queue-4.9/kernel-hung_task.c-disable-on-suspend.patch

   1 From 247952e5f2aad78b1a083c465816434289beceff Mon Sep 17 00:00:00 2001
   2 From: Vitaly Kuznetsov <vkuznets@redhat.com>
   3 Date: Wed, 17 Oct 2018 13:23:55 +0200
   4 Subject: kernel: hung_task.c: disable on suspend
   5
   6 [ Upstream commit a1c6ca3c6de763459a6e93b644ec6518c890ba1c ]
   7
   8 It is possible to observe hung_task complaints when system goes to
   9 suspend-to-idle state:
  10
  11  # echo freeze > /sys/power/state
  12
  13  PM: Syncing filesystems ... done.
  14  Freezing user space processes ... (elapsed 0.001 seconds) done.
  15  OOM killer disabled.
  16  Freezing remaining freezable tasks ... (elapsed 0.002 seconds) done.
  17  sd 0:0:0:0: [sda] Synchronizing SCSI cache
  18  INFO: task bash:1569 blocked for more than 120 seconds.
  19        Not tainted 4.19.0-rc3_+ #687
  20  "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  21  bash            D    0  1569    604 0x00000000
  22  Call Trace:
  23   ? __schedule+0x1fe/0x7e0
  24   schedule+0x28/0x80
  25   suspend_devices_and_enter+0x4ac/0x750
  26   pm_suspend+0x2c0/0x310
  27
  28 Register a PM notifier to disable the detector on suspend and re-enable
  29 back on wakeup.
  30
  31 Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
  32 Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
  33 Signed-off-by: Sasha Levin <sashal@kernel.org>
  34 ---
  35  kernel/hung_task.c | 30 +++++++++++++++++++++++++++++-
  36  1 file changed, 29 insertions(+), 1 deletion(-)
  37
  38 diff --git a/kernel/hung_task.c b/kernel/hung_task.c
  39 index fd781a468f32..fb00cf30abd1 100644
  40 --- a/kernel/hung_task.c
  41 +++ b/kernel/hung_task.c
  42 @@ -15,6 +15,7 @@
  43  #include <linux/lockdep.h>
  44  #include <linux/export.h>
  45  #include <linux/sysctl.h>
  46 +#include <linux/suspend.h>
  47  #include <linux/utsname.h>
  48  #include <trace/events/sched.h>
  49
  50 @@ -221,6 +222,28 @@ void reset_hung_task_detector(void)
  51  }
  52  EXPORT_SYMBOL_GPL(reset_hung_task_detector);
  53
  54 +static bool hung_detector_suspended;
  55 +
  56 +static int hungtask_pm_notify(struct notifier_block *self,
  57 +                             unsigned long action, void *hcpu)
  58 +{
  59 +       switch (action) {
  60 +       case PM_SUSPEND_PREPARE:
  61 +       case PM_HIBERNATION_PREPARE:
  62 +       case PM_RESTORE_PREPARE:
  63 +               hung_detector_suspended = true;
  64 +               break;
  65 +       case PM_POST_SUSPEND:
  66 +       case PM_POST_HIBERNATION:
  67 +       case PM_POST_RESTORE:
  68 +               hung_detector_suspended = false;
  69 +               break;
  70 +       default:
  71 +               break;
  72 +       }
  73 +       return NOTIFY_OK;
  74 +}
  75 +
  76  /*
  77   * kthread which checks for tasks stuck in D state
  78   */
  79 @@ -235,7 +258,8 @@ static int watchdog(void *dummy)
  80                 long t = hung_timeout_jiffies(hung_last_checked, timeout);
  81
  82                 if (t <= 0) {
  83 -                       if (!atomic_xchg(&reset_hung_task, 0))
  84 +                       if (!atomic_xchg(&reset_hung_task, 0) &&
  85 +                           !hung_detector_suspended)
  86                                 check_hung_uninterruptible_tasks(timeout);
  87                         hung_last_checked = jiffies;
  88                         continue;
  89 @@ -249,6 +273,10 @@ static int watchdog(void *dummy)
  90  static int __init hung_task_init(void)
  91  {
  92         atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
  93 +
  94 +       /* Disable hung task detector on suspend */
  95 +       pm_notifier(hungtask_pm_notify, 0);
  96 +
  97         watchdog_task = kthread_run(watchdog, NULL, "khungtaskd");
  98
  99         return 0;
 100 --
 101 2.19.1
 102