debug: softlockup looping fix
Rafael J. Wysocki reported weird, multi-seconds delays during
suspend/resume and bisected it back to:
commit 82a1fcb90287052aabfa235e7ffc693ea003fe69
Author: Ingo Molnar <mingo@elte.hu>
Date: Fri Jan 25 21:08:02 2008 +0100
softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasks
fix it:
- restore the old wakeup mechanism
- fix break usage in do_each_thread() { } while_each_thread().
- fix the hotplug switch stmt, a fall-through case was broken.
Bisected-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index c1d7655..7c2da88 100644
--- a/kernel/softlockup.c
+++ b/kernel/softlockup.c
@@ -101,6 +101,10 @@
now = get_timestamp(this_cpu);
+ /* Wake up the high-prio watchdog task every second: */
+ if (now > (touch_timestamp + 1))
+ wake_up_process(per_cpu(watchdog_task, this_cpu));
+
/* Warn about unreasonable delays: */
if (now <= (touch_timestamp + softlockup_thresh))
return;
@@ -191,11 +195,11 @@
read_lock(&tasklist_lock);
do_each_thread(g, t) {
if (!--max_count)
- break;
+ goto unlock;
if (t->state & TASK_UNINTERRUPTIBLE)
check_hung_task(t, now);
} while_each_thread(g, t);
-
+ unlock:
read_unlock(&tasklist_lock);
}
@@ -218,14 +222,19 @@
* debug-printout triggers in softlockup_tick().
*/
while (!kthread_should_stop()) {
+ set_current_state(TASK_INTERRUPTIBLE);
touch_softlockup_watchdog();
- msleep_interruptible(10000);
+ schedule();
+
+ if (kthread_should_stop())
+ break;
if (this_cpu != check_cpu)
continue;
if (sysctl_hung_task_timeout_secs)
check_hung_uninterruptible_tasks(this_cpu);
+
}
return 0;
@@ -259,13 +268,6 @@
wake_up_process(per_cpu(watchdog_task, hotcpu));
break;
#ifdef CONFIG_HOTPLUG_CPU
- case CPU_UP_CANCELED:
- case CPU_UP_CANCELED_FROZEN:
- if (!per_cpu(watchdog_task, hotcpu))
- break;
- /* Unbind so it can run. Fall thru. */
- kthread_bind(per_cpu(watchdog_task, hotcpu),
- any_online_cpu(cpu_online_map));
case CPU_DOWN_PREPARE:
case CPU_DOWN_PREPARE_FROZEN:
if (hotcpu == check_cpu) {
@@ -275,6 +277,14 @@
check_cpu = any_online_cpu(temp_cpu_online_map);
}
break;
+
+ case CPU_UP_CANCELED:
+ case CPU_UP_CANCELED_FROZEN:
+ if (!per_cpu(watchdog_task, hotcpu))
+ break;
+ /* Unbind so it can run. Fall thru. */
+ kthread_bind(per_cpu(watchdog_task, hotcpu),
+ any_online_cpu(cpu_online_map));
case CPU_DEAD:
case CPU_DEAD_FROZEN:
p = per_cpu(watchdog_task, hotcpu);
