linux-kernel - Re: [PATCH 1/4] mm, memcontrol: avoid duplicated memcg enable check

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Message-ID: <CAJD7tkYemGu0iqt+ZW9t5zr21PbHkFBRnc=EixiwoNbq0xq5Ew@mail.gmail.com>
Date: Mon, 2 Dec 2024 11:10:31 -0800
From: Yosry Ahmed <yosryahmed@...gle.com>
To: Kairui Song <kasong@...cent.com>
Cc: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>, 
	Chris Li <chrisl@...nel.org>, Hugh Dickins <hughd@...gle.com>, 
	"Huang, Ying" <ying.huang@...el.com>, Roman Gushchin <roman.gushchin@...ux.dev>, 
	Shakeel Butt <shakeel.butt@...ux.dev>, Johannes Weiner <hannes@...xchg.org>, 
	Barry Song <baohua@...nel.org>, Michal Hocko <mhocko@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] mm, memcontrol: avoid duplicated memcg enable check

On Mon, Dec 2, 2024 at 10:42 AM Kairui Song <ryncsn@...il.com> wrote:
>
> From: Kairui Song <kasong@...cent.com>
>
> mem_cgroup_uncharge_swap() implies a mem_cgroup_disabled() check,
> which is already checked by the caller here. Skip it by calling
> __mem_cgroup_uncharge_swap() directly.
>
> Signed-off-by: Kairui Song <kasong@...cent.com>
> ---
>  mm/memcontrol.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 7b3503d12aaf..d3d1eb506eee 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -4615,7 +4615,7 @@ void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
>                  * let's not wait for it.  The page already received a
>                  * memory+swap charge, drop the swap entry duplicate.
>                  */
> -               mem_cgroup_uncharge_swap(entry, nr_pages);
> +               __mem_cgroup_uncharge_swap(entry, nr_pages);

Would it be better to instead remove the mem_cgroup_disabled() check
here and have a single check in this path?

Anyway, FWIW:

Reviewed-by: Yosry Ahmed <yosryahmed@...gle.com>

>         }
>  }
>
> --
> 2.47.0
>