From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932169Ab2HQOqO (ORCPT ); Fri, 17 Aug 2012 10:46:14 -0400 Received: from e3.ny.us.ibm.com ([32.97.182.143]:43267 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755359Ab2HQOqA (ORCPT ); Fri, 17 Aug 2012 10:46:00 -0400 Date: Fri, 17 Aug 2012 07:44:37 -0700 From: "Paul E. McKenney" To: Fengguang Wu Cc: Thomas Gleixner , Steven Rostedt , linux-kernel@vger.kernel.org Subject: Re: lockdep warning on rt_mutex_lock() Message-ID: <20120817144437.GC2872@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20120817100635.GA30765@localhost> <20120817134328.GB2872@linux.vnet.ibm.com> <20120817140240.GB539@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120817140240.GB539@localhost> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12081714-8974-0000-0000-00000C4CBB2A Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 17, 2012 at 10:02:40PM +0800, Fengguang Wu wrote: > On Fri, Aug 17, 2012 at 06:43:28AM -0700, Paul E. McKenney wrote: > > On Fri, Aug 17, 2012 at 06:06:35PM +0800, Fengguang Wu wrote: > > > Greetings, > > > > > > FYI, a lockdep warning: > > > > Certainly looks problematic! > > > > Any hint as to what version of the kernel produced this splat? > > (Yes, lazy of me to ask, I know, but I am not seeing it in my testing.) > > It happens on both 3.5.0 and 3.6-rc1. Will bisect (try older kernels) help? > Bisect is handy for me :) Bisection would be very welcome!!! ;-) > Sorry the back trace in the original email only happens in _one_ test box. > That makes it hard to reproduce.. > > The more common test boxes see these traces (with different config). > I'll send full config/dmesg for the first one in another email. Ah, I see part of my difficulty earlier -- I was looking at TREE_PREEMPT_RCU rather than the TINY_PREEMPT_RCU you are actually running here. Thanx, Paul > [ 24.647556] init: Temporary process spawn error: No such file or directory > [ 24.806072] ------------[ cut here ]------------ > [ 24.807042] WARNING: at /c/kernel-tests/src/linux/kernel/lockdep.c:3493 check_flags+0x113/0x2a7() > [ 24.807042] Hardware name: Bochs > [ 24.807042] Pid: 8, comm: rcu_kthread Not tainted 3.6.0-rc1-00011-gf8cdda8 #2 > [ 24.807042] Call Trace: > [ 24.807042] [] ? up+0x50/0x5c > [ 24.807042] [] warn_slowpath_common+0xb3/0xe1 > [ 24.807042] [] warn_slowpath_null+0x23/0x2c > [ 24.807042] [] check_flags+0x113/0x2a7 > [ 24.807042] [] lock_is_held+0x4b/0xe4 > [ 24.807042] [] __might_sleep+0x4e/0x277 > [ 24.807042] [] rt_mutex_lock+0x23/0x54 > [ 24.807042] [] rcu_boost+0xeb/0x140 > [ 24.807042] [] ? _raw_spin_unlock_irqrestore+0x78/0xeb > [ 24.807042] [] ? spin_unlock_irqrestore+0x10/0x19 > [ 24.807042] [] ? finish_wait+0x8f/0x9f > [ 24.807042] [] rcu_kthread+0xf2/0x1f0 > [ 24.807042] [] ? abort_exclusive_wait+0xb7/0xb7 > [ 