On Thu, 2016-07-21 at 11:26 -0400, Tejun Heo wrote: > 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.
So if I as the cgroup ns owner am moving a task from A to A_subdir, the admin scanning tasks in all of A may miss this task in motion because all the tasks files can't be scanned atomically? James
