From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0b-00069f02.pphosted.com (mx0b-00069f02.pphosted.com [205.220.177.32]) (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 E69E51EBFE2 for ; Fri, 4 Apr 2025 14:20:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=205.220.177.32 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743776419; cv=fail; b=ofMSC9HFloSFTfp3Bg3T0CJ+KuRwQSkXWpuuZ0MEBuvxmoSLDAUwU8MeCe9mdl9g47b4xgb0jIsN+6sUyDO4UMmU89urPP6RUG8dMnMM8P+VxqpXxMJBngIWsN7BcN1oGhMITUwt+mOBJHzPFVQ29CRkI/J7Zd4RxvmTRICzZRA= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743776419; c=relaxed/simple; bh=sFC1VkJVsxLzHXvdEOVJTwGoD4hRKBMGtemcuJx+mPI=; h=Date:From:To:Cc:Subject:Message-ID:References:Content-Type: Content-Disposition:In-Reply-To:MIME-Version; b=QO5gPBHLc7sIldYhtftNneHQuZYPBeGeFZ4FtIv/nHe4j7aKScvOJt6ZMXFr0LbMl5QfpjYZv19dsCnmP8H9/AEpZdbv711bh3RamKplLAX/MMA/sk4QyYR/sK0N2XuhXRavKr14+G4mhWmcc7bvZ95JOezC1T+iKCrTpH/1bpI= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oracle.com; spf=pass smtp.mailfrom=oracle.com; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b=lW3a2LZI; dkim=pass (1024-bit key) header.d=oracle.onmicrosoft.com header.i=@oracle.onmicrosoft.com header.b=w3gZ2uCG; arc=fail smtp.client-ip=205.220.177.32 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oracle.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oracle.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="lW3a2LZI"; dkim=pass (1024-bit key) header.d=oracle.onmicrosoft.com header.i=@oracle.onmicrosoft.com header.b="w3gZ2uCG" Received: from pps.filterd (m0246630.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 534Du4WL027721; Fri, 4 Apr 2025 14:19:15 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=cc :content-type:date:from:in-reply-to:message-id:mime-version :references:subject:to; s=corp-2023-11-20; bh=Spw69sBqqlJQ3suk2R 3cST7Od3UiV0VBKZcsjZkfwWU=; b=lW3a2LZIDnHM4iAnxscpfO9B6uylS/8gq0 542MITIyJHLsiS0HvkJv6QuX4QYBAk0etrAXMyktw13Yj6NmvnzkMn/+z9WXHFiA 8cxCt8EH9MrhvDe9VOASvcJOiqNwuVg+ru/L3dVQayT1oB2g2z80/NP9PDWQ1iV9 QkTTo+gjnGSVxXmEWW+NRP0uy2ANGsrtK0V1QAzTr8pQauZsIsK8xWc5RNE00mh9 Yw7b37JeiE4KHXxgo+DyyPSHiBBcSHg32jXNi7RVx2uXn/fnqHRX3MUBZrOFdnwN yxli3K9mZRPKa7AWJJP0LXeV6Kyd5tlJtA/mgonAv4SzeDOsjmzw== Received: from iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (iadpaimrmta03.appoci.oracle.com [130.35.103.27]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 45p79cf8wd-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 04 Apr 2025 14:19:15 +0000 (GMT) Received: from pps.filterd (iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com [127.0.0.1]) by iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (8.18.1.2/8.18.1.2) with ESMTP id 534DJR8u022437; Fri, 4 Apr 2025 14:19:14 GMT Received: from nam12-dm6-obe.outbound.protection.outlook.com (mail-dm6nam12lp2176.outbound.protection.outlook.com [104.47.59.176]) by iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (PPS) with ESMTPS id 45t2ykuev0-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 04 Apr 2025 14:19:14 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=RTP1Yl86oBFAHISFvTSYIQ+BrFw8ttxM+rqaCV3jlf8KSxKQZiaEivffn1yZsJAxk40XiA+vYdmzwQWCaiJANQsTu0nql98E3fgRS6w3+ZQziczXNY/HT5vwMdBEjpHMbBa8JPXITutDJIDzwHYORegZczlN/vdU7C5b6ZpmPYlcZtIicCl5NshinZ0Ip5Gt3sLlly0kCLG8v8STEFkNYkNT9aPtFcVJr9rt/TmkzSE7Iz+eWDTFe0NVSpiUcl9uTXGHOPX6Ujc2kTD2huWpmeJr7hA7C2GVW/1I3UQTtChbLDBCJzcxDUHPxGjvwiFpEWGQrFIa7bb+Qf7lHsuv/g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=Spw69sBqqlJQ3suk2R3cST7Od3UiV0VBKZcsjZkfwWU=; b=KP2qJtGQzd0qJNu9j4b5K1qDpWkhU0iRrHrqY3FJidKI9An28T9TYv6SjSOGXYD66uHitRIxAeBwlrpbBWwH0lQ5tQtzNsB6QskQVCP9LOs8eOyAOwiY9QuzPCL0drY6YEudbtGrvs/QVQUx/cHrQyXBRxBZ/5sH1kw7kVsAWKT+eXxBOXZGIooeCiE1V5Qr01Pvaq12kesey/tHYPr8gszln9ubQwuN78NEAuxwjkv94ltXLpAwUJ+wgDRPf8yZMssifQDoToarioWkXDK6lDLH9wEDScW1vr7oF+WHBRzmlMdp0ZhZduVnhHBCimQmxf+lnO3KhTp1EqPW6lX5sw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=oracle.com; dmarc=pass action=none header.from=oracle.com; dkim=pass header.d=oracle.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.onmicrosoft.com; s=selector2-oracle-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=Spw69sBqqlJQ3suk2R3cST7Od3UiV0VBKZcsjZkfwWU=; b=w3gZ2uCGsJGycPvXqnqx9nm6T/pDr/u20ER4wRy5UQShfbjR9UGgvDw5qsohvEFWEWYk75XTL+oT5qooCa4Eo0VhrmMhAyNnMj60atovMrBpbcTxvppAIeH3t5EPF29FEbcZcW+zyniHAM99tfLxaZ8dG3yNDcf+601oD78WGTA= Received: from BL4PR10MB8229.namprd10.prod.outlook.com (2603:10b6:208:4e6::14) by PH0PR10MB5817.namprd10.prod.outlook.com (2603:10b6:510:12a::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8583.41; Fri, 4 Apr 2025 14:19:10 +0000 Received: from BL4PR10MB8229.namprd10.prod.outlook.com ([fe80::552b:16d2:af:c582]) by BL4PR10MB8229.namprd10.prod.outlook.com ([fe80::552b:16d2:af:c582%3]) with mapi id 15.20.8583.041; Fri, 4 Apr 2025 14:19:09 +0000 Date: Fri, 4 Apr 2025 15:19:04 +0100 From: Lorenzo Stoakes To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, kernel test robot , Dan Carpenter , Andrew Morton , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Rik van Riel , "H. Peter Anvin" , Linus Torvalds Subject: Re: [PATCH v1] x86/mm/pat: (un)track_pfn_copy() fix + improvements Message-ID: <5dd880b5-2166-4c7d-be65-d1b3bd3dad3e@lucifer.local> References: <20250404124931.2255618-1-david@redhat.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250404124931.2255618-1-david@redhat.com> X-ClientProxiedBy: LO4P265CA0289.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:38f::12) To BL4PR10MB8229.namprd10.prod.outlook.com (2603:10b6:208:4e6::14) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL4PR10MB8229:EE_|PH0PR10MB5817:EE_ X-MS-Office365-Filtering-Correlation-Id: dc186224-6283-4255-3373-08dd7383a9fe X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|7416014|376014|366016|7053199007; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?NoQSgikQO2ZBI3whEGrNygK7ImGgmIrAwwl7u7Fmynbs3lF4hG8DGhpk7vtK?