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Commit e538759b authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Greg Kroah-Hartman
Browse files

kernel: hung_task.c: disable on suspend 



[ Upstream commit a1c6ca3c6de763459a6e93b644ec6518c890ba1c ]

It is possible to observe hung_task complaints when system goes to
suspend-to-idle state:

 # echo freeze > /sys/power/state

 PM: Syncing filesystems ... done.
 Freezing user space processes ... (elapsed 0.001 seconds) done.
 OOM killer disabled.
 Freezing remaining freezable tasks ... (elapsed 0.002 seconds) done.
 sd 0:0:0:0: [sda] Synchronizing SCSI cache
 INFO: task bash:1569 blocked for more than 120 seconds.
       Not tainted 4.19.0-rc3_+ #687
 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
 bash            D    0  1569    604 0x00000000
 Call Trace:
  ? __schedule+0x1fe/0x7e0
  schedule+0x28/0x80
  suspend_devices_and_enter+0x4ac/0x750
  pm_suspend+0x2c0/0x310

Register a PM notifier to disable the detector on suspend and re-enable
back on wakeup.

Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 1cc5afab

kernel/hung_task.c

+29 −1
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include <linux/lockdep.h>

#include <linux/export.h>

#include <linux/sysctl.h>

#include <linux/suspend.h>

#include <linux/utsname.h>

#include <trace/events/sched.h>
@@ -221,6 +222,28 @@ void reset_hung_task_detector(void) 
}

EXPORT_SYMBOL_GPL(reset_hung_task_detector);



static bool hung_detector_suspended;



static int hungtask_pm_notify(struct notifier_block *self,

			      unsigned long action, void *hcpu)

{

	switch (action) {

	case PM_SUSPEND_PREPARE:

	case PM_HIBERNATION_PREPARE:

	case PM_RESTORE_PREPARE:

		hung_detector_suspended = true;

		break;

	case PM_POST_SUSPEND:

	case PM_POST_HIBERNATION:

	case PM_POST_RESTORE:

		hung_detector_suspended = false;

		break;

	default:

		break;

	}

	return NOTIFY_OK;

}



/*

 * kthread which checks for tasks stuck in D state

 */
@@ -235,7 +258,8 @@ static int watchdog(void *dummy) 
		long t = hung_timeout_jiffies(hung_last_checked, timeout);



		if (t <= 0) {

			if (!atomic_xchg(&reset_hung_task, 0))

			if (!atomic_xchg(&reset_hung_task, 0) &&

			    !hung_detector_suspended)

				check_hung_uninterruptible_tasks(timeout);

			hung_last_checked = jiffies;

			continue;
@@ -249,6 +273,10 @@ static int watchdog(void *dummy) 
static int __init hung_task_init(void)

{

	atomic_notifier_chain_register(&panic_notifier_list, &panic_block);



	/* Disable hung task detector on suspend */

	pm_notifier(hungtask_pm_notify, 0);



	watchdog_task = kthread_run(watchdog, NULL, "khungtaskd");



	return 0;