When follow_page peeks a page, the page could be reclaimed under heavy
memory pressure and thus be offlined while it's still being used by the
do_pages_stat_array(). Use FOLL_GET to hold the page refcnt to fix this
potential issue.
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
---
mm/migrate.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index 7b1c0b988234..98a968e6f465 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1788,13 +1788,18 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
goto set_status;
/* FOLL_DUMP to ignore special (like zero) pages */
- page = follow_page(vma, addr, FOLL_DUMP);
+ page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
err = PTR_ERR(page);
if (IS_ERR(page))
goto set_status;
- err = page ? page_to_nid(page) : -ENOENT;
+ if (page) {
+ err = page_to_nid(page);
+ put_page(page);
+ } else {
+ err = -ENOENT;
+ }
set_status:
*status = err;
--
2.23.0
