Revert "mm/slab : fix compilation errors for Samsung kernel"

This reverts commit 9c65ac04b94b8531a5eb462e0d4d9f50d29cb984.
Revert "Revert "Revert "Asynchronous I/O latency to a solid-state disk greatly increased"""

This reverts commit 131f6f13abee35c6d0519d8d91f79908af737650.