Messages in this thread Patch in this message | | | From | Paul Gortmaker <> | Subject | [PATCH 2/2] tick/nohz: WARN_ON --> WARN_ON_ONCE to prevent console saturation | Date | Mon, 6 Dec 2021 09:59:50 -0500 |
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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 <npiggin@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> --- 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 6bffe5af8cb1..19e6b861de97 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
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