[patch 3/3] mm: memcontrol: rewrite uncharge API fix - migrate before re-mapping

[Johannes Weiner <hannes@cmpxchg.org>]

Mapped file accounting depends on the the page being charged already,
or it won't get accounted properly, and the mapped file counter will
underflow during unmap later on.

Move mem_cgroup_migrate() before remove_migration_ptes().

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
 mm/migrate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index ab43fbfff8ba..7f5a42403fae 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -781,11 +781,11 @@ static int move_to_new_page(struct page *newpage, struct page *page,
 		if (!PageAnon(newpage))
 			newpage->mapping = NULL;
 	} else {
+		mem_cgroup_migrate(page, newpage, false);
 		if (remap_swapcache)
 			remove_migration_ptes(page, newpage);
 		if (!PageAnon(page))
 			page->mapping = NULL;
-		mem_cgroup_migrate(page, newpage, false);
 	}
 
 	unlock_page(newpage);
-- 
2.0.0

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