linux-kernel - Re: [PATCH] mm: vmscan: skip the file folios in proactive reclaim if swappiness is MAX

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250312153618.e24f399d2d9767ebef87519f@linux-foundation.org>
Date: Wed, 12 Mar 2025 15:36:18 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Zhongkun He <hezhongkun.hzk@...edance.com>
Cc: mhocko@...e.com, hannes@...xchg.org, muchun.song@...ux.dev,
 linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: vmscan: skip the file folios in proactive reclaim
 if swappiness is MAX

On Wed, 12 Mar 2025 17:43:37 +0800 Zhongkun He <hezhongkun.hzk@...edance.com> wrote:

> With this patch 'commit <68cd9050d871> ("mm: add swappiness= arg to
> memory.reclaim")', we can submit an additional swappiness=<val> argument
> to memory.reclaim. It is very useful because we can dynamically adjust
> the reclamation ratio based on the anonymous folios and file folios of
> each cgroup. For example,when swappiness is set to 0, we only reclaim
> from file pages.
> 
> However,we have also encountered a new issue: when swappiness is set to
> the MAX_SWAPPINESS, it may still only reclaim file folios. This is due
> to the knob of cache_trim_mode, which depends solely on the ratio of
> inactive folios, regardless of whether there are a large number of cold
> folios in anonymous folio list.
> 
> So, we hope to add a new control logic where proactive memory reclaim only
> reclaims from anonymous folios when swappiness is set to MAX_SWAPPINESS.
> For example, something like this:
> 
> echo "2M swappiness=200" > /sys/fs/cgroup/memory.reclaim
> 
> will perform reclaim on the rootcg with a swappiness setting of 200 (max
> swappiness) regardless of the file folios. Users have a more comprehensive
> view of the application's memory distribution because there are many
> metrics available.
> 
> With this patch, the swappiness argument of memory.reclaim has a more
> precise semantics: 0 means reclaiming only from file pages, while 200
> means reclaiming just from anonymous pages.

Please update Documentation/admin-guide/cgroup-v2.rst for this.