Re: [PATCH] mm, oom_adj: avoid meaningless loop to find processes sharing mm

[Tetsuo Handa]

On 2018/10/09 21:58, Michal Hocko wrote:
> On Tue 09-10-18 21:52:12, Tetsuo Handa wrote:
>> On 2018/10/09 20:10, Michal Hocko wrote:
>>> On Tue 09-10-18 19:00:44, Tetsuo Handa wrote:
>>>>> 2) add OOM_SCORE_ADJ_MIN and do not kill tasks sharing mm and do not
>>>>> reap the mm in the rare case of the race.
>>>>
>>>> That is no problem. The mistake we made in 4.6 was that we updated oom_score_adj
>>>> to -1000 (and allowed unprivileged users to OOM-lockup the system).
>>>
>>> I do not follow.
>>>
>>
>> http://tomoyo.osdn.jp/cgi-bin/lxr/source/mm/oom_kill.c?v=linux-4.6.7#L493
> 
> Ahh, so you are not referring to the current upstream code. Do you see
> any specific problem with the current one (well, except for the possible
> race which I have tried to evaluate).
> 

Yes. "task_will_free_mem(current) in out_of_memory() returns false due to MMF_OOM_SKIP
being already set" is a problem for clone(CLONE_VM without CLONE_THREAD/CLONE_SIGHAND)
with the current code.