[Devel] [PATCH vz8 21/42] mm/gup: Let __get_user_pages_locked() return -EINTR for fatal signal

[Andrey Ryabinin]

From: Hillf Danton <hdanton at sina.com>

__get_user_pages_locked() will return 0 instead of -EINTR after commit
4426e945df588 ("mm/gup: allow VM_FAULT_RETRY for multiple times") which
added extra code to allow gup detect fatal signal faster.

Restore the original -EINTR behavior.

Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Peter Zijlstra <peterz at infradead.org>
Fixes: 4426e945df58 ("mm/gup: allow VM_FAULT_RETRY for multiple times")
Reported-by: syzbot+3be1a33f04dc782e9fd5 at syzkaller.appspotmail.com
Signed-off-by: Hillf Danton <hdanton at sina.com>
Acked-by: Michal Hocko <mhocko at suse.com>
Signed-off-by: Peter Xu <peterx at redhat.com>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>

https://jira.sw.ru/browse/PSBM-102938
(cherry picked from commit ae46d2aa6a7fbe8ca0946f24b061b6ccdc6c3f25)
Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
 mm/gup.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/mm/gup.c b/mm/gup.c
index 3d08b68c210f..049e05960e1e 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -941,8 +941,11 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
 		 * start trying again otherwise it can loop forever.
 		 */
 
-		if (fatal_signal_pending(current))
+		if (fatal_signal_pending(current)) {
+			if (!pages_done)
+				pages_done = -EINTR;
 			break;
+		}
 
 		*locked = 1;
 		ret = down_read_killable(&mm->mmap_sem);
-- 
2.25.3