Re: [PATCH] mm/oom_kill: revert watchdog reset in global OOM process

Vlastimil Babka
2025-02-12T09:34:08Z

On 2/12/25 10:19, Chen Ridong wrote:
>
>
> On 2025/2/12 16:57, Michal Hocko wrote:
>> On Wed 12-02-25 02:57:07, Chen Ridong wrote:
>>> From: Chen Ridong <chenridong@huawei.com>
>>>
>>> Unlike memcg OOM, which is relatively common, global OOM events are rare
>>> and typically indicate that the entire system is under severe memory
>>> pressure. The commit ade81479c7dd ("memcg: fix soft lockup in the OOM
>>> process") added the touch_softlockup_watchdog in the global OOM handler to
>>> suppess the soft lockup issues. However, while this change can suppress
>>> soft lockup warnings, it does not address RCU stalls, which can still be
>>> detected and may cause unnecessary disturbances. Simply remove the
>>> modification from the global OOM handler.
>>>
>>> Fixes: ade81479c7dd ("memcg: fix soft lockup in the OOM process")
>>
>> But this is not really fixing anything, is it? While this doesn't
>> address a potential RCU stall it doesn't address any actual problem.
>> So why do we want to do this?
>>
>
>
> [1]
> https://lore.kernel.org/cgroups/0d9ea655-5c1a-4ba9-9eeb-b45d74cc68d0@huaweicloud.com/
>
> As previously discussed, the work I have done on the global OOM is 'half
> of the job'. Based on our discussions, I thought that it would be best
> to abandon this approach for global OOM. Therefore, I am sending this
> patch to revert the changes.
>
> Or just leave it?

I suggested that part doesn't need to be in the patch, but if it was merged
with it, we can just leave it there. Thanks.