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Thu, 10 Sep 2026 04:08:00 +0000 Message-ID: Date: Wed, 9 Sep 2026 21:07:58 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v11 18/23] fs/resctrl: Call arch code for every mount To: Tony Luck , Fenghua Yu , "Maciej Wieczor-Retman" , Peter Newman , James Morse , Babu Moger , Drew Fustini , Dave Martin , Chen Yu , David E Box , CC: Christoph Hellwig , , References: <20260831174421.13921-1-tony.luck@intel.com> <20260831174421.13921-19-tony.luck@intel.com> From: Reinette Chatre Content-Language: en-US In-Reply-To: <20260831174421.13921-19-tony.luck@intel.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: MW4PR03CA0234.namprd03.prod.outlook.com (2603:10b6:303:b9::29) 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_|DSWPR11MB9583:EE_ X-MS-Office365-Filtering-Correlation-Id: e5db65a9-0049-4de2-7b8b-08df0ef11a4d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|366016|376014|7416014|1800799024|4143699003|10067099003|22082099003|11063799006|56012099006|18002099003|921020; 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Without such serialization calling resctrl_arch_pre_mount() on > every mount before acquiring rdtgroup_mutex would open up many complex > races between mount and unmount operations. > > Add resctrl_mount_lock to provide serialization and protect resctrl_mounted. > > Signed-off-by: Tony Luck > --- > diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c > index 3ac518ed2368..7f09d76dbf8c 100644 > --- a/fs/resctrl/rdtgroup.c > +++ b/fs/resctrl/rdtgroup.c > @@ -30,6 +30,9 @@ > > #include "internal.h" > > +/* Mutex protecting resctrl_mounted and mount/unmount operations */ Could you please expand this to highlight that changes to resctrl_mounted should be made with resctrl_mount_lock *and* rdtgroup_mutex held. > +static DEFINE_MUTEX(resctrl_mount_lock); > + > /* Mutex to protect rdtgroup access. */ > DEFINE_MUTEX(rdtgroup_mutex); > > @@ -3149,6 +3152,7 @@ static void resctrl_unmount(void) > { > struct rdt_resource *r; > > + mutex_lock(&resctrl_mount_lock); > cpus_read_lock(); > mutex_lock(&rdtgroup_mutex); > > @@ -3166,6 +3170,8 @@ static void resctrl_unmount(void) > resctrl_mounted = false; > mutex_unlock(&rdtgroup_mutex); > cpus_read_unlock(); > + resctrl_arch_unmount(); > + mutex_unlock(&resctrl_mount_lock); > } > > static int rdt_get_tree(struct fs_context *fc) > @@ -3177,24 +3183,27 @@ static int rdt_get_tree(struct fs_context *fc) > struct rdt_resource *r; > int ret; > > - DO_ONCE_SLEEPABLE(resctrl_arch_pre_mount); Please note that after this series the comment above resctrl_arch_pre_mount() in resctrl.h still reads: "Architecture hook called at beginning of first file system mount attempt" The sashiko reported issues look real to me. Reinette