linux-kernel - Re: [PATCH] mm: bail out from partial cgroup_reclaim inside shrink

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Message-ID: <CAGWkznGom7mCk=6dHT6EDouexo2YLFiYpzeTcS4Nexuww4__dA@mail.gmail.com>
Date: Mon, 9 Feb 2026 15:36:17 +0800
From: Zhaoyang Huang <huangzhaoyang@...il.com>
To: "zhaoyang.huang" <zhaoyang.huang@...soc.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Yu Zhao <yuzhao@...gle.com>, 
	Michal Hocko <mhocko@...nel.org>, Rik van Riel <riel@...riel.com>, 
	Shakeel Butt <shakeel.butt@...ux.dev>, Roman Gushchin <roman.gushchin@...ux.dev>, 
	Johannes Weiner <hannes@...xchg.org>, linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	steve.kang@...soc.com
Subject: Re: [PATCH] mm: bail out from partial cgroup_reclaim inside shrink_lruvec

On Thu, Feb 5, 2026 at 2:47 PM zhaoyang.huang <zhaoyang.huang@...soc.com> wrote:
>
> From: Zhaoyang Huang <zhaoyang.huang@...soc.com>
>
> Oversize reclaiming observed in "echo xxx > memory.reclaim". This commit
> would like to sync the stop criteria in shrink_node_memcgs to
> shrink_lruvec to have partial cgroup_reclaim bail out as early as it can
> be.
>
> Signed-off-by: Zhaoyang Huang <zhaoyang.huang@...soc.com>
> ---
>  mm/vmscan.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 670fe9fae5ba..03bda1094621 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -4832,8 +4832,8 @@ static bool should_abort_scan(struct lruvec *lruvec, struct scan_control *sc)
>         int i;
>         enum zone_watermarks mark;
>
> -       /* don't abort memcg reclaim to ensure fairness */
> -       if (!root_reclaim(sc))
> +       /* don't abort full walk memcg reclaim to ensure fairness */
> +       if (!root_reclaim(sc) && sc->memcg_full_walk)
>                 return false;
>
>         if (sc->nr_reclaimed >= max(sc->nr_to_reclaim, compact_gap(sc->order)))
> --
Talk more about motivation. Nowadays, android systems replace madivse
with memory.reclaim to implement user space memory management which
desires to reclaim a certain amount of memcg's memory. However,
oversized reclaiming is observed as there is no limitation within
try_to_shrink_lruvec when MGLRU enabled. This commit would like to fix
this by judging sc->memcg_full_walk.

> 2.25.1
>