From: Roman Gushchin <guro@fb.com>
To: Oleg Nesterov <oleg@redhat.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 16:41:05 +0000 [thread overview]
Message-ID: <20190214164100.GA8688@tower.DHCP.thefacebook.com> (raw)
In-Reply-To: <20190214162612.GC19102@redhat.com>
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
next prev parent reply other threads:[~2019-02-14 16:41 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
2019-02-14 16:41 ` Roman Gushchin [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190214164100.GA8688@tower.DHCP.thefacebook.com \
--to=guro@fb.com \
--cc=Kernel-team@fb.com \
--cc=cgroups@vger.kernel.org \
--cc=guroan@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=oleg@redhat.com \
--cc=tj@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).