linux-kernel - Re: [PATCH net-next v7 1/7] netmem: introduce struct netmem

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250626174904.4a6125c9@kernel.org>
Date: Thu, 26 Jun 2025 17:49:04 -0700
From: Jakub Kicinski <kuba@...nel.org>
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,
 almasrymina@...gle.com, 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, tariqt@...dia.com, edumazet@...gle.com, pabeni@...hat.com,
 saeedm@...dia.com, leon@...nel.org, ast@...nel.org, daniel@...earbox.net,
 david@...hat.com, lorenzo.stoakes@...cle.com, Liam.Howlett@...cle.com,
 vbabka@...e.cz, rppt@...nel.org, surenb@...gle.com, mhocko@...e.com,
 horms@...nel.org, linux-rdma@...r.kernel.org, bpf@...r.kernel.org,
 vishal.moola@...il.com, hannes@...xchg.org, ziy@...dia.com,
 jackmanb@...gle.com
Subject: Re: [PATCH net-next v7 1/7] netmem: introduce struct netmem_desc
 mirroring struct page

On Wed, 25 Jun 2025 13:33:44 +0900 Byungchul Park wrote:
> +/* A memory descriptor representing abstract networking I/O vectors,
> + * generally for non-pages memory that doesn't have its corresponding
> + * struct page and needs to be explicitly allocated through slab.

I still don't get what your final object set is going to be.

We have 
 - CPU-readable buffers (struct page)
 - un-readable buffers (struct net_iov)
 - abstract reference which can be a pointer to either of the
   above two (bitwise netmem_ref)

You say you want to evacuate page pool state from struct page
so I'd expect you to add a type which can always be fed into
some form of $type_to_virt(). A type which can always be cast
to net_iov, but not vice versa. So why are you putting things
inside net_iov, not outside.

> + * net_iovs are allocated and used by networking code, and the size of
> + * the chunk is PAGE_SIZE.

FWIW not for long. Patches to make the size of net_iov configurable 
are in progress.