linux-kernel - Re: [PATCH 4/4] slab: use struct freelist_counters as parameters in relevant functions

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Message-ID: <aRWXsVuiSCv062su@hyeyoo>
Date: Thu, 13 Nov 2025 17:32:49 +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 4/4] slab: use struct freelist_counters as parameters in
 relevant functions

On Fri, Nov 07, 2025 at 02:51:26PM +0100, Vlastimil Babka wrote:
> In functions such as [__]slab_update_freelist() and
> __slab_update_freelist_fast/slow() we pass old and new freelist and
> counters as 4 separate parameters. The underlying
> __update_freelist_fast() then constructs struct freelist_counters
> variables for passing the full freelist+counter combinations to cmpxchg
> double.
> 
> In most cases we actually start with struct freelist_counters variables,
> but then pass the individual fields, only to construct new struct
> freelist_counters variables. While it's all inlined and thus should be
> efficient, we can simplify this code.
> 
> Thus replace the 4 parameters for individual fields with two
> freelist_aba_t pointers wherever applicable. __update_freelist_fast()

nit: I guess you meant struct freelist_counters pointers, because
freelist_aba_t is gone.

> can then pass them directly to try_cmpxchg_freelist().
> 
> The code is also more obvious as the pattern becomes unified such that
> we set up "old" and "new" struct freelist_counters variables upfront as
> we fully need them to be, and simply call [__]slab_update_freelist() on
> them.  Previously some of the "new" values would be hidden as one of the
> many parameters and thus make it harder to figure out what the code
> does.
> 
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
> ---

Nice!

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

-- 
Cheers,
Harry / Hyeonggon