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Subject: Re: [PATCH] kernel/sched: Fix sched_fork() access an invalid
 sched_task_group
To:     Tejun Heo <tj@kernel.org>
CC:     <linux-kernel@vger.kernel.org>, <juri.lelli@redhat.com>,
        <mingo@redhat.com>, <peterz@infradead.org>,
        <vincent.guittot@linaro.org>
References: <20210826112635.7404-1-zhangqiao22@huawei.com>
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From:   Zhang Qiao <zhangqiao22@huawei.com>
In-Reply-To: <YTjk8oiFa5EfDPn9@slm.duckdns.org>
Message-ID: <3036e192-20ba-4345-66e6-14fa8b765d59@huawei.com>
Date:   Thu, 9 Sep 2021 17:45:16 +0800
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?? 2021/9/9 0:29, Tejun Heo д??:
> Hello,
> 
> On Wed, Sep 08, 2021 at 07:32:06PM +0800, Zhang Qiao wrote:
>> I will update this patch by following the steps below:
>> 1)rename cgroup_subsys->fork() to cgroup_subsys->post_fork();
>> 2)add cgroup_subsys->fork() and the cpu_cgroup_fork() callback like this:
>>
>> void cpu_cgroup_fork(struct task_struct *task) {
>> ....
>> 	p->sched_task_group = task_group(current);
>> 	__set_task_cpu(p, smp_processor_id());
>> 	if (p->sched_class->task_fork)
>> 		p->sched_class->task_fork(p);
>> ....
>>
>>
>> 3)call cgroup_subsys->fork() after cgroup_can_fork().
>>
>> Do you have any suggestion?
> 
> I'm not following why it needs to shuffle the callbacks. Can't you just
Just to provide a placeholder to call task_fork(). But thought about it,
there are indeed some problems with this modification.

Thanks.

Zhang Qiao

> relocate the fectching of task_group after can_fork?>
> Thanks.
>