Revert "Reverted some unuseful things"

This reverts commit 2eb3ea882cd16c45f4cb27ea894801b0b59e0504.
Revert " mm: clear node in N_HIGH_MEMORY and stop kswapd when all memory is of…"

This reverts commit 496415616165cba0fa55e6fae7b005e60ed0c159.
Revert "mm: vmscan: have kswapd sleep for a short interval and double check it should be asleep"

This reverts commit 364325ccff7b26268d60202a1280cfec6615fd69.

Conflicts:
	include/linux/vmstat.h
	mm/vmscan.c
	mm/vmstat.c
Revert "mm: vmscan: stop kswapd waiting on congestion when the min watermark is not being met"

This reverts commit 39f0cbdb63dadb65ffe4459a436b980aa42b76ac.

Conflicts:
	mm/vmscan.c