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Tue, 27 Oct 2020 17:32:26 +0000 Received: from MW3PR11MB4555.namprd11.prod.outlook.com ([fe80::7067:d996:719:10fa]) by MW3PR11MB4555.namprd11.prod.outlook.com ([fe80::7067:d996:719:10fa%5]) with mapi id 15.20.3477.029; Tue, 27 Oct 2020 17:32:26 +0000 From: "Xiong, Jianxin" To: Christoph Hellwig , Jason Gunthorpe CC: Daniel Vetter , "linux-rdma@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , Leon Romanovsky , "Doug Ledford" , "Vetter, Daniel" , Christian Koenig Subject: RE: [PATCH v6 1/4] RDMA/umem: Support importing dma-buf as user memory region Thread-Topic: [PATCH v6 1/4] RDMA/umem: Support importing dma-buf as user memory region Thread-Index: AQHWqVlE332Lg1o1rU+Qqd8CQ3VTXKmlZiqAgAAZZoCAAOHDgIADcnmAgAFKJgCAAJZW4A== Date: Tue, 27 Oct 2020 17:32:26 +0000 Message-ID: References: <1603471201-32588-1-git-send-email-jianxin.xiong@intel.com> <1603471201-32588-2-git-send-email-jianxin.xiong@intel.com> <20201023164911.GF401619@phenom.ffwll.local> <20201023182005.GP36674@ziepe.ca> <20201024074807.GA3112@infradead.org> <20201026122637.GQ36674@ziepe.ca> <20201027080816.GA2692@infradead.org> In-Reply-To: <20201027080816.GA2692@infradead.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: dlp-version: 11.5.1.3 dlp-product: dlpe-windows dlp-reaction: no-action authentication-results: infradead.org; 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x-ms-exchange-antispam-messagedata: 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 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: MW3PR11MB4555.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: d4e861fc-370f-4592-d78b-08d87a9e459b X-MS-Exchange-CrossTenant-originalarrivaltime: 27 Oct 2020 17:32:26.3590 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: 8vRvY3fKcJIvd2hZNKvm+xVAwdS050sSVj98wV9UBsBpfu4Dqy6zwDXi7Ll6/IXyM9qEJLHgM62K19dLuQp60A== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CO1PR11MB4961 X-OriginatorOrg: intel.com Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org > -----Original Message----- > From: Christoph Hellwig > Sent: Tuesday, October 27, 2020 1:08 AM > To: Jason Gunthorpe > Cc: Christoph Hellwig ; Daniel Vetter ; Xiong, Jianxin ; linux- > rdma@vger.kernel.org; dri-devel@lists.freedesktop.org; Leon Romanovsky ; Doug Ledford ; > Vetter, Daniel ; Christian Koenig > Subject: Re: [PATCH v6 1/4] RDMA/umem: Support importing dma-buf as user = memory region >=20 > On Mon, Oct 26, 2020 at 09:26:37AM -0300, Jason Gunthorpe wrote: > > On Sat, Oct 24, 2020 at 08:48:07AM +0100, Christoph Hellwig wrote: > > > On Fri, Oct 23, 2020 at 03:20:05PM -0300, Jason Gunthorpe wrote: > > > > The problem is we have RDMA drivers that assume SGL's have a valid > > > > struct page, and these hacky/wrong P2P sgls that DMABUF creates > > > > cannot be passed into those drivers. > > > > > > RDMA drivers do not assume scatterlist have a valid struct page, > > > scatterlists are defined to have a valid struct page. Any > > > scatterlist without a struct page is completely buggy. > > > > It is not just having the struct page, it needs to be a CPU accessible > > one for memcpy/etc. They aren't correct with the > > MEMORY_DEVICE_PCI_P2PDMA SGLs either. >=20 > Exactly. In the function ib_umem_dmabuf_sgt_slice() (part of this patch) we could ge= nerate a dma address array instead of filling the scatterlist 'umem->sg_head'. The= array would be handled similar to 'umem_odp->dma_list'. With such change, the RDM= A drivers wouldn't see incorrectly formed scatterlist. The check for dma_virt= _ops here wouldn't be needed either. Would such proposal address the concern here? -Jianxin =20