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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> 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> X-Rspam-User: X-Rspamd-Queue-Id: 7FC50C000C X-Rspamd-Server: rspam08 X-Stat-Signature: yybhy9xctxpc8oth8se7xuhh7n1qrz18 X-HE-Tag: 1773318141-555877 X-HE-Meta: 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 TkCmNnor Eiz3psRsfxDnBKk86kZdvyIxrX2z1Kdjji6oidyH+4miioKQLZcgydZ9pnZYQt+BPL5VFMusp+i7FSSKoCzeizk4MsajjNX28N+nY77f7klRjFTgymS82H1yZoxUIyemLSaJbTbsWY1wuhdrt0I7VDh+yo2+R9O4oenVmH2XUAIDgsUj/Xz1Tdx+92scMBz2dmcQ92Zh9+ePD7bW7HBFN9+dYGhTgVKaW1sVgkCJ1QxYjJAwgQw4fLWomnaMZYJ0FVzLFuKyKzfwh/0bRPgBxgIAHqhQ9Ad/jjFV/ev0wJaUgg4rA/xkrDGyUInS/NiUt1ZCIn7D9+0yaUYM= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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