linux-kernel - Re: [RFC 01/19] netmem: rename struct net_iov to struct netmem

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Message-ID: <20250513020007.GB577@system.software.com>
Date: Tue, 13 May 2025 11:00:07 +0900
From: Byungchul Park <byungchul@...com>
To: Mina Almasry <almasrymina@...gle.com>
Cc: Pavel Begunkov <asml.silence@...il.com>, 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, ast@...nel.org, daniel@...earbox.net,
	davem@...emloft.net, john.fastabend@...il.com,
	andrew+netdev@...n.ch, edumazet@...gle.com, pabeni@...hat.com,
	vishal.moola@...il.com
Subject: Re: [RFC 01/19] netmem: rename struct net_iov to struct netmem_desc

On Mon, May 12, 2025 at 12:14:13PM -0700, Mina Almasry wrote:
> On Mon, May 12, 2025 at 6:29 AM Byungchul Park <byungchul@...com> wrote:
> >
> > On Mon, May 12, 2025 at 02:11:13PM +0100, Pavel Begunkov wrote:
> > > On 5/9/25 12:51, Byungchul Park wrote:
> > > > To simplify struct page, the page pool members of struct page should be
> > > > moved to other, allowing these members to be removed from struct page.
> > > >
> > > > Reuse struct net_iov for also system memory, that already mirrored the
> > > > page pool members.
> > > >
> > > > Signed-off-by: Byungchul Park <byungchul@...com>
> > > > ---
> > > >   include/linux/skbuff.h                  |  4 +--
> > > >   include/net/netmem.h                    | 20 ++++++------
> > > >   include/net/page_pool/memory_provider.h |  6 ++--
> > > >   io_uring/zcrx.c                         | 42 ++++++++++++-------------
> > >
> > > You're unnecessarily complicating it for yourself. It'll certainly
> > > conflict with changes in the io_uring tree, and hence it can't
> > > be taken normally through the net tree.
> > >
> > > Why are you renaming it in the first place? If there are good
> >
> > It's because the struct should be used for not only io vetor things but
> > also system memory.  Current network code uses struct page as system
> > memory descriptor but struct page fields for page pool will be gone.
> >
> > So I had to reuse struct net_iov and I thought renaming it made more
> > sense.  It'd be welcome if you have better idea.
> >
> 
> As I said in another thread, struct page should not embed struct

I don't understand here.  Can you explain more?  Do you mean do not use
place holder?

> net_iov as-is. struct net_iov already has fields that are unrelated to
> page (like net_iov_owner) and more will be added in the future.
> 
> I think what Matthew seems to agree with AFAIU in the other thread is
> creating a new struct, struct netmem_desc, and having struct net_iov
> embed netmem_desc.

This would look better.  I will try.

	Byungchul

> -- 
> Thanks,
> Mina