From: Thomas Gleixner <[email protected]> This patch has been added to the 3.12 stable tree. If you have any objections, please let us know.
=============== commit 0e576acbc1d9600cf2d9b4a141a2554639959d50 upstream. 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 <[email protected]> Reported-by: Borislav Petkov <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Signed-off-by: Jiri Slaby <[email protected]> --- kernel/time/tick-sched.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 3612fc77f834..d78253eb3b74 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -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; -- 1.9.0 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
