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[82.132.213.196]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c2aa9b14925sm14081966b.19.2026.09.22.06.37.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 22 Sep 2026 06:37:14 -0700 (PDT) Message-ID: Date: Tue, 22 Sep 2026 14:37:08 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 06/13] nvme-pci: implement dma-buf backed requests To: Christoph Hellwig Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org, Sumit Semwal , =?UTF-8?Q?Christian_K=C3=B6nig?= , Keith Busch , Sagi Grimberg , Alexander Viro , Christian Brauner , Jan Kara , Andrew Morton , Jens Axboe , Nitesh Shetty , Kanchan Joshi , Anuj Gupta , Tushar Gohad , William Power , Phil Cayton , Matthew Brost , Alasdair Kergon , Mike Snitzer , Mikulas Patocka , Benjamin Marzinski , dm-devel@lists.linux.dev References: <20260922132016.GA30684@lst.de> Content-Language: en-US From: Pavel Begunkov In-Reply-To: <20260922132016.GA30684@lst.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Christoph, On 9/22/26 14:20, Christoph Hellwig wrote: > On Mon, Sep 21, 2026 at 02:38:50PM +0100, Pavel Begunkov wrote: >> Enable BIO_DMABUF_MAP backed requests. On registration we map the > > This is now REQ_DMABUF. Will change > Sashiko had a few comments, which I think are correct - if we use > dma_map_sg to map the data, we need to use the sync_sg APIs to > transfer ownership. That only matters on non-coherent architectures > with MMU, but we need to get it right. I've seen that and fixed everything locally that should be fixed, apart from the sync. I wonder what we can do about that? I can somehow replace it with the sg variant for now, but sync'ing the entire possibly multi-GB mapping for, let's say, a 512B I/O, sounds not wise. And I can think of another place that does mix sync_single with sgs. > And the reset deadlock also looks plausible. -- Pavel Begunkov