From c9ad17c991492f4390f42598f6ab0531f87eed07 Mon Sep 17 00:00:00 2001
From: Petr Mladek <pmladek@suse.com>
Date: Thu, 29 Apr 2021 22:54:23 -0700
Subject: [PATCH] watchdog: explicitly update timestamp when reporting
softlockup
Git-commit: c9ad17c991492f4390f42598f6ab0531f87eed07
Patch-mainline: v5.13-rc1
References: bsc#1185982
The softlockup situation might stay for a long time or even forever. When
it happens, the softlockup debug messages are printed in regular intervals
defined by get_softlockup_thresh().
There is a mystery. The repeated message is printed after the full
interval that is defined by get_softlockup_thresh(). But the timer
callback is called more often as defined by sample_period. The code looks
like the soflockup should get reported in every sample_period when it was
once behind the thresh.
It works only by chance. The watchdog is touched when printing the stall
report, for example, in printk_stack_address().
Make the behavior clear and predictable by explicitly updating the
timestamp in watchdog_timer_fn() when the report gets printed.
Link: https://lkml.kernel.org/r/20210311122130.6788-3-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/watchdog.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 8440e62bfec4..8efd2a8d9f10 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -410,6 +410,9 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
}
}
+ /* Start period for the next softlockup warning. */
+ update_touch_ts();
+
pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
smp_processor_id(), duration,
current->comm, task_pid_nr(current));
--
2.26.2