If folios were freed from under us, there's no need to reclaim them. Skip
these folios to save lots of cpu cycles and avoid possible unnecessary
disk I/O.
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
---
v2:
use folio_ref_freeze to guard against race with GUP (fast). Many thanks
Matthew for pointing this out.
---
mm/vmscan.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 13d34d9593bb..547ae7ae6ab1 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1610,13 +1610,19 @@ static unsigned int shrink_page_list(struct list_head *page_list,
folio = lru_to_folio(page_list);
list_del(&folio->lru);
+ nr_pages = folio_nr_pages(folio);
+
+ if (folio_ref_count(folio) == 1 &&
+ folio_ref_freeze(folio, 1)) {
+ /* folio was freed from under us. So we are done. */
+ goto free_it;
+ }
+
if (!folio_trylock(folio))
goto keep;
VM_BUG_ON_FOLIO(folio_test_active(folio), folio);
- nr_pages = folio_nr_pages(folio);
-
/* Account the number of base pages */
sc->nr_scanned += nr_pages;
--
2.23.0
