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[142.162.112.119]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8946a1e3d28sm30951806d6.7.2026.01.21.07.41.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Jan 2026 07:41:37 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1viaKv-00000006EjK-1pDz; Wed, 21 Jan 2026 11:41:37 -0400 Date: Wed, 21 Jan 2026 11:41:37 -0400 From: Jason Gunthorpe To: Leon Romanovsky Cc: Sumit Semwal , Christian =?utf-8?B?S8O2bmln?= , Alex Deucher , David Airlie , Simona Vetter , Gerd Hoffmann , Dmitry Osipenko , Gurchetan Singh , Chia-I Wu , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Lucas De Marchi , Thomas =?utf-8?Q?Hellstr=C3=B6m?= , Rodrigo Vivi , Kevin Tian , Joerg Roedel , Will Deacon , Robin Murphy , Felix Kuehling , Alex Williamson , Ankit Agrawal , Vivek Kasireddy , linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, virtualization@lists.linux.dev, intel-xe@lists.freedesktop.org, linux-rdma@vger.kernel.org, iommu@lists.linux.dev, kvm@vger.kernel.org Subject: Re: [PATCH v4 8/8] vfio: Validate dma-buf revocation semantics Message-ID: <20260121154137.GD961572@ziepe.ca> References: <20260121-dmabuf-revoke-v4-0-d311cbc8633d@nvidia.com> <20260121-dmabuf-revoke-v4-8-d311cbc8633d@nvidia.com> <20260121134712.GZ961572@ziepe.ca> <20260121144701.GF13201@unreal> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260121144701.GF13201@unreal> On Wed, Jan 21, 2026 at 04:47:01PM +0200, Leon Romanovsky wrote: > > We need to push an urgent -rc fix to implement a pin function here > > that always fails. That was missed and it means things like rdma can > > import vfio when the intention was to block that. It would be bad for > > that uAPI mistake to reach a released kernel. > > I don't see any urgency here. In the current kernel, the RDMA importer > prints a warning to indicate it was attached to the wrong exporter. > VFIO also invokes dma_buf_move_notify(). The design of vfio was always that it must not work with RDMA because we cannot tolerate the errors that happen due to ignoring the move_notify. The entire purpose of this series could be stated as continuing to block RDMA while opening up other pining users. So it must be addressed urgently before someone builds an application relying on this connection. Jason