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[47.54.130.67]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-517fb61d948sm133785221cf.1.2026.06.16.05.40.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 16 Jun 2026 05:40:19 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wZT5X-0000000Fzb5-0uZr; Tue, 16 Jun 2026 09:40:19 -0300 Date: Tue, 16 Jun 2026 09:40:19 -0300 From: Jason Gunthorpe To: "Kasireddy, Vivek" Cc: Bobby Eshleman , Donald Hunter , Jakub Kicinski , "David S. Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Andrew Lunn , Gerd Hoffmann , Sumit Semwal , Christian =?utf-8?B?S8O2bmln?= , Shuah Khan , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , "linux-media@vger.kernel.org" , "linaro-mm-sig@lists.linaro.org" , "linux-kselftest@vger.kernel.org" , "sdf@fomichev.me" , "razor@blackwall.org" , "daniel@iogearbox.net" , "almasrymina@google.com" , "matttbe@kernel.org" , "skhawaja@google.com" , "dw@davidwei.uk" , Bobby Eshleman Subject: Re: [PATCH net-next v2 2/4] udmabuf: emit one sg entry per pinned folio Message-ID: <20260616124019.GA3577091@ziepe.ca> References: <20260611-tcpdm-large-niovs-v2-0-ee2bf15e7523@meta.com> <20260611-tcpdm-large-niovs-v2-2-ee2bf15e7523@meta.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Jun 16, 2026 at 06:04:03AM +0000, Kasireddy, Vivek wrote: > > This is helpful for importers like net/core/devmem that expect dmabuf sg > IMO, udmabuf needs to detect whether importers can handle segments that > are > PAGE_SIZE and set the entries appropriately. Please look into how the > GPU drivers and other dmabuf exporters/importers handle this situation, so > that we can adopt best practices to address this issue. Importers have to handle arbitary scatterlists, devmem is just broken if it can't handle the output of sg_alloc_table_from_pages(). Jason