On 2018/08/20 19:53, Michal Hocko wrote:
> On Mon 20-08-18 19:37:45, Tetsuo Handa wrote:
>> Commit 696453e66630ad45 ("mm, oom: task_will_free_mem should skip
>> oom_reaped tasks") changed to select next OOM victim as soon as
>> MMF_OOM_SKIP is set. But since OOM victims can try ALLOC_OOM allocation
>> and then give up (if !memcg OOM) or can use forced charge and then retry
>> (if memcg OOM), OOM victims do not need to select next OOM victim unless
>> they are doing __GFP_NOFAIL allocations.
>
> I do not like this at all. It seems hackish to say the least. And more
> importantly...
>
>> This is a quick mitigation because syzbot is hitting WARN(1) caused by
>> this race window [1]. More robust fix (e.g. make it possible to reclaim
>> more memory before MMF_OOM_SKIP is set, wait for some more after
>> MMF_OOM_SKIP is set) is a future work.
>
> .. there is already a patch (by Johannes) for that warning IIRC.
You mean http://lkml.kernel.org/r/20180808144515.GA9276@xxxxxxxxxxx ?
But I can't find that patch in linux-next.git . And as far as I know,
no patch was sent to linux.git for handling this problem. Therefore,
I wrote this patch so that we can apply for 4.19-rc1.
