Pull scheduler fixes from Ingo Molnar: "Two smaller fixes - plus a context tracking tracing fix that is a bit bigger" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: tracing/context-tracking: Add preempt_schedule_context() for tracing sched: Fix clear NOHZ_BALANCE_KICK sched/x86: Construct all sibling maps if smt
Showing the changes to kernel (2 of 4 files). Show all
Unified · Split
| @@ -70,6 +70,46 @@ void user_enter(void) · 69 unmodified lines | |||
| 70 | local_irq_restore(flags); | 70 | local_irq_restore(flags); |
| 71 | } | 71 | } |
| 72 | 72 | ||
| 73 | #ifdef CONFIG_PREEMPT | ||
| 74 | /** | ||
| 75 | * preempt_schedule_context - preempt_schedule called by tracing | ||
| 76 | * | ||
| 77 | * The tracing infrastructure uses preempt_enable_notrace to prevent | ||
| 78 | * recursion and tracing preempt enabling caused by the tracing | ||
| 79 | * infrastructure itself. But as tracing can happen in areas coming | ||
| 80 | * from userspace or just about to enter userspace, a preempt enable | ||
| 81 | * can occur before user_exit() is called. This will cause the scheduler | ||
| 82 | * to be called when the system is still in usermode. | ||
| 83 | * | ||
| 84 | * To prevent this, the preempt_enable_notrace will use this function | ||
| 85 | * instead of preempt_schedule() to exit user context if needed before | ||
| 86 | * calling the scheduler. | ||
| 87 | */ | ||
| 88 | void __sched notrace preempt_schedule_context(void) | ||
| 89 | { | ||
| 90 | struct thread_info *ti = current_thread_info(); | ||
| 91 | enum ctx_state prev_ctx; | ||
| 92 | |||
| 93 | if (likely(ti->preempt_count || irqs_disabled())) | ||
| 94 | return; | ||
| 95 | |||
| 96 | /* | ||
| 97 | * Need to disable preemption in case user_exit() is traced | ||
| 98 | * and the tracer calls preempt_enable_notrace() causing | ||
| 99 | * an infinite recursion. | ||
| 100 | */ | ||
| 101 | preempt_disable_notrace(); | ||
| 102 | prev_ctx = exception_enter(); | ||
| 103 | preempt_enable_no_resched_notrace(); | ||
| 104 | |||
| 105 | preempt_schedule(); | ||
| 106 | |||
| 107 | preempt_disable_notrace(); | ||
| 108 | exception_exit(prev_ctx); | ||
| 109 | preempt_enable_notrace(); | ||
| 110 | } | ||
| 111 | EXPORT_SYMBOL_GPL(preempt_schedule_context); | ||
| 112 | #endif /* CONFIG_PREEMPT */ | ||
| 73 | 113 | ||
| 74 | /** | 114 | /** |
| 75 | * user_exit - Inform the context tracking that the CPU is | 115 | * user_exit - Inform the context tracking that the CPU is |
| @@ -633,7 +633,19 @@ void wake_up_nohz_cpu(int cpu) · 632 unmodified lines | |||
| 633 | static inline bool got_nohz_idle_kick(void) | 633 | static inline bool got_nohz_idle_kick(void) |
| 634 | { | 634 | { |
| 635 | int cpu = smp_processor_id(); | 635 | int cpu = smp_processor_id(); |
| 636 | return idle_cpu(cpu) && test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)); | 636 | |
| 637 | if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu))) | ||
| 638 | return false; | ||
| 639 | |||
| 640 | if (idle_cpu(cpu) && !need_resched()) | ||
| 641 | return true; | ||
| 642 | |||
| 643 | /* | ||
| 644 | * We can't run Idle Load Balance on this CPU for this time so we | ||
| 645 | * cancel it and clear NOHZ_BALANCE_KICK | ||
| 646 | */ | ||
| 647 | clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)); | ||
| 648 | return false; | ||
| 637 | } | 649 | } |
| 638 | 650 | ||
| 639 | #else /* CONFIG_NO_HZ_COMMON */ | 651 | #else /* CONFIG_NO_HZ_COMMON */ |
| @@ -1393,8 +1405,9 @@ static void sched_ttwu_pending(void) · 753 unmodified lines | |||
| 1393 | 1405 | ||
| 1394 | void scheduler_ipi(void) | 1406 | void scheduler_ipi(void) |
| 1395 | { | 1407 | { |
| 1396 | if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick() | 1408 | if (llist_empty(&this_rq()->wake_list) |
| 1397 | && !tick_nohz_full_cpu(smp_processor_id())) | 1409 | && !tick_nohz_full_cpu(smp_processor_id()) |
| 1410 | && !got_nohz_idle_kick()) | ||
| 1398 | return; | 1411 | return; |
| 1399 | 1412 | ||
| 1400 | /* | 1413 | /* |
| @@ -1417,7 +1430,7 @@ void scheduler_ipi(void) · 16 unmodified lines | |||
| 1417 | /* | 1430 | /* |
| 1418 | * Check if someone kicked us for doing the nohz idle load balance. | 1431 | * Check if someone kicked us for doing the nohz idle load balance. |
| 1419 | */ | 1432 | */ |
| 1420 | if (unlikely(got_nohz_idle_kick() && !need_resched())) { | 1433 | if (unlikely(got_nohz_idle_kick())) { |
| 1421 | this_rq()->idle_balance = 1; | 1434 | this_rq()->idle_balance = 1; |
| 1422 | raise_softirq_irqoff(SCHED_SOFTIRQ); | 1435 | raise_softirq_irqoff(SCHED_SOFTIRQ); |
| 1423 | } | 1436 | } |