From: Tejun Heo <tj@kernel.org>
To: Roman Gushchin <guro@fb.com>
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>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH v2 3/6] cgroup: cgroup v2 freezer
Date: Tue, 13 Nov 2018 12:58:31 -0800 [thread overview]
Message-ID: <20181113205831.GP2509588@devbig004.ftw2.facebook.com> (raw)
In-Reply-To: <20181113205507.GB15590@tower.DHCP.thefacebook.com>
On Tue, Nov 13, 2018 at 08:55:11PM +0000, Roman Gushchin wrote:
> > > > > + if (lock_task_sighand(task, &flags)) {
> > > > > + if (test_bit(CGRP_FREEZE, &dst->flags))
> > > > > + task->jobctl |= JOBCTL_TRAP_FREEZE;
> > > > > + else
> > > > > + task->jobctl &= ~JOBCTL_TRAP_FREEZE;
> > > >
> > > > How are these flags synchronized?
> > >
> > > Using the css_set_lock.
> >
> > But other JOBCTL_TRAP bits aren't synchronized by css_set_lock, right?
>
> But if we don't touch this bit anywhere else, should be fine, right?
But other JOBCTL_TRAP_ bits aren't synchronized with css_set_lock, so
they can be updated (read-modify-write) concurrently and clobber each
other, no?
Thanks.
--
tejun
next prev parent reply other threads:[~2018-11-13 20:58 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-12 23:04 [PATCH v2 0/6] freezer for cgroup v2 Roman Gushchin
2018-11-12 23:04 ` [PATCH] cgroup: document cgroup v2 freezer interface Roman Gushchin
2018-11-12 23:04 ` [PATCH v2 1/6] cgroup: rename freezer.c into legacy_freezer.c Roman Gushchin
2018-11-12 23:04 ` [PATCH v2 2/6] cgroup: implement __cgroup_task_count() helper Roman Gushchin
2018-11-12 23:04 ` [PATCH v2 3/6] cgroup: cgroup v2 freezer Roman Gushchin
2018-11-13 2:08 ` Tejun Heo
2018-11-13 18:47 ` Roman Gushchin
2018-11-13 19:15 ` Tejun Heo
2018-11-13 20:55 ` Roman Gushchin
2018-11-13 20:58 ` Tejun Heo [this message]
2018-11-13 15:37 ` Oleg Nesterov
2018-11-13 15:43 ` Tejun Heo
2018-11-13 16:00 ` Oleg Nesterov
2018-11-13 15:48 ` Oleg Nesterov
2018-11-13 21:59 ` Roman Gushchin
2018-11-14 16:56 ` Oleg Nesterov
2018-11-14 17:06 ` Roman Gushchin
2018-11-14 17:36 ` Oleg Nesterov
2018-11-14 17:39 ` Roman Gushchin
2018-11-28 17:36 ` Roman Gushchin
2018-11-12 23:04 ` [PATCH v2 4/6] kselftests: cgroup: don't fail on cg_kill_all() error in cg_destroy() Roman Gushchin
2018-11-12 23:04 ` [PATCH v2 5/6] kselftests: cgroup: add freezer controller self-tests Roman Gushchin
2018-11-12 23:04 ` [PATCH v2 6/6] cgroup: document cgroup v2 freezer interface Roman Gushchin
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