From e5a119c4a6835a53f93fcfba6c177daef58467e3 Mon Sep 17 00:00:00 2001 From: Barry Song Date: Sun, 30 Jun 2024 11:41:55 +1200 Subject: [PATCH] mm/vmscan: drop checking if _deferred_list is empty before using TTU_SYNC The optimization of list_empty(&folio->_deferred_list) aimed to prevent increasing the PTL duration when a large folio is partially unmapped, for example, from subpage 0 to subpage (nr - 2). But Ryan's commit 5ed890ce5147 ("mm: vmscan: avoid split during shrink_folio_list()") actually splits this kind of large folios. This makes the "optimization" useless. Additionally, the list_empty() technically required a data_race() annotation. Link: https://lkml.kernel.org/r/20240629234155.53524-1-21cnbao@gmail.com Signed-off-by: Barry Song Reviewed-by: Ryan Roberts Reviewed-by: David Hildenbrand Signed-off-by: Andrew Morton --- mm/vmscan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 3d4c681c6d40..0761f91b407f 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1291,7 +1291,7 @@ retry: * try_to_unmap acquire PTL from the first PTE, * eliminating the influence of temporary PTE values. */ - if (folio_test_large(folio) && list_empty(&folio->_deferred_list)) + if (folio_test_large(folio)) flags |= TTU_SYNC; try_to_unmap(folio, flags); -- 2.49.0