Re: [PATCH 2/4] mm/swap_cgroup: remove swap_cgroup_cmpxchg

[Yosry Ahmed <yosryahmed@google.com>]

On Mon, Dec 2, 2024 at 10:42 AM Kairui Song <ryncsn@gmail.com> wrote:
>
> From: Kairui Song <kasong@tencent.com>
>
> This function is never used after commit 6b611388b626
> ("memcg-v1: remove charge move code").
>
> Signed-off-by: Kairui Song <kasong@tencent.com>

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

> ---
>  include/linux/swap_cgroup.h |  2 --
>  mm/swap_cgroup.c            | 29 -----------------------------
>  2 files changed, 31 deletions(-)
>
> diff --git a/include/linux/swap_cgroup.h b/include/linux/swap_cgroup.h
> index ae73a87775b3..d521ad1c4164 100644
> --- a/include/linux/swap_cgroup.h
> +++ b/include/linux/swap_cgroup.h
> @@ -6,8 +6,6 @@
>
>  #if defined(CONFIG_MEMCG) && defined(CONFIG_SWAP)
>
> -extern unsigned short swap_cgroup_cmpxchg(swp_entry_t ent,
> -                                       unsigned short old, unsigned short new);
>  extern unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id,
>                                          unsigned int nr_ents);
>  extern unsigned short lookup_swap_cgroup_id(swp_entry_t ent);
> diff --git a/mm/swap_cgroup.c b/mm/swap_cgroup.c
> index f63d1aa072a1..1770b076f6b7 100644
> --- a/mm/swap_cgroup.c
> +++ b/mm/swap_cgroup.c
> @@ -45,35 +45,6 @@ static struct swap_cgroup *lookup_swap_cgroup(swp_entry_t ent,
>         return &ctrl->map[offset];
>  }
>
> -/**
> - * swap_cgroup_cmpxchg - cmpxchg mem_cgroup's id for this swp_entry.
> - * @ent: swap entry to be cmpxchged
> - * @old: old id
> - * @new: new id
> - *
> - * Returns old id at success, 0 at failure.
> - * (There is no mem_cgroup using 0 as its id)
> - */
> -unsigned short swap_cgroup_cmpxchg(swp_entry_t ent,
> -                                       unsigned short old, unsigned short new)
> -{
> -       struct swap_cgroup_ctrl *ctrl;
> -       struct swap_cgroup *sc;
> -       unsigned long flags;
> -       unsigned short retval;
> -
> -       sc = lookup_swap_cgroup(ent, &ctrl);
> -
> -       spin_lock_irqsave(&ctrl->lock, flags);
> -       retval = sc->id;
> -       if (retval == old)
> -               sc->id = new;
> -       else
> -               retval = 0;
> -       spin_unlock_irqrestore(&ctrl->lock, flags);
> -       return retval;
> -}
> -
>  /**
>   * swap_cgroup_record - record mem_cgroup for a set of swap entries
>   * @ent: the first swap entry to be recorded into
> --
> 2.47.0
>