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Subject[PATCH v4 3/8] swap: Use swap_count() in swap_page_trans_huge_swapped()
Date
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.huang@intel.com>
Suggested-and-reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shaohua Li <shli@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Dan Williams <dan.j.williams@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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