We used to have a single swap address space with swp_entry_t.val
as its radix tree index. This is not the case anymore. Now Each
swp_type() has its own address space and should use swp_offset()
as radix tree index.

Signed-off-by: Yu Zhao <yuz...@google.com>
---
 mm/shmem.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index d44991ea5ed4..a92c6ae26915 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;
-       pgoff_t swap_index;
+       swp_entry_t entry;
        int error;
 
+       VM_BUG_ON(PageSwapCache(*pagep));
+
        oldpage = *pagep;
-       swap_index = page_private(oldpage);
+       entry.val = page_private(oldpage);
        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);
 
        /*
@@ -1540,7 +1542,8 @@ static int shmem_replace_page(struct page **pagep, gfp_t 
gfp,
         * a nice clean interface for us to replace oldpage by newpage there.
         */
        xa_lock_irq(&swap_mapping->i_pages);
-       error = shmem_replace_entry(swap_mapping, swap_index, oldpage, newpage);
+       error = shmem_replace_entry(swap_mapping, swp_offset(entry),
+                                   oldpage, newpage);
        if (!error) {
                __inc_node_page_state(newpage, NR_FILE_PAGES);
                __dec_node_page_state(oldpage, NR_FILE_PAGES);
-- 
2.19.1.1215.g8438c0b245-goog

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