Re: patch] cpusets, cgroups: disallow attaching kthreadd

From: Peter Zijlstra
Date: Wed Oct 19 2011 - 03:51:20 EST


On Tue, 2011-10-18 at 13:38 -0700, David Rientjes wrote:
>
> 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.

My thinking is that kthreadd is the mother of all kernel threads and the
kernel assumes it can spawn kthreads without constraints, a valid
assumption IMO.

Therefore the kthreadd thread should live in the root cgroup at all
times, irrespective of whatever controllers are or aren't actually safe.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/