Re: [PATCH v1 3/3] cgroup: relax common ancestor restriction for direct descendants

[Tejun Heo]

Hello, James.

On Thu, Jul 21, 2016 at 08:16:34AM -0700, James Bottomley wrote:
> > That'd be one side.  The other side is the one moving.  Let's say the
> > system admin thing wants to move all processe from A proper to B.  It
> > would do that by draining processes from A's procs file into B's and
> > even that is multistep and can race.
> 
> So the second part is that once we allow the creation of
> subdirectories, there's no unified tasks file, so there's no way of
> draining A proper without enumerating and descending into the cgroupns
> created subtrees in A?

Not that.  If it races, it will end up moving processes which are no
longer in A proper.  Such operations or distinctions might not be
meaningful under many circumstances but it'd be a pretty big hole in
the API to create and I can't really declare these holes are gonna be
okay with confidence.

Thanks.

-- 
tejun