From: saeed bishara <saeed.bishara.os@gmail.com>
To: "Björn Töpel" <bjorn@kernel.org>
Cc: Magnus Karlsson <magnus.karlsson@intel.com>,
Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
Stanislav Fomichev <sdf@fomichev.me>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@kernel.org>,
Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
Jonathan Corbet <corbet@lwn.net>,
Shuah Khan <skhan@linuxfoundation.org>,
Randy Dunlap <rdunlap@infradead.org>,
Alexander Duyck <alexanderduyck@fb.com>,
kernel-team@meta.com, Andrew Lunn <andrew+netdev@lunn.ch>,
Jesper Dangaard Brouer <hawk@kernel.org>,
Ilias Apalodimas <ilias.apalodimas@linaro.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
John Fastabend <john.fastabend@gmail.com>,
Pavel Begunkov <asml.silence@gmail.com>,
Jens Axboe <axboe@kernel.dk>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
Jiri Olsa <jolsa@kernel.org>,
Emil Tsalapatis <emil@etsalapatis.com>,
Ihor Solodrai <ihor.solodrai@linux.dev>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
io-uring@vger.kernel.org, Mina Almasry <almasrymina@google.com>,
"Mike Marciniszyn (Meta)" <mike.marciniszyn@gmail.com>,
Weiming Shi <bestswngs@gmail.com>,
Nikolay Aleksandrov <razor@blackwall.org>,
David Wei <dw@davidwei.uk>,
Alexander Lobakin <aleksander.lobakin@intel.com>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
Stuart Clark <stuclar@meta.com>
Subject: Re: [PATCH net-next v1 01/11] net: Get skb fragment addresses through netmem
Date: Thu, 12 Nov 2026 10:32:32 +0200 [thread overview]
Message-ID: <CAHfVqdVYBbs8zu40nEaCDvGVNeXHe2DXh0dGxEcgL3kP8S8_HQ@mail.gmail.com> (raw)
In-Reply-To: <20261110102039.1002605-2-bjorn@kernel.org>
On Tue, Nov 10, 2026 at 12:27 PM Björn Töpel <bjorn@kernel.org> wrote:
>
> skb_frag_address() goes through struct page, so a net_iov never has an
> address. Only unreadable memory should lack one: XDP and BPF read
> fragments through this helper, and AF_XDP UMEM will back readable
> net_iovs. netmem_address() also returns NULL, not a bogus pointer, for
> an unmapped highmem page.
Does this mean that skb_frag_address_safe() is practically identical
to skb_frag_address()? I assume highmem page is the only case where
non niov page isn't mapped.
>
> *
> - * Returns: the address of the data within @frag. The page must already
> - * be mapped.
> + * Returns: the address of the data within @frag, or %NULL if the CPU cannot
> + * read it.
"CPU cannot read" isn't accurate, I assume that in iouring case the
buffer is mapped to userspace.
> */
next prev parent reply other threads:[~2026-11-12 8:32 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-10 10:20 [PATCH net-next v1 00/11] xsk: Zero copy through page-pool memory providers Björn Töpel
2026-11-10 10:20 ` [PATCH net-next v1 01/11] net: Get skb fragment addresses through netmem Björn Töpel
2026-11-12 8:32 ` saeed bishara [this message]
2026-11-10 10:20 ` [PATCH net-next v1 02/11] net: Add memory provider capabilities Björn Töpel
2026-11-10 22:19 ` Stanislav Fomichev
2026-11-11 12:41 ` Björn Töpel
2026-11-11 23:01 ` Stanislav Fomichev
2026-11-11 22:41 ` netdev-bot+sashiko
2026-11-10 10:20 ` [PATCH net-next v1 03/11] xdp: Copy buffers with restricted lifetime Björn Töpel
2026-11-10 22:32 ` Stanislav Fomichev
2026-11-11 13:27 ` Björn Töpel
2026-11-11 23:05 ` Stanislav Fomichev
2026-11-11 22:41 ` netdev-bot+sashiko
2026-11-10 10:20 ` [PATCH net-next v1 04/11] xsk: Allocate UMEM chunks through page_pool Björn Töpel
2026-11-10 15:08 ` Magnus Karlsson
2026-11-11 13:51 ` Björn Töpel
2026-11-10 23:02 ` Stanislav Fomichev
2026-11-11 13:59 ` Björn Töpel
2026-11-11 23:09 ` Stanislav Fomichev
2026-11-11 22:41 ` netdev-bot+sashiko
2026-11-10 10:20 ` [PATCH net-next v1 05/11] xsk: Install UMEM page pool providers in the core Björn Töpel
2026-11-10 23:50 ` Stanislav Fomichev
2026-11-11 14:01 ` Björn Töpel
2026-11-11 8:59 ` Magnus Karlsson
2026-11-11 19:26 ` Björn Töpel
2026-11-12 8:08 ` Magnus Karlsson
2026-11-11 22:41 ` netdev-bot+sashiko
2026-11-10 10:20 ` [PATCH net-next v1 06/11] page_pool: Coordinate refill with memory providers Björn Töpel
2026-11-10 23:51 ` Stanislav Fomichev
2026-11-11 19:37 ` Björn Töpel
2026-11-11 23:13 ` Stanislav Fomichev
2026-11-11 22:41 ` netdev-bot+sashiko
2026-11-10 10:20 ` [PATCH net-next v1 07/11] xsk: Deliver provider chunks without copying Björn Töpel
2026-11-11 22:41 ` netdev-bot+sashiko
2026-11-11 23:20 ` Stanislav Fomichev
2026-11-10 10:20 ` [PATCH net-next v1 08/11] eth: fbnic: Support XDP redirect Björn Töpel
2026-11-10 10:20 ` [PATCH net-next v1 09/11] eth: fbnic: Use netmem for RX headers and XDP_TX Björn Töpel
2026-11-10 10:20 ` [PATCH net-next v1 10/11] eth: fbnic: Support RX buffers it cannot split Björn Töpel
2026-11-11 21:45 ` Dimitri Daskalakis
2026-11-11 22:41 ` netdev-bot+sashiko
2026-11-10 10:20 ` [PATCH net-next v1 11/11] eth: fbnic: Support AF_XDP page pool zero copy Björn Töpel
2026-11-11 22:41 ` netdev-bot+sashiko
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