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From: Tejun Heo <tj@kernel.org>
To: Zhang Qiao <zhangqiao22@huawei.com>
Cc: mingo@redhat.com, peterz@infradead.org,
	linux-kernel@vger.kernel.org, juri.lelli@redhat.com,
	vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
	rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
	bristot@redhat.com
Subject: Re: [PATCH v2] kernel/sched: Fix sched_fork() access an invalid sched_task_group
Date: Mon, 13 Sep 2021 08:01:00 -1000	[thread overview]
Message-ID: <YT+R3EnFgs78Vyvh@slm.duckdns.org> (raw)
In-Reply-To: <20210911075054.6358-1-zhangqiao22@huawei.com>

Hello,

On Sat, Sep 11, 2021 at 03:50:54PM +0800, Zhang Qiao wrote:
> Between cgroup_can_fork() and cgroup_post_fork(), the cgroup
> membership is fixed and thus sched_task_group can't change. So
> call sched_fork() after cgroup_can_fork() and update the child's
> sched_task_group before it is used.

The part being fixed looks correct to me but it's difficult to for me to
assess whether the whole relocation of the sched_fork() hook doesn't change
anything else. Besides, even if we decide to relocate the sched_fork hook, I
think it'd be better to separate the two changes - one is a relatively safe
bug fix, the other is a code reorganization with possibly subtle side
effects. So, I think it'd be better to produce a patch which just fixes the
bug even if that ends up introducing another function in the flow.

Thanks.

-- 
tejun

  reply	other threads:[~2021-09-13 18:01 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-11  7:50 Zhang Qiao
2021-09-13 18:01 ` Tejun Heo [this message]
2021-09-14  8:20   ` Zhang Qiao
2021-09-14 16:23     ` Tejun Heo
2021-09-15  3:10       ` Zhang Qiao

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