From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qv1-f48.google.com (mail-qv1-f48.google.com [209.85.219.48]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BD82B1C8603 for ; Tue, 7 Apr 2026 01:12:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.48 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775524334; cv=none; b=EliOuxH0joM7bOWCi/I+lbRXtPbqLOqxsmyawz+bueU0hXE6VuhX4hQQD28BA2Vk4ZtuhKShS9Nxyv6NMjY4wiX/nN2+MdiqMC/fdXema4hvqpAC1CenMd8R1+U/V9ndiXJwa6FOHYTJyZzB2bDAb69gfyxn9Snd25PoMzkFYo0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775524334; c=relaxed/simple; bh=T63k1uJxSq+Df7WJDfeXbmrwdzhkKi+FAbSdKxJ5VGE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ErOXofUdfj+p3SpBOlKYwV5lEPWX4rgkgr0gLT3G3nwDAt4I4zcyMDUC+pDRFDP+AxklRu1C3K2B893GKXjW6tkKFZLC2juqmph00qWBAvexBPYLgPCPGAb92pHCIvfiLZeqGNdEy3JI7wR1Y9bDH/VYYPH0yplcSfwI2L2qCnw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca; spf=pass smtp.mailfrom=ziepe.ca; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b=L+qU2ktr; arc=none smtp.client-ip=209.85.219.48 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ziepe.ca Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="L+qU2ktr" Received: by mail-qv1-f48.google.com with SMTP id 6a1803df08f44-8a4b8c3a30bso61446246d6.3 for ; Mon, 06 Apr 2026 18:12:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; t=1775524331; x=1776129131; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=xaTS/cjbwD199MSee68/inAfCQq7y2tm4S22SDQ6gKc=; b=L+qU2ktrhBHZSnbRtcg7IO67KjbqSqTFBCxs0yVj0azEMmmCiTlBi2JVsuWIxvNku9 Pqz72fFCpBbCHHa6WqqB5PUxBtwezunqd0D0EabEcZv1dTGid6F8ohvJu+CiFaAjqm+3 xJ8vRIOFHyeWhmzlG0+dfjIt1U4N189+cBuQaNECSRUYdkeR+bOEyL67iiQEozNilPyY ktLHrzgnEJJT8qM7u+poY7LUPkdIPa7RNR8CPGVuCrOkfHcj6omOkAxpVpoewoe9YN4k DZNKR2q+j0pSpTHHvlFq6U600byFApCJ23OST8WE7QW4q7rVHOFqkSaPGAcVSkcL+f9F j4dQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1775524331; x=1776129131; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=xaTS/cjbwD199MSee68/inAfCQq7y2tm4S22SDQ6gKc=; b=n9coroVmJ968M92GmeBE/cG0bv8XGvC+Z9Lb0y2U6pCNedrZX4B41Z4Sj5mIZwIt/O LozOkHT9eatxVTB0cNoUolXy5kGtNpDxT1mOhqdQuFevYPaJ9+uJuUwA/bek6Cle5AZr kZyeVzVjMJUg4tUGvCxvhrymCt48M0hfM9L7EaWeFLjpptOz2NYOYSqp5dp/Pzlob036 XqFCwIAE0ISkvUYI1dvTUYGTJld4bRJnd+x+SUg6+6exO0K1WmwOWD4dE/pv79xS8tXS XmX2vOvvk2zPN+Iz+W+sSqDMMw+1njlQ1zAnzuQqgqxZSdSgu3Yx0+VEdnZ6Ctyn/1MV yC2Q== X-Forwarded-Encrypted: i=1; AJvYcCVaz40ZG+MQqQUgaGPVpyZqCbO7UtC5kesv0nFjDGVDkuuc/b/zJE8+V1VUQz0DM+kJYH8Cqzw=@vger.kernel.org X-Gm-Message-State: AOJu0YxNb/Dgi2K7ZZEKvdcGjUYgF4xAtGlCoJLWR3g+1ZRG5eKtx0v4 xv/rRJkpQ5fvYFffCPbvEvwV9csc4A53jClAvTTj8MEd8tR6adJhucJMLKrZOiO5EnA= X-Gm-Gg: AeBDies8uqp3qsmtIRSVeq+ELMInw2zW1c78UvwSRHrZndgXLZWwSn1eni1Uy5kdzKK NDkDMweM825v07aKOE0YspalHZ1U+KsbTY7AF61wFufBfGdObNoQA8XsYEAjuVxSRSn+ZWNxvfC BLsphIbTVIMHl1Dbj4o6d1bV4l8vzXJI8WSHi7kcNrHN6o32RfngGbuvxRaZFp73M5dlyVSTlgN OMPfTeCCscEAM/l3tEKQXVAFHnCXCrJ6YX00H+OcGzPL2XWGOwxql8CFYdLYcM1G2allv1O+7Vo loRuEBIrpSzeTKxBhFFk7c3ulfjL7viDA7UZN6EdfgCcZxorrcfw2USX+/UHuy3V9CmVJ+ooRK3 YrVa0Y5Eun6vbziunpaBBW1nLmeg3IbnBSLi8C0ZOg9WHbSBWkTVgbb7+nGm9nRSZotg/SkJA7W oiQbgH43JuhjZSSbRDL3yC2ZQvpet+8oRH3wU9EsB0vZBqSbWqjJW8Tt/WVKJDk73iTZKSoaLvG oIMLFae X-Received: by 2002:a05:6214:518e:b0:8aa:6dee:4b93 with SMTP id 6a1803df08f44-8aa6dee68e7mr101997526d6.16.1775524331555; Mon, 06 Apr 2026 18:12:11 -0700 (PDT) Received: from ziepe.ca (mctnnbsa70w-159-2-73-22.dhcp-dynamic.fibreop.nb.bellaliant.net. [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: stable@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