[PATCH 4.14 165/228] xen/balloon: make the balloon wait interruptible

[Greg Kroah-Hartman]

From: Roger Pau Monne <roger.pau@xxxxxxxxxx>

commit 88a479ff6ef8af7f07e11593d58befc644244ff7 upstream.

So it can be killed, or else processes can get hung indefinitely
waiting for balloon pages.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20200727091342.52325-3-roger.pau@xxxxxxxxxx
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/xen/balloon.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -633,11 +633,13 @@ static int add_ballooned_pages(int nr_pa
 	if (xen_hotplug_unpopulated) {
 		st = reserve_additional_memory();
 		if (st != BP_ECANCELED) {
+			int rc;
+
 			mutex_unlock(&balloon_mutex);
-			wait_event(balloon_wq,
+			rc = wait_event_interruptible(balloon_wq,
 				   !list_empty(&ballooned_pages));
 			mutex_lock(&balloon_mutex);
-			return 0;
+			return rc ? -ENOMEM : 0;
 		}
 	}