linux-kernel - Re: [PATCH v2 01/11] mm/slab: fix the theoretical race by holding proper lock

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Date:	Tue, 12 Apr 2016 11:38:39 -0500 (CDT)
From:	Christoph Lameter <cl@...ux.com>
To:	js1304@...il.com
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Jesper Dangaard Brouer <brouer@...hat.com>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH v2 01/11] mm/slab: fix the theoretical race by holding
 proper lock

On Tue, 12 Apr 2016, js1304@...il.com wrote:

> @@ -2222,6 +2241,7 @@ static void drain_cpu_caches(struct kmem_cache *cachep)
>  {
>  	struct kmem_cache_node *n;
>  	int node;
> +	LIST_HEAD(list);
>
>  	on_each_cpu(do_drain, cachep, 1);
>  	check_irq_on();
> @@ -2229,8 +2249,13 @@ static void drain_cpu_caches(struct kmem_cache *cachep)
>  		if (n->alien)
>  			drain_alien_cache(cachep, n->alien);
>
> -	for_each_kmem_cache_node(cachep, node, n)
> -		drain_array(cachep, n, n->shared, 1, node);
> +	for_each_kmem_cache_node(cachep, node, n) {
> +		spin_lock_irq(&n->list_lock);
> +		drain_array_locked(cachep, n->shared, node, true, &list);
> +		spin_unlock_irq(&n->list_lock);
> +
> +		slabs_destroy(cachep, &list);

Can the slabs_destroy() call be moved outside of the loop? It may be
faster then?