From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12164C02180 for ; Thu, 16 Jan 2025 09:04:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3336C6B0082; Thu, 16 Jan 2025 04:04:45 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2BC906B0085; Thu, 16 Jan 2025 04:04:45 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 15D456B0088; Thu, 16 Jan 2025 04:04:45 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id EB2456B0082 for ; Thu, 16 Jan 2025 04:04:44 -0500 (EST) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 69FD614096E for ; Thu, 16 Jan 2025 09:04:44 +0000 (UTC) X-FDA: 83012729688.15.DBFADC1 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf08.hostedemail.com (Postfix) with ESMTP id 6CCD5160021 for ; Thu, 16 Jan 2025 09:04:42 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=none; spf=pass (imf08.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1737018282; h=from:from:sender: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=EG2rL8p+a5cZ+Vdn3SFy/ivXsCon7QS9ohDqlggwOe8=; b=xcFCn0tneOs6RG0PLlOkVaTdO7ItIzznduurWAUZVCjXPj4PHNEUlWOhs/N8cOLImhjC3X NgtOIEtxoWZ+WohJK33PCz9JUIUXV7h37qbZNqQeYbrEK/7EhChkx521yK3WJdHWn9q7ZJ 26g5vCSzUIF7xwpkrFceFfgi2TbWyTw= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=none; spf=pass (imf08.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1737018282; a=rsa-sha256; cv=none; b=p/+a/JFAEKcSrWMmyHFw6/JyqlbeXjjKPih9x1I2JoRIFZCBn/5HyIP+g48GMg2PmzUvcy FBUX2O+grzwYW8WZFnykJZLM0SQjUA/H6uuULnzAzMoAcjgzDq0WBElQQ0pXhfaBsffLYc COBILr+AVfd07JRtnYpMr4KqfFP+n/E= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C8A9911FB; Thu, 16 Jan 2025 01:05:09 -0800 (PST) Received: from [10.57.94.252] (unknown [10.57.94.252]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 247763F673; Thu, 16 Jan 2025 01:04:39 -0800 (PST) Message-ID: <873aede9-bfcd-4c95-a93d-ec1881554f39@arm.com> Date: Thu, 16 Jan 2025 09:04:37 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 1/2] mm: Clear uffd-wp PTE/PMD state on mremap() Content-Language: en-GB To: Peter Xu 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 References: <20250107144755.1871363-1-ryan.roberts@arm.com> <20250107144755.1871363-2-ryan.roberts@arm.com> From: Ryan Roberts In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 6CCD5160021 X-Stat-Signature: 8zxfj94g44q31g5e6w673qpq1whjfyrj X-Rspam-User: X-HE-Tag: 1737018282-903341 X-HE-Meta: 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 Hn4SLqdV d7X3VGUPfqoKNHsXziO3oSjJs8oLwEdRRCfyNzn3639gfU7+MfsBM/LZz0vcBKisNbKfouW/Y/aAmOYR6LxvQy9cl1Sd1uHNQUZ3XucOcNDzYsWwd+5LFt2OrvJdnsH2gb6jdzzb9B1esAs8ncYYv3hr9QIOVsPBVmchFICpDtEn9lw94/RLzqMcesif+NA0p+75Qoz6/2oa5Z4OUYTq6bTOWcGaAti6lkVwz845f1vHg7ShJ/qRRdbkl9jw1q2HK1x/ZOztqqetFske/gJBdc/aZdL/pcAOLBvWyINXsG79zGsMRvF4V8wfKzCQYAasAU1gZX4RN/L5ArMY= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 15/01/2025 20:28, Peter Xu wrote: > 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 Great thanks! > > 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 Noted, I'll aim to get it right in future. > > Thanks again. >