linux-kernel - Re: [PATCH v3] memcg: fix soft lockup in the OOM process

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Message-ID: <0d9ea655-5c1a-4ba9-9eeb-b45d74cc68d0@huaweicloud.com>
Date: Tue, 14 Jan 2025 20:19:35 +0800
From: Chen Ridong <chenridong@...weicloud.com>
To: Michal Hocko <mhocko@...e.com>, Vlastimil Babka <vbabka@...e.cz>
Cc: Andrew Morton <akpm@...ux-foundation.org>, hannes@...xchg.org,
 yosryahmed@...gle.com, roman.gushchin@...ux.dev, shakeel.butt@...ux.dev,
 muchun.song@...ux.dev, davidf@...eo.com, handai.szj@...bao.com,
 rientjes@...gle.com, kamezawa.hiroyu@...fujitsu.com,
 RCU <rcu@...r.kernel.org>, linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 cgroups@...r.kernel.org, chenridong@...wei.com, wangweiyang2@...wei.com
Subject: Re: [PATCH v3] memcg: fix soft lockup in the OOM process



On 2025/1/14 17:30, Michal Hocko wrote:
> On Tue 14-01-25 10:20:28, Vlastimil Babka wrote:
>> On 1/14/25 09:40, Michal Hocko wrote:
>>> On Mon 13-01-25 19:45:46, Andrew Morton wrote:
> [...]
>>>>> For global OOM, system is likely to struggle, do we have to do some
>>>>> works to suppress RCU detete?
>>>>
>>>> rcu_cpu_stall_reset()?
>>>
>>> Do we really care about those? The code to iterate over all processes
>>> under RCU is there (basically) since ever and yet we do not seem to have
>>> many reports of stalls? Chen's situation is specific to memcg OOM and
>>> touching the global case was mostly for consistency reasons.
>>
>> Then I'd rather not touch the global case then if it's theoretical?
> 
> No strong opinion on this on my side. The only actual reason
> touch_softlockup_watchdog is there is becuase it originally had
> incorrectly cond_resched there. If half silencing (soft lock up
> detector only) disturbs people then let's just drop that hunk.

So do I. If there are no other opinions, I will drop it.

Best regards,
Ridong