From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Subject: Re: [PATCHv3 8/8] cgroup: Add documentation for cgroup namespaces
Date: Wed, 7 Jan 2015 17:45:11 -0500
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To: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
Cc: Richard Weinberger <richard-/L3Ra7n9ekc@public.gmane.org>, Linux Containers <containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>, Serge Hallyn <serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA@public.gmane.org>, "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>, Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Linux API <linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, cgroups mailinglist <cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>

On Wed, Jan 07, 2015 at 04:14:40PM -0600, Eric W. Biederman wrote:
> I see what you mean.  If it is indeed the case than a mount of cgroupfs
> using the unified hiearchy and can not specify which controllers are
> present under that mount that very significant bug and presents a very
> significant regression in user space flexibility.

The parent always controls which controllers are made available at the
children level.  Only if the parent enables a controller, its
children, whether they're namespaces or not, can choose to further
distribute resources using that controller.  It's a straight-forward
top-down thing.

-- 
tejun