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Wed, 08 Jul 2026 07:36:10 -0700 (PDT) Received: from ziepe.ca ([159.2.72.92]) by smtp.gmail.com with ESMTPSA id af79cd13be357-92e90bb8629sm1426076385a.19.2026.07.08.07.36.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Jul 2026 07:36:09 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1whTNh-00000002wv9-0Sc6; Wed, 08 Jul 2026 11:36:09 -0300 Date: Wed, 8 Jul 2026 11:36:09 -0300 From: Jason Gunthorpe To: Peiyang He Cc: kevin.tian@intel.com, joro@8bytes.org, will@kernel.org, robin.murphy@arm.com, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, syzkaller@googlegroups.com Subject: Re: [BUG] iommufd: dma-buf-backed iopt_pages wrongly reaches userspace GUP path and triggers lockdep warning Message-ID: <20260708143609.GI118978@ziepe.ca> References: 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: On Wed, Jul 08, 2026 at 06:44:25PM +0800, Peiyang He wrote: > ============= > Suggested fix > ============= > > If above analysis is correct, we should add dma-buf rejection in iopt_area_add_access() > or/and iommufd_access_pin_pages(), similar to iopt_pages_rw_access(). Yes, this is right, it is definitely a meaningful bug that DMABUF is not blocked from access. Do you want to send a patch? Jason