Revert "sched: add wait_for_completion_io[_timeout]"

This reverts commit 0c043a856ade42d6e5b9274d5b380cab63c5a8ac.
Revert "block: account iowait time when waiting for completion of IO request"

This reverts commit b25ee4870b389984f036820f28ca1144ac01607e.
Revert "hashtable: introduce a small and naive hashtable"

This reverts commit 9d5be593cb5f586ae7f03be270d02150bb3220e4.
Revert "block,elevator: use new hashtable implementation"

This reverts commit 60d5b770cda2bd2d40fb69ea202f636a490486ba.
Revert "mm/ksm.c: use new hashtable implementation"

This reverts commit bd1ddb79f3ce69e02c0a50fc38daa1603a0e8c38.
Revert "cgroup: use new hashtable implementation"

This reverts commit 5a269b695ae9b0aff00073b5a51be5212856eb36.
Revert "mm/huge_memory: use new hashtable implementation"

This reverts commit d42134334cd43bc466f58cb3184c73fe5a542d5e.
Revert "jbd2: optimize jbd2_journal_force_commit"

This reverts commit 668683261af5c7ffad963cbfbcd6d5c93d91dbe6.
Revert "smp: patches from mainline 3.5 to hopefully help with hotplug efficiency"

This reverts commit 98372af155c04b4ab4d8adb66580570fcabcd4c7.