From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932546AbdDETQm (ORCPT ); Wed, 5 Apr 2017 15:16:42 -0400 Received: from mail.kernel.org ([198.145.29.136]:47668 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753677AbdDETQe (ORCPT ); Wed, 5 Apr 2017 15:16:34 -0400 Date: Wed, 5 Apr 2017 15:16:28 -0400 From: Steven Rostedt To: Tejun Heo Cc: LKML Subject: [WARNING] kernel/workqueue.c:2041 process_one_work (when cpu goes offline) Message-ID: <20170405151628.33df783f@gandalf.local.home> X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Tejun, My tests have started to recently trigger this warning quite often, which causes my tests to fail. The test that triggers this is running the mmiotracer which forces all but one CPU offline. ------------[ cut here ]------------ WARNING: CPU: 0 PID: 6 at /work/autotest/nobackup/linux-test.git/kernel/workqueue.c:2041 process_one_work+0x90/0x485 Modules linked in: ppdev parport_pc parport [last unloaded: trace_events_sample] CPU: 0 PID: 6 Comm: vmstat Not tainted 4.11.0-rc5-test+ #3 Hardware name: MSI MS-7823/CSM-H87M-G43 (MS-7823), BIOS V1.6 02/22/2014 Call Trace: dump_stack+0x68/0x92 __warn+0xc2/0xdd warn_slowpath_null+0x1d/0x1f process_one_work+0x90/0x485 process_scheduled_works+0x2c/0x33 rescuer_thread+0x19c/0x295 ? process_scheduled_works+0x33/0x33 kthread+0xf4/0xf9 ? __list_del_entry+0x22/0x22 ret_from_fork+0x2e/0x40 ---[ end trace ed53fc9d3ce10aa8 ]--- #ifdef CONFIG_LOCKDEP /* * It is permissible to free the struct work_struct from * inside the function that is called from it, this we need to * take into account for lockdep too. To avoid bogus "held * lock freed" warnings as well as problems when looking into * work->lockdep_map, make a copy and use that here. */ struct lockdep_map lockdep_map; lockdep_copy_map(&lockdep_map, &work->lockdep_map); #endif /* ensure we're on the correct CPU */ WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && <<--- line 2041 raw_smp_processor_id() != pool->cpu); /* * A single work shouldn't be executed concurrently by * multiple workers on a single cpu. Check whether anyone is * already processing the work. If so, defer the work to the * currently executing one. */ I'm assuming that this thread was migrated due to the CPU offlining and causes pool->cpu not to equal raw_smp_processor_id(). Or should that not be happening? Thoughts? -- Steve