mm/damon/paddr: fix missing folio_put()

damon_get_folio() would always increase folio _refcount and
folio_isolate_lru() would increase folio _refcount if the folio's lru flag
is set.

If an unevictable folio isolated successfully, there will be two more
_refcount.  The one from folio_isolate_lru() will be decreased in
folio_puback_lru(), but the other one from damon_get_folio() will be left
behind.  This causes a pin page.

Whatever the case, the _refcount from damon_get_folio() should be
decreased.

Link: https://lkml.kernel.org/r/20230222064223.6735-1-andrew.yang@mediatek.com
Fixes: 57223ac29584 ("mm/damon/paddr: support the pageout scheme")
Signed-off-by: andrew.yang <andrew.yang@mediatek.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>	[5.16.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 607bb69e526cf9d659274b333c921ad0f602348b..6c655d9b5639106722baed45b3f27fae1ca20664 100644 (file)
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -250,12 +250,11 @@ static unsigned long damon_pa_pageout(struct damon_region *r, struct damos *s)
                        folio_put(folio);
                        continue;
                }
-               if (folio_test_unevictable(folio)) {
+               if (folio_test_unevictable(folio))
                        folio_putback_lru(folio);
-               } else {
+               else
                        list_add(&folio->lru, &folio_list);
-                       folio_put(folio);
-               }
+               folio_put(folio);
        }
        applied = reclaim_pages(&folio_list);
        cond_resched();