From: Petr Mladek pmladek@suse.com
[ Upstream commit c9ad17c991492f4390f42598f6ab0531f87eed07 ]
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 Signed-off-by: Sasha Levin sashal@kernel.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));