In swap_page_trans_huge_swapped(), to identify whether there's any
page table mapping for a 4k sized swap entry, "si->swap_map[i] !=
SWAP_HAS_CACHE" is used.  This works correctly now, because all users
of the function will only call it after checking SWAP_HAS_CACHE.  But
as pointed out by Daniel, it is better to use "swap_count(map[i])"
here, because it works for "map[i] == 0" case too.

And this makes the implementation more consistent between normal and
huge swap entry.

Signed-off-by: "Huang, Ying" <ying.hu...@intel.com>
Suggested-and-reviewed-by: Daniel Jordan <daniel.m.jor...@oracle.com>
Acked-by: Dave Hansen <dave.han...@linux.intel.com>
Cc: Michal Hocko <mho...@suse.com>
Cc: Johannes Weiner <han...@cmpxchg.org>
Cc: Shaohua Li <s...@kernel.org>
Cc: Hugh Dickins <hu...@google.com>
Cc: Minchan Kim <minc...@kernel.org>
Cc: Rik van Riel <r...@redhat.com>
Cc: Dan Williams <dan.j.willi...@intel.com>
---
 mm/swapfile.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 7283104bfafa..833613e59ef7 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1497,12 +1497,12 @@ static bool swap_page_trans_huge_swapped(struct 
swap_info_struct *si,
 
        ci = lock_cluster_or_swap_info(si, offset);
        if (!ci || !cluster_is_huge(ci)) {
-               if (map[roffset] != SWAP_HAS_CACHE)
+               if (swap_count(map[roffset]))
                        ret = true;
                goto unlock_out;
        }
        for (i = 0; i < SWAPFILE_CLUSTER; i++) {
-               if (map[offset + i] != SWAP_HAS_CACHE) {
+               if (swap_count(map[offset + i])) {
                        ret = true;
                        break;
                }
-- 
2.16.4

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