Re: [PATCH memcg 1/3] mm: do not firce global OOM from inside dying tasks

Vasily Averin
2021-10-20T13:52:53Z

On 20.10.2021 15:33, Michal Hocko wrote:
> s@firce@force@
>
> On Wed 20-10-21 15:12:19, Vasily Averin wrote:
>> There is no sense to force global OOM if current task is dying.
>
> This really begs for much more information. Feel free to get an
> inspiration from my previous attempt to achieve something similar.
> In minimum it is important to mention that the OOM killer is already
> handled at the page allocator level for the global OOM and at the
> charging level for the memcg one. Both have much more information
> about the scope of allocation/charge request. This means that either the
> OOM killer has been invoked properly and didn't lead to the allocation
> success or it has been skipped because it couldn't have been invoked.
> In both cases triggering it from here is pointless and even harmful.
>
> Another argument is that it is more reasonable to let killed task die
> rather than hit the oom killer and retry the allocation.

Thank you,
I'll update patch description later,
this time I would like to clarify patch content.

>> Signed-off-by: Vasily Averin <vvs-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
>> ---
>> mm/oom_kill.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
>> index 831340e7ad8b..1deef8c7a71b 100644
>> --- a/mm/oom_kill.c
>> +++ b/mm/oom_kill.c
>> @@ -1137,6 +1137,9 @@ void pagefault_out_of_memory(void)
>> if (mem_cgroup_oom_synchronize(true))
>> return;
>>
>> + if (fatal_signal_pending(current))
>> + return;
>> +
>> if (!mutex_trylock(&oom_lock))
>> return;
>> out_of_memory(&oc);
>> --
>> 2.32.0
>