Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422868AbaDKQJJ (ORCPT ); Fri, 11 Apr 2014 12:09:09 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:56468 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759441AbaDKQHk (ORCPT ); Fri, 11 Apr 2014 12:07:40 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Stephen Boyd , Viresh Kumar , "Rafael J. Wysocki" , Krzysztof Kozlowski Subject: [PATCH 3.10 41/41] cpufreq: Fix timer/workqueue corruption due to double queueing Date: Fri, 11 Apr 2014 09:10:12 -0700 Message-Id: <20140411160936.059119908@linuxfoundation.org> X-Mailer: git-send-email 1.9.0 In-Reply-To: <20140411160932.865173041@linuxfoundation.org> References: <20140411160932.865173041@linuxfoundation.org> User-Agent: quilt/0.60-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Stephen Boyd commit 3617f2ca6d0eba48114308532945a7f1577816a4 upstream. When a CPU is hot removed we'll cancel all the delayed work items via gov_cancel_work(). Normally this will just cancels a delayed timer on each CPU that the policy is managing and the work won't run, but if the work is already running the workqueue code will wait for the work to finish before continuing to prevent the work items from re-queuing themselves like they normally do. This scheme will work most of the time, except for the case where the work function determines that it should adjust the delay for all other CPUs that the policy is managing. If this scenario occurs, the canceling CPU will cancel its own work but queue up the other CPUs works to run. For example: CPU0 CPU1 ---- ---- cpu_down() ... __cpufreq_remove_dev() cpufreq_governor_dbs() case CPUFREQ_GOV_STOP: gov_cancel_work(dbs_data, policy); cpu0 work is canceled timer is canceled cpu1 work is canceled od_dbs_timer() gov_queue_work(*, *, true); cpu0 work queued cpu1 work queued cpu2 work queued ... cpu1 work is canceled cpu2 work is canceled ... At the end of the GOV_STOP case cpu0 still has a work queued to run although the code is expecting all of the works to be canceled. __cpufreq_remove_dev() will then proceed to re-initialize all the other CPUs works except for the CPU that is going down. The CPUFREQ_GOV_START case in cpufreq_governor_dbs() will trample over the queued work and debugobjects will spit out a warning: WARNING: at lib/debugobjects.c:260 debug_print_object+0x94/0xbc() ODEBUG: init active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x10 Modules linked in: CPU: 0 PID: 1491 Comm: sh Tainted: G W 3.10.0 #19 [] (unwind_backtrace+0x0/0x11c) from [] (show_stack+0x10/0x14) [] (show_stack+0x10/0x14) from [] (warn_slowpath_common+0x4c/0x6c) [] (warn_slowpath_common+0x4c/0x6c) from [] (warn_slowpath_fmt+0x2c/0x3c) [] (warn_slowpath_fmt+0x2c/0x3c) from [] (debug_print_object+0x94/0xbc) [] (debug_print_object+0x94/0xbc) from [] (__debug_object_init+0x2d0/0x340) [] (__debug_object_init+0x2d0/0x340) from [] (init_timer_key+0x14/0xb0) [] (init_timer_key+0x14/0xb0) from [] (cpufreq_governor_dbs+0x3e8/0x5f8) [] (cpufreq_governor_dbs+0x3e8/0x5f8) from [] (__cpufreq_governor+0xdc/0x1a4) [] (__cpufreq_governor+0xdc/0x1a4) from [] (__cpufreq_remove_dev.isra.10+0x3b4/0x434) [] (__cpufreq_remove_dev.isra.10+0x3b4/0x434) from [] (cpufreq_cpu_callback+0x60/0x80) [] (cpufreq_cpu_callback+0x60/0x80) from [] (notifier_call_chain+0x38/0x68) [] (notifier_call_chain+0x38/0x68) from [] (__cpu_notify+0x28/0x40) [] (__cpu_notify+0x28/0x40) from [] (_cpu_down+0x7c/0x2c0) [] (_cpu_down+0x7c/0x2c0) from [] (cpu_down+0x24/0x40) [] (cpu_down+0x24/0x40) from [] (store_online+0x2c/0x74) [] (store_online+0x2c/0x74) from [] (dev_attr_store+0x18/0x24) [] (dev_attr_store+0x18/0x24) from [] (sysfs_write_file+0x100/0x148) [] (sysfs_write_file+0x100/0x148) from [] (vfs_write+0xcc/0x174) [] (vfs_write+0xcc/0x174) from [] (SyS_write+0x38/0x64) [] (SyS_write+0x38/0x64) from [] (ret_fast_syscall+0x0/0x30) Signed-off-by: Stephen Boyd Acked-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki Cc: Krzysztof Kozlowski Signed-off-by: Greg Kroah-Hartman --- drivers/cpufreq/cpufreq_governor.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/cpufreq/cpufreq_governor.c +++ b/drivers/cpufreq/cpufreq_governor.c @@ -177,6 +177,9 @@ void gov_queue_work(struct dbs_data *dbs { int i; + if (!policy->governor_enabled) + return; + if (!all_cpus) { __gov_queue_work(smp_processor_id(), dbs_data, delay); } else { -- 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/