24.807042] [] ? __rcu_process_callbacks+0x1b4/0x1b4 > [ 24.807042] [] kthread+0x95/0xa4 > [ 24.807042] [] kernel_thread_helper+0x4/0x10 > [ 24.807042] [] ? retint_restore_args+0x13/0x13 > [ 24.807042] [] ? freezing+0x2c/0x2c > [ 24.807042] [] ? gs_change+0x13/0x13 > > [ 22.951027] [sched_delayed] sched: RT throttling activated > [ 34.752102] ------------[ cut here ]------------ > [ 34.753023] WARNING: at /c/kernel-tests/src/tip/kernel/lockdep.c:3493 check_flags+0xc1/0x1d0() > [ 34.753023] Pid: 6, comm: rcu_kthread Not tainted 3.5.0-03701-g899852a #1 > [ 34.753023] Call Trace: > [ 34.753023] [] ? check_flags+0xc1/0x1d0 > [ 34.753023] [] warn_slowpath_common+0x66/0x90 > [ 34.753023] [] warn_slowpath_null+0x15/0x20 > [ 34.753023] [] check_flags+0xc1/0x1d0 > [ 34.753023] [] lock_acquire+0x63/0xe0 > [ 34.753023] [] ? update_curr_rt+0xd6/0x190 > [ 34.753023] [] _raw_spin_lock+0x3b/0x50 > [ 34.753023] [] ? rt_mutex_slowlock+0x38/0x150 > [ 34.753023] [] rt_mutex_slowlock+0x38/0x150 > [ 34.753023] [] ? __raw_spin_lock_init+0x38/0x70 > [ 34.753023] [] rt_mutex_lock+0x28/0x30 > [ 34.753023] [] rcu_boost+0x76/0xf0 > [ 34.753023] [] rcu_kthread+0xa5/0x140 > [ 34.753023] [] ? abort_exclusive_wait+0xa0/0xa0 > [ 34.753023] [] ? __rcu_process_callbacks+0x100/0x100 > [ 34.753023] [] kthread+0x8d/0xa0 > [ 34.753023] [] kernel_thread_helper+0x4/0x10 > [ 34.753023] [] ? retint_restore_args+0x13/0x13 > [ 34.753023] [] ? kthread_flush_work_fn+0x10/0x10 > [ 34.753023] [] ? gs_change+0x13/0x13 > > [ 11.635806] HugeTLB registered 4 MB page size, pre-allocated 0 pages > [ 12.105729] ------------[ cut here ]------------ > [ 12.105729] WARNING: at /c/kernel-tests/src/i386/kernel/lockdep.c:3493 check_flags+0xaa/0x190() > [ 12.105729] Hardware name: Bochs > [ 12.105729] Pid: 6, comm: rcu_kthread Not tainted 3.5.0-rc5+ #30 > [ 12.105729] Call Trace: > [ 12.105729] [] warn_slowpath_common+0x7a/0xa0 > [ 12.105729] [] ? check_flags+0xaa/0x190 > [ 12.105729] [] ? check_flags+0xaa/0x190 > [ 12.105729] [] warn_slowpath_null+0x1d/0x20 > [ 12.105729] [] check_flags+0xaa/0x190 > [ 12.105729] [] lock_acquire+0x3c/0xb0 > [ 12.105729] [] ? sched_clock+0x8/0x10 > [ 12.105729] [] ? sched_clock_local.constprop.2+0x15/0x150 > [ 12.105729] [] _raw_spin_lock+0x40/0x70 > [ 12.105729] [] ? rt_mutex_slowlock+0x26/0x130 > [ 12.105729] [] rt_mutex_slowlock+0x26/0x130 > [ 12.105729] [] ? debug_check_no_locks_freed+0x127/0x160 > [ 12.105729] [] ? put_lock_stats.isra.19+0xd/0x30 > [ 12.105729] [] rt_mutex_lock+0x19/0x20 > [ 12.105729] [] rcu_kthread+0x10c/0x1c0 > [ 12.105729] [] ? preempt_schedule+0x2f/0x50 > [ 12.105729] [] ? complete+0x49/0x60 > [ 12.105729] [] ? __rcu_process_callbacks+0x110/0x110 > [ 12.105729] [] kthread+0x67/0x70 > [ 12.105729] [] ? kthread_flush_work_fn+0x10/0x10 > [ 12.105729] [] kernel_thread_helper+0x6/0xd > > Thanks, > Fengguang >