linux-kernel - Re: [PATCH 2/4] slab: turn freelist_aba_t to a struct and fully define counters there

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Message-ID: <aRWJ8kp7Bo5ZD6sl@hyeyoo>
Date: Thu, 13 Nov 2025 16:34:10 +0900
From: Harry Yoo <harry.yoo@...cle.com>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Lameter <cl@...two.org>,
        David Rientjes <rientjes@...gle.com>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] slab: turn freelist_aba_t to a struct and fully
 define counters there

On Fri, Nov 07, 2025 at 02:51:24PM +0100, Vlastimil Babka wrote:
> In struct slab we currently have freelist and counters pair, where
> counters itself is a union of unsigned long with a sub-struct of
> several smaller fields. Then for the usage with double cmpxchg we have
> freelist_aba_t that duplicates the definition of the freelist+counters
> with implicitly the same layout as the full definition in struct slab.
> 
> Thanks to -fms-extension we can now move the full counters definition to
> freelist_aba_t (while changing it to struct freelist_counters as a
> typedef is unnecessary and discouraged) and replace the relevant part in
> struct slab to an unnamed reference to it.
> 
> The immediate benefit is the removal of duplication and no longer
> relying on the same layout implicitly. It also allows further cleanups
> thanks to having the full definition of counters in struct
> freelist_counters.
> 
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
> ---

Nice cleanup!

Looks good to me,
Reviewed-by: Harry Yoo <harry.yoo@...cle.com>

-- 
Cheers,
Harry / Hyeonggon