linux-kernel - Re: [PATCH net-next v9 4/8] netmem: use netmem_desc instead of page to access ->pp in __netmem_get

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Message-ID: <CAHS8izM8a-1k=q6bJAXuien1w6Zr+HAJ=XFo-3mbgM3=YBBtog@mail.gmail.com>
Date: Thu, 10 Jul 2025 11:25:12 -0700
From: Mina Almasry <almasrymina@...gle.com>
To: Byungchul Park <byungchul@...com>
Cc: willy@...radead.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-mm@...ck.org, kernel_team@...ynix.com, kuba@...nel.org, 
	ilias.apalodimas@...aro.org, harry.yoo@...cle.com, hawk@...nel.org, 
	akpm@...ux-foundation.org, davem@...emloft.net, john.fastabend@...il.com, 
	andrew+netdev@...n.ch, asml.silence@...il.com, toke@...hat.com, 
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	hannes@...xchg.org, ziy@...dia.com, jackmanb@...gle.com
Subject: Re: [PATCH net-next v9 4/8] netmem: use netmem_desc instead of page
 to access ->pp in __netmem_get_pp()

On Thu, Jul 10, 2025 at 1:28 AM Byungchul Park <byungchul@...com> wrote:
>
> To eliminate the use of the page pool fields in struct page, the page
> pool code should use netmem descriptor and APIs instead.
>
> However, __netmem_get_pp() still accesses ->pp via struct page.  So
> change it to use struct netmem_desc instead, since ->pp no longer will
> be available in struct page.
>
> Signed-off-by: Byungchul Park <byungchul@...com>
> ---
>  include/net/netmem.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/net/netmem.h b/include/net/netmem.h
> index 11e9de45efcb..283b4a997fbc 100644
> --- a/include/net/netmem.h
> +++ b/include/net/netmem.h
> @@ -306,7 +306,7 @@ static inline struct net_iov *__netmem_clear_lsb(netmem_ref netmem)
>   */
>  static inline struct page_pool *__netmem_get_pp(netmem_ref netmem)
>  {
> -       return __netmem_to_page(netmem)->pp;
> +       return __netmem_to_nmdesc(netmem)->pp;
>  }
>

__netmem_to_nmdesc should introduced with this patch.

But also, I wonder why not modify all the callsites of
__netmem_to_page to the new __netmem_to_nmdesc and delete the
__nemem_to_page helper?


-- 
Thanks,
Mina