From: Petr Mladek <pmladek@xxxxxxxx> Subject: watchdog: explicitly update timestamp when reporting softlockup 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@xxxxxxxx Signed-off-by: Petr Mladek <pmladek@xxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Laurence Oberman <loberman@xxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Vincent Whitchurch <vincent.whitchurch@xxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/watchdog.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/watchdog.c~watchdog-explicitly-update-timestamp-when-reporting-softlockup +++ a/kernel/watchdog.c @@ -410,6 +410,9 @@ static enum hrtimer_restart watchdog_tim } } + /* 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)); _
