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Thu, 28 May 2026 20:08:51 +0000 Date: Thu, 28 May 2026 13:08:46 -0700 From: "Luck, Tony" To: Reinette Chatre CC: , , , , , , , , , , , , , , Subject: Re: [PATCH v3 0/9] x86,fs/resctrl: Fix long-standing issues Message-ID: References: Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: BY3PR03CA0022.namprd03.prod.outlook.com (2603:10b6:a03:39a::27) To DS7PR11MB6077.namprd11.prod.outlook.com (2603:10b6:8:87::16) 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: DS7PR11MB6077:EE_|PH0PR11MB4983:EE_ X-MS-Office365-Filtering-Correlation-Id: 010c0f14-9c3b-4707-f8b7-08debcf4ef00 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|7416014|376014|1800799024|56012099006|11063799006|22082099003|18002099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DS7PR11MB6077.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(366016)(7416014)(376014)(1800799024)(56012099006)(11063799006)(22082099003)(18002099003);DIR:OUT;SFP:1101; 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Reinette > found a memory leak in the mount error path while refactoring code for a > solution to the mount hang. > > During review of V1 of this series Sashiko found a new UAF on unmount issue > that was fixed in V2. > > During review of V2 Sashiko uncovered a couple more new issues: TOCTOU > involving rdtgroup_kn_put() that may lead to UAF or double-free, double > free of pseudo-locked regions, potential deadlock between resctrl unmount and > info file readers. Sashiko also found that the CPU offline fix in V2 is flawed > in its use of is_percpu_thread(). > > Address all issues identified. This version is significantly different from V2 > because of the additional fixes and reworking of the CPU offline fix. I do not > consider this version quite "polished" but after all changes made to address > all the issues identified by Sashiko I would like to check-in with folks (and > Sashiko) on where the fixes are headed and would appreciate any feedback. Several of these patches are either authored or co-authored by me, so I'm uncertain about the ethics of piling on a Reviewed-by tag. Apart from patch 6 to fix sashiko reported issues in pseudo-locking everything looks good. I agree with Reinette's assessment[1] that pursuing the bizarre corner case races for pseudo-locking should not be a priority. That patch can be dropped. -Tony [1] https://lore.kernel.org/all/e40a924f-5398-43bd-821a-2ff9873c5a4c@intel.com/