While running some testing on code that happened to allow the variable
tick_nohz_full_running to get set but with no "possible" NOHZ cores to
back up that setting, I tripped this WARN:
if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE))
WARN_ON(tick_nohz_full_running);
The console was overwhemled with an endless stream of one WARN per tick
per core and there was no way to even see what was going on w/o using a
serial console to capture it and then trace it back to this guy.
Changing it to ONCE reveals that we get the message we need in a
civilized fashion, and the system can limp along until rebooted.
Fixes: 08ae95f4fd3b ("nohz_full: Allow the boot CPU to be nohz_full")
Cc: Nicholas Piggin <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Signed-off-by: Paul Gortmaker <[email protected]>
---
kernel/time/tick-sched.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 17a283ce2b20..5e80ee44c32a 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -186,7 +186,7 @@ static void tick_sched_do_timer(struct tick_sched *ts, ktime_t now)
*/
if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE)) {
#ifdef CONFIG_NO_HZ_FULL
- WARN_ON(tick_nohz_full_running);
+ WARN_ON_ONCE(tick_nohz_full_running);
#endif
tick_do_timer_cpu = cpu;
}
--
2.17.1