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[159.2.73.22]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8a593908b47sm160088906d6.11.2026.04.06.18.12.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Apr 2026 18:12:10 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1w9uzC-0000000EA12-1dZT; Mon, 06 Apr 2026 22:12:10 -0300 Date: Mon, 6 Apr 2026 22:12:10 -0300 From: Jason Gunthorpe To: Sina Hassani Cc: kevin.tian@intel.com, joro@8bytes.org, will@kernel.org, robin.murphy@arm.com, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, Aaron Wisner , stable@vger.kernel.org Subject: Re: [PATCH v2] Fixes a race in iopt_unmap_iova_range Message-ID: <20260407011210.GM2551565@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 Mon, Apr 06, 2026 at 04:07:01PM -0700, Sina Hassani wrote: > io_pagetable *iopt, unsigned long start, > unmapped_bytes += area_last - area_first + 1; > > down_write(&iopt->iova_rwsem); > + > + /* Do not reconsider things already unmapped in case of > + * concurrent allocation */ > + start = area_last + 1; area_last can be ULONG_MAX so this literally overflows to 0. It is why I formed the suggestion I gave as I did Jason