Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753285AbbGNPyT (ORCPT ); Tue, 14 Jul 2015 11:54:19 -0400 Received: from mail-lb0-f169.google.com ([209.85.217.169]:36451 "EHLO mail-lb0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752318AbbGNPyQ (ORCPT ); Tue, 14 Jul 2015 11:54:16 -0400 MIME-Version: 1.0 Date: Tue, 14 Jul 2015 12:54:15 -0300 Message-ID: Subject: mx6: suspicious RCU usage From: Fabio Estevam To: Russell King Cc: "linux-arm-kernel@lists.infradead.org" , Peter Zijlstra , Paul McKenney , rostedt@goodmis.org, linux-kernel Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3687 Lines: 99 Hi, I am running 4.2-rc2 on a mx6q board and I see the following warning when doing a suspend/resume cycle: $ echo mem > /sys/power/state PM: Syncing filesystems ... done. Freezing user space processes ... (elapsed 0.003 seconds) done. Freezing remaining freezable tasks ... (elapsed 0.003 seconds) done. Suspending console(s) (use no_console_suspend to debug) (Press GPIO button to wake up the system) PM: suspend of devices complete after 101.667 msecs PM: suspend devices took 0.110 seconds PM: late suspend of devices complete after 11.073 msecs PM: noirq suspend of devices complete after 9.432 msecs Disabling non-boot CPUs ... =============================== [ INFO: suspicious RCU usage. ] 4.2.0-rc2 #247 Not tainted ------------------------------- kernel/sched/fair.c:5032 suspicious rcu_dereference_check() usage! other info that might help us debug this: RCU used illegally from offline CPU! rcu_scheduler_active = 1, debug_locks = 0 3 locks held by swapper/1/0: #0: ((cpu_died).wait.lock){......}, at: [<800643e0>] complete+0x1c/0x4c #1: (&p->pi_lock){-.-.-.}, at: [<8004f7e8>] try_to_wake_up+0x34/0x3c8 #2: (rcu_read_lock){......}, at: [<80057b68>] select_task_rq_fair+0x64/0x9e8 stack backtrace: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.2.0-rc2 #247 Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree) Backtrace: [<80012ee8>] (dump_backtrace) from [<80013084>] (show_stack+0x18/0x1c) r6:000013a8 r5:00000000 r4:00000000 r3:00000000 [<8001306c>] (show_stack) from [<8078d364>] (dump_stack+0x88/0xa4) [<8078d2dc>] (dump_stack) from [<800676d8>] (lockdep_rcu_suspicious+0xbc/0x11c) r5:809497c4 r4:be076780 [<8006761c>] (lockdep_rcu_suspicious) from [<80058200>] (select_task_rq_fair+0x6fc/0x9e8) r7:80a94fc0 r6:00000001 r5:00000000 r4:00000000 [<80057b04>] (select_task_rq_fair) from [<8004f8cc>] (try_to_wake_up+0x118/0x3c8) r10:80a94fc0 r9:00000000 r8:00000000 r7:80000093 r6:80a98b2c r5:bd748f8c r4:bd748b80 [<8004f7b4>] (try_to_wake_up) from [<8004fb90>] (default_wake_function+0x14/0x18) r10:00000003 r9:8004fb7c r8:00000000 r7:00000000 r6:80a9dc34 r5:00000001 r4:80a9dc28 [<8004fb7c>] (default_wake_function) from [<80063b18>] (__wake_up_common+0x58/0x98) [<80063ac0>] (__wake_up_common) from [<80063b74>] (__wake_up_locked+0x1c/0x24) r10:80a98b2c r9:807993ac r8:80a98a10 r7:80afc552 r6:60000093 r5:80a9dc10 r4:80a9dc14 [<80063b58>] (__wake_up_locked) from [<80064400>] (complete+0x3c/0x4c) [<800643c4>] (complete) from [<807870e0>] (cpu_die+0x3c/0xa4) r6:80a923e4 r5:00000001 r4:80a98968 r3:00000002 [<807870a4>] (cpu_die) from [<80010798>] (arch_cpu_idle_dead+0x10/0x14) r5:80a989c4 r4:00000000 [<80010788>] (arch_cpu_idle_dead) from [<80064798>] (cpu_startup_entry+0x1d8/0x200) [<800645c0>] (cpu_startup_entry) from [<80015e34>] (secondary_start_kernel+0x120/0x13c) r7:80aff360 [<80015d14>] (secondary_start_kernel) from [<1000962c>] (0x1000962c) r5:00000015 r4:4e08806a CPU1: shutdown CPU2: shutdown CPU3: shutdown Enabling non-boot CPUs ... CPU1 is up CPU2 is up CPU3 is up PM: noirq resume of devices complete after 2.185 msecs PM: early resume of devices complete after 2.786 msecs PM: resume of devices complete after 204.223 msecs PM: resume devices took 0.200 seconds ata1: SATA link down (SStatus 0 SControl 300) PM: Finishing wakeup. Restarting tasks ... done. I haven't started bisecting it yet, but if someone has some ideas, please let me know. Regards, Fabio Estevam -- 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/