From: Jakub Kicinski <kuba@kernel•org>
To: Byungchul Park <byungchul@sk•com>
Cc: linux-mm@kvack•org, netdev@vger•kernel.org,
linux-kernel@vger•kernel.org, kernel_team@skhynix•com,
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linux-rdma@vger•kernel.org, sfr@canb•auug.org.au, dw@davidwei•uk,
ap420073@gmail•com, dtatulea@nvidia•com
Subject: Re: [RFC mm v5 1/2] page_pool: check nmdesc->pp to see its usage as page pool for net_iov not page-backed
Date: Fri, 7 Nov 2025 17:41:29 -0800 [thread overview]
Message-ID: <20251107174129.62a3f39c@kernel.org> (raw)
In-Reply-To: <20251107044708.GA54407@system.software.com>
On Fri, 7 Nov 2025 13:47:08 +0900 Byungchul Park wrote:
> The offset of page_type in struct page cannot be used in struct net_iov
> for the same purpose, since the offset in struct net_iov is for storing
> (struct net_iov_area *)owner.
owner does not have to be at a fixed offset. Can we not move owner
to _pp_mapping_pad ? Or reorder it with type, enum net_iov_type
only has 2 values we can smoosh it with page_type easily.
> Yeah, you can tell 'why don't we add the field, page_type, to struct
> net_iov (or struct netmem_desc)' so as to be like:
>
> struct net_iov {
> union {
> struct netmem_desc desc;
> struct
> {
> unsigned long _flags;
> unsigned long pp_magic;
> struct page_pool *pp;
> unsigned long _pp_mapping_pad;
> unsigned long dma_addr;
> atomic_long_t pp_ref_count;
> + unsigned int page_type; // add this field newly
> };
> };
> struct net_iov_area *owner; // the same offet of page_type
> enum net_iov_type type;
> };
>
> I think we can make it anyway but it makes less sense to add page_type
> to struct net_iov, only for PGTY_netpp.
>
> It'd be better to use netmem_desc->pp for that purpose, IMO.
next prev parent reply other threads:[~2025-11-08 1:41 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-03 7:51 [RFC mm v5 0/2] mm, page_pool: introduce a new page type for page pool in page type Byungchul Park
2025-11-03 7:51 ` [RFC mm v5 1/2] page_pool: check nmdesc->pp to see its usage as page pool for net_iov not page-backed Byungchul Park
2025-11-03 12:24 ` Toke Høiland-Jørgensen
2025-11-06 11:07 ` Pavel Begunkov
2025-11-07 1:33 ` Jakub Kicinski
2025-11-07 1:59 ` Byungchul Park
2025-11-07 2:08 ` Jakub Kicinski
2025-11-07 4:47 ` Byungchul Park
2025-11-08 1:41 ` Jakub Kicinski [this message]
2025-11-08 2:24 ` Byungchul Park
2025-11-08 2:29 ` Byungchul Park
2025-11-08 2:37 ` Jakub Kicinski
2025-11-10 1:09 ` Byungchul Park
2025-11-11 1:40 ` Byungchul Park
2025-11-11 1:56 ` Jakub Kicinski
2025-11-11 2:17 ` Byungchul Park
2025-11-11 2:45 ` Byungchul Park
2025-11-11 12:36 ` Toke Høiland-Jørgensen
2025-11-12 7:41 ` Byungchul Park
2025-11-15 1:23 ` Jakub Kicinski
2025-11-17 4:25 ` Byungchul Park
2025-11-03 7:51 ` [RFC mm v5 2/2] mm: introduce a new page type for page pool in page type Byungchul Park
2025-11-03 12:26 ` Toke Høiland-Jørgensen
2025-11-03 12:39 ` Byungchul Park
2025-11-03 14:50 ` Toke Høiland-Jørgensen
2025-11-06 11:08 ` Pavel Begunkov
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