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mm/vmscan: drop checking if _deferred_list is empty before using TTU_SYNC

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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 5ed890ce51 ("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 <v-songbaohua@oppo.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Barry Song 2024-06-30 11:41:55 +12:00 committed by Andrew Morton
parent 689d92cc81
commit e5a119c4a6
1 changed files with 1 additions and 1 deletions
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2
mm/vmscan.c
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@ -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);