From b426ed7889be80359cb4edef142e5c5fa697b068 Mon Sep 17 00:00:00 2001 From: Kefeng Wang Date: Wed, 13 Sep 2023 17:51:30 +0800 Subject: [PATCH] mm: migrate: remove PageHead() check for HugeTLB in add_page_for_migration() There is some different between hugeTLB and THP behave when passed the address of a tail page, for THP, it will migrate the entire THP page, but for HugeTLB, it will return -EACCES, or -ENOENT before commit e66f17ff7177 ("mm/hugetlb: take page table lock in follow_huge_pmd()"), -EACCES The page is mapped by multiple processes and can be moved only if MPOL_MF_MOVE_ALL is specified. -ENOENT The page is not present. But when check manual[1], both of the two errnos are not suitable, it is better to keep the same behave between hugetlb and THP when passed the address of a tail page, so let's just remove the PageHead() check for HugeTLB. [1] https://man7.org/linux/man-pages/man2/move_pages.2.html Link: https://lkml.kernel.org/r/20230913095131.2426871-8-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang Suggested-by: Mike Kravetz Acked-by: Zi Yan Cc: David Hildenbrand Cc: "Huang, Ying" Cc: Hugh Dickins Cc: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton --- mm/migrate.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index ce01d03e635a..8495e7e02dd4 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -2096,10 +2096,8 @@ static int add_page_for_migration(struct mm_struct *mm, const void __user *p, goto out_putfolio; if (folio_test_hugetlb(folio)) { - if (PageHead(page)) { - isolated = isolate_hugetlb(folio, pagelist); - err = isolated ? 1 : -EBUSY; - } + isolated = isolate_hugetlb(folio, pagelist); + err = isolated ? 1 : -EBUSY; } else { isolated = folio_isolate_lru(folio); if (!isolated) {