= =?us-ascii?Q?1y3BSU5E4yYyzrF9E81WgYsUvZ8EmS9nGLddzRw9sBWWi2vlzsaMOPjHhJ6+?= =?us-ascii?Q?rQUKBeK35M612YfeDGJfTScw9p/EnbKh3RjrUYxpOxv4pH8aiZ5OO1NYU9Ee?= =?us-ascii?Q?Q7CspbdH9p6/rjrvhm5DDeqBtnjlSL987W/7icgKRJT3Didjrd9xUYnVUqUM?= =?us-ascii?Q?Z7UB6rKw166YyKsXfz9ZsoJK/vPfCpytq1yG1PhxTPZBqiVN7120tB9Wo1Vs?= =?us-ascii?Q?lLxM2/n5X/g9tJVskH4I5Z1GPEYhazF/tLkPPbhCZ1Cu8GkRIVu4g+lt5J9u?= =?us-ascii?Q?vgOqVXT8ezwT0Azs2yY0Wz9/iug4fHBUTB+YFa06h3jfp/bCYJYx7br6ZrPe?= =?us-ascii?Q?kUBdrhIzORXwqkfRZBNYLOHJ90dOLq4yXzt27K7xh8YBkvA25M6YNn1r451M?= =?us-ascii?Q?V/JFh+LafybC8FaFID3bcuO2P8hJqHPZPR3I8oHt4ovPntnAdq47oLPl3aJC?= =?us-ascii?Q?WbAoiSQCIjDAPAYspmLrHyPhlO6ucdkhFEEOwx0OzIENIUvqoM6MlwvIuAZu?= =?us-ascii?Q?kLhwVSudR+LMgFlzJDU7KSj3BjQ4Z0u3qnOdLavj/ij8lBS6qv5QVSW/1A73?= =?us-ascii?Q?RmN8uYWJTCLBU1jhHUHIsQ0yCGsI0OAOIUSDkup1qwBHta9odkqoUC+Zc9FN?= =?us-ascii?Q?GM6qRngf6cO0ho0RUSSvrBqXw82Q9/sQ3PzBz6GBXEL3PVBnM8c2ukEsesVn?= =?us-ascii?Q?wenBtoq9kTQbOiPAWo/EAAPw7pN6HP1YQ9XF3tJhiDRFq2FGMWaGdfd25lG/?= =?us-ascii?Q?xsn6XQa0yR7OJd38zWeyDP9plUJ/V5kGpHNSxnXdKEDavuz44xhYRJTpsKOE?= =?us-ascii?Q?7zzgHosiufRxZ8fBQY0fFdn4YQtsb8S7BrG3vCChguZdEwmAMEsy43FJqZuM?= =?us-ascii?Q?Y2+WhbTeoWulSx7fHOVDGUGFLsku++2pVATT7yCEmSLUbiJlP1ShQTdsJPsU?= =?us-ascii?Q?MVHYUR7uNPasowRYWAuiZ5PIe3tjx2/S2ysCFFdQDX+X0IMNvi4mHRER7q0U?= =?us-ascii?Q?V6xJzFk/Co6Vv4v00mMtm0GVg9fvPWIjhFfp3tY1FjbNwjL7TIVc4kp9yLQI?= =?us-ascii?Q?eWqXLqOEqOOKUbAdIOfTET7suy735ZDcjSZvkyHjAR5RG+nCiNsVpTPUYdd8?= =?us-ascii?Q?M+lmIfQO1EJXjiSkofBJOc0GaDcsqpxHfB+7qMTOzxBJSKcYvclmFh4pFuv8?= =?us-ascii?Q?1ee3dA8yXx+MkXjDNyGtWlMyo44gdfa8DGhpfht0LvF2lt0rr+MWfaeFL/iI?= =?us-ascii?Q?Vi15Vl+KPjNjeaRBW3Zpp/UL/GJDeHJrwQyfInUabwiPSuGPeXJHBq8gZLRC?= =?us-ascii?Q?3+un+Pn6HedaxadTY4jYjrh7jMvI?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BL4PR10MB8229.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(7416014)(376014)(366016)(7053199007);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?spDCtTu1FFrNlj++S88hzwZQ4xsHOG1OAKr3p4FeZ6Fw5+maxvaTxrL+NEoY?= =?us-ascii?Q?O60JkUSRUBjV5pWWv3p11umFch43BqW64JBadtiOxgcOUiccbcUlX4RoCQ8r?= =?us-ascii?Q?t43fXmsTp6RLGn1Cc3Dk1a1RfFLAUjyXFRMBuoTwpnaDvLP0w8BAWnGIy2dS?= =?us-ascii?Q?BCmQnriu0Pg6jIHLVjKmfp1CC9g7L3r3PUPwKE8YnGGOkr5TSMivCR6NZOKy?= =?us-ascii?Q?wNRJmVTz1RZMXlQdlxUPcNjZ0vzNUtyPeYWm3dzt+TtxIAjMOswWngW2YoX8?= =?us-ascii?Q?Eh6nOuqp3AX9P0WGVgsySLYnvnyKvlL0DXPnrGCY/CjjtDh+c7mHjPyb7P+m?= =?us-ascii?Q?miWAN/hSWiN+ESagwu21cIbVFX/aodtCw7ionrXbOwSH3BDGc6go1FSggibU?= =?us-ascii?Q?TPtaFuxD4lM+lGiAFTrHFDdaonWsO11n3bXNxWfnSwSpxLSoAb1Bmg4M3eRy?= =?us-ascii?Q?yXkfrYgXlR696Pv5JgoOqMOHLzKlrR5E/UGcKFYa1O5mTHyzkaIj9GKsatnD?