linux-kernel - Re: [RFC 05/26] mm, slub: extract get_partial() from new_slab

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Message-ID: <20210525115451.GO30378@techsingularity.net>
Date:   Tue, 25 May 2021 12:54:51 +0100
From:   Mel Gorman <mgorman@...hsingularity.net>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Pekka Enberg <penberg@...nel.org>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jann Horn <jannh@...gle.com>
Subject: Re: [RFC 05/26] mm, slub: extract get_partial() from
 new_slab_objects()

On Tue, May 25, 2021 at 01:39:25AM +0200, Vlastimil Babka wrote:
> The later patches will need more fine grained control over individual actions
> in ___slab_alloc(), the only caller of new_slab_objects(), so this is a first
> preparatory step with no functional change.
> 
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
> <SNIP>
> @@ -2748,6 +2743,10 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
>  		goto redo;
>  	}
>  
> +	freelist = get_partial(s, gfpflags, node, c);
> +	if (freelist)
> +		goto check_new_page;
> +
>  	freelist = new_slab_objects(s, gfpflags, node, &c);
>  
>  	if (unlikely(!freelist)) {

It's a nit-pick, but why did you not simply do something like this
instead of the goto?

	freelist = get_partial(s, gfpflags, node, c);
	if (!freelist)
		freelist = new_slab_objects(s, gfpflags, node, &c);

	if (unlikely(!freelist))
		...

If nothing else, the label may be misleading because c->page may not
be new.

-- 
Mel Gorman
SUSE Labs