From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758270Ab2CWMG1 (ORCPT ); Fri, 23 Mar 2012 08:06:27 -0400 Received: from mga14.intel.com ([143.182.124.37]:49684 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754988Ab2CWMG0 convert rfc822-to-8bit (ORCPT ); Fri, 23 Mar 2012 08:06:26 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="122408204" From: "Liu, Chuansheng" To: Peter Zijlstra CC: "linux-kernel@vger.kernel.org" , Yanmin Zhang , "tglx@linutronix.de" , "Srivatsa S. Bhat" Subject: RE: [PATCH] Fix the race between smp_call_function and CPU booting Thread-Topic: [PATCH] Fix the race between smp_call_function and CPU booting Thread-Index: AQHNCOzHl9Dk+9huC0G/K4y8uLiScJZ3yAYA Date: Fri, 23 Mar 2012 12:06:22 +0000 Message-ID: <27240C0AC20F114CBF8149A2696CBE4A05D689@SHSMSX101.ccr.corp.intel.com> References: <27240C0AC20F114CBF8149A2696CBE4A053BE8@SHSMSX101.ccr.corp.intel.com> <1331546307.18960.26.camel@twins> <27240C0AC20F114CBF8149A2696CBE4A054D70@SHSMSX101.ccr.corp.intel.com> <1331654251.18960.78.camel@twins> <27240C0AC20F114CBF8149A2696CBE4A0556FA@SHSMSX101.ccr.corp.intel.com> <1331718197.18960.106.camel@twins> <27240C0AC20F114CBF8149A2696CBE4A056F47@SHSMSX101.ccr.corp.intel.com> <1331808391.18960.160.camel@twins> <27240C0AC20F114CBF8149A2696CBE4A05806B@SHSMSX101.ccr.corp.intel.com> <1331891364.18960.221.camel@twins> <27240C0AC20F114CBF8149A2696CBE4A058AAE@SHSMSX101.ccr.corp.intel.com> <1332151397.18960.252.camel@twins> <27240C0AC20F114CBF8149A2696CBE4A05A6BF@SHSMSX101.ccr.corp.intel.com> <1332245842.18960.413.camel@twins> <27240C0AC20F114CBF8149A2696CBE4A05B485@SHSMSX101.ccr.corp.intel.com> <1332332739.18960.488.camel@twins> <27240C0AC20F114CBF8149A2696CBE4A05C092@SHSMSX101.ccr.corp.intel.com> <1332498333.16159.9.camel@twins> <27240C0AC20F114CBF8149A2696CBE4A05D65B@SHSMSX101.ccr.corp.intel.com> <1332504120.16159.17.camel@twins> In-Reply-To: <1332504120.16159.17.camel@twins> Accept-Language: zh-CN, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sorry to not see your scripts in details. If so, I has something wrong about merging your change of select_fallback_rq()? I am using 3.0.8. I indeed see the warning even with the change of select_fallback_rq(). > -----Original Message----- > From: Peter Zijlstra [mailto:peterz@infradead.org] > Sent: Friday, March 23, 2012 8:02 PM > To: Liu, Chuansheng > Cc: linux-kernel@vger.kernel.org; Yanmin Zhang; tglx@linutronix.de; Srivatsa S. > Bhat > Subject: RE: [PATCH] Fix the race between smp_call_function and CPU booting > > On Fri, 2012-03-23 at 11:32 +0000, Liu, Chuansheng wrote: > > In fact, I started two scripts running: > > 1/ One script: > > echo 0 > /sys/devices/system/cpuX/online echo 1 > > > /sys/devices/system/cpuX/online Rerunning the above commands in loop > > > > 2/Another script: > > echo 1 > /debug/smp_call_test > > usleep 50000 > > Rerunning the above command in loop > > > > This race issue can be easy to be reproduced in several minutes; For > > simplify your test as mine(just two CPUs), you can set other > > non-booting CPUs as offline at first and just leave one non-booting CPU. > > So this is exactly what I did and it ran for 30+ minutes without fail. I found I > forgot to log the serial output so I just re-ran this to make sure. 10+ minutes > and not a single WARN in the console output. > > If I pop my change to select_fallback_rq() I can indeed trigger this: > > ------------[ cut here ]------------ > WARNING: at /usr/src/linux-2.6/arch/x86/kernel/smp.c:120 > native_smp_send_reschedule+0x5b/0x60() > Hardware name: X8DTN > Modules linked in: [last unloaded: scsi_wait_scan] > Pid: 1542, comm: abrtd Not tainted 3.3.0-01725-gd6eb054-dirty #63 Call Trace: > [] warn_slowpath_common+0x7f/0xc0 > [] warn_slowpath_null+0x1a/0x20 [] > native_smp_send_reschedule+0x5b/0x60 > [] try_to_wake_up+0x1fa/0x2c0 [] ? > sched_slice.isra.38+0x5c/0x90 [] > wake_up_process+0x15/0x20 [] process_timeout+0xe/0x10 > [] run_timer_softirq+0x143/0x460 [] ? > timerqueue_add+0x74/0xc0 [] ? usleep_range+0x50/0x50 > [] __do_softirq+0xbd/0x290 [] ? > clockevents_program_event+0x74/0x100 > [] ? tick_program_event+0x24/0x30 [] > call_softirq+0x1c/0x30 [] do_softirq+0x55/0x90 > [] irq_exit+0x9e/0xe0 [] > smp_apic_timer_interrupt+0x6e/0x99 > [] apic_timer_interrupt+0x67/0x70 ---[ end trace > d2b2cbf78c1ddd2e ]--- > > > But let me re-run with the select_fallback_rq() change and let it run > for several hours while I go play outside..