linux-kernel - Re: [PATCH v6 16/45] rcu: dynamically allocate the rcu-kfree shrinker

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Message-ID: <ZQATp6yFd/GXY9hN@pc636>
Date:   Tue, 12 Sep 2023 09:30:47 +0200
From:   Uladzislau Rezki <urezki@...il.com>
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,
        brauner@...nel.org, paulmck@...nel.org, tytso@....edu,
        steven.price@....com, cel@...nel.org, senozhatsky@...omium.org,
        yujie.liu@...el.com, gregkh@...uxfoundation.org,
        muchun.song@...ux.dev, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
        Joel Fernandes <joel@...lfernandes.org>,
        Muchun Song <songmuchun@...edance.com>, rcu@...r.kernel.org
Subject: Re: [PATCH v6 16/45] rcu: dynamically allocate the rcu-kfree shrinker

On Mon, Sep 11, 2023 at 05:44:15PM +0800, Qi Zheng wrote:
> Use new APIs to dynamically allocate the rcu-kfree shrinker.
> 
> Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
> Reviewed-by: Joel Fernandes (Google) <joel@...lfernandes.org>
> Reviewed-by: Muchun Song <songmuchun@...edance.com>
> CC: rcu@...r.kernel.org
> ---
>  kernel/rcu/tree.c | 21 ++++++++++++---------
>  1 file changed, 12 insertions(+), 9 deletions(-)
> 
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index cb1caefa8bd0..06e2ed495c02 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -3449,13 +3449,6 @@ kfree_rcu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
>  	return freed == 0 ? SHRINK_STOP : freed;
>  }
>  
> -static struct shrinker kfree_rcu_shrinker = {
> -	.count_objects = kfree_rcu_shrink_count,
> -	.scan_objects = kfree_rcu_shrink_scan,
> -	.batch = 0,
> -	.seeks = DEFAULT_SEEKS,
> -};
> -
>  void __init kfree_rcu_scheduler_running(void)
>  {
>  	int cpu;
> @@ -4931,6 +4924,7 @@ static void __init kfree_rcu_batch_init(void)
>  {
>  	int cpu;
>  	int i, j;
> +	struct shrinker *kfree_rcu_shrinker;
>  
>  	/* Clamp it to [0:100] seconds interval. */
>  	if (rcu_delay_page_cache_fill_msec < 0 ||
> @@ -4962,8 +4956,17 @@ static void __init kfree_rcu_batch_init(void)
>  		INIT_DELAYED_WORK(&krcp->page_cache_work, fill_page_cache_func);
>  		krcp->initialized = true;
>  	}
> -	if (register_shrinker(&kfree_rcu_shrinker, "rcu-kfree"))
> -		pr_err("Failed to register kfree_rcu() shrinker!\n");
> +
> +	kfree_rcu_shrinker = shrinker_alloc(0, "rcu-kfree");
> +	if (!kfree_rcu_shrinker) {
> +		pr_err("Failed to allocate kfree_rcu() shrinker!\n");
> +		return;
> +	}
> +
> +	kfree_rcu_shrinker->count_objects = kfree_rcu_shrink_count;
> +	kfree_rcu_shrinker->scan_objects = kfree_rcu_shrink_scan;
> +
> +	shrinker_register(kfree_rcu_shrinker);
>  }
>  
>  void __init rcu_init(void)
> -- 
> 2.30.2
> 
Reviewed-by: Uladzislau Rezki (Sony) <urezki@...il.com>

Makes sense to me. Thank you for improving it.

--
Uladzislau Rezki