From: Oleg Nesterov <oleg@redhat.com>
To: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Tejun Heo <tj@kernel.org>,
dvyukov@google.com, Li Zefan <lizefan@huawei.com>,
Johannes Weiner <hannes@cmpxchg.org>,
akpm@linux-foundation.org, arnd@arndb.de, 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 17:52:25 +0200 [thread overview]
Message-ID: <20191025155224.GC6020@redhat.com> (raw)
In-Reply-To: <20191025143224.wtwkkimqq4644iqq@wittgenstein>
On 10/25, Christian Brauner wrote:
>
> On Fri, Oct 25, 2019 at 04:13:25PM +0200, Oleg Nesterov wrote:
> > Almost every usage of task->flags (load or sore) can be reported as "data race".
> >
> > Say, you do
> >
> > if (task->flags & PF_KTHREAD)
> >
> > while this task does
> >
> > current->flags |= PF_FREEZER_SKIP;
> > schedule().
> >
> > this is data race.
>
> Right, but I thought we agreed on WONTFIX in those scenarios?
> The alternative is to READ_ONCE()/WRITE_ONCE() all of these.
Well, in my opinion this is WONTFIX, but I won't argue if someone
adds _ONCE to all of these. Same for task->state, exit_state, and
more.
Oleg.
prev parent reply other threads:[~2019-10-25 15:52 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <0000000000003b1e8005956939f1@google.com>
[not found] ` <20191021142111.GB1339@redhat.com>
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
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 [this message]
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