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dkim=none (message not signed) header.d=none;kernel.org; dmarc=none action=none header.from=oracle.com; Received: from BY5PR10MB4196.namprd10.prod.outlook.com (2603:10b6:a03:20d::23) by SJ0PR10MB4415.namprd10.prod.outlook.com (2603:10b6:a03:2dc::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4308.21; Tue, 13 Jul 2021 21:37:31 +0000 Received: from BY5PR10MB4196.namprd10.prod.outlook.com ([fe80::8d2a:558d:ab4a:9c2a]) by BY5PR10MB4196.namprd10.prod.outlook.com ([fe80::8d2a:558d:ab4a:9c2a%5]) with mapi id 15.20.4308.027; Tue, 13 Jul 2021 21:37:31 +0000 Subject: Re: [PATCH 5.12 669/700] hugetlb: address ref count racing in prep_compound_gigantic_page To: Greg Kroah-Hartman , linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org, Jann Horn , Youquan Song , Andrea Arcangeli , Jan Kara , John Hubbard , "Kirill A . Shutemov" , Matthew Wilcox , Michal Hocko , Muchun Song , Andrew Morton , Linus Torvalds , Sasha Levin References: <20210712060924.797321836@linuxfoundation.org> <20210712061047.079512160@linuxfoundation.org> From: Mike Kravetz Message-ID: Date: Tue, 13 Jul 2021 14:37:28 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 In-Reply-To: <20210712061047.079512160@linuxfoundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: MW4PR04CA0370.namprd04.prod.outlook.com (2603:10b6:303:81::15) To BY5PR10MB4196.namprd10.prod.outlook.com (2603:10b6:a03:20d::23) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [192.168.2.112] (50.38.35.18) by MW4PR04CA0370.namprd04.prod.outlook.com (2603:10b6:303:81::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4308.21 via Frontend Transport; Tue, 13 Jul 2021 21:37:30 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 9bc23d21-c2be-4d09-7af7-08d946466b6c X-MS-TrafficTypeDiagnostic: SJ0PR10MB4415: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:873; 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Although this is a real potential issue, it was only found during code inspection. It has existed for more than 10 years and I am unaware of anyone hitting this in actual use. In addition, this proposed fix will likely be updated/simplified based on more discussions. -- Mike Kravetz