From: Srivatsa Vaddagiri <vatsa@in.ibm.com>
To: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Andrew Morton <akpm@osdl.org>,
David Howells <dhowells@redhat.com>,
Christoph Hellwig <hch@infradead.org>,
Ingo Molnar <mingo@elte.hu>, Linus Torvalds <torvalds@osdl.org>,
linux-kernel@vger.kernel.org, Gautham shenoy <ego@in.ibm.com>
Subject: Re: [PATCH] fix-flush_workqueue-vs-cpu_dead-race-update
Date: Sun, 7 Jan 2007 16:13:28 +0530 [thread overview]
Message-ID: <20070107104328.GC13579@in.ibm.com> (raw)
In-Reply-To: <20070106173416.GA3771@tv-sign.ru>
On Sat, Jan 06, 2007 at 08:34:16PM +0300, Oleg Nesterov wrote:
> I suspect this can't help either.
>
> The problem is that flush_workqueue() may be called while cpu hotplug event
> in progress and CPU_DEAD waits for kthread_stop(), so we have the same dead
> lock if work->func() does flush_workqueue(). This means that Andrew's change
> to use preempt_disable() is good and anyway needed.
Well ..a lock_cpu_hotplug() in run_workqueue() and support for recursive
calls to lock_cpu_hotplug() by the same thread will avoid the problem
you mention. This will need changes to task_struct to track the
recursion depth. Alternately this can be supported w/o changes to
task_struct by 'biasing' readers over writers as I believe Gautham's
patches [1] do.
1. http://lkml.org/lkml/2006/10/26/65
--
Regards,
vatsa
next prev parent reply other threads:[~2007-01-07 10:43 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-17 22:34 [PATCH, RFC] reimplement flush_workqueue() Oleg Nesterov
2006-12-18 3:09 ` Linus Torvalds
2006-12-19 0:27 ` Andrew Morton
2006-12-19 0:43 ` Oleg Nesterov
2006-12-19 1:00 ` Andrew Morton
2007-01-04 11:32 ` Srivatsa Vaddagiri
2007-01-04 14:29 ` Oleg Nesterov
2007-01-04 15:56 ` Srivatsa Vaddagiri
2007-01-04 16:31 ` Oleg Nesterov
2007-01-04 16:57 ` Srivatsa Vaddagiri
2007-01-04 17:18 ` Andrew Morton
2007-01-04 18:09 ` Oleg Nesterov
2007-01-04 18:31 ` Andrew Morton
2007-01-05 9:03 ` Srivatsa Vaddagiri
2007-01-05 14:07 ` Oleg Nesterov
2007-01-06 15:24 ` Srivatsa Vaddagiri
2007-01-05 8:56 ` Srivatsa Vaddagiri
2007-01-05 12:42 ` Oleg Nesterov
2007-01-06 15:11 ` Srivatsa Vaddagiri
2007-01-06 15:10 ` [PATCH] fix-flush_workqueue-vs-cpu_dead-race-update Oleg Nesterov
2007-01-06 15:45 ` Srivatsa Vaddagiri
2007-01-06 16:30 ` Oleg Nesterov
2007-01-06 16:38 ` Srivatsa Vaddagiri
2007-01-06 17:34 ` Oleg Nesterov
2007-01-07 10:43 ` Srivatsa Vaddagiri [this message]
2007-01-07 12:56 ` Oleg Nesterov
2007-01-07 14:22 ` Oleg Nesterov
2007-01-07 14:42 ` Oleg Nesterov
2007-01-07 16:43 ` Srivatsa Vaddagiri
2007-01-07 17:01 ` Srivatsa Vaddagiri
2007-01-07 17:33 ` Oleg Nesterov
2007-01-07 17:18 ` Oleg Nesterov
2007-01-07 16:21 ` Srivatsa Vaddagiri
2007-01-07 17:09 ` Oleg Nesterov
2007-01-06 19:11 ` Andrew Morton
2007-01-06 19:13 ` Ingo Molnar
2007-01-07 11:00 ` Srivatsa Vaddagiri
2007-01-07 19:59 ` Andrew Morton
2007-01-07 21:01 ` [PATCH] flush_cpu_workqueue: don't flush an empty ->worklist Oleg Nesterov
2007-01-08 23:54 ` Andrew Morton
2007-01-09 5:04 ` Srivatsa Vaddagiri
2007-01-09 5:26 ` Andrew Morton
2007-01-09 6:56 ` Ingo Molnar
2007-01-09 9:33 ` Srivatsa Vaddagiri
2007-01-09 9:44 ` Ingo Molnar
2007-01-09 9:51 ` Andrew Morton
2007-01-09 10:09 ` Srivatsa Vaddagiri
2007-01-09 10:15 ` Andrew Morton
2007-01-09 15:07 ` Oleg Nesterov
2007-01-09 15:59 ` Srivatsa Vaddagiri
2007-01-09 16:38 ` Oleg Nesterov
2007-01-09 16:46 ` Srivatsa Vaddagiri
2007-01-09 16:56 ` Oleg Nesterov
2007-01-14 23:54 ` Oleg Nesterov
2007-01-15 4:33 ` Srivatsa Vaddagiri
2007-01-15 12:54 ` Oleg Nesterov
2007-01-15 13:08 ` Oleg Nesterov
2007-01-15 16:18 ` Srivatsa Vaddagiri
2007-01-15 16:55 ` Oleg Nesterov
2007-01-16 5:26 ` Srivatsa Vaddagiri
2007-01-16 13:27 ` Oleg Nesterov
2007-01-17 6:17 ` Srivatsa Vaddagiri
2007-01-17 15:47 ` Oleg Nesterov
2007-01-17 16:12 ` Srivatsa Vaddagiri
2007-01-17 17:01 ` Oleg Nesterov
2007-01-17 16:25 ` Srivatsa Vaddagiri
2007-01-07 21:51 ` [PATCH] fix-flush_workqueue-vs-cpu_dead-race-update Oleg Nesterov
2007-01-08 15:22 ` Srivatsa Vaddagiri
2007-01-08 15:56 ` Oleg Nesterov
2007-01-08 16:31 ` Srivatsa Vaddagiri
2007-01-08 17:06 ` Oleg Nesterov
2007-01-08 18:37 ` Pallipadi, Venkatesh
2007-01-09 1:11 ` Srivatsa Vaddagiri
2007-01-09 4:39 ` Srivatsa Vaddagiri
2007-01-09 14:38 ` Oleg Nesterov
2007-01-08 15:37 ` Srivatsa Vaddagiri
2007-01-04 12:02 ` [PATCH, RFC] reimplement flush_workqueue() Srivatsa Vaddagiri
2007-01-04 14:38 ` Oleg Nesterov
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