linux-kernel - Re: [PATCH] mm: memcontrol: Set the correct memcg swappiness restriction

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Message-ID: <YQOekWWgtZUfim4M@dhcp22.suse.cz>
Date:   Fri, 30 Jul 2021 08:39:13 +0200
From:   Michal Hocko <mhocko@...e.com>
To:     Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc:     akpm@...ux-foundation.org, hannes@...xchg.org,
        vdavydov.dev@...il.com, cgroups@...r.kernel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: memcontrol: Set the correct memcg swappiness
 restriction

On Fri 30-07-21 14:26:35, Baolin Wang wrote:
> Since commit c843966c556d ("mm: allow swappiness that prefers reclaiming
> anon over the file workingset") has expended the swappiness value to
> make swap to be preferred in some systems. We should also change the
> memcg swappiness restriction to allow memcg swap-preferred.
> 
> Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>

Yes, this looks like an omission. It doesn't really make sense to have
two different constrains on the value.

Acked-by: Michal Hocko <mhocko@...e.com>

Thanks!

> ---
>  mm/memcontrol.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 6580c23..988fc94 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -4046,7 +4046,7 @@ static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
>  {
>  	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
>  
> -	if (val > 100)
> +	if (val > 200)
>  		return -EINVAL;
>  
>  	if (!mem_cgroup_is_root(memcg))
> -- 
> 1.8.3.1

-- 
Michal Hocko
SUSE Labs