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: <87jz07pajq.fsf@toke.dk>
Date: Mon, 03 Nov 2025 13:26:01 +0100
From: Toke Høiland-Jørgensen <toke@...hat.com>
To: Byungchul Park <byungchul@...com>, linux-mm@...ck.org,
 netdev@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, kernel_team@...ynix.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:

> 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?

-Toke