From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 9E2688F77 for ; Wed, 15 Jan 2025 20:28:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736972888; cv=none; b=fG7wc+4d7i1M6AildRrk1Y/bXETsTZ0Z8YbbEpxLvHgdOl3Am1nZUMdmPTvDAZVqhgWmd/SA60WQEg+nrhkjwcq3x6q1lkUUvdkp+gVOokhAWua0hJyfveagx6FlRYgNKFhxu/8QlxPpjhHHLoQGeZWl2QzU2vOjLOCDadi2LiM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736972888; c=relaxed/simple; bh=j2tbwbmQn5ojyoQrRWYpmGHNivSH/dzW0guO2sBJeaM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QJsytFR06dNDKxXTQxnmzdrFglst92WTHBUvHh9BrWrNNclbCiHU/0IRvpuEu+/K+8EnikbI7S0LJwiwLV/ekyA8At/8C4+rjz46wi5hGMUgYXyAcBKbQ/Y5/okukNijwpoAHOA+unX4OJG81jLxOi5/p5nvsCCaoBGspPKF/U4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=B0aQhSg8; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="B0aQhSg8" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1736972885; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=aLWon5AXaxh3rMajeQBRrd7Zc/AYxckEZbRB/3d+iIc=; b=B0aQhSg81U6FwQm4HyqLiUKMYZre7aLIOL0rCELZD29g1PBPyD9A13p4Q4gXlJMhSYmNgf tMgZTEsHyRh8r32KUkER6jkDwJwMsPGH0m1G7wqtfeGjhO5o+C0L+VVsW6Bby0fGLPVDd+ FXmtgrm66tCYrzYrLKpAxtf3tKxLk24= Received: from mail-qv1-f72.google.com (mail-qv1-f72.google.com [209.85.219.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-665-2ZgoJFKdOuui7bOKfLKM3A-1; Wed, 15 Jan 2025 15:28:04 -0500 X-MC-Unique: 2ZgoJFKdOuui7bOKfLKM3A-1 X-Mimecast-MFC-AGG-ID: 2ZgoJFKdOuui7bOKfLKM3A Received: by mail-qv1-f72.google.com with SMTP id 6a1803df08f44-6d8860ab00dso4270266d6.0 for ; Wed, 15 Jan 2025 12:28:04 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1736972884; x=1737577684; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=aLWon5AXaxh3rMajeQBRrd7Zc/AYxckEZbRB/3d+iIc=; b=ELFp0HL69hwIIeS1hvXN9IzDkRkcWSO73ISGYG4/CizmX0P4kgFgvj0j8DEmnyKmOT D+pcPnbaH43A6aGXy2/y53zMuNQFWFJt3J81N1vJ9MAUUR5YnBp7IHObJ++mQPmgVeHN sJv5eHzXGVY2ZA+JuO1W5iNXwErudGm9qF0WKR2HbLPbJxZ2zh7KKcZzcrSFSTT/L/GH mvLvZMWfz178+kXA+JMyz5WJMujPv3MwPc5qlhxDMEq+5o9G0w6PQZ6qKTpQA0FAKcsw p2BUhaC+qFLoGThBO3AsYZmygnumEboEtUCh0dWGJljdU0CvHxX1FV1KR06ndqST6F1B TDpQ== X-Forwarded-Encrypted: i=1; AJvYcCWxDpldzQ1pBMK1rXG+q2OXEZZHdHk24l/gGZD8vYGLHGaW6nzcohZdkQKTYiZgD8X4qHUowhjwXcLu0LQ=@vger.kernel.org X-Gm-Message-State: AOJu0Yzs82WfwAN8XheuYFTMxTTKl3DcGv8uAsHnm4RJz8Ti4RW23EqA PEBcvmT0rC+pntV9iT1SfUifjLNin0Sme/qLw5X4zpTJFQHOcjspckI0swpdJsOb9kXZG5JBjGW h7UTmd034T+i4zeLVrdE1qORp3IfN8z/uJ4FpeY4ulL3E9YnESq8gll0+MvvsLg== X-Gm-Gg: ASbGncsz7eT61rF+aQPVRDTAir7LTuficm6rO6YKWzCH+FFlUwa3W2FOXh+3ZwUAOeI E8qoejQwC1JBWkTUMqVcIgtPi8EzZrXcSJkkNUR/QiPli8B49BltPBVgq+Q8MWLay3cQ8VkxO8V 635lH8UbZVtbKANQoaYUPi86WETfrvz89gW7MLYhuyY7v8+lwIWRcB6SW6iSWr+YRcDzZlrP5MT fy54Px1GbFl9FM4J3P84g10/ntcsfMYHGKOW/8HNLxCJreTnmNrMJJF0+tk9gA7QcuRN50/XTEv xLQ/FUYICouhL+earQ== X-Received: