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Mon, 23 Jun 2025 12:27:09 -0700 (PDT) Message-ID: <3b71cfa9-6c6f-48f7-8457-dac915438216@gmail.com> Date: Mon, 23 Jun 2025 20:28:31 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v6 1/9] netmem: introduce struct netmem_desc mirroring struct page To: Mina Almasry , Harry Yoo Cc: Byungchul Park , David Hildenbrand , willy@infradead.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel_team@skhynix.com, kuba@kernel.org, ilias.apalodimas@linaro.org, hawk@kernel.org, akpm@linux-foundation.org, davem@davemloft.net, john.fastabend@gmail.com, andrew+netdev@lunn.ch, toke@redhat.com, tariqt@nvidia.com, edumazet@google.com, pabeni@redhat.com, saeedm@nvidia.com, leon@kernel.org, ast@kernel.org, daniel@iogearbox.net, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, horms@kernel.org, linux-rdma@vger.kernel.org, bpf@vger.kernel.org, vishal.moola@gmail.com, hannes@cmpxchg.org, ziy@nvidia.com, jackmanb@google.com References: <20250620041224.46646-1-byungchul@sk.com> <20250620041224.46646-2-byungchul@sk.com> <8eaf52bf-4c3c-4007-afe5-a22da9f228f9@redhat.com> <20250623102821.GC3199@system.software.com> Content-Language: en-US From: Pavel Begunkov In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam11 X-Rspam-User: X-Rspamd-Queue-Id: 6DD411C0009 X-Stat-Signature: i3uicoysh3xa6ctkd971uocrkdcoj8jm X-HE-Tag: 1750706832-242714 X-HE-Meta: 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 j0xHnqg8 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 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: On 6/23/25 20:09, Mina Almasry wrote: > On Mon, Jun 23, 2025 at 5:18 AM Harry Yoo wrote: >> >> On Mon, Jun 23, 2025 at 07:28:21PM +0900, Byungchul Park wrote: >>> On Mon, Jun 23, 2025 at 11:32:16AM +0200, David Hildenbrand wrote: >>>> On 20.06.25 06:12, Byungchul Park wrote: >>>>> To simplify struct page, the page pool members of struct page should be >>>>> moved to other, allowing these members to be removed from struct page. >>>>> >>>>> Introduce a network memory descriptor to store the members, struct >>>>> netmem_desc, and make it union'ed with the existing fields in struct >>>>> net_iov, allowing to organize the fields of struct net_iov. >>>> >>>> It would be great adding some result from the previous discussions in >>>> here, such as that the layout of "struct net_iov" can be changed because >>>> it is not a "struct page" overlay, what the next steps based on this >>> >>> I think the network folks already know how to use and interpret their >>> data struct, struct net_iov for sure.. but I will add the comment if it >>> you think is needed. Thanks for the comment. >> >> I agree with David - it's not immediately obvious at first glance. >> That was my feedback on the previous version as well :) >> >> I think it'd be great to add that explanation, since this is where MM and >> networking intersect. >> > > I think a lot of people are now saying the same thing: (1) lets keep > net_iov and page/netmem_desc separate, and (2) lets add comments > explaining their relation so this intersection between MM and > networking is not confused in the long term . > > For #1, concretely I would recommend removing the union inside struct > net_iov? And also revert all the changes to net_iov for that matter. Without it the merge logistics will get more complicated than it should be because of conflicts with changes in the io_uring tree. It's a temporary solution, I'll convert once the series is merged and reaches io_uring. -- Pavel Begunkov