From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756933Ab2IGITV (ORCPT ); Fri, 7 Sep 2012 04:19:21 -0400 Received: from mga11.intel.com ([192.55.52.93]:48306 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752088Ab2IGITQ (ORCPT ); Fri, 7 Sep 2012 04:19:16 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.80,384,1344236400"; d="scan'208";a="219241720" Date: Fri, 7 Sep 2012 16:17:29 +0800 From: Fengguang Wu To: Peter Zijlstra Cc: Michael Wang , LKML , x86@kernel.org, Suresh Siddha , Venkatesh Pallipadi Subject: Re: WARNING: cpu_is_offline() at native_smp_send_reschedule() Message-ID: <20120907081729.GA19473@localhost> References: <20120905011152.GA19853@localhost> <5046D69F.9000705@linux.vnet.ibm.com> <1346842480.2461.11.camel@laptop> <20120905125700.GA5833@localhost> <20120907012058.GA9000@localhost> <1347002596.18408.84.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1347002596.18408.84.camel@twins> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 07, 2012 at 09:23:16AM +0200, Peter Zijlstra wrote: > On Fri, 2012-09-07 at 09:20 +0800, Fengguang Wu wrote: > > > FYI, the bisect result is > > > > commit 554cecaf733623b327eef9652b65965eb1081b81 > > Author: Diwakar Tundlam > > Date: Wed Mar 7 14:44:26 2012 -0800 > > > > sched/nohz: Correctly initialize 'next_balance' in 'nohz' idle balancer > > > > The 'next_balance' field of 'nohz' idle balancer must be initialized > > to jiffies. Since jiffies is initialized to negative 300 seconds the > > 'nohz' idle balancer does not run for the first 300s (5mins) after > > bootup. If no new processes are spawed or no idle cycles happen, the > > load on the cpus will remain unbalanced for that duration. > > > > Signed-off-by: Diwakar Tundlam > > Signed-off-by: Peter Zijlstra > > Link: http://lkml.kernel.org/r/1DD7BFEDD3147247B1355BEFEFE4665237994F30EF@HQMAIL04.nvidia.com > > Signed-off-by: Ingo Molnar > > Oh fun.. does the below 'fix' it? > > The thing I'm thinking of a tick happening right after we set jiffies > but before the zalloc (specifically the memset(0)) is complete. Since > we've already registered the softirq we can end up in the load-balancer > and see a completely weird idle mask. > > Hmm? The may be more causes, since I still get the warning: [ 9.816279] reboot: machine restart [ 9.835796] ------------[ cut here ]------------ [ 9.836558] WARNING: at /c/wfg/linux/arch/x86/kernel/smp.c:123 native_smp_send_reschedule+0x46/0x50() [ 9.839792] Pid: 18, comm: kworker/0:1 Not tainted 3.6.0-rc3-bisect-00005-gb374aa1-dirty #49 [ 9.839792] Call Trace: [ 9.839792] [<7902f42a>] warn_slowpath_common+0x5a/0x80 [ 9.839792] [<7901ee16>] ? native_smp_send_reschedule+0x46/0x50 [ 9.839792] [<7901ee16>] ? native_smp_send_reschedule+0x46/0x50 [ 9.839792] [<7902f4fd>] warn_slowpath_null+0x1d/0x20 [ 9.839792] [<7901ee16>] native_smp_send_reschedule+0x46/0x50 [ 9.839792] [<7905fdad>] trigger_load_balance+0x1bd/0x250 [ 9.839792] [<79056d14>] scheduler_tick+0xd4/0x100 [ 9.839792] [<7903bde5>] update_process_times+0x55/0x70 [ 9.839792] [<79071187>] tick_sched_timer+0x57/0xb0 [ 9.839792] [<793accee>] ? do_raw_spin_unlock+0x4e/0x90 [ 9.839792] [<7904e0b7>] __run_hrtimer.isra.29+0x57/0x100 [ 9.839792] [<79071130>] ? tick_nohz_handler+0xe0/0xe0 [ 9.839792] [<7904ed45>] hrtimer_interrupt+0xe5/0x280 [ 9.839792] [<7905a5a7>] ? sched_clock_cpu+0xc7/0x150 [ 9.839792] [<7901f9a4>] smp_apic_timer_interrupt+0x54/0x90 [ 9.839792] [<79882631>] apic_timer_interrupt+0x31/0x40 [ 9.839792] [<7905007b>] ? call_srcu+0x2b/0x70 [ 9.839792] [<793a00e0>] ? __bitmap_intersects+0x10/0x80 [ 9.839792] [<7988194f>] ? _raw_spin_unlock_irq+0x1f/0x40 [ 9.839792] [<7905307f>] finish_task_switch+0x7f/0xd0 [ 9.839792] [<79053038>] ? finish_task_switch+0x38/0xd0 [ 9.839792] [<7988044a>] __schedule+0x38a/0x770 [ 9.839792] [<79045529>] ? worker_thread+0x1a9/0x380 [ 9.839792] [<793accee>] ? do_raw_spin_unlock+0x4e/0x90 [ 9.839792] [<7988084e>] schedule+0x1e/0x50 [ 9.839792] [<7904552e>] worker_thread+0x1ae/0x380 [ 9.839792] [<79056ed9>] ? complete+0x49/0x60 [ 9.839792] [<79045380>] ? manage_workers.isra.23+0x250/0x250 [ 9.839792] [<79049ff8>] kthread+0x78/0x80 [ 9.839792] [<79880000>] ? __up.isra.0+0xd/0x2d [ 9.839792] [<79049f80>] ? insert_kthread_work+0x70/0x70 [ 9.839792] [<798830c6>] kernel_thread_helper+0x6/0xd Thanks, Fengguang