From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8F8AA37FF57 for ; Thu, 9 Apr 2026 12:33:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775737984; cv=none; b=JG1kXZqS33PonZWxGrcum88IKAmDFkyQhh+59b8KKmyQqqKf2RQaxI6orZ8oHBsM+Eu9hanQA6aqJQQsGR4xIFqlbq5oVMoxJaEiu0sQnDC19rrsyvkkOnu03Pc6OBd5MPw3H7dcVMGOExGdqGWsclYEws6yxm6SXt2E16BeDqc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775737984; c=relaxed/simple; bh=EMtQMIGflMLuZ8kQf/KGMu851XNT4k4jQNOfmNdkAJ8=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=qtrkLXokKWLTJPhxrYrkGPazpOcxzsPqhrOhavBS+YJOYtBDpMX5RDgkIvoWNFXg9YhjD+MwYdr6fWAXMatTaB8rTfR40xRnWvvpvyl/oQbaBpOtQlvnfaaeWKw9eyEQ5gBX7ySrZvUeMoiWs0g1twjOpHPvP8HU61OcN70CWeQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DBj2af0n; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DBj2af0n" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 574B5C2BC87; Thu, 9 Apr 2026 12:32:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775737984; bh=EMtQMIGflMLuZ8kQf/KGMu851XNT4k4jQNOfmNdkAJ8=; h=Date:Subject:To:References:From:In-Reply-To:From; b=DBj2af0nEK3h3p2KLYwy0F3WgZMw0JkP9b4E5lRDlGSBfOw4gEeoBfO0+H6Y7wuSd CKCFPPvOPvEvvpRz7Y+4zBFgbEfAKqB2md57TvZb2anZnL+BchTgHUX0Kgl8tPoRO+ f68bS693HuF96e+PEbOWfW1QHY7jfYEOHedPtOkaUCTWHON1qI1gYy80z+iB6hwyRl 5NBJcTHZ1IRbJ3uoWISwRQPxzPl+UysNxN6O8PmAZrKYQbQYzEO0TG4KseMU4HCzpD W24kJ+XFsmi96AXVvuwhRwoom4AzNsUl8YnozQW09e9IfEnHZfFUOBbqKbpjpynjON 00huP/O8x7Unw== Message-ID: <86820d0e-3d35-41af-98ef-d713d3e71c9e@kernel.org> Date: Thu, 9 Apr 2026 14:32:56 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 5/5] riscv: mm: Fix TOCTOU race in remove_pte_mapping To: Michael Neuling , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , "Mike Rapoport (Microsoft)" , "Vishal Moola (Oracle)" , Albert Ou , Aleksa Paunovic , Aleksandar Rikalo , Alexandre Ghiti , Andrew Jones , Andrew Morton , Arnd Bergmann , Djordje Todorovic , Guo Ren , Junhui Liu , Kevin Brodsky , Lorenzo Stoakes , Nam Cao , Oleg Nesterov , Oscar Salvador , Palmer Dabbelt , Paul Walmsley , Qinglin Pan , Raj Vishwanathan4 , linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org References: <20260409091143.1348853-1-mikey@neuling.org> <20260409091143.1348853-6-mikey@neuling.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/9/26 11:11, Michael Neuling wrote: > remove_pte_mapping() reads the PTE via ptep_get() (a READ_ONCE) into a > local variable, but then checks pte_present(*ptep) by dereferencing the > pointer directly, reading the PTE a second time. If another CPU modifies > the PTE between the two reads Is that even possible? The code does not use any locking, so nothing would be safe here if races could happen, no? -- Cheers, David