xen/balloon: make the balloon wait interruptible

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@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200727091342.52325-3-roger.pau@citrix.com
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index ff6660f1fa68bee2e23bbcac1f381c4a62d4b337..a8e0836dffd4bf1ae6b7f2c18be36f867e82a360 100644 (file)
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -633,11 +633,13 @@ static int add_ballooned_pages(int nr_pages)
        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;
                }
        }