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Tue, 7 Jul 2026 23:54:56 +0000 Message-ID: Date: Tue, 7 Jul 2026 16:54:54 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 08/10] fs/resctrl: Prevent deadlock and use-after-free in info file handlers To: "Luck, Tony" CC: , , , , , , , , , , , , , , References: From: Reinette Chatre Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: MW4PR04CA0136.namprd04.prod.outlook.com (2603:10b6:303:84::21) To SJ2PR11MB8370.namprd11.prod.outlook.com (2603:10b6:a03:540::20) 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: SJ2PR11MB8370:EE_|DS3PR11MB9819:EE_ X-MS-Office365-Filtering-Correlation-Id: 8f102fb7-d582-41f2-f7b5-08dedc8325d8 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|7416014|376014|23010399003|1800799024|56012099006|4143699003|11063799006|18002099003|22082099003|3023799007; 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>> - struct rdt_resource *r = s->res; >> + struct rdt_resource *r; >> + > > Extra blank line added here. >> >> + if (!info_kn_lock(of->kn)) >> + return -ENOENT; >> + r = s->res; >> seq_printf(seq, "%u\n", r->cache.min_cbm_bits); >> + info_kn_unlock(of->kn); >> + >> return 0; >> } >> > > ... > >> @@ -1652,8 +1718,8 @@ static int mbm_config_show(struct seq_file *s, struct rdt_resource *r, u32 evtid >> struct rdt_l3_mon_domain *dom; >> bool sep = false; >> >> - cpus_read_lock(); >> - mutex_lock(&rdtgroup_mutex); >> + lockdep_assert_cpus_held(); >> + lockdep_assert_held(&rdtgroup_mutex); >> >> list_for_each_entry_rcu(dom, &r->mon_domains, hdr.list, lockdep_is_cpus_held()) { >> if (sep) >> @@ -1670,8 +1736,6 @@ static int mbm_config_show(struct seq_file *s, struct rdt_resource *r, u32 evtid >> } >> seq_puts(s, "\n"); >> >> - mutex_unlock(&rdtgroup_mutex); >> - cpus_read_unlock(); >> > > Extra blank line here after deleting those two lines. > Thank you very much. I plan to send a new version of this series based on -rc3 next week unless I learn about a better way to handle this before then. Reinette