[PATCH] mm: migrate: add isolate_movable_page() stub implementation

[Arnd Bergmann <arnd@arndb.de>]

Without CONFIG_MIGRATION, we get a build failure when trying to
call isolate_movable_page():

mm/memory-failure.c: In function '__soft_offline_page':
mm/memory-failure.c:1656:10: error: implicit declaration of function 'isolate_movable_page';did you mean 'isolate_huge_page'? [-Werror=implicit-function-declaration]

This adds one more static inline helper function in the header
declaring it. This returns false to indicate that the
page was not isolated.

Fixes: mmotm ("HWPOISON: soft offlining for non-lru movable pages")
Fixes: bda807d44454 ("mm: migrate: support non-lru movable page migration")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 include/linux/migrate.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index ae8d475a9385..09dd6e924106 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -57,6 +57,9 @@ static inline int migrate_pages(struct list_head *l, new_page_t new,
 		int reason)
 	{ return -ENOSYS; }
 
+static inline bool isolate_movable_page(struct page *page, isolate_mode_t mode)
+	{ return false; }
+
 static inline int migrate_prep(void) { return -ENOSYS; }
 static inline int migrate_prep_local(void) { return -ENOSYS; }
 
-- 
2.9.0