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[142.162.112.119]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-89a65cfd520sm33832386d6.36.2026.03.12.05.22.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Mar 2026 05:22:19 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1w0f3S-00000006euK-0fs1; Thu, 12 Mar 2026 09:22:18 -0300 Date: Thu, 12 Mar 2026 09:22:18 -0300 From: Jason Gunthorpe To: Leon Romanovsky Cc: Marek Szyprowski , Robin Murphy , "Michael S. Tsirkin" , Petr Tesarik , Jonathan Corbet , Shuah Khan , Jason Wang , Xuan Zhuo , Eugenio =?utf-8?B?UMOpcmV6?= , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Joerg Roedel , Will Deacon , Andrew Morton , iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, virtualization@lists.linux.dev, linux-rdma@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 7/8] RDMA/umem: Tell DMA mapping that UMEM requires coherency Message-ID: <20260312122218.GF1469476@ziepe.ca> References: <20260311-dma-debug-overlap-v2-0-e00bc2ca346d@nvidia.com> <20260311-dma-debug-overlap-v2-7-e00bc2ca346d@nvidia.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260311-dma-debug-overlap-v2-7-e00bc2ca346d@nvidia.com> On Wed, Mar 11, 2026 at 09:08:50PM +0200, Leon Romanovsky wrote: > From: Leon Romanovsky > > The RDMA subsystem exposes DMA regions through the verbs interface, which > assumes a coherent system. Use the DMA_ATTR_REQUIRE_COHERENCE attribute to > ensure coherency and avoid taking the SWIOTLB path. > > In addition, a given region may be exported multiple times, which will trigger > warnings about cacheline overlaps. These warnings are suppressed when using > the new attribute. > Signed-off-by: Leon Romanovsky > --- > drivers/infiniband/core/umem.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) Reviewed-by: Jason Gunthorpe Jason