[PATCH v3] mm: use swp_offset as key in shmem_replace_page()

[Yu Zhao]

We changed key of swap cache tree from swp_entry_t.val to
swp_offset. Need to do so in shmem_replace_page() as well.

Fixes: f6ab1f7f6b2d ("mm, swap: use offset of swap entry as key of swap cache")
Cc: stable@xxxxxxxxxxxxxxx # v4.9+
Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx>
---
 mm/shmem.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index d44991ea5ed4..42b70978e814 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1509,11 +1509,13 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp,
 {
 	struct page *oldpage, *newpage;
 	struct address_space *swap_mapping;
+	swp_entry_t entry;
 	pgoff_t swap_index;
 	int error;
 
 	oldpage = *pagep;
-	swap_index = page_private(oldpage);
+	entry.val = page_private(oldpage);
+	swap_index = swp_offset(entry);
 	swap_mapping = page_mapping(oldpage);
 
 	/*
@@ -1532,7 +1534,7 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp,
 	__SetPageLocked(newpage);
 	__SetPageSwapBacked(newpage);
 	SetPageUptodate(newpage);
-	set_page_private(newpage, swap_index);
+	set_page_private(newpage, entry.val);
 	SetPageSwapCache(newpage);
 
 	/*
-- 
2.19.1.1215.g8438c0b245-goog