The starting cpu is not yet in the online mask so irq_set_affinity() fails which results in per cpu timers for this cpu ending up on some other online cpu, ususally cpu 0. Use irq_force_affinity() which disables the online mask check and makes things work. Signed-off-by: Thomas Gleixner --- drivers/clocksource/exynos_mct.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) Index: tip/drivers/clocksource/exynos_mct.c =================================================================== --- tip.orig/drivers/clocksource/exynos_mct.c +++ tip/drivers/clocksource/exynos_mct.c @@ -430,6 +430,7 @@ static int exynos4_local_timer_setup(str evt->irq); return -EIO; } + irq_force_affinity(mct_irqs[MCT_L0_IRQ + cpu], cpumask_of(cpu)); } else { enable_percpu_irq(mct_irqs[MCT_L0_IRQ], 0); } @@ -450,7 +451,6 @@ static int exynos4_mct_cpu_notify(struct unsigned long action, void *hcpu) { struct mct_clock_event_device *mevt; - unsigned int cpu; /* * Grab cpu pointer in each case to avoid spurious @@ -461,12 +461,6 @@ static int exynos4_mct_cpu_notify(struct mevt = this_cpu_ptr(&percpu_mct_tick); exynos4_local_timer_setup(&mevt->evt); break; - case CPU_ONLINE: - cpu = (unsigned long)hcpu; - if (mct_int_type == MCT_INT_SPI) - irq_set_affinity(mct_irqs[MCT_L0_IRQ + cpu], - cpumask_of(cpu)); - break; case CPU_DYING: mevt = this_cpu_ptr(&percpu_mct_tick); exynos4_local_timer_stop(&mevt->evt);