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[47.54.130.67]) by smtp.gmail.com with ESMTPSA id af79cd13be357-914f8801390sm215458285a.36.2026.05.26.05.26.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 26 May 2026 05:26:57 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wRqs4-0000000DONN-3pnp; Tue, 26 May 2026 09:26:56 -0300 Date: Tue, 26 May 2026 09:26:56 -0300 From: Jason Gunthorpe To: Ankit Soni Cc: Kevin Tian , Joerg Roedel , Will Deacon , Robin Murphy , Sumit Semwal , Christian =?utf-8?B?S8O2bmln?= , Leon Romanovsky , Vasant Hegde , iommu@lists.linux.dev, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] iommufd: take dma_resv lock before dma_buf_unpin() in release path Message-ID: <20260526122656.GE2487554@ziepe.ca> References: <20260526111034.4079-1-Ankit.Soni@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260526111034.4079-1-Ankit.Soni@amd.com> X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Tue, May 26, 2026 at 11:10:34AM +0000, Ankit Soni wrote: > dma_buf_unpin() requires the caller to hold the exporter's dma_resv > lock: > > void dma_buf_unpin(struct dma_buf_attachment *attach) > { > ... > dma_resv_assert_held(dmabuf->resv); > ... > } > > iopt_release_pages() calls dma_buf_unpin() without taking that lock, > so every iommufd_ioas_destroy()/iommufd_ioas_unmap() that releases > the last reference on a DMABUF-backed iopt_pages triggers a WARN. > This was hit while running tools/testing/selftests/iommu/iommufd: Any idea why this is comming up now? Did I run the tests without some kind of debug option to turn on that assertion maybe? Jason