From 1ffdc9dfa14b3fb1e8108d8ee02a21ed772861da Mon Sep 17 00:00:00 2001 From: Haiyue Wang Date: Fri, 12 Aug 2022 16:49:21 +0800 Subject: [PATCH] mm: migration: fix the FOLL_GET failure on following huge page Not all huge page APIs support FOLL_GET option, so the __NR_move_pages will fail to get the page node information for huge page. This is an temporary solution to mitigate the racing fix. After supporting follow huge page by FOLL_GET is done, this fix can be reverted safely. Link: https://lkml.kernel.org/r/20220812084921.409142-1-haiyue.wang@intel.com Fixes: 4cd614841c06 ("mm: migration: fix possible do_pages_stat_array racing with memory offline") Signed-off-by: Haiyue Wang Reviewed-by: Miaohe Lin Cc: David Hildenbrand Cc: Huang Ying Cc: Muchun Song Signed-off-by: Andrew Morton --- mm/migrate.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index 0433a71d2bee..8bea00ee045f 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1852,6 +1852,7 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, for (i = 0; i < nr_pages; i++) { unsigned long addr = (unsigned long)(*pages); + unsigned int foll_flags = FOLL_DUMP; struct vm_area_struct *vma; struct page *page; int err = -EFAULT; @@ -1860,8 +1861,12 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, if (!vma) goto set_status; + /* Not all huge page follow APIs support 'FOLL_GET' */ + if (!is_vm_hugetlb_page(vma)) + foll_flags |= FOLL_GET; + /* FOLL_DUMP to ignore special (like zero) pages */ - page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); + page = follow_page(vma, addr, foll_flags); err = PTR_ERR(page); if (IS_ERR(page)) @@ -1869,7 +1874,8 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, if (page && !is_zone_device_page(page)) { err = page_to_nid(page); - put_page(page); + if (foll_flags & FOLL_GET) + put_page(page); } else { err = -ENOENT; } -- 2.50.1