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Fri, 29 May 2026 14:06:19 +0000 Message-ID: <6140c3f9-b172-4552-b96f-1b8514b0e75b@intel.com> Date: Fri, 29 May 2026 22:06:09 +0800 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 4/9] fs/resctrl: Fix deadlock for errors during mount To: Reinette Chatre CC: , , , , , , , , , , , , , , References: <2e44b91263f1ccc4403a969524594800bead95c4.1779476724.git.reinette.chatre@intel.com> Content-Language: en-US From: "Chen, Yu C" In-Reply-To: <2e44b91263f1ccc4403a969524594800bead95c4.1779476724.git.reinette.chatre@intel.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SI2PR02CA0005.apcprd02.prod.outlook.com (2603:1096:4:194::6) To DM4PR11MB6020.namprd11.prod.outlook.com (2603:10b6:8:61::19) 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: DM4PR11MB6020:EE_|PH8PR11MB8105:EE_ X-MS-Office365-Filtering-Correlation-Id: 17c41c52-5cc1-4ee9-4736-08debd8b7507 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|376014|1800799024|7416014|18002099003|22082099003|56012099006|11063799006|4143699003; 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> } > > - goto out; > + /* > + * Ensure root kn remains accessible after mutex is unlocked so that Maybe a little more accurate to say "Ensure rdt_root remains accessible"? Here we increase reference for rdtgroup_default.kn, and protect against UAF of kernfs_kill_sb(sb) -> info = kernfs_info(sb) -> kernfs_put(info->root->kn) where the info->root is UAF rather than the kn. Other looks good to me. Reviewed-by: Chen Yu thanks, Chenyu > + * kernfs_kill_sb() can run safely if called by kernfs_get_tree()'s > + * failure path after creating a superblock but before taking reference > + * on root kn. > + */ > + kernfs_get(rdtgroup_default.kn);