows
>> schedule_on_each_cpu() to be called from keventd added a race
>> condition. schedule_on_each_cpu() may race with cpu hotplug and end
>> up executing the function twice on a cpu.
>>
>> Fix it by moving direct execution into the section protected with
>> get/put_online_cpus(). While at it, update code such that direct
>> execution is done after works have been scheduled for all other cpus
>> and drop unnecessary cpu != orig test from flush loop.
>>
>> Signed-off-by: Tejun Heo<tj@kernel.org>
>> Cc: Andi Kleen<ak@linux.intel.com>
>> Cc: Oleg Nesterov<oleg@redhat.com>
>> ---
>>
>
> Shouldn't this patch go to .32 ?
> This looks like an important fix.
>
Is anything using preeempt notifier on affected architectures?
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
next prev parent reply other threads:[~2009-11-17 7:06 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-16 17:15 [PATCHSET] workqueue: prepare for concurrency managed workqueue Tejun Heo
2009-11-16 17:15 ` [PATCH 01/21] workqueue: fix race condition in schedule_on_each_cpu() Tejun Heo
2009-11-16 23:04 ` Frederic Weisbecker
2009-11-17 0:08 ` Tejun Heo
2009-11-17 7:04 ` Avi Kivity [this message]
2009-11-17 16:16 ` Tejun Heo
2009-11-16 17:15 ` [PATCH 02/21] sched, kvm: fix race condition involving sched_in_preempt_notifers Tejun Heo
2009-11-16 17:15 ` [PATCH 03/21] workqueue: Add debugobjects support Tejun Heo
2009-11-16 17:15 ` [PATCH 04/21] sched: implement scheduler notifiers Tejun Heo
2009-11-16 18:31 ` Avi Kivity
2009-11-16 18:43 ` Tejun Heo
2009-11-16 18:41 ` Peter Zijlstra
2009-11-16 18:54 ` Tejun Heo
2009-11-16 20:29 ` Peter Zijlstra
2009-11-17 16:16 ` Tejun Heo
2009-11-16 17:15 ` [PATCH 05/21] kvm: convert kvm to use new " Tejun Heo
2009-11-16 17:15 ` [PATCH 06/21] sched: drop preempt notifiers Tejun Heo
2009-11-16 17:15 ` [PATCH 07/21] sched: implement sched_notifier_wake_up_process() Tejun Heo
2009-11-16 17:15 ` [PATCH 08/21] scheduler: implement force_cpus_allowed_ptr() Tejun Heo
2009-11-17 5:14 ` Rusty Russell
2009-11-17 5:19 ` Tejun Heo
2009-11-16 17:15 ` [PATCH 09/21] acpi: use queue_work_on() instead of binding workqueue worker to cpu0 Tejun Heo
2009-11-16 17:15 ` [PATCH 10/21] stop_machine: reimplement without using workqueue Tejun Heo
2009-11-16 17:15 ` [PATCH 11/21] workqueue: misc/cosmetic updates Tejun Heo
2009-11-16 17:15 ` [PATCH 12/21] workqueue: merge feature parametesr into flags Tejun Heo
2009-11-16 17:15 ` [PATCH 13/21] workqueue: update cwq alignement and make one more flag bit available Tejun Heo
2009-11-16 17:15 ` [PATCH 14/21] workqueue: define both bit position and mask for work flags Tejun Heo
2009-11-16 17:15 ` [PATCH 15/21] workqueue: separate out process_one_work() Tejun Heo
2009-11-16 17:15 ` [PATCH 16/21] workqueue: temporarily disable workqueue tracing Tejun Heo
2009-11-16 17:15 ` [PATCH 17/21] workqueue: simple reimplementation of SINGLE_THREAD workqueue Tejun Heo
2009-11-17 0:47 ` Andy Walls
2009-11-17 5:23 ` Tejun Heo
2009-11-17 12:05 ` Andy Walls
2009-11-17 16:21 ` Tejun Heo
2009-11-17 16:26 ` Hi ... I want to introduce myself :) Setiajie 余鴻昌
2009-11-17 15:05 ` [PATCH 17/21] workqueue: simple reimplementation of SINGLE_THREAD workqueue Linus Torvalds
2009-11-17 16:12 ` Tejun Heo
2009-11-17 19:01 ` Linus Torvalds
2009-11-17 14:03 ` Johannes Berg
2009-11-17 16:24 ` Tejun Heo
2009-11-16 17:15 ` [PATCH 18/21] workqueue: reimplement workqueue flushing using color coded works Tejun Heo
2009-11-16 17:15 ` [PATCH 19/21] workqueue: introduce worker Tejun Heo
2009-11-17 11:39 ` Louis Rilling
2009-11-17 11:51 ` Louis Rilling
2009-11-17 16:25 ` Tejun Heo
2009-11-16 17:15 ` [PATCH 20/21] workqueue: reimplement work flushing using linked works Tejun Heo
2009-11-16 17:15 ` [PATCH 21/21] workqueue: reimplement workqueue freeze using cwq->frozen_works queue Tejun Heo
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