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t=1700000736; bh=CmbeBBJW6eNCnDWG7XFbzoz+Cww0cN4u7zfWKAxDRDQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=fURdyQnSVpbf5t99V71LcNGLgelOR6R2rlvm4Ps4Y94iRNSdGks4P+r39GuN8prsE SnwMYYPOcrMFzpgeZv5zPIx0DGuPNU0m4yZsJZH7GJ/3OycmmbUSdySaqA5cQpDsf1 54YN7mHw2Ctl2/qxN2x6uury/PSVoI5x19U6FVTmQOnITzYzOfTAjI1MJiWNYaUNMx 9N65IAi9cn+VznLN7nGXUZ/T5Xc/ufmD18N7dZH/ZWpRsySs1vJ06WkrIbw+Ea+hXA W2fV1SIKoKukwV8p6nFWFUwpDBuYf+L05OTkqLy9/75bseMChSyXwYbsZ51VS2y8Ra 8b2fSnaLiENmg== Date: Tue, 14 Nov 2023 17:25:34 -0500 From: Jakub Kicinski To: Yunsheng Lin Cc: Mina Almasry , , , , , Willem de Bruijn , Kaiyuan Zhang , Jesper Dangaard Brouer , Ilias Apalodimas , Eric Dumazet , Christian =?UTF-8?B?S8O2bmln?= , Jason Gunthorpe , Matthew Wilcox , Linux-MM Subject: Re: [PATCH RFC 3/8] memory-provider: dmabuf devmem memory provider Message-ID: <20231114172534.124f544c@kernel.org> In-Reply-To: <0c39bd57-5d67-3255-9da2-3f3194ee5a66@huawei.com> References: <20231113130041.58124-1-linyunsheng@huawei.com> <20231113130041.58124-4-linyunsheng@huawei.com> <20231113180554.1d1c6b1a@kernel.org> <0c39bd57-5d67-3255-9da2-3f3194ee5a66@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: F1E02140026 X-Stat-Signature: wa5e3f64turmeyph1ykxuxxhn7gq68sx X-Rspam-User: X-HE-Tag: 1700000737-482254 X-HE-Meta: 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 MOaVeO5C DRS7KzkdVjXJ8hMTdvyTGH6sPv/+BIL71rdDi0Zkt+oHc2oacHW/8Ne1Tx6/RYSXyPlvgaHE29gEN6K34TCO2wg2Fm4fJLkd6oFM+LCwZLkQw1Nd+CVnSmCKBRBHJwiJpd5c28EFW1pT3lE3aX6HM/7GS2ippbV54fQHz3Vv27iNH2F3RAzSefMFRFxQY44V4qrxN 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 Tue, 14 Nov 2023 16:23:29 +0800 Yunsheng Lin wrote: > I would expect net stack, page pool, driver still see the 'struct page', > only memory provider see the specific struct for itself, for the above, > devmem memory provider sees the 'struct page_pool_iov'. You can't lie to the driver that an _iov is a page either. The driver must explicitly "opt-in" to using the _iov variant, by calling the _iov set of APIs. Only drivers which can support header-data split can reasonably use the _iov API, for data pages.