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From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Yong Zhang <yong.zhang0@gmail.com>,
	Oleg Nesterov <oleg@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@elte.hu>, Li Zefan <lizf@cn.fujitsu.com>,
	Miao Xie <miaox@cn.fujitsu.com>
Subject: Re: [PATCH 1/2] cpuset: fix cpuset_cpus_allowed_fallback() don't update tsk->rt.nr_cpus_allowed
Date: Sat, 14 May 2011 20:17:16 +0900	[thread overview]
Message-ID: <BANLkTi=u1RMS3BHBir1o2WWJcfXm0jhkQQ@mail.gmail.com> (raw)
In-Reply-To: <1305306135.2466.173.camel@twins>

2011/5/14 Peter Zijlstra <a.p.zijlstra@chello.nl>:
> On Fri, 2011-05-13 at 14:42 +0800, Yong Zhang wrote:
>> > - rcu_cpu_kthread_should_stop() call set_cpus_allowed_ptr() again
>> > periodically.
>> >  then, it can reset cpumask if cpuset_cpus_allowed_fallback() change it.
>> >  my debug print obseve following cpumask change occur at boot time.
>> >     1) kthread_bind: bind cpu1
>> >     2) cpuset_cpus_allowed_fallback: bind possible cpu
>> >     3) rcu_cpu_kthread_should_stop: rebind cpu1
>> > - while tsk->rt.nr_cpus_allowed == 1, sched load balancer never be crash.
>>
>> Seems rcu_spawn_one_cpu_kthread() call wake_up_process() directly,
>> which is under hotplug event CPU_UP_PREPARE. Maybe it should be
>> under CPU_ONLINE.
>
> IIRC I talked to Paul about this a while back and ONLINE is too late,
> however STARTING should work. At the time he couldn't quite get that to
> work, but the above situation is indeed the root cause of our problems.
>
> We shouldn't try to run a cpu affine thread before the cpu in question
> is actually able to run stuff.
>
> I did me a little hackery and with the below patch my kernel still
> boots...
>
> Would that sort your issue?

Great!!
Unfortunately, I can't test this until next wednesday. but I'll do it
as far as possible soon.

Thanks.

  reply	other threads:[~2011-05-14 11:17 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-28 14:20 [RFC PATCH] cpuset: fix cpuset_cpus_allowed_fallback() don't update tsk->rt.nr_cpus_allowed KOSAKI Motohiro
2011-04-28 16:11 ` Oleg Nesterov
2011-05-02 10:42   ` KOSAKI Motohiro
2011-05-02 10:55     ` [PATCH 1/2] " KOSAKI Motohiro
2011-05-11 16:05       ` Peter Zijlstra
2011-05-13  5:48         ` KOSAKI Motohiro
2011-05-13  6:42           ` Yong Zhang
2011-05-13  7:33             ` KOSAKI Motohiro
2011-05-13  7:43               ` Yong Zhang
2011-05-13  9:34                 ` KOSAKI Motohiro
2011-05-13 17:02             ` Peter Zijlstra
2011-05-14 11:17               ` KOSAKI Motohiro [this message]
2011-05-16 13:37               ` Yong Zhang
2011-05-19  8:45                 ` Peter Zijlstra
2011-05-19  8:54                   ` Yong Zhang
2011-05-15 18:55             ` Paul E. McKenney
2011-05-16 13:26               ` Yong Zhang
2011-05-19  6:06                 ` [PATCH v2 1/2] rcu: don't bind offline cpu KOSAKI Motohiro
2011-05-19  6:08                   ` [PATCH v2 2/2] cpuset: fix cpuset_cpus_allowed_fallback() don't update tsk->rt.nr_cpus_allowed KOSAKI Motohiro
2011-05-28 16:35                     ` [tip:sched/urgent] cpuset: Fix cpuset_cpus_allowed_fallback(), " tip-bot for KOSAKI Motohiro
2011-06-20 10:20                       ` Peter Zijlstra
2011-06-21  9:54                         ` KOSAKI Motohiro
2011-05-19  8:34                   ` [PATCH v2 1/2] rcu: don't bind offline cpu Peter Zijlstra
2011-05-19  8:50                     ` KOSAKI Motohiro
2011-05-19  9:41                       ` Peter Zijlstra
2011-05-19 10:12                         ` KOSAKI Motohiro
2011-05-19 11:41                           ` Peter Zijlstra
2011-05-20 22:46                         ` Paul E. McKenney
2011-05-19  8:55                     ` Peter Zijlstra
2011-05-02 10:56     ` [PATCH 2/2] sched, cpuset: introduce do_set_cpus_allowed() helper function KOSAKI Motohiro
2011-05-02 12:58     ` [RFC PATCH] cpuset: fix cpuset_cpus_allowed_fallback() don't update tsk->rt.nr_cpus_allowed Paul E. McKenney

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