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Wed, 1 Apr 2026 00:22:17 +0000 Date: Tue, 31 Mar 2026 17:22:08 -0700 From: Matthew Brost To: Tejun Heo CC: , , , Carlos Santa , "Ryan Neph" , , Lai Jiangshan , Waiman Long Subject: Re: [PATCH] workqueue: Add pool_workqueue to pending_pwqs list when unplugging multiple inactive works Message-ID: References: <20260331221839.1033423-1-matthew.brost@intel.com> Content-Type: text/plain; charset="utf-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-ClientProxiedBy: MW4P223CA0004.NAMP223.PROD.OUTLOOK.COM (2603:10b6:303:80::9) To BL3PR11MB6508.namprd11.prod.outlook.com (2603:10b6:208:38f::5) Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL3PR11MB6508:EE_|SA1PR11MB7088:EE_ X-MS-Office365-Filtering-Correlation-Id: 6de6aedf-8c5d-4567-2478-08de8f84baea X-LD-Processed: 46c98d88-e344-4ed4-8496-4ed7712e255d,ExtAddr X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|366016|1800799024|22082099003|56012099003|18002099003; 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> > if (pwq->plugged) { > > pwq->plugged = false; > > - if (pwq_activate_first_inactive(pwq, true)) > > + if (pwq_activate_first_inactive(pwq, true)) { > > + if (!list_empty(&pwq->inactive_works)) { > > + struct worker_pool *pool = pwq->pool; > > + struct wq_node_nr_active *nna = > > + wq_node_nr_active(wq, pool->node); > > + > > + raw_spin_lock(&nna->lock); > > + if (list_empty(&pwq->pending_node)) > > + list_add_tail(&pwq->pending_node, > > + &nna->pending_pwqs); > > + raw_spin_unlock(&nna->lock); > > + } > > It's a bit gnarly to open code locking and list operation. Would just > calling pwq_activate_first_inactive(pwq, false) one more time work here? > That'd trigger tryinc_node_nr_active() failure in pwq_tryinc_nr_active() and > the addition to the pending list. As this is quite subtle, it'd be nice to > have some comment - it's compensating for the missed pwq_tryinc_nr_active() > call due to plugging, right? Yeah, I think that will work. Let me verify with my reproducer and adjust the patch accordingly. +1 on the comment as well—very subtle. Took a few days of reverse-engineering work queues to track down. Matt > > Thanks. > > -- > tejun