From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux Subject: 3.18: lockdep problems in cpufreq Date: Sun, 14 Dec 2014 21:36:55 +0000 Message-ID: <20141214213655.GA11285@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from gw-1.arm.linux.org.uk ([78.32.30.217]:58111 "EHLO pandora.arm.linux.org.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751023AbaLNVhL (ORCPT ); Sun, 14 Dec 2014 16:37:11 -0500 Content-Disposition: inline Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: linux-arm-kernel@lists.infradead.org, "Rafael J. Wysocki" , Viresh Kumar , linux-pm@vger.kernel.org Here's a nice Christmas present one of my iMX6 machines gave me tonight. I haven't begun to look into it. ====================================================== [ INFO: possible circular locking dependency detected ] 3.18.0+ #1453 Not tainted ------------------------------------------------------- rc.local/770 is trying to acquire lock: (cooling_cpufreq_lock){+.+.+.}, at: [] cpufreq_thermal_notifier+0x34/0xfc but task is already holding lock: ((cpufreq_policy_notifier_list).rwsem){++++.+}, at: [] __blocking_notifier_call_chain+0x34/0x68 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 ((cpufreq_policy_notifier_list).rwsem){++++.+}: [] down_write+0x44/0x9c [] blocking_notifier_chain_register+0x28/0xd8 [] cpufreq_register_notifier+0x68/0x90 [] __cpufreq_cooling_register.part.1+0x120/0x180 [] __cpufreq_cooling_register+0x98/0xa4 [] cpufreq_cooling_register+0x18/0x1c [] imx_thermal_probe+0x1c0/0x470 [imx_thermal] [] platform_drv_probe+0x50/0xac [] driver_probe_device+0x114/0x234 [] __driver_attach+0x9c/0xa0 [] bus_for_each_dev+0x5c/0x90 [] driver_attach+0x24/0x28 [] bus_add_driver+0xe0/0x1d8 [] driver_register+0x80/0xfc [] __platform_driver_register+0x50/0x64 [] 0xbf007018 [] do_one_initcall+0x88/0x1d8 [] load_module+0x1768/0x1ef8 [] SyS_init_module+0xe0/0xf4 [] ret_fast_syscall+0x0/0x48 -> #0 (cooling_cpufreq_lock){+.+.+.}: [] lock_acquire+0xb0/0x124 [] mutex_lock_nested+0x5c/0x3d8 [] cpufreq_thermal_notifier+0x34/0xfc [] notifier_call_chain+0x4c/0x8c [] __blocking_notifier_call_chain+0x50/0x68 [] blocking_notifier_call_chain+0x20/0x28 [] cpufreq_set_policy+0x7c/0x1d0 [] store_scaling_governor+0x74/0x9c [] store+0x90/0xc0 [] sysfs_kf_write+0x54/0x58 [] kernfs_fop_write+0xdc/0x190 [] vfs_write+0xac/0x1b4 [] SyS_write+0x44/0x90 [] ret_fast_syscall+0x0/0x48 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((cpufreq_policy_notifier_list).rwsem); lock(cooling_cpufreq_lock); lock((cpufreq_policy_notifier_list).rwsem); lock(cooling_cpufreq_lock); *** DEADLOCK *** 7 locks held by rc.local/770: #0: (sb_writers#6){.+.+.+}, at: [] vfs_write+0x18c/0x1b4 #1: (&of->mutex){+.+.+.}, at: [] kernfs_fop_write+0xa0/0x190 #2: (s_active#52){.+.+.+}, at: [] kernfs_fop_write+0xa8/0x190 #3: (cpu_hotplug.lock){++++++}, at: [] get_online_cpus+0x34/0x90 #4: (cpufreq_rwsem){.+.+.+}, at: [] store+0x58/0xc0 #5: (&policy->rwsem){+.+.+.}, at: [] store+0x70/0xc0 #6: ((cpufreq_policy_notifier_list).rwsem){++++.+}, at: [] __blocking_notifier_call_chain+0x34/0x68 stack backtrace: CPU: 0 PID: 770 Comm: rc.local Not tainted 3.18.0+ #1453 Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree) Backtrace: [] (dump_backtrace) from [] (show_stack+0x18/0x1c) r6:c0b85a80 r5:c0b75630 r4:00000000 r3:00000000 [] (show_stack) from [] (dump_stack+0x7c/0x98) [] (dump_stack) from [] (print_circular_bug+0x28c/0x2d8) r4:c0b85a80 r3:d0071d40 [] (print_circular_bug) from [] (__lock_acquire+0x1acc/0x1bb0) r10:c0b50660 r8:c09e6d80 r7:d0071d40 r6:c11d0f0c r5:00000007 r4:d0072240 [] (__lock_acquire) from [] (lock_acquire+0xb0/0x124) r10:00000000 r9:c04abfc4 r8:00000000 r7:00000000 r6:00000000 r5:c0a06f0c r4:00000000 [] (lock_acquire) from [] (mutex_lock_nested+0x5c/0x3d8) r10:ec853800 r9:c0a06ed4 r8:d0071d40 r7:c0a06ed4 r6:c11d0f0c r5:00000000 r4:c04abfc4 [] (mutex_lock_nested) from [] (cpufreq_thermal_notifier+0x34/0xfc) r10:ec853800 r9:ec85380c r8:d00d7d3c r7:c0a06ed4 r6:d00d7d3c r5:00000000 r4:fffffffe [] (cpufreq_thermal_notifier) from [] (notifier_call_chain+0x4c/0x8c) r7:00000000 r6:00000000 r5:00000000 r4:fffffffe [] (notifier_call_chain) from [] (__blocking_notifier_call_chain+0x50/0x68) r8:c0a072a4 r7:00000000 r6:d00d7d3c r5:ffffffff r4:c0a06fc8 r3:ffffffff [] (__blocking_notifier_call_chain) from [] (blocking_notifier_call_chain+0x20/0x28) r7:ec98b540 r6:c13ebc80 r5:ed76e600 r4:d00d7d3c [] (blocking_notifier_call_chain) from [] (cpufreq_set_policy+0x7c/0x1d0) [] (cpufreq_set_policy) from [] (store_scaling_governor+0x74/0x9c) r7:ec98b540 r6:0000000c r5:ec98b540 r4:ed76e600 [] (store_scaling_governor) from [] (store+0x90/0xc0) r6:0000000c r5:ed76e6d4 r4:ed76e600 [] (store) from [] (sysfs_kf_write+0x54/0x58) r8:0000000c r7:d00d7f78 r6:ec98b540 r5:0000000c r4:ec853800 r3:0000000c [] (sysfs_kf_write) from [] (kernfs_fop_write+0xdc/0x190) r6:ec98b540 r5:00000000 r4:00000000 r3:c0175330 [] (kernfs_fop_write) from [] (vfs_write+0xac/0x1b4) r10:0162aa70 r9:d00d6000 r8:0000000c r7:d00d7f78 r6:0162aa70 r5:0000000c r4:eccde500 [] (vfs_write) from [] (SyS_write+0x44/0x90) r10:0162aa70 r8:0000000c r7:eccde500 r6:eccde500 r5:00000000 r4:00000000 [] (SyS_write) from [] (ret_fast_syscall+0x0/0x48) r10:00000000 r8:c000edc4 r7:00000004 r6:000216cc r5:0000000c r4:0162aa70 -- FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up according to speedtest.net.