From: Roman Gushchin <guro@fb.com>
To: Tejun Heo <tj@kernel.org>
Cc: Roman Gushchin <guroan@gmail.com>,
Oleg Nesterov <oleg@redhat.com>,
"cgroups@vger.kernel.org" <cgroups@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Kernel Team <Kernel-team@fb.com>
Subject: Re: [PATCH v3 4/7] cgroup: cgroup v2 freezer
Date: Tue, 20 Nov 2018 17:39:03 +0000 [thread overview]
Message-ID: <20181120173858.GC21462@tower.DHCP.thefacebook.com> (raw)
In-Reply-To: <20181120164859.GY2509588@devbig004.ftw2.facebook.com>
On Tue, Nov 20, 2018 at 08:48:59AM -0800, Tejun Heo wrote:
> Hello,
>
> On Tue, Nov 20, 2018 at 04:43:52PM +0000, Roman Gushchin wrote:
> > > But that wouldn't udpate the cgroup's frozen state and generate
> > > notifications, right?
> >
> > Why? The task will be eventually trapped into cgroup_enter_frozen(),
> > and from there cgroup_update_frozen() will be called.
>
> Because the cgroup is no longer frozen?
>
> > You are right, that notification will not be issued, because the cgroup
> > is not changing its state (frozen->frozen). I'm not sure that it makes
> > sense to change the cgroup state back and forth in this case. Are there
> > any reasons I'm missing?
>
> Imagine the task being trapped in nfs or wherever and not getting into
> the freezer for an extended period of time.
Yeah, it's a good point. I've thought about it mostly in the fork() context,
where if freezing of a cgroup races with fork(), it makes no sense to
switch the cgroup state back and forth. But that case is different, as
the child will be trapped just on the return path from fork() call.
Thanks!
next prev parent reply other threads:[~2018-11-20 17:39 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-17 0:38 [PATCH v3 0/7] freezer for cgroup v2 Roman Gushchin
2018-11-17 0:38 ` [PATCH v3 1/7] cgroup: rename freezer.c into legacy_freezer.c Roman Gushchin
2018-11-17 0:38 ` [PATCH v3 2/7] cgroup: implement __cgroup_task_count() helper Roman Gushchin
2018-11-17 0:38 ` [PATCH v3 3/7] cgroup: protect cgroup->nr_(dying_)descendants by css_set_lock Roman Gushchin
2018-11-20 16:18 ` Tejun Heo
2018-11-17 0:38 ` [PATCH v3 4/7] cgroup: cgroup v2 freezer Roman Gushchin
2018-11-20 16:25 ` Tejun Heo
2018-11-20 16:33 ` Roman Gushchin
2018-11-20 16:36 ` Tejun Heo
2018-11-20 16:43 ` Roman Gushchin
2018-11-20 16:48 ` Tejun Heo
2018-11-20 17:39 ` Roman Gushchin [this message]
2018-11-20 18:05 ` Tejun Heo
2018-11-17 0:38 ` [PATCH v3 5/7] kselftests: cgroup: don't fail on cg_kill_all() error in cg_destroy() Roman Gushchin
2018-11-17 0:38 ` [PATCH v3 6/7] kselftests: cgroup: add freezer controller self-tests Roman Gushchin
2018-11-17 0:38 ` [PATCH v3 7/7] cgroup: document cgroup v2 freezer interface Roman Gushchin
2018-11-17 8:02 ` Mike Rapoport
2018-11-19 17:42 ` Roman Gushchin
2018-11-20 14:06 ` Mike Rapoport
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=20181120173858.GC21462@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