[PATCH] filemap: obey mapping->invalidate_lock lock/unlock order

[Miaohe Lin]

The invalidate_locks of two mappings should be unlocked in reverse order
relative to the locking order in filemap_invalidate_lock_two(). Modifying
the code to obey it.

Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
---
 mm/filemap.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/filemap.c b/mm/filemap.c
index 8ef861297ffb..9948b26e6400 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1009,6 +1009,8 @@ EXPORT_SYMBOL(filemap_invalidate_lock_two);
 void filemap_invalidate_unlock_two(struct address_space *mapping1,
 				   struct address_space *mapping2)
 {
+	if (mapping1 < mapping2)
+		swap(mapping1, mapping2);
 	if (mapping1)
 		up_write(&mapping1->invalidate_lock);
 	if (mapping2 && mapping1 != mapping2)
-- 
2.23.0