Patch "tick/nohz: Set the correct expiry when switching to nohz/lowres mode" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

tick/nohz: Set the correct expiry when switching to nohz/lowres mode

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
tick-nohz-set-the-correct-expiry-when-switching-to-nohz-lowres-mode.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Wanpeng Li <[email protected]>
Date: Wed, 27 Jan 2016 19:26:07 +0800
Subject: tick/nohz: Set the correct expiry when switching to nohz/lowres mode

From: Wanpeng Li <[email protected]>

commit 1ca8ec532fc2d986f1f4a319857bb18e0c9739b4 upstream.

commit 0ff53d096422 sets the next tick interrupt to the last jiffies update, i.e. in the past, because the forward operation is invoked before the set operation. There is no resulting damage (yet), but we get an extra pointless tick interrupt.

Revert the order so we get the next tick interrupt in the future.

---
 kernel/time/tick-sched.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -977,9 +977,9 @@ static void tick_nohz_switch_to_nohz(voi
 	/* Get the next period */
 	next = tick_init_jiffy_update();
 
-	hrtimer_forward_now(&ts->sched_timer, tick_period);
 	hrtimer_set_expires(&ts->sched_timer, next);
-	tick_program_event(next, 1);
+	hrtimer_forward_now(&ts->sched_timer, tick_period);
+	tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1);
 	tick_nohz_activate(ts, NOHZ_MODE_LOWRES);
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/tick-nohz-set-the-correct-expiry-when-switching-to-nohz-lowres-mode.patch