linux-kernel - Re: [PATCH 1/5] slab: make __slab

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Message-ID: <aQxbp0cikSkiON5M@harry>
Date: Thu, 6 Nov 2025 17:26:15 +0900
From: Harry Yoo <harry.yoo@...cle.com>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Lameter <cl@...two.org>,
        David Rientjes <rientjes@...gle.com>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Alexei Starovoitov <ast@...nel.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
        kasan-dev@...glegroups.com
Subject: Re: [PATCH 1/5] slab: make __slab_free() more clear

On Wed, Nov 05, 2025 at 10:05:29AM +0100, Vlastimil Babka wrote:
> The function is tricky and many of its tests are hard to understand. Try
> to improve that by using more descriptively named variables and added
> comments.
> 
> - rename 'prior' to 'old_head' to match the head and tail parameters
> - introduce a 'bool was_full' to make it more obvious what we are
>   testing instead of the !prior and prior tests

Yeah I recall these were cryptic when I was analyzing slab few years
ago :)

> - add or improve comments in various places to explain what we're doing
> 
> Also replace kmem_cache_has_cpu_partial() tests with
> IS_ENABLED(CONFIG_SLUB_CPU_PARTIAL) which are compile-time constants.
>
> We can do that because the kmem_cache_debug(s) case is handled upfront
> via free_to_partial_list().

This makes sense. By the way, should we also check IS_ENABLED(CONFIG_SLUB_TINY)
in kmem_cache_has_cpu_partial()?

> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
> ---

The code is much cleaner!

Reviewed-by: Harry Yoo <harry.yoo@...cle.com>

-- 
Cheers,
Harry / Hyeonggon