[PATCH RESEND] mm/zsmalloc.c: fix the migrated zspage statistics.

[Chanho Min]

When zspage is migrated to the other zone, the zone page state should
be updated as well, otherwise the NR_ZSPAGE for each zone shows wrong
counts including proc/zoneinfo in practice.

Cc: <stable@xxxxxxxxxxxxxxx>        [4.9+]
Fixes: 91537fee0013 ("mm: add NR_ZSMALLOC to vmstat")
Signed-off-by: Chanho Min <chanho.min@xxxxxxx>
Signed-off-by: Jinsuk Choi <jjinsuk.choi@xxxxxxx>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>
---
 mm/zsmalloc.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 2b2b9aa..22d17ec 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -2069,6 +2069,11 @@ static int zs_page_migrate(struct address_space *mapping, struct page *newpage,
 		zs_pool_dec_isolated(pool);
 	}
 
+	if (page_zone(newpage) != page_zone(page)) {
+		dec_zone_page_state(page, NR_ZSPAGES);
+		inc_zone_page_state(newpage, NR_ZSPAGES);
+	}
+
 	reset_page(page);
 	put_page(page);
 	page = newpage;
-- 
2.7.4