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

Pull scheduler fixes from Ingo Molnar:

 - Apply a number of membarrier related fixes and cleanups, which fixes
   a use-after-free race in the membarrier code

 - Introduce proper RCU protection for tasks on the runqueue - to get
   rid of the subtle task_rcu_dereference() interface that was easy to
   get wrong

 - Misc fixes, but also an EAS speedup

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Avoid redundant EAS calculation
  sched/core: Remove double update_max_interval() call on CPU startup
  sched/core: Fix preempt_schedule() interrupt return comment
  sched/fair: Fix -Wunused-but-set-variable warnings
  sched/core: Fix migration to invalid CPU in __set_cpus_allowed_ptr()
  sched/membarrier: Return -ENOMEM to userspace on memory allocation failure
  sched/membarrier: Skip IPIs when mm->mm_users == 1
  selftests, sched/membarrier: Add multi-threaded test
  sched/membarrier: Fix p->mm->membarrier_state racy load
  sched/membarrier: Call sync_core only before usermode for same mm
  sched/membarrier: Remove redundant check
  sched/membarrier: Fix private expedited registration check
  tasks, sched/core: RCUify the assignment of rq->curr
  tasks, sched/core: With a grace period after finish_task_switch(), remove unnecessary code
  tasks, sched/core: Ensure tasks are available for a grace period after leaving the runqueue
  tasks: Add a count of task RCU users
  sched/core: Convert vcpu_is_preempted() from macro to an inline function
  sched/fair: Remove unused cfs_rq_clock_task() function

1 files changed, 8 insertions, 2 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 70db597d6fd4..2c2e56bd8913 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1130,7 +1130,10 @@ struct task_struct {
 
 	struct tlbflush_unmap_batch	tlb_ubc;
 
-	struct rcu_head			rcu;
+	union {
+		refcount_t		rcu_users;
+		struct rcu_head		rcu;
+	};
 
 	/* Cache last used pipe for splice(): */
 	struct pipe_inode_info		*splice_pipe;
@@ -1839,7 +1842,10 @@ static inline void set_task_cpu(struct task_struct *p, unsigned int cpu)
  * running or not.
  */
 #ifndef vcpu_is_preempted
-# define vcpu_is_preempted(cpu)	false
+static inline bool vcpu_is_preempted(int cpu)
+{
+	return false;
+}
 #endif
 
 extern long sched_setaffinity(pid_t pid, const struct cpumask *new_mask);