linux-kernel - Re: [PATCH v4 9/9] mm, slub: skip percpu sheaves for remote object freeing

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Message-ID: <c60ae681-6027-0626-8d4e-5833982bf1f0@gentwo.org>
Date: Fri, 25 Apr 2025 10:35:36 -0700 (PDT)
From: "Christoph Lameter (Ampere)" <cl@...two.org>
To: Vlastimil Babka <vbabka@...e.cz>
cc: Suren Baghdasaryan <surenb@...gle.com>, 
    "Liam R. Howlett" <Liam.Howlett@...cle.com>, 
    David Rientjes <rientjes@...gle.com>, 
    Roman Gushchin <roman.gushchin@...ux.dev>, 
    Harry Yoo <harry.yoo@...cle.com>, Uladzislau Rezki <urezki@...il.com>, 
    linux-mm@...ck.org, linux-kernel@...r.kernel.org, rcu@...r.kernel.org, 
    maple-tree@...ts.infradead.org
Subject: Re: [PATCH v4 9/9] mm, slub: skip percpu sheaves for remote object
 freeing

On Fri, 25 Apr 2025, Vlastimil Babka wrote:

> @@ -5924,8 +5948,15 @@ void slab_free(struct kmem_cache *s, struct slab *slab, void *object,
>  	if (unlikely(!slab_free_hook(s, object, slab_want_init_on_free(s), false)))
>  		return;
>
> -	if (!s->cpu_sheaves || !free_to_pcs(s, object))
> -		do_slab_free(s, slab, object, object, 1, addr);
> +	if (s->cpu_sheaves) {
> +		if (likely(!IS_ENABLED(CONFIG_NUMA) ||
> +			   slab_nid(slab) == numa_node_id())) {

Ah. ok this removes remote object freeing to the pcs.

numa_mem_id() is needed to support memory less numa nodes.

> +			free_to_pcs(s, object);
> +			return;
> +		}
> +	}
> +
> +	do_slab_free(s, slab, object, object, 1, addr);
>  }
>
>  #ifdef CONFIG_MEMCG
>
>