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t=1700071052; bh=E3+pzFE8iRYk10BdpmIpByslUyT/gQ7QPb0/TlBw07E=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=sYMwAppSrkFvV55qdH71dJUqxdPf4EtCzT7b0rurs6aACyonFhzTdiwzdo1A2Rwt/ 4p2lM+kUPpklLWYibyFLRyndk751SQPckZZrT4NuTgBABNyNDqmhOs7nwEMSRLYlE+ HQPUpzMnCC1oBIIbqqafAZ8wFo0g0dAJZy9cTbxWiozd2mutJyPno5SsG/TxsAKZp2 A0scdnVV2KQ4M069VtaVI5APNpWlDj5rxGmpsTnDsLsNqAH/NwbYEeov5CHDnHb+cZ YHl1i1jAJ6oxfwysQQcqQ8wIM9e8hzADbH2frm4is9g+Xr721q45TnI1MzZJA1Q+eu 1J63Z1wtuZcNQ== Message-ID: Date: Wed, 15 Nov 2023 10:57:30 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 3/8] memory-provider: dmabuf devmem memory provider Content-Language: en-US To: Yunsheng Lin , Jason Gunthorpe , Mina Almasry Cc: Jakub Kicinski , davem@davemloft.net, pabeni@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Willem de Bruijn , Kaiyuan Zhang , Jesper Dangaard Brouer , Ilias Apalodimas , Eric Dumazet , =?UTF-8?Q?Christian_K=C3=B6nig?= , Matthew Wilcox , Linux-MM References: <20231113130041.58124-1-linyunsheng@huawei.com> <20231113130041.58124-4-linyunsheng@huawei.com> <20231113180554.1d1c6b1a@kernel.org> <0c39bd57-5d67-3255-9da2-3f3194ee5a66@huawei.com> From: David Ahern In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 3D19F160011 X-Stat-Signature: c3ct8tej9k6xcwwmgzjpyyookii1wb6y X-Rspam-User: X-HE-Tag: 1700071054-5466 X-HE-Meta: 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 htlfCqIm 5O9cMCupZHVHqLyPCrsrKJKE56yRA3kLkAv9cXWW0Js4UjgOhlKHpQ/chFd9eg0IoqyfoeUYJJLqU4XPYj3tAjvj7uKQQL3h9b1BcbT4S60LbuLhyk04T0NdkpWIZvny82pm1cyZqjk8BAcRo514jjO+2lwfDnOpV1iXS+3QS2XAKxLhwFEKtUfXSgODNK+n4Oiw/lPe0OZRwVYlcKfuQ7FR46piyEdP+wI3CFQCPqE8GllY= 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 11/15/23 2:21 AM, Yunsheng Lin wrote: > On 2023/11/14 21:16, Jason Gunthorpe wrote: >> On Tue, Nov 14, 2023 at 04:21:26AM -0800, Mina Almasry wrote: >> >>> Actually because you put the 'strtuct page for devmem' in >>> skb->bv_frag, the net stack will grab the 'struct page' for devmem >>> using skb_frag_page() then call things like page_address(), kmap, >>> get_page, put_page, etc, etc, etc. >> >> Yikes, please no. If net has its own struct page look alike it has to >> stay entirely inside net. A non-mm owned struct page should not be >> passed into mm calls. It is just way too hacky to be seriously >> considered :( > > Yes, that is something this patchset is trying to do, defining its own > struct page look alike for page pool to support devmem. > Networking needs to be able to move away from struct page references. The devmem and host memory for Rx use cases do not need to be page based.