[PATCH 3/7] Allow CONFIG_MIGRATION to be set without CONFIG_NUMA

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

CONFIG_MIGRATION currently depends on CONFIG_NUMA. move_pages() is the only
user of migration today and as this system call is only meaningful on NUMA,
it makes sense. However, memory compaction will operate within a zone and is
useful on both NUMA and non-NUMA systems. This patch allows CONFIG_MIGRATION
to be used in all memory models. To preserve existing behaviour, move_pages()
is only available when CONFIG_NUMA is set.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Andy Whitcroft <apw@shadowen.org>
---

 include/linux/migrate.h |   11 ++++++++---
 include/linux/mm.h      |    2 ++
 mm/Kconfig              |    5 ++++-
 mm/migrate.c            |    4 ++--
 4 files changed, 16 insertions(+), 6 deletions(-)

diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.22-rc2-mm1-005_migrate_nocontext/include/linux/migrate.h linux-2.6.22-rc2-mm1-015_migration_flatmem/include/linux/migrate.h
--- linux-2.6.22-rc2-mm1-005_migrate_nocontext/include/linux/migrate.h	2007-05-28 14:11:32.000000000 +0100
+++ linux-2.6.22-rc2-mm1-015_migration_flatmem/include/linux/migrate.h	2007-05-29 10:00:09.000000000 +0100
@@ -7,7 +7,7 @@
 
 typedef struct page *new_page_t(struct page *, unsigned long private, int **);
 
-#ifdef CONFIG_MIGRATION
+#ifdef CONFIG_SYSCALL_MOVE_PAGES
 /* Check if a vma is migratable */
 static inline int vma_migratable(struct vm_area_struct *vma)
 {
@@ -24,7 +24,14 @@ static inline int vma_migratable(struct 
 			return 0;
 	return 1;
 }
+#else
+static inline int vma_migratable(struct vm_area_struct *vma)
+{
+	return 0;
+}
+#endif
 
+#ifdef CONFIG_MIGRATION
 extern int isolate_lru_page(struct page *p, struct list_head *pagelist);
 extern int putback_lru_pages(struct list_head *l);
 extern int migrate_page(struct address_space *,
@@ -40,8 +47,6 @@ extern int migrate_vmas(struct mm_struct
 		const nodemask_t *from, const nodemask_t *to,
 		unsigned long flags);
 #else
-static inline int vma_migratable(struct vm_area_struct *vma)
-					{ return 0; }
 
 static inline int isolate_lru_page(struct page *p, struct list_head *list)
 					{ return -ENOSYS; }
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.22-rc2-mm1-005_migrate_nocontext/include/linux/mm.h linux-2.6.22-rc2-mm1-015_migration_flatmem/include/linux/mm.h
--- linux-2.6.22-rc2-mm1-005_migrate_nocontext/include/linux/mm.h	2007-05-24 10:13:34.000000000 +0100
+++ linux-2.6.22-rc2-mm1-015_migration_flatmem/include/linux/mm.h	2007-05-28 14:13:44.000000000 +0100
@@ -242,6 +242,8 @@ struct vm_operations_struct {
 	int (*set_policy)(struct vm_area_struct *vma, struct mempolicy *new);
 	struct mempolicy *(*get_policy)(struct vm_area_struct *vma,
 					unsigned long addr);
+#endif /* CONFIG_NUMA */
+#ifdef CONFIG_MIGRATION
 	int (*migrate)(struct vm_area_struct *vma, const nodemask_t *from,
 		const nodemask_t *to, unsigned long flags);
 #endif
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.22-rc2-mm1-005_migrate_nocontext/mm/Kconfig linux-2.6.22-rc2-mm1-015_migration_flatmem/mm/Kconfig
--- linux-2.6.22-rc2-mm1-005_migrate_nocontext/mm/Kconfig	2007-05-24 10:13:34.000000000 +0100
+++ linux-2.6.22-rc2-mm1-015_migration_flatmem/mm/Kconfig	2007-05-29 09:57:23.000000000 +0100
@@ -145,13 +145,16 @@ config SPLIT_PTLOCK_CPUS
 config MIGRATION
 	bool "Page migration"
 	def_bool y
-	depends on NUMA
 	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.
 
+config SYSCALL_MOVE_PAGES
+	def_bool y
+	depends on MIGRATION && NUMA
+
 config RESOURCES_64BIT
 	bool "64 bit Memory and IO resources (EXPERIMENTAL)" if (!64BIT && EXPERIMENTAL)
 	default 64BIT
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.22-rc2-mm1-005_migrate_nocontext/mm/migrate.c linux-2.6.22-rc2-mm1-015_migration_flatmem/mm/migrate.c
--- linux-2.6.22-rc2-mm1-005_migrate_nocontext/mm/migrate.c	2007-05-28 14:11:32.000000000 +0100
+++ linux-2.6.22-rc2-mm1-015_migration_flatmem/mm/migrate.c	2007-05-29 10:01:40.000000000 +0100
@@ -761,7 +761,7 @@ int migrate_pages_nocontext(struct list_
 	return __migrate_pages(from, get_new_page, private, 1);
 }
 
-#ifdef CONFIG_NUMA
+#ifdef CONFIG_SYSCALL_MOVE_PAGES
 /*
  * Move a list of individual pages
  */
@@ -1018,7 +1018,7 @@ out2:
 	mmput(mm);
 	return err;
 }
-#endif
+#endif /* CONFIG_SYSCALL_MOVE_PAGES */
 
 /*
  * Call migration functions in the vma_ops that may prepare