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[142.68.128.5]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7b32ac2dd40sm162560885a.10.2024.11.08.06.18.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 Nov 2024 06:18:13 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1t9PoT-00000002ZMb-04i0; Fri, 08 Nov 2024 10:18:13 -0400 Date: Fri, 8 Nov 2024 10:18:12 -0400 From: Jason Gunthorpe To: Mina Almasry Cc: netdev@vger.kernel.org, Jakub Kicinski , Pavel Begunkov , Willem de Bruijn , Kaiyuan Zhang , Samiullah Khawaja , linux-kernel@vger.kernel.org, "David S. Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Jesper Dangaard Brouer , Ilias Apalodimas Subject: Re: [PATCH net-next v2 4/5] page_pool: disable sync for cpu for dmabuf memory provider Message-ID: <20241108141812.GL35848@ziepe.ca> References: <20241107212309.3097362-1-almasrymina@google.com> <20241107212309.3097362-5-almasrymina@google.com> Precedence: bulk X-Mailing-List: netdev@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: <20241107212309.3097362-5-almasrymina@google.com> On Thu, Nov 07, 2024 at 09:23:08PM +0000, Mina Almasry wrote: > dmabuf dma-addresses should not be dma_sync'd for CPU/device. Typically > its the driver responsibility to dma_sync for CPU, but the driver should > not dma_sync for CPU if the netmem is actually coming from a dmabuf > memory provider. This is not completely true, it is not *all* dmabuf, just the parts of the dmabuf that are actually MMIO. If you do this you may want to block accepting dmabufs that have CPU pages inside them. Jason