linux-kernel - Re: [RFC 08/26] mm, slub: restructure new page checks in ___slab

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Message-ID: <20210525120954.GQ30378@techsingularity.net>
Date:   Tue, 25 May 2021 13:09:54 +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 08/26] mm, slub: restructure new page checks in
 ___slab_alloc()

On Tue, May 25, 2021 at 01:39:28AM +0200, Vlastimil Babka wrote:
> When we allocate slab object from a newly acquired page (from node's partial
> list or page allocator), we usually also retain the page as a new percpu slab.
> There are two exceptions - when pfmemalloc status of the page doesn't match our
> gfp flags, or when the cache has debugging enabled.
> 
> The current code for these decisions is not easy to follow, so restructure it
> and add comments. No functional change.
> 
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
>
> <SNIP>
>
> +	if (unlikely(!pfmemalloc_match(page, gfpflags)))
> +		/*
> +		 * For !pfmemalloc_match() case we don't load freelist so that
> +		 * we don't make further mismatched allocations easier.
> +		 */
> +		goto return_single;
> +
> +	goto load_freelist;
> +
> +return_single:
>  

This looked odd to me but I see other stuff goes between the two goto's
later in the series so

Acked-by: Mel Gorman <mgorman@...hsingularity.net>

-- 
Mel Gorman
SUSE Labs