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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 BY5PR10MB4116.namprd10.prod.outlook.com (2603:10b6:a03:203::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4331.21; Tue, 13 Jul 2021 21:38:28 +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 21:38:28 +0000 Subject: Re: [PATCH 5.13 768/800] 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: <20210712060912.995381202@linuxfoundation.org> <20210712061048.520052935@linuxfoundation.org> From: Mike Kravetz Message-ID: <96dcbea1-0b68-47f2-8954-fa36b61fdb0f@oracle.com> Date: Tue, 13 Jul 2021 14:38:26 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 In-Reply-To: <20210712061048.520052935@linuxfoundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: MW4PR04CA0364.namprd04.prod.outlook.com (2603:10b6:303:81::9) 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 MW4PR04CA0364.namprd04.prod.outlook.com (2603:10b6:303:81::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4308.20 via Frontend Transport; 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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