From b014bebab047e9fdf2df45f6504ccbeaca446321 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Thu, 7 Mar 2019 16:26:50 -0800 Subject: [PATCH] kernel/hung_task.c: Use continuously blocked time when reporting. Since commit a2e514453861 ("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@I-love.SAKURA.ne.jp Signed-off-by: Tetsuo Handa Acked-by: Dmitry Vyukov Cc: "Paul E. McKenney" Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/hung_task.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/hung_task.c b/kernel/hung_task.c index 0c11216171c9..f108a95882c6 100644 --- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -127,7 +127,7 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout) 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, " "),