diff options
| -rw-r--r-- | include/linux/sched/hotplug.h | 4 | ||||
| -rw-r--r-- | kernel/cpu.c | 9 | ||||
| -rw-r--r-- | kernel/sched/core.c | 22 |
3 files changed, 20 insertions, 15 deletions
diff --git a/include/linux/sched/hotplug.h b/include/linux/sched/hotplug.h index 412cdaba33eb..17e04859b9a4 100644 --- a/include/linux/sched/hotplug.h +++ b/include/linux/sched/hotplug.h @@ -18,10 +18,6 @@ extern int sched_cpu_dying(unsigned int cpu); # define sched_cpu_dying NULL #endif -#ifdef CONFIG_HOTPLUG_CPU -extern void idle_task_exit(void); -#else static inline void idle_task_exit(void) {} -#endif #endif /* _LINUX_SCHED_HOTPLUG_H */ diff --git a/kernel/cpu.c b/kernel/cpu.c index b605334f8ee6..7f3bf759cbdf 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -905,12 +905,13 @@ static int finish_cpu(unsigned int cpu) struct mm_struct *mm = idle->active_mm; /* - * idle_task_exit() will have switched to &init_mm, now - * clean up any remaining active_mm state. + * sched_force_init_mm() ensured the use of &init_mm, + * drop that refcount now that the CPU has stopped. */ - if (mm != &init_mm) - idle->active_mm = &init_mm; + WARN_ON(mm != &init_mm); + idle->active_mm = NULL; mmdrop_lazy_tlb(mm); + return 0; } diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 755ae4659b64..6fbf4c373a50 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7930,19 +7930,26 @@ void sched_setnuma(struct task_struct *p, int nid) #ifdef CONFIG_HOTPLUG_CPU /* - * Ensure that the idle task is using init_mm right before its CPU goes - * offline. + * Invoked on the outgoing CPU in context of the CPU hotplug thread + * after ensuring that there are no user space tasks left on the CPU. + * + * If there is a lazy mm in use on the hotplug thread, drop it and + * switch to init_mm. + * + * The reference count on init_mm is dropped in finish_cpu(). */ -void idle_task_exit(void) +static void sched_force_init_mm(void) { struct mm_struct *mm = current->active_mm; - BUG_ON(cpu_online(smp_processor_id())); - BUG_ON(current != this_rq()->idle); - if (mm != &init_mm) { - switch_mm(mm, &init_mm, current); + mmgrab_lazy_tlb(&init_mm); + local_irq_disable(); + current->active_mm = &init_mm; + switch_mm_irqs_off(mm, &init_mm, current); + local_irq_enable(); finish_arch_post_lock_switch(); + mmdrop_lazy_tlb(mm); } /* finish_cpu(), as ran on the BP, will clean up the active_mm state */ @@ -8344,6 +8351,7 @@ int sched_cpu_starting(unsigned int cpu) int sched_cpu_wait_empty(unsigned int cpu) { balance_hotplug_wait(); + sched_force_init_mm(); return 0; } |