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From: Oleg Nesterov <oleg@redhat.com>
To: Roman Gushchin <guro@fb.com>
Cc: Roman Gushchin <guroan@gmail.com>, Tejun Heo <tj@kernel.org>,
	Kernel Team <Kernel-team@fb.com>,
	"cgroups@vger.kernel.org" <cgroups@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v6 4/7] cgroup: cgroup v2 freezer
Date: Thu, 14 Feb 2019 17:26:13 +0100	[thread overview]
Message-ID: <20190214162612.GC19102@redhat.com> (raw)
In-Reply-To: <20190211213036.GA26063@tower.DHCP.thefacebook.com>

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.


  reply	other threads:[~2019-02-14 16:26 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-22  0:03 [PATCH v6 0/7] freezer for cgroup v2 Roman Gushchin
2018-12-22  0:03 ` [PATCH v6 1/7] cgroup: rename freezer.c into legacy_freezer.c Roman Gushchin
2018-12-22  0:03 ` [PATCH v6 2/7] cgroup: implement __cgroup_task_count() helper Roman Gushchin
2018-12-22  0:03 ` [PATCH v6 3/7] cgroup: protect cgroup->nr_(dying_)descendants by css_set_lock Roman Gushchin
2018-12-22  0:03 ` [PATCH v6 4/7] cgroup: cgroup v2 freezer Roman Gushchin
2019-01-25 12:27   ` Oleg Nesterov
2019-01-25 13:46     ` Oleg Nesterov
2019-01-28 19:59     ` Roman Gushchin
2019-01-30 16:52       ` Oleg Nesterov
2019-02-11 21:30         ` Roman Gushchin
2019-02-14 16:26           ` Oleg Nesterov [this message]
2019-02-14 16:41             ` Roman Gushchin
2019-01-25 13:43   ` Oleg Nesterov
2018-12-22  0:03 ` [PATCH v6 5/7] kselftests: cgroup: don't fail on cg_kill_all() error in cg_destroy() Roman Gushchin
2018-12-22  0:03 ` [PATCH v6 6/7] kselftests: cgroup: add freezer controller self-tests Roman Gushchin
2018-12-22  0:03 ` [PATCH v6 7/7] cgroup: document cgroup v2 freezer interface Roman Gushchin
2019-01-24 15:26 ` [PATCH v6 0/7] freezer for cgroup v2 Tejun Heo

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