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Received: from [127.0.0.2] (localhost [127.0.0.1]) by hr2.samba.org with esmtpsa (TLS1.3:ECDHE_SECP256R1__ECDSA_SECP256R1_SHA256__CHACHA20_POLY1305:256) (Exim) id 1uMNrR-008gCi-1d; Tue, 03 Jun 2025 09:23:09 +0000 Message-ID: <3df479c7-e42f-41e1-bc5e-88f3d783c5d1@samba.org> Date: Tue, 3 Jun 2025 11:22:33 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC v3 01/18] netmem: introduce struct netmem_desc mirroring struct page To: Mina Almasry , Byungchul Park Cc: 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, harry.yoo@oracle.com, hawk@kernel.org, akpm@linux-foundation.org, davem@davemloft.net, john.fastabend@gmail.com, andrew+netdev@lunn.ch, asml.silence@gmail.com, toke@redhat.com, tariqt@nvidia.com, edumazet@google.com, pabeni@redhat.com, saeedm@nvidia.com, leon@kernel.org, ast@kernel.org, daniel@iogearbox.net, david@redhat.com, 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 References: <20250529031047.7587-1-byungchul@sk.com> <20250529031047.7587-2-byungchul@sk.com> <20250530011002.GA3093@system.software.com> Content-Language: en-US From: Stefan Metzmacher In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: B54B240003 X-Rspamd-Server: rspam09 X-Stat-Signature: ag1dp9h5pg9kh6qgn86od7u9ksbp6ai1 X-HE-Tag: 1748942599-287303 X-HE-Meta: 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 6DywrPUL GW14cVTquGyb44PFNuauY7j98ebAkc8VrRVIcJKd/MAzMovrihzMMkHXsGP4PoZxI9MnXNRMtDAaXZzj2130ILHz87QyVpI/39AhhmB6D7xhVnbVX2DkgK+Sr+saMjK/XcLu6cXJxDeVC6uBc5qZkxjUDragDwzDAXHG9GclIFJC/RgYrRWewk2pkVBKN7R6aAm6ktqG0s7pXauQ7Q2tZoFqUW1fnG+OP+QM0xbUfgfGGY/esq2+rG8XLDgzT4ImuaoZkS/LCn1HG+reTS1xTjFs+oDZ7coE1lkVCA5sYpvWl4+7BpeAvsqkrOpGQ4XfCb6k6DoiuA59mDB+C/LTVkdW78j1o3MPYaxxlWE1I9O05FKygh39mzm5Re8uckNBwRrNjGYwM1mN1C1caFUjyJGvPaw== 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: Hi Mina, >> Do you mean? >> >> struct net_iov { >> /* Union for anonymous aliasing: */ >> union { >> struct netmem_desc desc; >> struct { >> unsigned long _flags; >> unsigned long pp_magic; >> struct page_pool *pp; >> unsigned long _pp_mapping_pad; >> unsigned long dma_addr; >> atomic_long_t pp_ref_count; >> }; >> }; >> struct net_iov_area *owner; >> enum net_iov_type type; >> }; >> >> Right? If so, I will. >> > > Yes, sounds good. > > Also, maybe having a union with the same fields for anonymous aliasing > can be error prone if someone updates netmem_desc and forgets to > update the mirror in struct net_iov. If you can think of a way to deal > with that, great, if not lets maybe put a comment on top of struct > netmem_desc: I haven't looked at the patch in detail, but to me it sounds a bit like the checks io_uring_init is doing. I hope this is in same way helpful here :-) metze