Re: [PATCH v6 4/7] cgroup: cgroup v2 freezer

[Oleg Nesterov]

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 ?

Oleg.