From e0eada00b127f9a684e3ccc3931d67791b1a76f7 Mon Sep 17 00:00:00 2001 From: Grygorii Strashko Date: Fri, 11 Sep 2015 21:21:23 +0300 Subject: [PATCH] ARM: smp: Move clear_tasks_mm_cpumask() call to __cpu_die() When running with the RT-kernel (4.1.5-rt5) on TI OMAP dra7-evm and trying to do Suspend to RAM, the following backtrace occurs: Disabling non-boot CPUs ... PM: noirq suspend of devices complete after 7.295 msecs Disabling non-boot CPUs ... BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:917 in_atomic(): 1, irqs_disabled(): 128, pid: 18, name: migration/1 INFO: lockdep is turned off. irq event stamp: 122 hardirqs last enabled at (121): [] _raw_spin_unlock_irqrestore+0x88/0x90 hardirqs last disabled at (122): [] _raw_spin_lock_irq+0x28/0x5c softirqs last enabled at (0): [] copy_process.part.52+0x410/0x19d8 softirqs last disabled at (0): [< (null)>] (null) Preemption disabled at:[< (null)>] (null) CPU: 1 PID: 18 Comm: migration/1 Tainted: G W 4.1.4-rt3-01046-g96ac8da #204 Hardware name: Generic DRA74X (Flattened Device Tree) [] (unwind_backtrace) from [] (show_stack+0x20/0x24) [] (show_stack) from [] (dump_stack+0x88/0xdc) [] (dump_stack) from [] (___might_sleep+0x198/0x2a8) [] (___might_sleep) from [] (rt_spin_lock+0x30/0x70) [] (rt_spin_lock) from [] (find_lock_task_mm+0x9c/0x174) [] (find_lock_task_mm) from [] (clear_tasks_mm_cpumask+0xb4/0x1ac) [] (clear_tasks_mm_cpumask) from [] (__cpu_disable+0x98/0xbc) [] (__cpu_disable) from [] (take_cpu_down+0x1c/0x50) [] (take_cpu_down) from [] (multi_cpu_stop+0x11c/0x158) [] (multi_cpu_stop) from [] (cpu_stopper_thread+0xc4/0x184) [] (cpu_stopper_thread) from [] (smpboot_thread_fn+0x18c/0x324) [] (smpboot_thread_fn) from [] (kthread+0xe8/0x104) [] (kthread) from [] (ret_from_fork+0x14/0x3c) CPU1: shutdown PM: Calling sched_clock_suspend+0x0/0x40 PM: Calling timekeeping_suspend+0x0/0x2e0 PM: Calling irq_gc_suspend+0x0/0x68 PM: Calling fw_suspend+0x0/0x2c PM: Calling cpu_pm_suspend+0x0/0x28 Also, sometimes system stucks right after displaying "Disabling non-boot CPUs ...". The root cause of above backtrace is task_lock() which takes a sleeping lock on -RT. To fix the issue, move clear_tasks_mm_cpumask() call from __cpu_disable() to __cpu_die() which is called on the thread which is asking for a target CPU to be shutdown. In addition, this change restores CPUhotplug functionality on TI OMAP dra7-evm and CPU1 can be unplugged/plugged many times. Signed-off-by: Grygorii Strashko Cc: Steven Rostedt Cc: Cc: Sekhar Nori Cc: Austin Schuh Cc: Cc: Russell King Cc: Cc: stable-rt@vger.kernel.org Link: http://lkml.kernel.org/r/1441995683-30817-1-git-send-email-grygorii.strashko@ti.com Signed-off-by: Thomas Gleixner --- arch/arm/kernel/smp.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index c9a0a529982793..7e5122af96ca4b 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -236,8 +236,6 @@ int __cpu_disable(void) flush_cache_louis(); local_flush_tlb_all(); - clear_tasks_mm_cpumask(cpu); - return 0; } @@ -255,6 +253,7 @@ void __cpu_die(unsigned int cpu) } pr_debug("CPU%u: shutdown\n", cpu); + clear_tasks_mm_cpumask(cpu); /* * platform_cpu_kill() is generally expected to do the powering off * and/or cutting of clocks to the dying CPU. Optionally, this may