netdev - Re: [RFC mm v5 2/2] mm: introduce a new page type for page pool in page type

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Message-ID: <87h5vbp3vi.fsf@toke.dk>
Date: Mon, 03 Nov 2025 15:50:09 +0100
From: Toke Høiland-Jørgensen <toke@...hat.com>
To: Byungchul Park <byungchul@...com>
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Subject: Re: [RFC mm v5 2/2] mm: introduce a new page type for page pool in
 page type

Byungchul Park <byungchul@...com> writes:

> On Mon, Nov 03, 2025 at 01:26:01PM +0100, Toke Høiland-Jørgensen wrote:
>> Byungchul Park <byungchul@...com> writes:
>> 
>> > Currently, the condition 'page->pp_magic == PP_SIGNATURE' is used to
>> > determine if a page belongs to a page pool.  However, with the planned
>> > removal of ->pp_magic, we should instead leverage the page_type in
>> > struct page, such as PGTY_netpp, for this purpose.
>> >
>> > Introduce and use the page type APIs e.g. PageNetpp(), __SetPageNetpp(),
>> > and __ClearPageNetpp() instead, and remove the existing APIs accessing
>> > ->pp_magic e.g. page_pool_page_is_pp(), netmem_or_pp_magic(), and
>> > netmem_clear_pp_magic().
>> >
>> > This work was inspired by the following link:
>> >
>> > [1] https://lore.kernel.org/all/582f41c0-2742-4400-9c81-0d46bf4e8314@gmail.com/
>> >
>> > While at it, move the sanity check for page pool to on free.
>> >
>> > Suggested-by: David Hildenbrand <david@...hat.com>
>> > Co-developed-by: Pavel Begunkov <asml.silence@...il.com>
>> > Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
>> > Signed-off-by: Byungchul Park <byungchul@...com>
>> > Acked-by: David Hildenbrand <david@...hat.com>
>> > Acked-by: Zi Yan <ziy@...dia.com>
>> > Acked-by: Mina Almasry <almasrymina@...gle.com>
>> 
>> Acked-by: Toke Høiland-Jørgensen <toke@...hat.com>
>> 
>> IIUC, this will allow us to move the PP-specific fields out of struct
>> page entirely at some point, right? What are the steps needed to get to
>> that point after this?
>
> Yes, it'd be almost done once this set gets merged :-)
>
> Will check if I can safely remove pp fields from struct page, and do
> it!

Sounds good, thanks!

-Toke