Commit 71afdf4f authored by Yang Yingliang's avatar Yang Yingliang Committed by Zheng Zengkai
Browse files

timer_list: avoid other cpu soft lockup when printing timer list 

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4IYRE



---------------------------

If system has many cpus (e.g. 128), it will spend a lot of time to
print message to the console when execute echo q > /proc/sysrq-trigger.
When /proc/sys/kernel/numa_balancing is enabled, if the migration threads
is woke up, the thread cannot continue until the print finish, it will
trigger a soft lockup.

PID: 619    TASK: ffffa02fdd8bec80  CPU: 121  COMMAND: "migration/121"
  #0 [ffff00000a103b10] __crash_kexec at ffff0000081bf200
  #1 [ffff00000a103ca0] panic at ffff0000080ec93c
  #2 [ffff00000a103d80] watchdog_timer_fn at ffff0000081f8a14
  #3 [ffff00000a103e00] __run_hrtimer at ffff00000819701c
  #4 [ffff00000a103e40] __hrtimer_run_queues at ffff000008197420
  #5 [ffff00000a103ea0] hrtimer_interrupt at ffff00000819831c
  #6 [ffff00000a103f10] arch_timer_dying_cpu at ffff000008b53144
  #7 [ffff00000a103f30] handle_percpu_devid_irq at ffff000008174e34
  #8 [ffff00000a103f70] generic_handle_irq at ffff00000816c5e8
  #9 [ffff00000a103f90] __handle_domain_irq at ffff00000816d1f4
 #10 [ffff00000a103fd0] gic_handle_irq at ffff000008081860
 --- <IRQ stack> ---
 #11 [ffff00000d6e3d50] el1_irq at ffff0000080834c8
 #12 [ffff00000d6e3d60] multi_cpu_stop at ffff0000081d9964
 #13 [ffff00000d6e3db0] cpu_stopper_thread at ffff0000081d9cfc
 #14 [ffff00000d6e3e10] smpboot_thread_fn at ffff00000811e0a8
 #15 [ffff00000d6e3e70] kthread at ffff000008118988

To avoid this soft lockup, add touch_all_softlockup_watchdogs()
in sysrq_timer_list_show()

Signed-off-by: default avatarYang Yingliang <yangyingliang@huawei.com>
Reviewed-By: default avatarXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: default avatarYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: default avatarwangxiongfeng 00379786 <wangxiongfeng2@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent afe2f64a

kernel/time/timer_list.c

+6 −2
Original line number Diff line number Diff line
@@ -289,13 +289,17 @@ void sysrq_timer_list_show(void) 


	timer_list_header(NULL, now);



	for_each_online_cpu(cpu)

	for_each_online_cpu(cpu) {

		touch_all_softlockup_watchdogs();

		print_cpu(NULL, cpu, now);

	}



#ifdef CONFIG_GENERIC_CLOCKEVENTS

	timer_list_show_tickdevices_header(NULL);

	for_each_online_cpu(cpu)

	for_each_online_cpu(cpu) {

		touch_all_softlockup_watchdogs();

		print_tickdevice(NULL, tick_get_device(cpu), cpu);

	}

#endif

	return;

}