[PATCH 0/4] sched/fair: Fix PELT wobblies

[Peter Zijlstra]

These here patches should hopefully fix all these pesky new task/group double
attach wobblies for which there have been a number of patch sets floating
about.

They have had minimal testing; they boot on x86_64 and I could create a cgroup
and stuff my bash in it.

Please as to have a close look.

Much thanks to Vincent and Yuyang.