| Message ID | 1441995683-30817-1-git-send-email-grygorii.strashko@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 48185a7..7ee0912 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -230,8 +230,6 @@ int __cpu_disable(void) flush_cache_louis(); local_flush_tlb_all(); - clear_tasks_mm_cpumask(cpu); - return 0; } @@ -247,6 +245,9 @@ void __cpu_die(unsigned int cpu) pr_err("CPU%u: cpu didn't die\n", cpu); return; } + + clear_tasks_mm_cpumask(cpu); + pr_notice("CPU%u: shutdown\n", cpu); /*
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): [<c06ac0ac>] _raw_spin_unlock_irqrestore+0x88/0x90 hardirqs last disabled at (122): [<c06abed0>] _raw_spin_lock_irq+0x28/0x5c softirqs last enabled at (0): [<c003d294>] 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) [<c0019134>] (unwind_backtrace) from [<c0014774>] (show_stack+0x20/0x24) [<c0014774>] (show_stack) from [<c06a70f4>] (dump_stack+0x88/0xdc) [<c06a70f4>] (dump_stack) from [<c006cab8>] (___might_sleep+0x198/0x2a8) [<c006cab8>] (___might_sleep) from [<c06ac4dc>] (rt_spin_lock+0x30/0x70) [<c06ac4dc>] (rt_spin_lock) from [<c013f790>] (find_lock_task_mm+0x9c/0x174) [<c013f790>] (find_lock_task_mm) from [<c00409ac>] (clear_tasks_mm_cpumask+0xb4/0x1ac) [<c00409ac>] (clear_tasks_mm_cpumask) from [<c00166a4>] (__cpu_disable+0x98/0xbc) [<c00166a4>] (__cpu_disable) from [<c06a2e8c>] (take_cpu_down+0x1c/0x50) [<c06a2e8c>] (take_cpu_down) from [<c00f2600>] (multi_cpu_stop+0x11c/0x158) [<c00f2600>] (multi_cpu_stop) from [<c00f2a9c>] (cpu_stopper_thread+0xc4/0x184) [<c00f2a9c>] (cpu_stopper_thread) from [<c0069058>] (smpboot_thread_fn+0x18c/0x324) [<c0069058>] (smpboot_thread_fn) from [<c00649c4>] (kthread+0xe8/0x104) [<c00649c4>] (kthread) from [<c0010058>] (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 <grygorii.strashko@ti.com> --- RFC: I'm not sure how safe this change is and will be appreciated for any comments. Most of arches call clear_tasks_mm_cpumask() from __cpu_disable(), but *powerpc* calls it from CPU_DEAD notifier. This patch follows powerpc's approach in general. This issue was first reported in: http://www.spinics.net/lists/linux-rt-users/msg13752.html arch/arm/kernel/smp.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)