Re: [PATCH 5/5] oom: dump_tasks() use find_lock_task_mm() too

[Minchan Kim <minchan.kim@gmail.com>]

On Thu, Jun 3, 2010 at 9:41 AM, KOSAKI Motohiro
<kosaki.motohiro@jp.fujitsu.com> wrote:
>> On Thu, Jun 3, 2010 at 9:06 AM, KOSAKI Motohiro
>> <kosaki.motohiro@jp.fujitsu.com> wrote:
>> >> > -           mm = p->mm;
>> >> > -           if (!mm) {
>> >> > -                   /*
>> >> > -                    * total_vm and rss sizes do not exist for tasks with no
>> >> > -                    * mm so there's no need to report them; they can't be
>> >> > -                    * oom killed anyway.
>> >> > -                    */
>> >>
>> >> Please, do not remove the comment for mm newbies unless you think it's useless.
>> >
>> > How is this?
>> >
>> >               task = find_lock_task_mm(p);
>> >               if (!task)
>> >                        /*
>> >                         * Probably oom vs task-exiting race was happen and ->mm
>> >                         * have been detached. thus there's no need to report them;
>> >                         * they can't be oom killed anyway.
>> >                         */
>> >                        continue;
>> >
>>
>> Looks good to adding story about racing. but my point was "total_vm
>> and rss sizes do not exist for tasks with no mm". But I don't want to
>> bother you due to trivial.
>> It depends on you. :)
>
>
> old ->mm check have two intention.
>
>   a) the task is kernel thread?
>   b) the task have alredy detached ->mm
> but a) is not strictly correct check because we should think use_mm().
> therefore we appended PF_KTHREAD check. then, here find_lock_task_mm()
> focus exiting race, I think.
>

No objection.

-- 
Kind regards,
Minchan Kim

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