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