[RFC] memory controller : backgorund reclaim and avoid excessive locking [0/5]

Hi, these are patches on my stack, now.

I believe test is not enough. Maybe there is BUG.

Before updating patches, I'd like to hear guys' advice against my concept
before going further.

TODO: 
 - test on NUMA (machine is not avilable in these days. but I will do)

This series inludes 2 series of patches.
One is updated "back-ground reclaiming with high-low watermark".
One is for avoid locking.

Updated series.
[1/5] -- high-low watermark for resource counter.
[2/5] -- background reclaim with high-low watermark.
[3/5] -- throttle # of direct reclaim

This series tries to improve page reclaiming.

New ones.
[4/5] -- borrow resource for avoiding counter->lock
[5/5] -- bulk freeing page_cgroup

This series tries to reduce contention on counter->lock and mz->lru_lock.
This 2 are the top most contended lock in lock_stat.

Any commetns are welcome.

Regards,
-Kame