linux-kernel - Re: [RFC mm v4 1/2] page_pool: check if nmdesc->pp is !NULL to confirm its usage as pp for net

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Message-ID: <20251029015608.GA37879@system.software.com>
Date: Wed, 29 Oct 2025 10:56:08 +0900
From: Byungchul Park <byungchul@...com>
To: Jakub Kicinski <kuba@...nel.org>
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Subject: Re: [RFC mm v4 1/2] page_pool: check if nmdesc->pp is !NULL to
 confirm its usage as pp for net_iov

On Tue, Oct 28, 2025 at 06:33:56PM -0700, Jakub Kicinski wrote:
> On Thu, 23 Oct 2025 16:44:09 +0900 Byungchul Park wrote:
> > As a preparation, the check for net_iov, that is not page-backed, should
> > avoid using ->pp_magic since net_iov doens't have to do with page type.
> 
> doesn't
> 
> > Instead, nmdesc->pp can be used if a net_iov or its nmdesc belongs to a
> > page pool, by making sure nmdesc->pp is NULL otherwise.
> 
> Please explain in the commit message why the new branch in
> netmem_is_pp() is necessary. We used to identify the pages based
> on PP_SIGNATURE, now we identify them based on page_type.

Yes, I will.  It'd be much better.  Thank you very much for the comment.

	Byungchul