[PATCH] Swap Migration V5: Add CONFIG_MIGRATION for page migration support

Include page migration if the system is NUMA or having a memory model that
allows distinct areas of memory (SPARSEMEM, DISCONTIGMEM).

And:
- Only include lru_add_drain_per_cpu if building for an SMP system.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/Kconfig b/mm/Kconfig
index b3db11f..a9cb80a 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -132,3 +132,10 @@
 	default "4096" if ARM && !CPU_CACHE_VIPT
 	default "4096" if PARISC && !PA20
 	default "4"
+
+#
+# support for page migration
+#
+config MIGRATION
+	def_bool y if NUMA || SPARSEMEM || DISCONTIGMEM
+	depends on SWAP