linux-kernel - Re: [PATCH v4 18/48] rcu: dynamically allocate the rcu-lazy shrinker

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Message-ID: <CAEXW_YTKHUeZHWtzeSG5Tt7MscNKjVTScBWkVDkC4Orisa7w=Q@mail.gmail.com>
Date:   Mon, 7 Aug 2023 10:16:03 -0400
From:   Joel Fernandes <joel@...lfernandes.org>
To:     Qi Zheng <zhengqi.arch@...edance.com>
Cc:     akpm@...ux-foundation.org, david@...morbit.com, tkhai@...ru,
        vbabka@...e.cz, roman.gushchin@...ux.dev, djwong@...nel.org,
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Subject: Re: [PATCH v4 18/48] rcu: dynamically allocate the rcu-lazy shrinker

On Mon, Aug 7, 2023 at 7:36 AM Qi Zheng <zhengqi.arch@...edance.com> wrote:
>
> Use new APIs to dynamically allocate the rcu-lazy shrinker.
>
> Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>

For RCU:
Reviewed-by: Joel Fernandes (Google) <joel@...lfernandes.org>

thanks,

- Joel


> ---
>  kernel/rcu/tree_nocb.h | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h
> index 5598212d1f27..e1c59c33738a 100644
> --- a/kernel/rcu/tree_nocb.h
> +++ b/kernel/rcu/tree_nocb.h
> @@ -1396,13 +1396,6 @@ lazy_rcu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
>
>         return count ? count : SHRINK_STOP;
>  }
> -
> -static struct shrinker lazy_rcu_shrinker = {
> -       .count_objects = lazy_rcu_shrink_count,
> -       .scan_objects = lazy_rcu_shrink_scan,
> -       .batch = 0,
> -       .seeks = DEFAULT_SEEKS,
> -};
>  #endif // #ifdef CONFIG_RCU_LAZY
>
>  void __init rcu_init_nohz(void)
> @@ -1410,6 +1403,7 @@ void __init rcu_init_nohz(void)
>         int cpu;
>         struct rcu_data *rdp;
>         const struct cpumask *cpumask = NULL;
> +       struct shrinker * __maybe_unused lazy_rcu_shrinker;
>
>  #if defined(CONFIG_NO_HZ_FULL)
>         if (tick_nohz_full_running && !cpumask_empty(tick_nohz_full_mask))
> @@ -1436,8 +1430,16 @@ void __init rcu_init_nohz(void)
>                 return;
>
>  #ifdef CONFIG_RCU_LAZY
> -       if (register_shrinker(&lazy_rcu_shrinker, "rcu-lazy"))
> -               pr_err("Failed to register lazy_rcu shrinker!\n");
> +       lazy_rcu_shrinker = shrinker_alloc(0, "rcu-lazy");
> +       if (!lazy_rcu_shrinker) {
> +               pr_err("Failed to allocate lazy_rcu shrinker!\n");
> +       } else {
> +               lazy_rcu_shrinker->count_objects = lazy_rcu_shrink_count;
> +               lazy_rcu_shrinker->scan_objects = lazy_rcu_shrink_scan;
> +               lazy_rcu_shrinker->seeks = DEFAULT_SEEKS;
> +
> +               shrinker_register(lazy_rcu_shrinker);
> +       }
>  #endif // #ifdef CONFIG_RCU_LAZY
>
>         if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {
> --
> 2.30.2
>