Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler changes from Ingo Molnar:
 "The main changes in this cycle were:

   - sched/fair load tracking fixes and cleanups (Byungchul Park)

   - Make load tracking frequency scale invariant (Dietmar Eggemann)

   - sched/deadline updates (Juri Lelli)

   - stop machine fixes, cleanups and enhancements for bugs triggered by
     CPU hotplug stress testing (Oleg Nesterov)

   - scheduler preemption code rework: remove PREEMPT_ACTIVE and related
     cleanups (Peter Zijlstra)

   - Rework the sched_info::run_delay code to fix races (Peter Zijlstra)

   - Optimize per entity utilization tracking (Peter Zijlstra)

   - ... misc other fixes, cleanups and smaller updates"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (57 commits)
  sched: Don't scan all-offline ->cpus_allowed twice if !CONFIG_CPUSETS
  sched: Move cpu_active() tests from stop_two_cpus() into migrate_swap_stop()
  sched: Start stopper early
  stop_machine: Kill cpu_stop_threads->setup() and cpu_stop_unpark()
  stop_machine: Kill smp_hotplug_thread->pre_unpark, introduce stop_machine_unpark()
  stop_machine: Change cpu_stop_queue_two_works() to rely on stopper->enabled
  stop_machine: Introduce __cpu_stop_queue_work() and cpu_stop_queue_two_works()
  stop_machine: Ensure that a queued callback will be called before cpu_stop_park()
  sched/x86: Fix typo in __switch_to() comments
  sched/core: Remove a parameter in the migrate_task_rq() function
  sched/core: Drop unlikely behind BUG_ON()
  sched/core: Fix task and run queue sched_info::run_delay inconsistencies
  sched/numa: Fix task_tick_fair() from disabling numa_balancing
  sched/core: Add preempt_count invariant check
  sched/core: More notrace annotations
  sched/core: Kill PREEMPT_ACTIVE
  sched/core, sched/x86: Kill thread_info::saved_preempt_count
  sched/core: Simplify preempt_count tests
  sched/core: Robustify preemption leak checks
  sched/core: Stop setting PREEMPT_ACTIVE
  ...

2 files changed, 1 insertions, 17 deletions

diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 737527b..9f95091 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -280,14 +280,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 		set_iopl_mask(next->iopl);
 
 	/*
-	 * If it were not for PREEMPT_ACTIVE we could guarantee that the
-	 * preempt_count of all tasks was equal here and this would not be
-	 * needed.
-	 */
-	task_thread_info(prev_p)->saved_preempt_count = this_cpu_read(__preempt_count);
-	this_cpu_write(__preempt_count, task_thread_info(next_p)->saved_preempt_count);
-
-	/*
 	 * Now maybe handle debug registers and/or IO bitmaps
 	 */
 	if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV ||
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index b35921a..e835d26 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -332,7 +332,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 	/*
 	 * Switch FS and GS.
 	 *
-	 * These are even more complicated than FS and GS: they have
+	 * These are even more complicated than DS and ES: they have
 	 * 64-bit bases are that controlled by arch_prctl.  Those bases
 	 * only differ from the values in the GDT or LDT if the selector
 	 * is 0.
@@ -401,14 +401,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 	 */
 	this_cpu_write(current_task, next_p);
 
-	/*
-	 * If it were not for PREEMPT_ACTIVE we could guarantee that the
-	 * preempt_count of all tasks was equal here and this would not be
-	 * needed.
-	 */
-	task_thread_info(prev_p)->saved_preempt_count = this_cpu_read(__preempt_count);
-	this_cpu_write(__preempt_count, task_thread_info(next_p)->saved_preempt_count);
-
 	/* Reload esp0 and ss1.  This changes current_thread_info(). */
 	load_sp0(tss, next);