mm/damon/paddr: fix missing folio_put()

From: "andrew.yang" <[email protected]>

commit 3f98c9a62c338bbe06a215c9491e6166ea39bf82 upstream.

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.

---

This is a backport of the mainline patch for v6.1.y and v6.2.y.

 mm/damon/paddr.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

index e1a4315c4be6..402d30b37aba 100644
@@ -219,12 +219,11 @@ static unsigned long damon_pa_pageout(struct damon_region *r)
 			put_page(page);
 			continue;
 		}
-		if (PageUnevictable(page)) {
+		if (PageUnevictable(page))
 			putback_lru_page(page);
-		} else {
+		else
 			list_add(&page->lru, &page_list);
-			put_page(page);
-		}
+		put_page(page);
 	}
 	applied = reclaim_pages(&page_list);
 	cond_resched();

2.25.1