linux-kernel - Re: [PATCH] memcg: avoid dead loop when setting memory.max

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Message-ID: <Z6u0o_xr9Lo7nwh-@tiehlicka>
Date: Tue, 11 Feb 2025 21:35:47 +0100
From: Michal Hocko <mhocko@...e.com>
To: Shakeel Butt <shakeel.butt@...ux.dev>
Cc: Chen Ridong <chenridong@...weicloud.com>, hannes@...xchg.org,
	roman.gushchin@...ux.dev, muchun.song@...ux.dev,
	akpm@...ux-foundation.org, cgroups@...r.kernel.org,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	chenridong@...wei.com, wangweiyang2@...wei.com
Subject: Re: [PATCH] memcg: avoid dead loop when setting memory.max

On Tue 11-02-25 11:04:21, Shakeel Butt wrote:
> On Tue, Feb 11, 2025 at 08:18:19AM +0000, Chen Ridong wrote:
[...]
> Wouldn't it be more robust if we put an upper bound on the else case of
> above condition i.e. fix number of retries? As you have discovered there
> is a hidden dependency on the forward progress of oom_reaper and this
> check/code-path which I think is not needed. 

Any OOM path has a dependency on oom_reaper or task exiting. Is there
any reason why this path should be any special? With cond_resched we can
look for a day where this will be just removed and the code will still
work. With a number of retries we will have a non-deterministic time
dependent behavior because number of retries rather than fwd progress
would define the failure mode.
-- 
Michal Hocko
SUSE Labs