[PATCH 3/4] mm: make remove_migration_ptes() beyond mm/migration.c

[Kirill A. Shutemov]

The patch makes remove_migration_ptes() available to be used in
split_huge_page().

New parameter 'locked' added: as with try_to_umap() we need a way to
indicate that caller holds rmap lock.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
 include/linux/rmap.h |  2 ++
 mm/migrate.c         | 13 ++++++++-----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 1fdde1ee7042..675b070f489a 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -257,6 +257,8 @@ int page_mkclean(struct page *);
  */
 int try_to_munlock(struct page *);
 
+void remove_migration_ptes(struct page *old, struct page *new, bool locked);
+
 /*
  * Called by memory-failure.c to kill processes.
  */
diff --git a/mm/migrate.c b/mm/migrate.c
index b1034f9c77e7..244a267fdb61 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -186,14 +186,17 @@ out:
  * Get rid of all migration entries and replace them by
  * references to the indicated page.
  */
-static void remove_migration_ptes(struct page *old, struct page *new)
+void remove_migration_ptes(struct page *old, struct page *new, bool locked)
 {
 	struct rmap_walk_control rwc = {
 		.rmap_one = remove_migration_pte,
 		.arg = old,
 	};
 
-	rmap_walk(new, &rwc);
+	if (locked)
+		rmap_walk_locked(new, &rwc);
+	else
+		rmap_walk(new, &rwc);
 }
 
 /*
@@ -698,7 +701,7 @@ static int writeout(struct address_space *mapping, struct page *page)
 	 * At this point we know that the migration attempt cannot
 	 * be successful.
 	 */
-	remove_migration_ptes(page, page);
+	remove_migration_ptes(page, page, false);
 
 	rc = mapping->a_ops->writepage(page, &wbc);
 
@@ -897,7 +900,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
 
 	if (page_was_mapped)
 		remove_migration_ptes(page,
-			rc == MIGRATEPAGE_SUCCESS ? newpage : page);
+			rc == MIGRATEPAGE_SUCCESS ? newpage : page, false);
 
 out_unlock_both:
 	unlock_page(newpage);
@@ -1065,7 +1068,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 
 	if (page_was_mapped)
 		remove_migration_ptes(hpage,
-			rc == MIGRATEPAGE_SUCCESS ? new_hpage : hpage);
+			rc == MIGRATEPAGE_SUCCESS ? new_hpage : hpage, false);
 
 	unlock_page(new_hpage);
 
-- 
2.7.0