Re: [PATCH v2 8/8] rcu/kfree: Fix kfree_rcu_shrink_count() return value

From: Uladzislau Rezki <urezki@gmail.com>
To: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org,
	rushikesh.s.kadam@intel.com, urezki@gmail.com,
	neeraj.iitr10@gmail.com, frederic@kernel.org, paulmck@kernel.org,
	rostedt@goodmis.org, vineeth@bitbyteword.org
Subject: Re: [PATCH v2 8/8] rcu/kfree: Fix kfree_rcu_shrink_count() return value
Date: Mon, 27 Jun 2022 20:56:43 +0200	[thread overview]
Message-ID: <Yrn9a5pOvhvL/eZj@pc638.lan> (raw)
In-Reply-To: <20220622225102.2112026-10-joel@joelfernandes.org>

> 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@joelfernandes.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@gmail.com>

--
Uladzislau Rezki