Tells us how many pages were reclaimed by kswapd.

The `pgsteal' statistic tells us how many pages were reclaimed
altogether.  So

	kswapd_steal - pgsteal

is the number of pages which were directly reclaimed by page allocating
processes.


Also, the `pgscan' data is currently counting the number of pages
scanned in shrink_cache() plus the number of pages scanned in
refill_inactive_zone().  These are rather separate concepts, so I
created the new `pgrefill' counter for refill_inactive_zone().
`pgscan' is now just the number of pages scanned in shrink_cache().