Revert "Revert "Manually patched to add RCU: Joe's RCU.""

This reverts commit 989e5eecd0989a8c2cab057b73a04948a4992d92.
Revert "Revert "Enabled Joe's rcu instead of preempt rcu subsystem""

This reverts commit 10cb021a653f222183edac5293a3eb8a77185e55.