remove PAGE_GROUP_BY_MOBILITY

Grouping pages by mobility can be disabled at compile-time. This was
considered undesirable by a number of people. However, in the current stack of
patches, it is not a simple case of just dropping the configurable patch as it
would cause merge conflicts.  This patch backs out the configuration option.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

init/Kconfig

@@ -607,19 +607,6 @@ config BASE_SMALL
 	default 0 if BASE_FULL
 	default 1 if !BASE_FULL
 
-config PAGE_GROUP_BY_MOBILITY
-	bool "Group pages based on their mobility in the page allocator"
-	def_bool y
-	help
-	  The standard allocator will fragment memory over time which means
-	  that high order allocations will fail even if kswapd is running. If
-	  this option is set, the allocator will try and group page types
-	  based on their ability to migrate or reclaim. This is a best effort
-	  attempt at lowering fragmentation which a few workloads care about.
-	  The loss is a more complex allocator that may perform slower. If
-	  you are interested in working with large pages, say Y and set
-	  /proc/sys/vm/min_free_bytes to 16374. Otherwise say N
-
 menuconfig MODULES
 	bool "Enable loadable module support"
 	help