Commit e5a119c4 authored by Barry Song's avatar Barry Song Committed by Andrew Morton
Browse files

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 5ed890ce ("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: default avatarBarry Song <v-songbaohua@oppo.com>
Reviewed-by: default avatarRyan Roberts <ryan.roberts@arm.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 689d92cc

mm/vmscan.c

+1 −1
Original line number Diff line number Diff line
@@ -1291,7 +1291,7 @@ static unsigned int shrink_folio_list(struct list_head *folio_list, 
			 * 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);