linux-kernel - Re: [RFC mm v6] mm: introduce a new page type for page pool in page type

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Message-ID: <87o6p0oqga.fsf@toke.dk>
Date: Mon, 17 Nov 2025 12:20:53 +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 v6] 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().
>
> Plus, add @page_type to struct net_iov at the same offset as struct page
> so as to use the page_type APIs for struct net_iov as well.  While at it,
> reorder @type and @owner in struct net_iov to avoid a hole and
> increasing the struct size.
>
> This work was inspired by the following link:
>
>   https://lore.kernel.org/all/582f41c0-2742-4400-9c81-0d46bf4e8314@gmail.com/
>
> While at it, move the sanity check for page pool to on the free path.
>
> 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>
> ---
> I dropped all the Reviewed-by and Acked-by given for network changes
> since I changed how to implement the part on the request from Jakub.
> Can I keep your tags?  Jakub, are you okay with this change?

LGTM, you can keep mine :)

-Toke