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Message-ID: <1334402250.2528.68.camel@twins>
Subject: Re: [patch] cgroups: disallow attaching kthreadd
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: David Rientjes <rientjes@google.com>
Cc: Mike Galbraith <mgalbraith@suse.de>, Tejun Heo <tj@kernel.org>,
        Paul Menage <paul@paulmenage.org>, LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Li Zefan <lizefan@huawei.com>
Date: Sat, 14 Apr 2012 13:17:30 +0200
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On Wed, 2012-04-04 at 23:07 -0700, David Rientjes wrote:
> On Thu, 5 Apr 2012, Mike Galbraith wrote:
> 
> > I submitted that, and it didn't fly.  I like the generic exclusion
> > better, so I submit that for consideration.
> > 
> 
> [+akpm]
> 
> The last time we went through this, it was left after Andrew had fixed it 
> up when the cpusets version was merged in -mm without any disagreement 
> from Peter who was cc'd and that version was acked both by myself and Paul 
> Menage at https://lkml.org/lkml/2011/12/14/402.  Andrew dropped it and 
> asked for a repost since there was some on-going scheduler work going on 
> in linux-next that caused that version not to apply.  No follow-up was 
> ever offered.
> 
> Why have we now gone in a completely different direction again?

I really absolutely hate the cpuset only feature. The whole point of
kthreadd's existence is to provide a clean environment to spawn kthreads
from. Adding kthreadd to controllers violates this premise.

New and fresh kthreads should always get a bare minimum state, this
includes not being part of any particular cgroup.