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Tue, 29 Sep 2020 18:13:27 +0000 Date: Tue, 29 Sep 2020 15:13:25 -0300 From: Jason Gunthorpe To: Christoph Hellwig CC: Leon Romanovsky , Doug Ledford , Yishai Hadas , Subject: Re: [PATCH rdma-next v2 1/4] IB/core: Improve ODP to use hmm_range_fault() Message-ID: <20200929181325.GA9475@nvidia.com> References: <20200922082104.2148873-1-leon@kernel.org> <20200922082104.2148873-2-leon@kernel.org> <20200929175946.GA767138@nvidia.com> <20200929180210.GA5012@infradead.org> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20200929180210.GA5012@infradead.org> X-ClientProxiedBy: BL0PR01CA0026.prod.exchangelabs.com (2603:10b6:208:71::39) To DM6PR12MB3834.namprd12.prod.outlook.com (2603:10b6:5:14a::12) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from mlx.ziepe.ca (156.34.48.30) by BL0PR01CA0026.prod.exchangelabs.com (2603:10b6:208:71::39) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3412.20 via Frontend Transport; Tue, 29 Sep 2020 18:13:26 +0000 Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kNK7x-003DtA-PE; Tue, 29 Sep 2020 15:13:25 -0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1601403195; bh=L1ZIeeHRMTt44FSSvtNqgQQm75eAeUQZyq/xGv5Fgb8=; h=ARC-Seal:ARC-Message-Signature:ARC-Authentication-Results:Date: From:To:CC:Subject:Message-ID:References:Content-Type: Content-Disposition:In-Reply-To:X-ClientProxiedBy:MIME-Version: X-MS-Exchange-MessageSentRepresentingType; b=rMBFPb+TWy9IL3BwimaJQk+N62r7EhbtZymASk5dNx+CRFapbhUPx6PPR+RWLu7Ht E0NvUxHORj/AWdNWo/LEw0DqgJ/yenl7HkB3D07Qz/sAu23Fl3BcMlpphdEHMFyA1D 2TbMkBvmH2az/tSZ6H3oMWHth3Qs3nfL8ALNMjYTjtxvXITpStTqpgFLSDJ2eDn6ml EnSPYGsOA9YnGXAKzMmDRmbGIVFZ45uds/xHfglElOq+U/cPf5XQlyAeyiWS2E+PA8 2PyAUHFUWyW28vSuEnSv5rBASqwJGRu1DFvqcjtPAxAy9udSFzyqAe7+Wsq9LSNWIA PDPTGCJYiMSMA== Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Tue, Sep 29, 2020 at 07:02:10PM +0100, Christoph Hellwig wrote: > On Tue, Sep 29, 2020 at 02:59:46PM -0300, Jason Gunthorpe wrote: > > This leaves *dma_addr set to ib_dma_mapping_error, which means the > > next try to map it will fail the if (!dma_addr) and produce a > > corrupted dma address. > > > > *dma_addr should be set to 0 here > > Maybe the code should use DMA_MAPPING_ERROR as the sentinel for a > not mapped entry? My eventual hope is to be able to send this DMA page list to the HW without having to parse and copy it like is done today. We already have it in a linear array that can be DMA'd from. However, the HW knows 0 means need-fault (the flag bits are zero), it doesn't know what to do with DMA_MAPPING_ERROR.. Jason