From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759744Ab2INRyG (ORCPT ); Fri, 14 Sep 2012 13:54:06 -0400 Received: from e1.ny.us.ibm.com ([32.97.182.141]:59988 "EHLO e1.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758624Ab2INRyB (ORCPT ); Fri, 14 Sep 2012 13:54:01 -0400 Date: Fri, 14 Sep 2012 10:53:22 -0700 From: "Paul E. McKenney" To: Linus Walleij Cc: John Stultz , Daniel Lezcano , linux-kernel@vger.kernel.org Subject: Re: RCU lockup in the SMP idle thread, help... Message-ID: <20120914175322.GI4257@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <50520E8A.9030408@linaro.org> <20120913165844.GW4257@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) x-cbid: 12091417-6078-0000-0000-00000F83171A Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 14, 2012 at 09:27:32AM +0200, Linus Walleij wrote: > On Thu, Sep 13, 2012 at 6:58 PM, Paul E. McKenney > wrote: > > On Thu, Sep 13, 2012 at 09:49:14AM -0700, John Stultz wrote: > >> I saw this once as well testing the fix to Daniel's deep idle hang > >> issue (also on 32 bit). > > John, what system was this? If it's not Snowball/ux500 we can atleast > conclude that > it's a generic bug, not machine-specific... > > >> Really briefly looking at the code in rcutree.c, I'm curious if > >> we're hitting a false positive on the 5 minute jiffies overflow? > > > > Hmmm... Might be. Does the patch below help? > > Sorry, nope, I get this: Could you please try reproducing with CONFIG_RCU_CPU_STALL_INFO=y? Thanx, Paul > root@ME:/ > root@ME:/ INFO: rcu_preempt detected stalls on CPUs/tasks: { 0} > (detected by 1, t=29545 jiffies) > [] (unwind_backtrace+0x0/0xf8) from [] > (rcu_check_callbacks+0x6e0/0x76c) > [] (rcu_check_callbacks+0x6e0/0x76c) from [] > (update_process_times+0x38/0x4c) > [] (update_process_times+0x38/0x4c) from [] > (tick_sched_timer+0x80/0xe4) > [] (tick_sched_timer+0x80/0xe4) from [] > (__run_hrtimer.isra.18+0x44/0xd0) > [] (__run_hrtimer.isra.18+0x44/0xd0) from [] > (hrtimer_interrupt+0x118/0x2b4) > [] (hrtimer_interrupt+0x118/0x2b4) from [] > (twd_handler+0x30/0x44) > [] (twd_handler+0x30/0x44) from [] > (handle_percpu_devid_irq+0x80/0xa0) > [] (handle_percpu_devid_irq+0x80/0xa0) from [] > (generic_handle_irq+0x20/0x30) > [] (generic_handle_irq+0x20/0x30) from [] > (handle_IRQ+0x4c/0xac) > [] (handle_IRQ+0x4c/0xac) from [] (gic_handle_irq+0x24/0x58) > [] (gic_handle_irq+0x24/0x58) from [] (__irq_svc+0x40/0x70) > Exception stack(0xcf865f88 to 0xcf865fd0) > 5f80: 00000020 c05c0a20 00000001 00000000 cf864000 cf864000 > 5fa0: c05dfe48 c02de0bc c05c3e90 412fc091 cf864000 00000000 01000000 cf865fd0 > 5fc0: c000f234 c000f238 60000013 ffffffff > [] (__irq_svc+0x40/0x70) from [] (default_idle+0x28/0x30) > [] (default_idle+0x28/0x30) from [] (cpu_idle+0x98/0xe4) > [] (cpu_idle+0x98/0xe4) from [<002d3094>] (0x2d3094) > INFO: rcu_preempt detected stalls on CPUs/tasks: { 0} (detected by 1, > t=30029 jiffies) > [] (unwind_backtrace+0x0/0xf8) from [] > (rcu_check_callbacks+0x6e0/0x76c) > [] (rcu_check_callbacks+0x6e0/0x76c) from [] > (update_process_times+0x38/0x4c) > [] (update_process_times+0x38/0x4c) from [] > (tick_sched_timer+0x80/0xe4) > [] (tick_sched_timer+0x80/0xe4) from [] > (__run_hrtimer.isra.18+0x44/0xd0) > [] (__run_hrtimer.isra.18+0x44/0xd0) from [] > (hrtimer_interrupt+0x118/0x2b4) > [] (hrtimer_interrupt+0x118/0x2b4) from [] > (twd_handler+0x30/0x44) > [] (twd_handler+0x30/0x44) from [] > (handle_percpu_devid_irq+0x80/0xa0) > [] (handle_percpu_devid_irq+0x80/0xa0) from [] > (generic_handle_irq+0x20/0x30) > [] (generic_handle_irq+0x20/0x30) from [] > (handle_IRQ+0x4c/0xac) > [] (handle_IRQ+0x4c/0xac) from [] (gic_handle_irq+0x24/0x58) > [] (gic_handle_irq+0x24/0x58) from [] (__irq_svc+0x40/0x70) > Exception stack(0xcf865f88 to 0xcf865fd0) > 5f80: 00000020 c05c0a20 00000001 00000000 cf864000 cf864000 > 5fa0: c05dfe48 c02de0bc c05c3e90 412fc091 cf864000 00000000 01000000 cf865fd0 > 5fc0: c000f234 c000f238 60000013 ffffffff > [] (__irq_svc+0x40/0x70) from [] (default_idle+0x28/0x30) > [] (default_idle+0x28/0x30) from [] (cpu_idle+0x98/0xe4) > [] (cpu_idle+0x98/0xe4) from [<002d3094>] (0x2d3094) > > I'm all confused .. > > Yours, > Linus Walleij >