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

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

   - refcount conversions

   - Solve the rq->leaf_cfs_rq_list can of worms for real.

   - improve power-aware scheduling

   - add sysctl knob for Energy Aware Scheduling

   - documentation updates

   - misc other changes"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (34 commits)
  kthread: Do not use TIMER_IRQSAFE
  kthread: Convert worker lock to raw spinlock
  sched/fair: Use non-atomic cpumask_{set,clear}_cpu()
  sched/fair: Remove unused 'sd' parameter from select_idle_smt()
  sched/wait: Use freezable_schedule() when possible
  sched/fair: Prune, fix and simplify the nohz_balancer_kick() comment block
  sched/fair: Explain LLC nohz kick condition
  sched/fair: Simplify nohz_balancer_kick()
  sched/topology: Fix percpu data types in struct sd_data & struct s_data
  sched/fair: Simplify post_init_entity_util_avg() by calling it with a task_struct pointer argument
  sched/fair: Fix O(nr_cgroups) in the load balancing path
  sched/fair: Optimize update_blocked_averages()
  sched/fair: Fix insertion in rq->leaf_cfs_rq_list
  sched/fair: Add tmp_alone_branch assertion
  sched/core: Use READ_ONCE()/WRITE_ONCE() in move_queued_task()/task_rq_lock()
  sched/debug: Initialize sd_sysctl_cpus if !CONFIG_CPUMASK_OFFSTACK
  sched/pelt: Skip updating util_est when utilization is higher than CPU's capacity
  sched/fair: Update scale invariance of PELT
  sched/fair: Move the rq_of() helper function
  sched/core: Convert task_struct.stack_refcount to refcount_t
  ...

include/linux/sched.h

@@ -21,6 +21,7 @@
 #include <linux/seccomp.h>
 #include <linux/nodemask.h>
 #include <linux/rcupdate.h>
+#include <linux/refcount.h>
 #include <linux/resource.h>
 #include <linux/latencytop.h>
 #include <linux/sched/prio.h>
@@ -356,12 +357,6 @@ struct util_est {
  * For cfs_rq, it is the aggregated load_avg of all runnable and
  * blocked sched_entities.
  *
- * load_avg may also take frequency scaling into account:
- *
- *   load_avg = runnable% * scale_load_down(load) * freq%
- *
- * where freq% is the CPU frequency normalized to the highest frequency.
- *
  * [util_avg definition]
  *
  *   util_avg = running% * SCHED_CAPACITY_SCALE
@@ -370,17 +365,14 @@ struct util_est {
  * a CPU. For cfs_rq, it is the aggregated util_avg of all runnable
  * and blocked sched_entities.
  *
- * util_avg may also factor frequency scaling and CPU capacity scaling:
+ * load_avg and util_avg don't direcly factor frequency scaling and CPU
+ * capacity scaling. The scaling is done through the rq_clock_pelt that
+ * is used for computing those signals (see update_rq_clock_pelt())
  *
- *   util_avg = running% * SCHED_CAPACITY_SCALE * freq% * capacity%
- *
- * where freq% is the same as above, and capacity% is the CPU capacity
- * normalized to the greatest capacity (due to uarch differences, etc).
- *
- * N.B., the above ratios (runnable%, running%, freq%, and capacity%)
- * themselves are in the range of [0, 1]. To do fixed point arithmetics,
- * we therefore scale them to as large a range as necessary. This is for
- * example reflected by util_avg's SCHED_CAPACITY_SCALE.
+ * N.B., the above ratios (runnable% and running%) themselves are in the
+ * range of [0, 1]. To do fixed point arithmetics, we therefore scale them
+ * to as large a range as necessary. This is for example reflected by
+ * util_avg's SCHED_CAPACITY_SCALE.
  *
  * [Overflow issue]
  *
@@ -607,7 +599,7 @@ struct task_struct {
 	randomized_struct_fields_start
 
 	void				*stack;
-	atomic_t			usage;
+	refcount_t			usage;
 	/* Per task flags (PF_*), defined further below: */
 	unsigned int			flags;
 	unsigned int			ptrace;
@@ -1187,7 +1179,7 @@ struct task_struct {
 #endif
 #ifdef CONFIG_THREAD_INFO_IN_TASK
 	/* A live task holds one reference: */
-	atomic_t			stack_refcount;
+	refcount_t			stack_refcount;
 #endif
 #ifdef CONFIG_LIVEPATCH
 	int patch_state;
@@ -1403,7 +1395,6 @@ extern struct pid *cad_pid;
 #define PF_UMH			0x02000000	/* I'm an Usermodehelper process */
 #define PF_NO_SETAFFINITY	0x04000000	/* Userland is not allowed to meddle with cpus_allowed */
 #define PF_MCE_EARLY		0x08000000      /* Early kill for mce process policy */
-#define PF_MUTEX_TESTER		0x20000000	/* Thread belongs to the rt mutex tester */
 #define PF_FREEZER_SKIP		0x40000000	/* Freezer should not count it as freezable */
 #define PF_SUSPEND_TASK		0x80000000      /* This thread called freeze_processes() and should not be frozen */
 
@@ -1753,9 +1744,9 @@ static __always_inline bool need_resched(void)
 static inline unsigned int task_cpu(const struct task_struct *p)
 {
 #ifdef CONFIG_THREAD_INFO_IN_TASK
-	return p->cpu;
+	return READ_ONCE(p->cpu);
 #else
-	return task_thread_info(p)->cpu;
+	return READ_ONCE(task_thread_info(p)->cpu);
 #endif
 }