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

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

[gregkh]

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 <stable@vger.kernel.org> know about it.


>From 1ca8ec532fc2d986f1f4a319857bb18e0c9739b4 Mon Sep 17 00:00:00 2001
From: Wanpeng Li <kernellwp@gmail.com>
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 <kernellwp@gmail.com>

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.

Fixes: commit 0ff53d096422 "tick: sched: Force tick interrupt and get rid of softirq magic"
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1453893967-3458-1-git-send-email-wanpeng.li@hotmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -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 kernellwp@gmail.com are

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