On Thu, Feb 14, 2019 at 05:26:13PM +0100, Oleg Nesterov wrote: > On 02/11, Roman Gushchin wrote: > > > > On Wed, Jan 30, 2019 at 05:52:01PM +0100, Oleg Nesterov wrote: > > > > > > Worse, this looks just wrong. In the latter case, cgroup becomes CGRP_FROZEN > > > right after a 2nd task migrates to this cgroup, before this new task calls > > > do_freezer_trap() or cgroup_enter_stopped(). > > > > You're right. So, it looks like the problem is in the equation > > nr_tasks_frozen + nr_tasks_stopped == nr_tasks_to_freeze , > > because a task can be frozen and stopped simultaneously. > > > > So, basically it has to be > > nr_tasks_frozen + nr_tasks_stopped >= nr_tasks_to_freeze instead. > > It seems you didn't read the paragraph above, or I missed something... > > How can "frozen + stopped >= to_freeze" fix the problem with the falsely true > CGRP_FROZEN ? It helps with the problem when cgroup is mistakenly reported as non-frozen, and adding a task makes it frozen due to increased nr_tasks_to_freeze. But you're right, it's not correct. I have to think more how to make the accounting work correctly with stopped tasks. Roman
