From 03e5f82ea632af329e32ec03d952b2d99497eeaa Mon Sep 17 00:00:00 2001 From: Baolin Wang Date: Mon, 24 Oct 2022 16:34:21 +0800 Subject: [PATCH] mm: migrate: fix return value if all subpages of THPs are migrated successfully During THP migration, if THPs are not migrated but they are split and all subpages are migrated successfully, migrate_pages() will still return the number of THP pages that were not migrated. This will confuse the callers of migrate_pages(). For example, the longterm pinning will failed though all pages are migrated successfully. Thus we should return 0 to indicate that all pages are migrated in this case Link: https://lkml.kernel.org/r/de386aa864be9158d2f3b344091419ea7c38b2f7.1666599848.git.baolin.wang@linux.alibaba.com Fixes: b5bade978e9b ("mm: migrate: fix the return value of migrate_pages()") Signed-off-by: Baolin Wang Reviewed-by: Alistair Popple Reviewed-by: Yang Shi Cc: David Hildenbrand Cc: "Huang, Ying" Cc: Zi Yan Cc: Signed-off-by: Andrew Morton --- mm/migrate.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/migrate.c b/mm/migrate.c index 1379e1912772..dff333593a8a 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1582,6 +1582,13 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, */ list_splice(&ret_pages, from); + /* + * Return 0 in case all subpages of fail-to-migrate THPs are + * migrated successfully. + */ + if (list_empty(from)) + rc = 0; + count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded); count_vm_events(PGMIGRATE_FAIL, nr_failed_pages); count_vm_events(THP_MIGRATION_SUCCESS, nr_thp_succeeded);