From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755432AbaFLDGO (ORCPT ); Wed, 11 Jun 2014 23:06:14 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:27690 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754452AbaFLDGN (ORCPT ); Wed, 11 Jun 2014 23:06:13 -0400 Message-ID: <539918F4.80109@oracle.com> Date: Wed, 11 Jun 2014 23:05:24 -0400 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: John Stultz CC: LKML , Thomas Gleixner , Dave Jones , Peter Zijlstra , Ingo Molnar Subject: Re: timekeeping: exiting task with held timekeeping locks References: <5398E07C.6030107@oracle.com> In-Reply-To: X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Source-IP: acsinet22.oracle.com [141.146.126.238] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/11/2014 07:30 PM, John Stultz wrote: > On Wed, Jun 11, 2014 at 4:04 PM, Sasha Levin wrote: >> > Hi all, >> > >> > While fuzzing with trinity inside a KVM tools guest running the latest -next >> > kernel I've stumbled on the following spew: >> > >> > [ 3460.136058] ===================================== >> > [ 3460.138017] [ BUG: trinity-c70/27193 still has locks held! ] >> > [ 3460.141491] 3.15.0-next-20140611-sasha-00022-g9466d2f-dirty #638 Not tainted >> > [ 3460.143219] ------------------------------------- >> > [ 3460.167979] 2 locks held by trinity-c70/27193: >> > [ 3460.169172] #0: (tick_broadcast_lock){-.-.-.}, at: tick_handle_periodic_broadcast (kernel/time/tick-broadcast.c:301) >> > [ 3460.468004] #1: (timekeeper_lock){-.-.-.}, at: update_wall_time (kernel/time/timekeeping.c:1371) >> > [ 3460.920025] >> > [ 3460.920025] stack backtrace: >> > [ 3460.928146] CPU: 0 PID: 27193 Comm: trinity-c70 Not tainted 3.15.0-next-20140611-sasha-00022-g9466d2f-dirty #638 >> > [ 3460.928648] can: request_module (can-proto-3) failed. >> > [ 3460.943111] ffff8800576ef4c8 ffff8800576efc88 ffffffffa551093c 0000000000000001 >> > [ 3460.962511] ffff880056f9b000 ffff8800576efca8 ffffffffa21c6a43 ffff880056f9bbe8 >> > [ 3461.007184] ffff880056f9bbe8 ffff8800576efd48 >> > [ 3461.017661] can: request_module (can-proto-0) failed. >> > [ 3461.045536] ffffffffa21636ea ffff8800576efcc8 >> > [ 3461.170992] Call Trace: >> > [ 3461.174122] dump_stack (lib/dump_stack.c:52) >> > [ 3461.558864] debug_check_no_locks_held (kernel/locking/lockdep.c:4107 kernel/locking/lockdep.c:4113) >> > [ 3461.577066] do_exit (kernel/exit.c:796) >> > [ 3461.592523] ? debug_smp_processor_id (lib/smp_processor_id.c:57) >> > [ 3461.629067] ? _raw_spin_unlock_irq (./arch/x86/include/asm/paravirt.h:819 include/linux/spinlock_api_smp.h:168 kernel/locking/spinlock.c:199) >> > [ 3461.671525] do_group_exit (kernel/exit.c:884) >> > [ 3461.717091] get_signal_to_deliver (kernel/signal.c:2347) >> > [ 3461.724142] ? vtime_account_user (kernel/sched/cputime.c:687) >> > [ 3461.800505] do_signal (arch/x86/kernel/signal.c:698) >> > [ 3461.808792] ? vtime_account_user (kernel/sched/cputime.c:687) >> > [ 3461.812780] ? preempt_count_sub (kernel/sched/core.c:2602) >> > [ 3461.824601] ? context_tracking_user_exit (./arch/x86/include/asm/paravirt.h:809 (discriminator 2) kernel/context_tracking.c:182 (discriminator 2)) >> > [ 3461.827619] ? __this_cpu_preempt_check (lib/smp_processor_id.c:63) >> > [ 3461.831486] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2557 kernel/locking/lockdep.c:2599) >> > [ 3461.841516] do_notify_resume (arch/x86/kernel/signal.c:751) >> > [ 3461.847056] retint_signal (arch/x86/kernel/entry_64.S:921) > > Huh.. Got me.. I don't see how the task can get out of > update_wall_time() w/o releasing the timekeeper_lock. Same with the > tick_broadcast_lock. Does this happen all the time or was this a > one-off? One-off, only seen once. Thanks, Sasha