Messages in this thread | | | Subject | Re: patch] cpusets, cgroups: disallow attaching kthreadd | From | Mike Galbraith <> | Date | Wed, 19 Oct 2011 06:00:39 +0200 |
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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
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