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From: Pavel Begunkov <asml.silence@gmail.com>
To: Mina Almasry <almasrymina@google.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-doc@vger.kernel.org, io-uring@vger.kernel.org,
	virtualization@lists.linux.dev, kvm@vger.kernel.org,
	linux-kselftest@vger.kernel.org,
	"David S. Miller" <davem@davemloft.net>,
	"Eric Dumazet" <edumazet@google.com>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Simon Horman" <horms@kernel.org>,
	"Donald Hunter" <donald.hunter@gmail.com>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Andrew Lunn" <andrew+netdev@lunn.ch>,
	"Jeroen de Borst" <jeroendb@google.com>,
	"Harshitha Ramamurthy" <hramamurthy@google.com>,
	"Kuniyuki Iwashima" <kuniyu@amazon.com>,
	"Willem de Bruijn" <willemb@google.com>,
	"Jens Axboe" <axboe@kernel.dk>,
	"David Ahern" <dsahern@kernel.org>,
	"Neal Cardwell" <ncardwell@google.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	"Jason Wang" <jasowang@redhat.com>,
	"Xuan Zhuo" <xuanzhuo@linux.alibaba.com>,
	"Eugenio Pérez" <eperezma@redhat.com>,
	"Stefan Hajnoczi" <stefanha@redhat.com>,
	"Stefano Garzarella" <sgarzare@redhat.com>,
	"Shuah Khan" <shuah@kernel.org>,
	sdf@fomichev.me, dw@davidwei.uk,
	"Jamal Hadi Salim" <jhs@mojatatu.com>,
	"Victor Nogueira" <victor@mojatatu.com>,
	"Pedro Tammela" <pctammela@mojatatu.com>,
	"Samiullah Khawaja" <skhawaja@google.com>
Subject: Re: [PATCH net-next v9 2/9] net: add get_netmem/put_netmem support
Date: Tue, 22 Apr 2025 19:20:59 +0100	[thread overview]
Message-ID: <957b74ed-f29c-4bb8-b819-af4e1168d6c1@gmail.com> (raw)
In-Reply-To: <CAHS8izPw9maOMqLALTLc22eOKnutyLK9azOs4FzO1pfaY8xE6g@mail.gmail.com>

On 4/22/25 14:56, Mina Almasry wrote:
> On Tue, Apr 22, 2025 at 1:43 AM Pavel Begunkov <asml.silence@gmail.com> wrote:
>>
>> On 4/18/25 00:15, Mina Almasry wrote:
>>> Currently net_iovs support only pp ref counts, and do not support a
>>> page ref equivalent.
>>
>> Makes me wonder why it's needed. In theory, nobody should ever be
>> taking page references without going through struct ubuf_info
>> handling first, all in kernel users of these pages should always
>> be paired with ubuf_info, as it's user memory, it's not stable,
>> and without ubuf_info the user is allowed to overwrite it.
>>
> 
> The concern about the stability of the from-userspace data is already
> called out in the MSG_ZEROCOPY documentation that we're piggybacking
> devmem TX onto:

Sure, I didn't object that. There is no problem as long as the
ubuf_info semantics is followed, which by extension mean that
any ref manipulation should already be gated on ubuf_info, and
there should be no need in changing generic paths.

-- 
Pavel Begunkov


  reply	other threads:[~2025-04-22 18:19 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-17 23:15 [PATCH net-next v9 0/9] Device memory TCP TX Mina Almasry
2025-04-17 23:15 ` [PATCH net-next v9 1/9] netmem: add niov->type attribute to distinguish different net_iov types Mina Almasry
2025-04-22  8:17   ` Pavel Begunkov
2025-04-22 14:03     ` Mina Almasry
2025-04-22 19:53       ` Pavel Begunkov
2025-04-22 20:46         ` Mina Almasry
2025-04-17 23:15 ` [PATCH net-next v9 2/9] net: add get_netmem/put_netmem support Mina Almasry
2025-04-22  8:45   ` Pavel Begunkov
2025-04-22 13:56     ` Mina Almasry
2025-04-22 18:20       ` Pavel Begunkov [this message]
2025-04-22 18:30         ` Mina Almasry
2025-04-22 19:47           ` Pavel Begunkov
2025-04-22 20:04             ` Pavel Begunkov
2025-04-22 21:10               ` Mina Almasry
2025-04-23 10:49                 ` Pavel Begunkov
2025-04-17 23:15 ` [PATCH net-next v9 3/9] net: devmem: TCP tx netlink api Mina Almasry
2025-04-17 23:15 ` [PATCH net-next v9 4/9] net: devmem: Implement TX path Mina Almasry
2025-04-17 23:15 ` [PATCH net-next v9 5/9] net: add devmem TCP TX documentation Mina Almasry
2025-04-17 23:15 ` [PATCH net-next v9 6/9] net: enable driver support for netmem TX Mina Almasry
2025-04-17 23:15 ` [PATCH net-next v9 7/9] gve: add netmem TX support to GVE DQO-RDA mode Mina Almasry
2025-04-22 17:43   ` Harshitha Ramamurthy
2025-04-22 21:30     ` Mina Almasry
2025-04-22 23:00       ` Harshitha Ramamurthy
2025-04-17 23:15 ` [PATCH net-next v9 8/9] net: check for driver support in netmem TX Mina Almasry
2025-04-17 23:15 ` [PATCH net-next v9 9/9] selftests: ncdevmem: Implement devmem TCP TX Mina Almasry

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