Hello, On Thu, Nov 14, 2019 at 08:33:40PM +0100, Michal Hocko wrote: > > It is useful for controlling admissions of new userspace visible uses > > - e.g. a tracepoint shouldn't be allowed to be attached to a cgroup > > which has already been deleted. > > I am not sure I understand. Roman says that the cgroup can get offline > right after the function returns. How is "already deleted" different > from "just deleted"? I thought that the state is preserved at least > while the rcu lock is held but my memory is dim here. It's the same difference as between "opening a file and deleting it" and "deleting a file and opening it". We shoud allow the former while not allowing the latter. > > We're just using it too liberally. > > Can we get a doc update to be explicit about sensible usecases so that > others can be dropped accordingly? Yeah, we should audit and convert the uses and update the doc. Thanks. -- tejun