= =?us-ascii?Q?yff1GkbAUvu3Jc9L31tvENH4CDQ+SEncpRV/ozYQjsVWzhDQJjb/BKFj2h4c?= =?us-ascii?Q?3hgGeEBnQNei/5B/oHAUTQj5wWNogqPo5+9Qji/00x/RWCr1BEjoyHtlu/ls?= =?us-ascii?Q?gYkl4C0xXAu+m2AskI8Zpyv8AOqEtIV3bVJo6KPeiY5ETdyDz/QMI6QOXNf3?= =?us-ascii?Q?82C09NLY9A76hvowqc7gITfq7vI0zwXeDxwp2KIx76ZG0G+fOWkxAWUrdQhW?= =?us-ascii?Q?S7lWuuBqqfvZzJz16WsxPooPYknxuagAXXO76H/SaSdPrZojgml7WJjfLX93?= =?us-ascii?Q?53gK87ZAT5fCcECXBYrwVt3edrO80NibriVBNxwZCfV+fO7ruoAGFIH7uUWM?= =?us-ascii?Q?TskmYtBO+Pbq6CcqgsXrHNSFnSGyRTloKeM65Ce49U1zvgybZHNv8RhHUANj?= =?us-ascii?Q?rSHh4nJbUK0tf6MzLmHeCCkPwPG79oV981SYlEqADrCjJ5XsgxcpBHTN6RlS?= =?us-ascii?Q?Llw+3DRAeWuDxXxvjyoJSWUCPX4BUTvJAlN0nZnkQnQq2Zsx02hzkB5ABC4+?= =?us-ascii?Q?AFrZMDz8XvV11MMRmWlT1wtieACzV3V3xg36UvadqXoivJ9nub6CReNxDTDF?= =?us-ascii?Q?mnD5Rrvd40SJH5BQo3OzXacmPB2N2yWAHKEDPm51NR0VdFLNvSwbMVhg36o/?= =?us-ascii?Q?jI4FZuEcleVx6Ejg1TRiYUdxGi3DQkuCmCTjZFJfbz3RPPFVsaEpQvuh4FDM?= =?us-ascii?Q?jws/dpyoZQWGzcbesdpvs7MXDL1IaXmUZ1LAmZsznj3BtbUd63QPQ6/AKQyE?= =?us-ascii?Q?eykgMC9RfmVZzQwm0g3ILKSVtXxFEz1Mp6g/CHXRzt0XgJ4qBRwGmbj6J3gp?= =?us-ascii?Q?iHV3Cu4Kdg18CRjL85Nc0y1iH2hlvDYTO4Fs20+arL9ybBliABk5Fe7VHHRs?= =?us-ascii?Q?F/2djoUwVmFjwZ/Ks5UKLf6iFbgClMhqXi+epEDdmaJFOhyAp5McR2BASGyv?= =?us-ascii?Q?9Rny2o9DCV61vYVcJt7jIJflaRtvWzuUpU1reRnxZb4FYbCc8mkHeonfS2P/?= =?us-ascii?Q?YfsHasieWLIwGLZ0nVWX877n4Jc1oX1jIy1CwgmqxFtPFyJG81LXRtdC/Nhj?= =?us-ascii?Q?Pw=3D=3D?= X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: 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 X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-Network-Message-Id: dc186224-6283-4255-3373-08dd7383a9fe X-MS-Exchange-CrossTenant-AuthSource: BL4PR10MB8229.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Apr 2025 14:19:08.9770 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: h3w7IAMsTHQ227R7MUaGzx0aXw/ejnydTfK1lO/ByxPasU9YqvB0cD3iWS3yVMncRtY1A4syWcso7OJDFvo4OxZWsEimkUK1lt9VqwvTUgY= X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR10MB5817 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1095,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-04-04_06,2025-04-03_03,2024-11-22_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 phishscore=0 bulkscore=0 suspectscore=0 mlxlogscore=999 adultscore=0 malwarescore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2502280000 definitions=main-2504040099 X-Proofpoint-GUID: ms6GWbUG8J3ZkwDqg6dpTc0lFqUoXe_i X-Proofpoint-ORIG-GUID: ms6GWbUG8J3ZkwDqg6dpTc0lFqUoXe_i On Fri, Apr 04, 2025 at 02:49:31PM +0200, David Hildenbrand wrote: > We got a late smatch warning and some additional review feedback. > > smatch warnings: > mm/memory.c:1428 copy_page_range() error: uninitialized symbol 'pfn'. > > We actually use the pfn only when it is properly initialized; however, > we may pass an uninitialized value to a function -- although it will not > use it that likely still is UB