[PATCH] mm, mempolicy: fix up gup usage in lookup_node

[Michal Hocko]

ba841078cd05 ("mm/mempolicy: Allow lookup_node() to handle fatal signal") has
added a special casing for 0 return value because that was a possible
gup return value when interrupted by fatal signal. This has been fixed
by ae46d2aa6a7f ("mm/gup: Let __get_user_pages_locked() return -EINTR
for fatal signal") in the mean time so ba841078cd05 can be reverted.
This patch however doesn't go all the way to revert it because 0 return
value is impossible. We always get an error or 1 for a single page
request.

Fixes: ba841078cd05 ("mm/mempolicy: Allow lookup_node() to handle fatal signal")
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
---
 mm/mempolicy.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 48ba9729062e..1965e2681877 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -927,10 +927,7 @@ static int lookup_node(struct mm_struct *mm, unsigned long addr)
 
 	int locked = 1;
 	err = get_user_pages_locked(addr & PAGE_MASK, 1, 0, &p, &locked);
-	if (err == 0) {
-		/* E.g. GUP interrupted by fatal signal */
-		err = -EFAULT;
-	} else if (err > 0) {
+	if (err > 0) {
 		err = page_to_nid(p);
 		put_page(p);
 	}
-- 
2.25.1

-- 
Michal Hocko
SUSE Labs