From: Lai Jiangshan <laijs@cn.fujitsu.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@elte.hu>,
Rusty Russell <rusty@rustcorp.com.au>,
linux-kernel@vger.kernel.org, Li Zefan <lizf@cn.fujitsu.com>,
Miao Xie <miaox@cn.fujitsu.com>, Paul Menage <menage@google.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Gautham R Shenoy <ego@in.ibm.com>
Subject: Re: [PATCH] cpusets: rework guarantee_online_cpus() to fix deadlock with cpu_down()
Date: Tue, 04 Aug 2009 15:35:44 +0800 [thread overview]
Message-ID: <4A77E4D0.20900@cn.fujitsu.com> (raw)
In-Reply-To: <20090802065504.GA27164@redhat.com>
Oleg Nesterov wrote:
> On 08/02, Lai Jiangshan wrote:
>> Oleg Nesterov wrote:
>>
>>> - do NOT scan cs->parent cpusets. If there are no online CPUs in
>>> cs->cpus_allowed, we use cpu_online_mask. This is only possible
>>> when we are called by cpu_down() hooks, in that case
>>> cpuset_track_online_cpus(CPU_DEAD) will fix things later.
>>>
>>
>> We must scan cs->parent cpusets.
>> A task is constrained by a cpuset,
>
> Yes, the task esacpes its cpuset. With or without this patch.
> Because cs->cpus_allowed has no online CPUs.
>
>> it must be constrained
>> this cpuset's parent too.
>
> It will be constained again, after scan_for_empty_cpusets(), no?
cpuset_cpus_allowed() is not only used for CPU offline.
sched_setaffinity() also uses it. The task will not be constained again.
Or I missed something.
Lai
next prev parent reply other threads:[~2009-08-04 7:35 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-29 2:33 + cpu_hotplug-dont-affect-current-tasks-affinity.patch added to -mm tree Oleg Nesterov
2009-07-29 21:21 ` Oleg Nesterov
2009-07-29 21:22 ` [PATCH] cpusets: fix deadlock with cpu_down()->cpuset_lock() Oleg Nesterov
2009-07-29 23:00 ` Oleg Nesterov
2009-07-30 1:53 ` Lai Jiangshan
2009-07-30 17:51 ` Oleg Nesterov
2009-07-31 2:23 ` Lai Jiangshan
2009-08-01 4:42 ` [PATCH] cpusets: rework guarantee_online_cpus() to fix deadlock with cpu_down() Oleg Nesterov
2009-08-01 5:34 ` Oleg Nesterov
2009-08-02 2:18 ` Lai Jiangshan
2009-08-02 6:55 ` Oleg Nesterov
2009-08-04 7:35 ` Lai Jiangshan [this message]
2009-08-04 16:36 ` Oleg Nesterov
2009-07-29 21:42 ` [PATCH 0/1] cpu_hotplug: don't play with current->cpus_allowed Oleg Nesterov
2009-07-29 21:43 ` [PATCH 1/1] " Oleg Nesterov
2009-07-30 2:01 ` Lai Jiangshan
2009-07-30 16:32 ` Oleg Nesterov
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