From: Tejun Heo <tj@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Li Zefan <lizefan@huawei.com>,
Johannes Weiner <hannes@cmpxchg.org>,
akpm@linux-foundation.org, arnd@arndb.de, christian@brauner.io,
deepa.kernel@gmail.com, ebiederm@xmission.com, elver@google.com,
guro@fb.com, linux-kernel@vger.kernel.org,
syzkaller-bugs@googlegroups.com, cgroups@vger.kernel.org,
kernel-team@fb.com
Subject: Re: [PATCH cgroup/for-5.5] cgroup: remove cgroup_enable_task_cg_lists() optimization
Date: Fri, 25 Oct 2019 05:56:06 -0700 [thread overview]
Message-ID: <20191025125606.GI3622521@devbig004.ftw2.facebook.com> (raw)
In-Reply-To: <20191024190351.GD3622521@devbig004.ftw2.facebook.com>
On Thu, Oct 24, 2019 at 12:03:51PM -0700, Tejun Heo wrote:
> cgroup_enable_task_cg_lists() is used to lazyily initialize task
> cgroup associations on the first use to reduce fork / exit overheads
> on systems which don't use cgroup. Unfortunately, locking around it
> has never been actually correct and its value is dubious given how the
> vast majority of systems use cgroup right away from boot.
>
> This patch removes the optimization. For now, replace the cg_list
> based branches with WARN_ON_ONCE()'s to be on the safe side. We can
> simplify the logic further in the future.
>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Reported-by: Oleg Nesterov <oleg@redhat.com>
Applying to cgroup/for-5.5.
Thanks.
--
tejun
next prev parent reply other threads:[~2019-10-25 12:56 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-21 10:34 KCSAN: data-race in exit_signals / prepare_signal syzbot
2019-10-21 11:19 ` Christian Brauner
2019-10-21 12:00 ` Oleg Nesterov
2019-10-21 12:15 ` Marco Elver
2019-10-21 13:47 ` Oleg Nesterov
2019-10-21 12:51 ` Christian Brauner
2019-10-21 14:21 ` cgroup_enable_task_cg_lists && PF_EXITING (Was: KCSAN: data-race in exit_signals / prepare_signal) Oleg Nesterov
2019-10-24 17:54 ` Tejun Heo
2019-10-24 19:03 ` [PATCH cgroup/for-5.5] cgroup: remove cgroup_enable_task_cg_lists() optimization Tejun Heo
2019-10-25 12:56 ` Tejun Heo [this message]
2019-10-25 13:33 ` Christian Brauner
2019-10-25 14:13 ` Oleg Nesterov
2019-10-25 14:32 ` Christian Brauner
2019-10-25 15:52 ` Oleg Nesterov
2019-10-25 17:05 ` Christian Brauner
2019-10-28 16:48 ` Oleg Nesterov
2019-10-28 17:30 ` Christian Brauner
2019-10-28 17:46 ` Marco Elver
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