From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757734AbdJKRuT (ORCPT ); Wed, 11 Oct 2017 13:50:19 -0400 Received: from us-smtp-delivery-194.mimecast.com ([63.128.21.194]:32363 "EHLO us-smtp-delivery-194.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757389AbdJKRuH (ORCPT ); Wed, 11 Oct 2017 13:50:07 -0400 From: Trond Myklebust To: "tj@kernel.org" CC: "bfields@fieldses.org" , "linux-kernel@vger.kernel.org" , "lorenzo.pieralisi@arm.com" , "jlayton@poochiereds.net" , "linux-nfs@vger.kernel.org" , "jiangshanlai@gmail.com" , "anna.schumaker@netapp.com" Subject: Re: net/sunrpc: v4.14-rc4 lockdep warning Thread-Topic: net/sunrpc: v4.14-rc4 lockdep warning Thread-Index: AQHTQSrsNS+3n/veiEmJminQ1Tz/9qLb14GAgAFHSgCAAC4wgIAACH+AgAGa5IA= Date: Wed, 11 Oct 2017 17:49:59 +0000 Message-ID: <1507744197.50316.3.camel@primarydata.com> References: <20171009181738.GA30680@red-moon> <1507573931.3516.3.camel@primarydata.com> <20171010140336.GI3301751@devbig577.frc2.facebook.com> <1507654135.4442.4.camel@primarydata.com> <20171010171919.GO3301751@devbig577.frc2.facebook.com> In-Reply-To: <20171010171919.GO3301751@devbig577.frc2.facebook.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [68.49.162.121] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;DM5PR11MB0076;20:AWsklydD/YaM9sAzilsjIIcdjlFiNc2n0kYFFW5r74MlmVecVviDfutL0whqvb8flh7OPBoIjE9YoHFTlCR8T7Fr5yiNWbAwe1tT2EKHH5J4B5Jo3jgIFHh8BP/SmnEf9PmltXCmAlAQ5hC4s/iujDUqy8Y8imzKms9Naq9J1ps= x-ms-exchange-antispam-srfa-diagnostics: SSOS; x-ms-office365-filtering-correlation-id: 2300ef12-f3c2-474a-aa7c-08d510d07de3 x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(22001)(2017030254152)(2017082002075)(2017052603199)(201703131423075)(201702281549075);SRVR:DM5PR11MB0076; x-ms-traffictypediagnostic: DM5PR11MB0076: x-exchange-antispam-report-test: UriScan:; x-microsoft-antispam-prvs: x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(100000700101)(100105000095)(100000701101)(100105300095)(100000702101)(100105100095)(6040450)(2401047)(5005006)(8121501046)(93006095)(93001095)(100000703101)(100105400095)(3002001)(10201501046)(6041248)(20161123562025)(201703131423075)(201702281528075)(201703061421075)(201703061406153)(20161123564025)(20161123558100)(2016111802025)(20161123555025)(20161123560025)(6043046)(6072148)(201708071742011)(100000704101)(100105200095)(100000705101)(100105500095);SRVR:DM5PR11MB0076;BCL:0;PCL:0;RULEID:(100000800101)(100110000095)(100000801101)(100110300095)(100000802101)(100110100095)(100000803101)(100110400095)(100000804101)(100110200095)(100000805101)(100110500095);SRVR:DM5PR11MB0076; x-forefront-prvs: 0457F11EAF x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(6009001)(346002)(376002)(39830400002)(377424004)(24454002)(199003)(51914003)(189002)(53936002)(102836003)(6116002)(3660700001)(3280700002)(66066001)(36756003)(86362001)(50986999)(189998001)(76176999)(14454004)(99286003)(54356999)(4326008)(6512007)(2906002)(6246003)(478600001)(54906003)(4001150100001)(25786009)(103116003)(2501003)(6506006)(77096006)(229853002)(6486002)(101416001)(97736004)(39060400002)(5640700003)(2950100002)(93886005)(2351001)(316002)(8936002)(3846002)(1730700003)(8676002)(2900100001)(68736007)(305945005)(81166006)(6436002)(6916009)(81156014)(106356001)(7736002)(33646002)(105586002)(5660300001);DIR:OUT;SFP:1102;SCL:1;SRVR:DM5PR11MB0076;H:DM5PR11MB0075.namprd11.prod.outlook.com;FPR:;SPF:None;PTR:InfoNoRecords;A:1;MX:1;LANG:en; spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-ID: MIME-Version: 1.0 X-OriginatorOrg: primarydata.com X-MS-Exchange-CrossTenant-originalarrivaltime: 11 Oct 2017 17:49:59.2857 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 03193ed6-8726-4bb3-a832-18ab0d28adb7 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR11MB0076 X-MC-Unique: BSjFszZuNlSdUImNjMTAXQ-1 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by nfs id v9BHoNgd032298 On Tue, 2017-10-10 at 10:19 -0700, tj@kernel.org wrote: > Hello, > > On Tue, Oct 10, 2017 at 04:48:57PM +0000, Trond Myklebust wrote: > > Thanks for the explanation. What I'm not really understanding here > > though, is how the work item could be queued at all. We have a > > wait_on_bit_lock() in xprt_destroy() that should mean the xprt- > > > task_cleanup work item has completed running, and that it cannot > > > be > > > > requeued. > > > > Is there a possibility that the flush_queue() might be triggered > > despite the work item not being queued? > > Yeah, for sure. The lockdep annotations don't distinguish those > cases and assume the worst case. > OK. Let's just remove that call to cancel_work_sync() then. As I said, it should be redundant due to the wait_on_bit_lock(). -- Trond Myklebust Linux NFS client maintainer, PrimaryData trond.myklebust@primarydata.com