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Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <20250505131446.7448e9bf@kernel.org> <165f5d5b-34f2-40de-b0ec-8c1ca36babe8@lunn.ch> <0aa1b4a2-47b2-40a4-ae14-ce2dd457a1f7@lunn.ch> <1015189.1746187621@warthog.procyon.org.uk> <1021352.1746193306@warthog.procyon.org.uk> <1069540.1746202908@warthog.procyon.org.uk> <1216273.1746539449@warthog.procyon.org.uk> To: Christoph Hellwig Cc: dhowells@redhat.com, Jakub Kicinski , Andrew Lunn , Eric Dumazet , "David S. Miller" , David Hildenbrand , John Hubbard , willy@infradead.org, netdev@vger.kernel.org, linux-mm@kvack.org, Willem de Bruijn Subject: Re: Reorganising how the networking layer handles memory MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <1352786.1746625783.1@warthog.procyon.org.uk> Date: Wed, 07 May 2025 14:49:43 +0100 Message-ID: <1352787.1746625783@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Stat-Signature: ukszqq6yo1nx8i656x3wb9efa9bjwu67 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 4F380A001F X-Rspam-User: X-HE-Tag: 1746625795-495566 X-HE-Meta: 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 Q8CquUAg XMciMc1RJMNwWlFtV1T0y5LQeuaRTNdPQ5TkkFR29lOXUaH09YhIfzzahMkNt5m2p7LvT+MjNhiRE5Ow8dluVSEDn1WFnt+B6JXE7wicSZdF5ldLz55xNKbWusL+CYALZ7H8rN9M8eCdWb489si/jS2JPev4orMp4zyzXFDySr4GBbVZQGOgiU3Ln22CJcWtYENxLCYf4yf9qVxIFm7kb7RwnsNCpfx9XN+FG9GhSxpd2/UoP+8eAUr6iHLq87W1ugLZwhmqD8rEix+ENHfZWgE8cebK638c4xgl+jJpUq7YzHqrdY+5QMj/P+SJA0U0klii41zZPz4fjoM6C8/3BmBqX6SWhmFhuYtvLObNLlxbDMhR/qbVOF4ZGlQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Christoph Hellwig wrote: > > Christoph Hellwig would like to make it such that the extractor gets > > {phyaddr,len} rather than {page,off,len} - so all you, the network layer, > > see is that you've got a span of memory to use as your buffer. How that > > span of memory is managed is the responsibility of whoever called > > sendmsg() - and they need a callback to be able to handle that. > > Not sure what the extractor is Just a function that tries to get information out of the iov_iter. In the case of the networking layer, something like zerocopy_fill_skb_from_iter() that calls iov_iter_get_pages2() currently. David