[PATCH v3] kernel/hung_task.c: disable on suspend
From: Vitaly Kuznetsov <vkuznets@redhat.com>
Date: 2018-10-16 16:55:22
Also in:
lkml
Subsystem:
hung task detector, the rest · Maintainers:
Andrew Morton, Linus Torvalds
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: Vitaly Kuznetsov <vkuznets@redhat.com>
---
Changes since v2:
- Resurrect 'v1' as zeroing timeouts can be racy [Rafael J. Wysocki]
---
kernel/hung_task.c | 28 +++++++++++++++++++++++++++-
1 file changed, 27 insertions(+), 1 deletion(-)
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index b9132d1269ef..41955c5d8427 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c@@ -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 <linux/sched/signal.h> #include <linux/sched/debug.h>
@@ -242,6 +243,26 @@ 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: + hung_detector_suspended = true; + break; + case PM_POST_SUSPEND: + case PM_POST_HIBERNATION: + hung_detector_suspended = false; + break; + default: + break; + } + return NOTIFY_OK; +} + /* * kthread which checks for tasks stuck in D state */
@@ -261,7 +282,8 @@ static int watchdog(void *dummy) interval = min_t(unsigned long, interval, timeout); t = hung_timeout_jiffies(hung_last_checked, interval); 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;
@@ -275,6 +297,10 @@ 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;
--
2.17.1