Re: [patch] cgroups: disallow attaching kthreadd

From: David Rientjes
Date: Thu Apr 05 2012 - 04:00:49 EST


On Thu, 5 Apr 2012, Mike Galbraith wrote:

> That question made perfect sense to me. Putting a global resource in
> any bin of any sort makes little if any sense.
>

This has nothing to do with global resources, it has to do with
PF_THREAD_BOUND since those threads cannot move amongst these cgroups.

For cgroups that do not have anything to do with cpu affinity,
PF_THREAD_BOUND means nothing to their attachment rules. This patch is
addressing kthreadd since it, as the changelog says, has the ability to
spawn threads that become PF_THREAD_BOUND. By logic, we then can't allow
kthreadd to be attached to cgroups where PF_THREAD_BOUND matters either.

I know we've been through several iterations on this over the past several
months and the patch getting dropped a couple times along the way, but I
really do appreciate your time and effort spent in developing this fix,
it's very helpful.
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