From: Jan Stancek <jstancek@xxxxxxxxxx>
Subject: mm: migrate: initialize err in do_migrate_pages
After commit 236c32eb1096 ("mm: migrate: clean up migrate_prep{_local}")',
do_migrate_pages can return uninitialized variable 'err' (which is
propagated to user-space as error) when 'from' and 'to' nodesets are
identical. This can be reproduced with LTP migrate_pages01, which calls
migrate_pages() with same set for both old/new_nodes.
Add 'err' initialization back.
Link: https://lkml.kernel.org/r/456a021c7ef3636d7668cec9dcb4a446a4244812.1609855564.git.jstancek@xxxxxxxxxx
Fixes: 236c32eb1096 ("mm: migrate: clean up migrate_prep{_local}")
Signed-off-by: Jan Stancek <jstancek@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Acked-by: Yang Shi <shy828301@xxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Song Liu <songliubraving@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mempolicy.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/mempolicy.c~mm-migrate-initialize-err-in-do_migrate_pages
+++ a/mm/mempolicy.c
@@ -1111,7 +1111,7 @@ int do_migrate_pages(struct mm_struct *m
const nodemask_t *to, int flags)
{
int busy = 0;
- int err;
+ int err = 0;
nodemask_t tmp;
migrate_prep();
_
