Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752570Ab3GAEmO (ORCPT ); Mon, 1 Jul 2013 00:42:14 -0400 Received: from e28smtp04.in.ibm.com ([122.248.162.4]:39730 "EHLO e28smtp04.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751346Ab3GAEmL (ORCPT ); Mon, 1 Jul 2013 00:42:11 -0400 Message-ID: <51D10899.1080501@linux.vnet.ibm.com> Date: Mon, 01 Jul 2013 12:42:01 +0800 From: Michael Wang User-Agent: Mozilla/5.0 (X11; Linux i686; rv:16.0) Gecko/20121011 Thunderbird/16.0.1 MIME-Version: 1.0 To: Sergey Senozhatsky CC: Jiri Kosina , Borislav Petkov , "Rafael J. Wysocki" , Viresh Kumar , "Srivatsa S. Bhat" , linux-kernel@vger.kernel.org, cpufreq@vger.kernel.org, linux-pm@vger.kernel.org Subject: Re: [LOCKDEP] cpufreq: possible circular locking dependency detected References: <20130625211544.GA2270@swordfish> In-Reply-To: <20130625211544.GA2270@swordfish> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13070104-5564-0000-0000-00000898ED4C Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5508 Lines: 115 Hi, Sergey On 06/26/2013 05:15 AM, Sergey Senozhatsky wrote: [snip] > > [ 60.277848] Chain exists of: > (&(&j_cdbs->work)->work) --> &j_cdbs->timer_mutex --> cpu_hotplug.lock > > [ 60.277864] Possible unsafe locking scenario: > > [ 60.277869] CPU0 CPU1 > [ 60.277873] ---- ---- > [ 60.277877] lock(cpu_hotplug.lock); > [ 60.277885] lock(&j_cdbs->timer_mutex); > [ 60.277892] lock(cpu_hotplug.lock); > [ 60.277900] lock((&(&j_cdbs->work)->work)); > [ 60.277907] > *** DEADLOCK *** It may caused by that 'j_cdbs->work.work' and 'j_cdbs->timer_mutex' has the same lock class, although they are different lock... This may help fix the issue: diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c index 5af40ad..aa05eaa 100644 --- a/drivers/cpufreq/cpufreq_governor.c +++ b/drivers/cpufreq/cpufreq_governor.c @@ -229,6 +229,8 @@ static void set_sampling_rate(struct dbs_data *dbs_data, } } +static struct lock_class_key j_cdbs_key; + int cpufreq_governor_dbs(struct cpufreq_policy *policy, struct common_dbs_data *cdata, unsigned int event) { @@ -366,6 +368,8 @@ int (struct cpufreq_policy *policy, kcpustat_cpu(j).cpustat[CPUTIME_NICE]; mutex_init(&j_cdbs->timer_mutex); + lockdep_set_class(&j_cdbs->timer_mutex, &j_cdbs_key); + INIT_DEFERRABLE_WORK(&j_cdbs->work, dbs_data->cdata->gov_dbs_timer); } Would you like to take a try? Regards, Michael Wang > > [ 60.277915] 6 locks held by bash/2225: > [ 60.277919] #0: (sb_writers#6){.+.+.+}, at: [] vfs_write+0x1c3/0x1f0 > [ 60.277937] #1: (&buffer->mutex){+.+.+.}, at: [] sysfs_write_file+0x3c/0x150 > [ 60.277954] #2: (s_active#61){.+.+.+}, at: [] sysfs_write_file+0xc3/0x150 > [ 60.277972] #3: (x86_cpu_hotplug_driver_mutex){+.+...}, at: [] cpu_hotplug_driver_lock+0x17/0x20 > [ 60.277990] #4: (cpu_add_remove_lock){+.+.+.}, at: [] cpu_down+0x22/0x50 > [ 60.278007] #5: (cpu_hotplug.lock){+.+.+.}, at: [] cpu_hotplug_begin+0x2b/0x60 > [ 60.278023] > stack backtrace: > [ 60.278031] CPU: 3 PID: 2225 Comm: bash Not tainted 3.10.0-rc7-dbg-01385-g241fd04-dirty #1744 > [ 60.278037] Hardware name: Acer Aspire 5741G /Aspire 5741G , BIOS V1.20 02/08/2011 > [ 60.278042] ffffffff8204e110 ffff88014df6b9f8 ffffffff815b3d90 ffff88014df6ba38 > [ 60.278055] ffffffff815b0a8d ffff880150ed3f60 ffff880150ed4770 3871c4002c8980b2 > [ 60.278068] ffff880150ed4748 ffff880150ed4770 ffff880150ed3f60 ffff88014df6bb00 > [ 60.278081] Call Trace: > [ 60.278091] [] dump_stack+0x19/0x1b > [ 60.278101] [] print_circular_bug+0x2b6/0x2c5 > [ 60.278111] [] __lock_acquire+0x1766/0x1d30 > [ 60.278123] [] ? __kernel_text_address+0x58/0x80 > [ 60.278134] [] lock_acquire+0xa4/0x200 > [ 60.278142] [] ? flush_work+0x5/0x280 > [ 60.278151] [] flush_work+0x3d/0x280 > [ 60.278159] [] ? flush_work+0x5/0x280 > [ 60.278169] [] ? mark_held_locks+0x94/0x140 > [ 60.278178] [] ? __cancel_work_timer+0x77/0x120 > [ 60.278188] [] ? trace_hardirqs_on_caller+0xfd/0x1c0 > [ 60.278196] [] __cancel_work_timer+0x8a/0x120 > [ 60.278206] [] cancel_delayed_work_sync+0x13/0x20 > [ 60.278214] [] cpufreq_governor_dbs+0x529/0x6f0 > [ 60.278225] [] cs_cpufreq_governor_dbs+0x17/0x20 > [ 60.278234] [] __cpufreq_governor+0x48/0x100 > [ 60.278244] [] __cpufreq_remove_dev.isra.14+0x80/0x3c0 > [ 60.278255] [] cpufreq_cpu_callback+0x38/0x4c > [ 60.278265] [] notifier_call_chain+0x5d/0x110 > [ 60.278275] [] __raw_notifier_call_chain+0xe/0x10 > [ 60.278284] [] _cpu_down+0x88/0x330 > [ 60.278292] [] ? cpu_hotplug_driver_lock+0x17/0x20 > [ 60.278302] [] cpu_down+0x36/0x50 > [ 60.278311] [] store_online+0x98/0xd0 > [ 60.278320] [] dev_attr_store+0x18/0x30 > [ 60.278329] [] sysfs_write_file+0xdb/0x150 > [ 60.278337] [] vfs_write+0xbd/0x1f0 > [ 60.278347] [] ? fget_light+0x320/0x4b0 > [ 60.278355] [] SyS_write+0x4c/0xa0 > [ 60.278364] [] tracesys+0xd0/0xd5 > [ 60.280582] smpboot: CPU 1 is now offline > > > -ss > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/