[PATCH] page migration reorg

Centralize the page migration functions in anticipation of additional
tinkering.  Creates a new file mm/migrate.c

1. Extract buffer_migrate_page() from fs/buffer.c

2. Extract central migration code from vmscan.c

3. Extract some components from mempolicy.c

4. Export pageout() and remove_from_swap() from vmscan.c

5. Make it possible to configure NUMA systems without page migration
   and non-NUMA systems with page migration.

I had to so some #ifdeffing in mempolicy.c that may need a cleanup.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/mm/Kconfig b/mm/Kconfig
index a9cb80ae6409..bd80460360db 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -137,5 +137,11 @@ config SPLIT_PTLOCK_CPUS
 # support for page migration
 #
 config MIGRATION
+        bool "Page migration"
         def_bool y if NUMA || SPARSEMEM || DISCONTIGMEM
         depends on SWAP
+        help
+          Allows the migration of the physical location of pages of processes
+          while the virtual addresses are not changed. This is useful for
+          example on NUMA systems to put pages nearer to the processors accessing
+          the page.