[RFC PATCH 1/8] mm: fix shmem swapout statistic

[Baolin Wang <baolin.wang@linux.alibaba.com>]

As we know, shmem not only supports the sharing of anonymous pages, but also
the RAM-based temporary filesystem. Therefore, shmem swapouts should not be
marked as anonymous swapout statistics. Fix it by adding folio_test_anon().

Fixes: d0f048ac39f6 ("mm: add per-order mTHP anon_swpout and anon_swpout_fallback counters")
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
---
 mm/page_io.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/page_io.c b/mm/page_io.c
index 46c603dddf04..b181b81f39e3 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -217,7 +217,9 @@ static inline void count_swpout_vm_event(struct folio *folio)
 		count_memcg_folio_events(folio, THP_SWPOUT, 1);
 		count_vm_event(THP_SWPOUT);
 	}
-	count_mthp_stat(folio_order(folio), MTHP_STAT_ANON_SWPOUT);
+
+	if (folio_test_anon(folio))
+		count_mthp_stat(folio_order(folio), MTHP_STAT_ANON_SWPOUT);
 #endif
 	count_vm_events(PSWPOUT, folio_nr_pages(folio));
 }
-- 
2.39.3