Merge branch 'stacking-fixes' (vfs stacking fixes from Jann)

Merge filesystem stacking fixes from Jann Horn.

* emailed patches from Jann Horn <jannh@google.com>:
  sched: panic on corrupted stack end
  ecryptfs: forbid opening files without mmap handler
  proc: prevent stacking filesystems on top
prepare_task_switch(struct rq *rq, struct task_struct *prev,
		    struct task_struct *next)
{
	sched_info_switch(rq, prev, next);
	perf_event_task_sched_out(prev, next);
	fire_sched_out_preempt_notifiers(prev, next);
	prepare_lock_switch(rq, next);
	prepare_arch_switch(next);
}

prepare_task_switch(struct rq *rq, struct task_struct *prev,
		    struct task_struct *next)
{
	sched_info_switch(rq, prev, next);
	perf_event_task_sched_out(prev, next);
	fire_sched_out_preempt_notifiers(prev, next);
	prepare_lock_switch(rq, next);
	prepare_arch_switch(next);
}
