The patch titled
Subject: kernel/hung_task.c: Use continuously blocked time when reporting.
has been added to the -mm tree. Its filename is
kernel-hung_taskc-use-continuously-blocked-time-when-reporting.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kernel-hung_taskc-use-continuously-blocked-time-when-reporting.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kernel-hung_taskc-use-continuously-blocked-time-when-reporting.patch
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------------------------------------------------------
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Subject: kernel/hung_task.c: Use continuously blocked time when reporting.
Since commit a2e514453861dd39 ("kernel/hung_task.c: allow to set checking
interval separately from timeout") added hung_task_check_interval_secs,
setting a value different from hung_task_timeout_secs
echo 0 > /proc/sys/kernel/hung_task_panic
echo 120 > /proc/sys/kernel/hung_task_timeout_secs
echo 5 > /proc/sys/kernel/hung_task_check_interval_secs
causes confusing output as if the task was blocked for
hung_task_timeout_secs seconds from the previous report.
[ 399.395930] INFO: task kswapd0:75 blocked for more than 120 seconds.
[ 405.027637] INFO: task kswapd0:75 blocked for more than 120 seconds.
[ 410.659725] INFO: task kswapd0:75 blocked for more than 120 seconds.
[ 416.292860] INFO: task kswapd0:75 blocked for more than 120 seconds.
[ 421.932305] INFO: task kswapd0:75 blocked for more than 120 seconds.
Although we could update t->last_switch_time after sched_show_task(t) if
we want to report only every 120 seconds, reporting every 5 seconds might
not be very bad for monitoring after a problematic situation has started.
Thus, let's use continuously blocked time instead of updating previously
reported time.
[ 677.985011] INFO: task kswapd0:80 blocked for more than 122 seconds.
[ 693.856126] INFO: task kswapd0:80 blocked for more than 138 seconds.
[ 709.728075] INFO: task kswapd0:80 blocked for more than 154 seconds.
[ 725.600018] INFO: task kswapd0:80 blocked for more than 170 seconds.
[ 741.473133] INFO: task kswapd0:80 blocked for more than 186 seconds.
Link: http://lkml.kernel.org/r/1551175083-10669-1-git-send-email-penguin-kernel@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Acked-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/hung_task.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/hung_task.c~kernel-hung_taskc-use-continuously-blocked-time-when-reporting
+++ a/kernel/hung_task.c
@@ -127,7 +127,7 @@ static void check_hung_task(struct task_
if (sysctl_hung_task_warnings > 0)
sysctl_hung_task_warnings--;
pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
- t->comm, t->pid, timeout);
+ t->comm, t->pid, (jiffies - t->last_switch_time) / HZ);
pr_err(" %s %s %.*s\n",
print_tainted(), init_utsname()->release,
(int)strcspn(init_utsname()->version, " "),
_
Patches currently in -mm which might be from penguin-kernel@xxxxxxxxxxxxxxxxxxx are
memcg-killed-threads-should-not-invoke-memcg-oom-killer.patch
mmoom-dont-kill-global-init-via-memoryoomgroup.patch
info-task-hung-in-generic_file_write_iter.patch
info-task-hung-in-generic_file_write-fix.patch
kernel-hung_taskc-use-continuously-blocked-time-when-reporting.patch
