Commit 0e576acb authored Nov 29, 2013 by Thomas Gleixner

nohz: Fix another inconsistency between CONFIG_NO_HZ=n and nohz=off



If CONFIG_NO_HZ=n tick_nohz_get_sleep_length() returns NSEC_PER_SEC/HZ.

If CONFIG_NO_HZ=y and the nohz functionality is disabled via the
command line option "nohz=off" or not enabled due to missing hardware
support, then tick_nohz_get_sleep_length() returns 0. That happens
because ts->sleep_length is never set in that case.

Set it to NSEC_PER_SEC/HZ when the NOHZ mode is inactive.

Reported-by: Michal Hocko <mhocko@suse.cz>
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

parent 70fe8217

kernel/time/tick-sched.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -711,8 +711,10 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
		return false;
		}

		if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE))
		if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE)) {
		ts->sleep_length = (ktime_t) { .tv64 = NSEC_PER_SEC/HZ };
		return false;
		}

		if (need_resched())
		return false;