From: Mike Galbraith <mgalbraith@suse.de>
To: David Rientjes <rientjes@google.com>
Cc: Tejun Heo <htejun@gmail.com>, Li Zefan <lizf@cn.fujitsu.com>,
LKML <linux-kernel@vger.kernel.org>,
Paul Menage <paul@paulmenage.org>
Subject: Re: [patch] cpusets: allow PF_THREAD_BOUND kworkers to escape from a cpuset
Date: Fri, 23 Sep 2011 11:42:16 +0200 [thread overview]
Message-ID: <1316770936.6641.11.camel@marge.simson.net> (raw)
In-Reply-To: <alpine.DEB.2.00.1109230204270.29350@chino.kir.corp.google.com>
On Fri, 2011-09-23 at 02:12 -0700, David Rientjes wrote:
> On Fri, 23 Sep 2011, Mike Galbraith wrote:
>
> > Done, your ACK added as well.
> >
> > kworkers can be born in a cpuset, leaving them adrift on an unsinkable ship.
> > Allow them to be moved to the root cpuset so the cpuset can be destroyed.
> >
>
> Thanks Li for the cc since I introduced this flag.
>
> Does this even work?
Yup, but..
> You've modified cpuset_can_attach() to allow the attach for the cgroup
> interface, but the actual function that attaches the task in the cpuset
> code should fail since it does set_cpus_allowed_ptr() which should return
> -EINVAL because of the PF_THREAD_BOUND. That should have emitted a
> WARN_ON() if this patch was tested.
..you're right that it warns. It was tested, but I didn't notice that
it had griped at me.
> kworkers can always move themselves to the root cpuset, so that's probably
> the better way of handling this than requiring userspace to do so.
kworker is sleeping in a cpuset that the user wants to depopulate and
destroy. I wasn't requiring the user to do that, was allowing him to.
> And it seems like the workqueue code has a comment specifically about cpu
> hotplug and why changing their cpumask shouldn't be allowed that was added
> by Tejun Heo in db7bccf45cb8 ("workqueue: reimplement CPU hotplugging
> support using trustee"). So let's cc him here as well at his
> non-kernel.org address.
No, we don't want top muck around with their masks.
-Mike
next prev parent reply other threads:[~2011-09-23 9:42 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-23 6:21 [patch] cpusets: allow PF_THREAD_BOUND kworkers to escape from a cpuset Mike Galbraith
2011-09-23 7:00 ` Li Zefan
2011-09-23 7:19 ` Mike Galbraith
2011-09-23 9:12 ` David Rientjes
2011-09-23 9:42 ` Mike Galbraith [this message]
2011-09-23 10:53 ` Mike Galbraith
2011-09-23 13:27 ` David Rientjes
2011-09-23 14:33 ` Mike Galbraith
2011-09-23 18:16 ` Mike Galbraith
2011-09-23 20:20 ` David Rientjes
2011-09-24 3:21 ` Tejun Heo
2011-10-10 5:34 ` Mike Galbraith
2011-10-10 8:03 ` [patch] cpusets, cgroups: disallow attaching kthreadd Mike Galbraith
2011-10-10 16:43 ` Tejun Heo
2011-10-11 2:31 ` Mike Galbraith
2011-10-11 14:08 ` Peter Zijlstra
2011-10-11 16:57 ` Mike Galbraith
2011-10-12 1:22 ` David Rientjes
2011-10-12 1:45 ` Mike Galbraith
2011-10-12 1:20 ` David Rientjes
2011-10-18 8:10 ` patch] " Mike Galbraith
2011-10-18 8:16 ` David Rientjes
2011-10-18 8:42 ` Peter Zijlstra
2011-10-18 8:47 ` Mike Galbraith
2011-10-18 9:06 ` Peter Zijlstra
2011-10-18 9:23 ` Mike Galbraith
2011-10-18 10:11 ` Mike Galbraith
2011-10-18 20:38 ` David Rientjes
2011-10-19 4:00 ` Mike Galbraith
2011-10-19 4:53 ` Paul Menage
2011-10-19 4:56 ` Paul Menage
2011-10-19 5:28 ` Mike Galbraith
2011-10-19 7:50 ` Peter Zijlstra
2011-10-19 19:47 ` David Rientjes
2011-10-20 10:32 ` Peter Zijlstra
2011-10-20 21:24 ` David Rientjes
2011-10-19 4:57 ` Paul Menage
2011-10-19 5:24 ` [patch-final] " Mike Galbraith
2011-10-19 7:54 ` Peter Zijlstra
2011-10-19 8:00 ` Paul Menage
2011-10-19 8:21 ` Mike Galbraith
2011-10-26 20:27 ` David Rientjes
2011-11-10 20:51 ` David Rientjes
2011-12-06 20:13 ` David Rientjes
2011-12-06 22:47 ` Andrew Morton
2011-12-06 23:53 ` David Rientjes
2011-12-07 0:05 ` Andrew Morton
2011-12-07 3:18 ` [resubmit] " Mike Galbraith
2011-12-07 4:36 ` Mike Galbraith
2011-12-07 22:03 ` David Rientjes
2011-12-14 20:16 ` Andrew Morton
2011-12-15 2:50 ` David Rientjes
2012-01-06 22:06 ` Andrew Morton
2012-01-07 6:34 ` Mike Galbraith
2012-01-07 7:59 ` Andrew Morton
2011-12-07 22:01 ` David Rientjes
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