linux-kernel - Re: [[PATCH v2] 2/2] futex: Only delay OOM reaper for processes using robust futex

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Message-ID: <aJBKijr1nR1CleBL@tiehlicka>
Date: Mon, 4 Aug 2025 07:52:10 +0200
From: Michal Hocko <mhocko@...e.com>
To: zhongjinji@...or.com
Cc: linux-mm@...ck.org, akpm@...ux-foundation.org, rientjes@...gle.com,
	shakeel.butt@...ux.dev, npache@...hat.com,
	linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
	peterz@...radead.org, dvhart@...radead.org, dave@...olabs.net,
	andrealmeid@...lia.com, liulu.liu@...or.com, feng.han@...or.com
Subject: Re: [[PATCH v2] 2/2] futex: Only delay OOM reaper for processes
 using robust futex

On Fri 01-08-25 23:36:49, zhongjinji@...or.com wrote:
> From: zhongjinji <zhongjinji@...or.com>
> 
> After merging the patch
> https://lore.kernel.org/all/20220414144042.677008-1-npache@redhat.com/T/#u,
> the OOM reaper runs less frequently because many processes exit within 2 seconds.
> 
> However, when a process is killed, timely handling by the OOM reaper allows
> its memory to be freed faster.
> 
> Since relatively few processes use robust futex, delaying the OOM reaper for
> all processes is undesirable, as many killed processes cannot release memory
> more quickly.

Could you elaborate more about why this is really needed? OOM should be
a very slow path. Why do you care about this potential improvement in
that situation? In other words what is the usecase?

-- 
Michal Hocko
SUSE Labs