in C. > > Fix it by always initializing pfn when track_pfn_copy() returns 0 -- > just as we document ("On success, stores the pfn to be passed to > untrack_pfn_copy()"). In addition, to avoid further wrong smatch > warnings, just initialize pfn = 0 in the caller as well. > > While at it, clarify the doc of untrack_pfn_copy(), that internal checks > make sure if we actually have to untrack anything. > > Fixes: dc84bc2aba85 ("x86/mm/pat: Fix VM_PAT handling when fork() fails in copy_page_range()") > Reported-by: kernel test robot > Reported-by: Dan Carpenter > Closes: https://lore.kernel.org/r/202503270941.IFILyNCX-lkp@intel.com/ > Cc: Andrew Morton > Cc: Lorenzo Stoakes > Cc: Dave Hansen > Cc: Andy Lutomirski > Cc: Peter Zijlstra > Cc: Thomas Gleixner > Cc: Ingo Molnar > Cc: Borislav Petkov > Cc: Rik van Riel > Cc: "H. Peter Anvin" > Cc: Linus Torvalds > Signed-off-by: David Hildenbrand LGTM, Reviewed-by: Lorenzo Stoakes > --- > arch/x86/mm/pat/memtype.c | 4 +++- > include/linux/pgtable.h | 5 ++++- > mm/memory.c | 2 +- > 3 files changed, 8 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/mm/pat/memtype.c b/arch/x86/mm/pat/memtype.c > index 72d8cbc611583..9ad3e5b055d8a 100644 > --- a/arch/x86/mm/pat/memtype.c > +++ b/arch/x86/mm/pat/memtype.c > @@ -992,8 +992,10 @@ int track_pfn_copy(struct vm_area_struct *dst_vma, > pgprot_t pgprot; > int rc; > > - if (!(src_vma->vm_flags & VM_PAT)) > + if (!(src_vma->vm_flags & VM_PAT)) { > + *pfn = 0; > return 0; > + } > > /* > * Duplicate the PAT information for the dst VMA based on the src > diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h > index e2b705c149454..9457064292141 100644 > --- a/include/linux/pgtable.h > +++ b/include/linux/pgtable.h > @@ -1517,12 +1517,15 @@ static inline void track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot, > static inline int track_pfn_copy(struct vm_area_struct *dst_vma, > struct vm_area_struct *src_vma, unsigned long *pfn) > { > + *pfn = 0; > return 0; > } > > /* > * untrack_pfn_copy is called when a VM_PFNMAP VMA failed to copy during > - * copy_page_range(), but after track_pfn_copy() was already called. > + * copy_page_range(), but after track_pfn_copy() was already called. Can > + * be called even if track_pfn_copy() did not actually track anything: > + * handled internally. > */ > static inline void untrack_pfn_copy(struct vm_area_struct *dst_vma, > unsigned long pfn) > diff --git a/mm/memory.c b/mm/memory.c > index 2d8c265fc7d60..1a35165622e1c 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -1361,7 +1361,7 @@ copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) > struct mm_struct *dst_mm = dst_vma->vm_mm; > struct mm_struct *src_mm = src_vma->vm_mm; > struct mmu_notifier_range range; > - unsigned long next, pfn; > + unsigned long next, pfn = 0; > bool is_cow; > int ret; > > -- > 2.48.1 >