From 31ce0d7ef8412e3f38cf90bb90b7436130c60614 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Tue, 9 Apr 2024 21:22:54 +0200 Subject: mm/migrate: use folio_likely_mapped_shared() in add_page_for_migration() We want to limit the use of page_mapcount() to the places where it is absolutely necessary. In add_page_for_migration(), we actually want to check if the folio is mapped shared, to reject such folios. So let's use folio_likely_mapped_shared() instead. For small folios, fully mapped THP, and hugetlb folios, there is no change. For partially mapped, shared THP, we should now do a better job at rejecting such folios. Link: https://lkml.kernel.org/r/20240409192301.907377-12-david@redhat.com Signed-off-by: David Hildenbrand Cc: Chris Zankel Cc: Hugh Dickins Cc: John Paul Adrian Glaubitz Cc: Jonathan Corbet Cc: Matthew Wilcox (Oracle) Cc: Max Filippov Cc: Miaohe Lin Cc: Muchun Song Cc: Naoya Horiguchi Cc: Peter Xu Cc: Richard Chang Cc: Rich Felker Cc: Ryan Roberts Cc: Yang Shi Cc: Yin Fengwei Cc: Yoshinori Sato Cc: Zi Yan Signed-off-by: Andrew Morton --- mm/migrate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm/migrate.c') diff --git a/mm/migrate.c b/mm/migrate.c index 285072bca29c..d87ce32645d4 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -2140,7 +2140,7 @@ static int add_page_for_migration(struct mm_struct *mm, const void __user *p, goto out_putfolio; err = -EACCES; - if (page_mapcount(page) > 1 && !migrate_all) + if (folio_likely_mapped_shared(folio) && !migrate_all) goto out_putfolio; err = -EBUSY; -- cgit v1.2.3