Re: [PATCH] slab: Remove slab_folio()

["Vlastimil Babka (SUSE)" <vbabka@kernel.org>]

On 9/23/26 21:45, Harry Yoo wrote:
> On Wed, Sep 23, 2026 at 07:36:51PM +0100, Matthew Wilcox (Oracle) wrote:
>> This is the final step of divorcing struct slab from struct folio.
>> It's still tied to struct page, but there are no more mentions of folios
>> in the slab code.
>> 
>> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
>> ---
> 
> Looks good to me,
> Reviewed-by: Harry Yoo (Meta) <harry@kernel.org>
> 
> With a tiny little nit:
> 
>> @@ -184,15 +169,16 @@ static inline struct slab *page_slab(const struct page *page)
>>   * slab_page - The first struct page allocated for a slab
>>   * @s: The slab.
>>   *
>> - * A convenience wrapper for converting slab to the first struct page of the
>> - * underlying folio, to communicate with code not yet converted to folio or
>> - * struct slab.
>> + * A convenience wrapper for returning the first page allocated to this slab.
>> + * to communicate with code not yet converted to struct slab.
>     * A convenience wrapper for returning the first "struct" page allocated to this
>     * "slab" to communicate with code not yet converted to struct slab.
>>   */
> 
> Perhaps you meant this?

Yeah, and I wonder about the "code not yet converted" part, and if there's
anything we can still convert right now. What I can see among slab_page() users:

- slab_order() - we could probably add order (aliasing page's order for now)
to struct slab right now and that would be future-proof

But:
- slab_address() - I guess can only be converted once slab is divorced from
page?
- __kasan_poison_slab - same as above?
- several VM_BUG_ON_PAGE() usages - same?
- validate_slab_ptr() - same?
__free_slab() - same, obviously