[PATCH 1/7] Allow CONFIG_MIGRATION to be set without CONFIG_NUMA

[Mel Gorman <mel@csn.ul.ie>]

CONFIG_MIGRATION currently depends on CONFIG_NUMA. The current users of
page migration such as sys_move_pages(), sys_migrate_pages() and cpuset
process migration are ordinarily only beneficial on NUMA.

As memory compaction will operate within a zone and is useful on both NUMA
and non-NUMA systems, this patch allows CONFIG_MIGRATION to be set if the
user selects CONFIG_COMPACTION as an option.

TODO
  o After this patch is applied, the migration core is available but it
    also makes NUMA-specific features available. This is too much
    exposure so revisit this.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
---
 mm/Kconfig |   12 +++++++++++-
 1 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/mm/Kconfig b/mm/Kconfig
index 17b8947..1d8e2b2 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -168,12 +168,22 @@ config SPLIT_PTLOCK_CPUS
 	default "4"
 
 #
+# support for memory compaction
+config COMPACTION
+	bool "Allow for memory compaction"
+	def_bool y
+	select MIGRATION
+	depends on EXPERIMENTAL && HUGETLBFS
+	help
+	  Allows the compaction of memory for the allocation of huge pages.
+
+#
 # support for page migration
 #
 config MIGRATION
 	bool "Page migration"
 	def_bool y
-	depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE
+	depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION
 	help
 	  Allows the migration of the physical location of pages of processes
 	  while the virtual addresses are not changed. This is useful for
-- 
1.6.5

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