linux-kernel - Re: [PATCH v2 8/8] rcu/kfree: Fix kfree_rcu_shrink

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Message-ID: <Yrn9a5pOvhvL/eZj@pc638.lan>
Date:   Mon, 27 Jun 2022 20:56:43 +0200
From:   Uladzislau Rezki <urezki@...il.com>
To:     "Joel Fernandes (Google)" <joel@...lfernandes.org>
Cc:     rcu@...r.kernel.org, linux-kernel@...r.kernel.org,
        rushikesh.s.kadam@...el.com, urezki@...il.com,
        neeraj.iitr10@...il.com, frederic@...nel.org, paulmck@...nel.org,
        rostedt@...dmis.org, vineeth@...byteword.org
Subject: Re: [PATCH v2 8/8] rcu/kfree: Fix kfree_rcu_shrink_count() return
 value

> As per the comments in include/linux/shrinker.h, .count_objects callback
> should return the number of freeable items, but if there are no objects
> to free, SHRINK_EMPTY should be returned. The only time 0 is returned
> should be when we are unable to determine the number of objects, or the
> cache should be skipped for another reason.
> 
> Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
> ---
>  kernel/rcu/tree.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 711679d10cbb..935788e8d2d7 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -3722,7 +3722,7 @@ kfree_rcu_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
>  		atomic_set(&krcp->backoff_page_cache_fill, 1);
>  	}
>  
> -	return count;
> +	return count == 0 ? SHRINK_EMPTY : count;
>  }
>  
>  static unsigned long
> -- 
> 2.37.0.rc0.104.g0611611a94-goog
> 
Looks good to me!

Reviewed-by: Uladzislau Rezki (Sony) <urezki@...il.com>

--
Uladzislau Rezki