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.