From: Mike Galbraith <efault@gmx.de>
To: David Rientjes <rientjes@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
LKML <linux-kernel@vger.kernel.org>, Tejun Heo <htejun@gmail.com>,
Li Zefan <lizf@cn.fujitsu.com>, Paul Menage <paul@paulmenage.org>
Subject: Re: patch] cpusets, cgroups: disallow attaching kthreadd
Date: Wed, 19 Oct 2011 06:00:39 +0200 [thread overview]
Message-ID: <1318996839.6222.20.camel@marge.simson.net> (raw)
In-Reply-To: <alpine.DEB.2.00.1110181336150.2639@chino.kir.corp.google.com>
On Tue, 2011-10-18 at 13:38 -0700, David Rientjes wrote:
> On Tue, 18 Oct 2011, Mike Galbraith wrote:
>
> > From: Peter Zijlstra <a.p.zijlstra@chello.nl>
> >
> > cgroups: disallow attaching kthreadd
> >
> > Allowing kthreadd to be moved to a non-root group makes no sense, it being
> > a global resource, and needlessly leads unsuspecting users toward trouble.
> >
> > 1. An RT workqueue worker thread spawned in a task group with no rt_runtime
> > allocated is not schedulable. Simple user error, but harmful to the box.
> >
> > 2. A worker thread which acquires PF_THREAD_BOUND can never leave a cpuset,
> > rendering the cpuset immortal.
> >
>
> Eek, this seems like complete overkill, there may be cgroups now or in the
> future that it would be perfectly acceptable to move kthreadd into without
> any negative effects. There's no reason to restrict it this broadly,
> that's why I thought your change to cpusets was fine and acked it. It's
> the perfect candidate for what the ->can_attach() pointer for a cgroup can
> identify is problematic for _that_ cgroup.
Oh my, I can't win.
Either of the two patchlets will do the trick, so maintainer's choice.
> > Save the user some unexpected trouble, just say no.
> >
> > Signed-off-by: Mike Galbraith <efault@gmx.de>
> >
>
> A patch from Peter that only has your sign-off?
The only thing in it from me was a comment, figured I should post a from
line as a matter of propriety. Guess not. If this variant is the one
that flies, the from line can be dropped. I doubt Peter counts his
credits, and even if he did, he wouldn't notice _this one_ missing :)
-Mike
next prev parent reply other threads:[~2011-10-19 4:00 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
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 [this message]
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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