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authorMiaohe Lin <linmiaohe@huawei.com>2022-04-29 09:16:08 +0300
committerakpm <akpm@linux-foundation.org>2022-04-29 09:16:08 +0300
commit4cd614841c06338a087769ee3cfa96718784d1f5 (patch)
treeee09e7c06e2513b977739324f12cc9ee7d88f263 /mm/migrate.c
parent3f26c88bd66cd8ab1731763c68df7fe23a7671c0 (diff)
downloadlinux-4cd614841c06338a087769ee3cfa96718784d1f5.tar.xz
mm/migration: fix possible do_pages_stat_array racing with memory offline
When follow_page peeks a page, the page could be migrated and then 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 race. Link: https://lkml.kernel.org/r/20220318111709.60311-12-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/migrate.c')
-rw-r--r--mm/migrate.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/mm/migrate.c b/mm/migrate.c
index cb3fa7c24081..35f6416d2953 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1796,13 +1796,18 @@ 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;