by 2002:ad4:576c:0:b0:6d8:8b9d:1500 with SMTP id 6a1803df08f44-6df9b2ddabfmr548161556d6.36.1736972883937; Wed, 15 Jan 2025 12:28:03 -0800 (PST) X-Google-Smtp-Source: AGHT+IHkSIbuo3F6Xt9mSQetiuDbpnaGmRVyr2seY+8TScQrao1ZzQitek2oxSDQy2ErmvKglV0oCg== X-Received: by 2002:ad4:576c:0:b0:6d8:8b9d:1500 with SMTP id 6a1803df08f44-6df9b2ddabfmr548161216d6.36.1736972883643; Wed, 15 Jan 2025 12:28:03 -0800 (PST) Received: from x1n (pool-99-254-114-190.cpe.net.cable.rogers.com. [99.254.114.190]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6dfad9adf79sm68242536d6.51.2025.01.15.12.28.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jan 2025 12:28:02 -0800 (PST) Date: Wed, 15 Jan 2025 15:28:00 -0500 From: Peter Xu To: Ryan Roberts Cc: Andrew Morton , Muchun Song , "Liam R. Howlett" , Lorenzo Stoakes , Vlastimil Babka , Jann Horn , Shuah Khan , David Hildenbrand , =?utf-8?Q?Miko=C5=82aj?= Lenczewski , Mark Rutland , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v1 1/2] mm: Clear uffd-wp PTE/PMD state on mremap() Message-ID: References: <20250107144755.1871363-1-ryan.roberts@arm.com> <20250107144755.1871363-2-ryan.roberts@arm.com> 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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250107144755.1871363-2-ryan.roberts@arm.com> On Tue, Jan 07, 2025 at 02:47:52PM +0000, Ryan Roberts wrote: > When mremap()ing a memory region previously registered with userfaultfd > as write-protected but without UFFD_FEATURE_EVENT_REMAP, an > inconsistency in flag clearing leads to a mismatch between the vma flags > (which have uffd-wp cleared) and the pte/pmd flags (which do not have > uffd-wp cleared). This mismatch causes a subsequent mprotect(PROT_WRITE) > to trigger a warning in page_table_check_pte_flags() due to setting the > pte to writable while uffd-wp is still set. > > Fix this by always explicitly clearing the uffd-wp pte/pmd flags on any > such mremap() so that the values are consistent with the existing > clearing of VM_UFFD_WP. Be careful to clear the logical flag regardless > of its physical form; a PTE bit, a swap PTE bit, or a PTE marker. Cover > PTE, huge PMD and hugetlb paths. > > Co-developed-by: Mikołaj Lenczewski > Signed-off-by: Mikołaj Lenczewski > Signed-off-by: Ryan Roberts > Closes: https://lore.kernel.org/linux-mm/810b44a8-d2ae-4107-b665-5a42eae2d948@arm.com/ > Fixes: 63b2d4174c4a ("userfaultfd: wp: add the writeprotect API to userfaultfd ioctl") > Cc: stable@vger.kernel.org Nothing I see wrong: Reviewed-by: Peter Xu One trivial thing: some multiple-line comments is following the net/ coding style rather than mm/, but well.. I don't think it's a huge deal. https://www.kernel.org/doc/html/v4.10/process/coding-style.html#commenting Thanks again. -- Peter Xu