Re: [PATCH v5] cgroup: Add new capability to allow a process to migrate other tasks between cgroups

From: John Stultz
Date: Tue Dec 13 2016 - 13:47:27 EST

On Tue, Dec 13, 2016 at 10:40 AM, Tejun Heo <tj@xxxxxxxxxx> wrote:
> Hello,
> On Tue, Dec 13, 2016 at 08:08:16AM -0800, John Stultz wrote:
>> On Tue, Dec 13, 2016 at 1:47 AM, Michael Kerrisk (man-pages)
>> <mtk.manpages@xxxxxxxxx> wrote:
>> > On 13 December 2016 at 02:39, John Stultz <john.stultz@xxxxxxxxxx> wrote:
>> > So, back to the discussion of silos. I understand the argument for
>> > wanting a new silo. But, in that case can we at least try not to make
>> > it a single-use silo?
>> >
>> > How about CAP_CGROUP_CONTROL or some such, with the idea that this
>> > might be a capability that allows the holder to step outside usual
>> > cgroup rules? At the moment, that capability would allow only one such
>> > step, but maybe there would be others in the future.
>> This sounds reasonable to me. Tejun/Andy: Objections?
> Control group control? The word control has a specific meaning for
> cgroups and that second control doesn't make much sense to me.

But this would go against the long tradition of RAS syndrome and
things like "struct task_struct". :)

> Given
> how this is mostly to patch up a hole in v1's delegation model and how
> migration operations are different from others, I doubt that we will
> end up overloading it. Maybe just CAP_CGROUP?

Sounds ok to me.