Revert "Revert "smp: Fix SMP function call empty cpu mask race""

This reverts commit 66095e4d25b3e45bde311d761b74ed473a91585d.
Revert "Revert "sched: Fix migration thread runtime bogosity""

This reverts commit 1973e3c273a6e8f25953bf35684eaca80a046085.
Revert "Revert "workqueue: add missing smp_wmb() in process_one_work()""

This reverts commit 030fbbd05f4fe35fc2142596d4c2774c6b561e85.
Revert "Revert "sched: Fix race in task_group()""

This reverts commit ffdbe68b99dbfaef8fe915820974e5ad6c81a31b.
Revert "Revert "sched: fix divide by zero at {thread_group,task}_times""

This reverts commit 28bafb8402d330d88cdffae12d26ce0db902ad1c.
Revert "Revert "workqueue: perform cpu down operations from low priority cpu_notifier()""

This reverts commit aeb2d867497d6a7e04f2fa235e9c39e4d29d2588.