Re: rc5+tip/master: Marking clocksource 'tsc' as unstable because the skew is too large:

[Thomas Gleixner]

On Thu, 30 Jun 2016, Mike Galbraith wrote:
> 
> Lunch rendered me (yawn) comatose, so I'm a bit late, but sent.

Patch below should fix the issue - the timer one, not yours :)

Thanks,

        tglx

8<------------

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 3e0c4e60bf6a..2b72eda3dc79 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -531,28 +531,37 @@ __internal_add_timer(struct timer_base *base, struct 
timer_list *timer)
 static void
 trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer)
 {
+       if (!IS_ENABLED(CONFIG_NO_HZ_COMMON) || !base->nohz_active)
+               return;
+
+       /*
+        * This wants some optimizing similar to the below, but we do that
+        * when we switch from push to pull for deferrable timers.
+        */
+       if (timer->flags & TIMER_DEFERRABLE) {
+               if (tick_nohz_full_cpu(base->cpu))
+                       wake_up_nohz_cpu(base->cpu);
+               return;
+       }
+
        /*
         * We might have to IPI the remote CPU if the base is idle and the
         * timer is not deferrable. If the other cpu is on the way to idle
         * then it can't set base->is_idle as we hold base lock.
         */
-       if (!IS_ENABLED(CONFIG_NO_HZ_COMMON) || !base->is_idle ||
-           (timer->flags & TIMER_DEFERRABLE))
+       if (!base->is_idle)
                return;
 
        /* Check whether this is the new first expiring timer */
        if (time_after_eq(timer->expires, base->next_expiry))
                return;
-       base->next_expiry = timer->expires;
 
        /*
-        * Check whether the other CPU is in dynticks mode and needs to be
-        * triggered to reevaluate the timer wheel.  We are protected against
-        * the other CPU fiddling with the timer by holding the timer base
-        * lock.
+        * Set the next expiry time and kick the cpu so it can reevaluate the
+        * wheel
         */
-       if (tick_nohz_full_cpu(base->cpu))
-               wake_up_nohz_cpu(base->cpu);
+       base->next_expiry = timer->expires;
+       wake_up_nohz_cpu(base->cpu);
 }
 
 static void