[PATCH] mm balloon: umount balloon_mnt when remove vb device

With CONFIG_BALLOON_COMPACTION=y, it will mount balloon_mnt for
balloon page migration when probe a virtio_balloon device, however
do not unmount it when remove the device, fix it.

Fixes: b1123ea6d3b3 ("mm: balloon: use general non-lru movable page feature")
Signed-off-by: Yisheng Xie <redacted>
---
 drivers/virtio/virtio_balloon.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 181793f..9d2738e 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c

@@ -615,8 +615,12 @@ static void virtballoon_remove(struct virtio_device *vdev)
 	cancel_work_sync(&vb->update_balloon_stats_work);
 
 	remove_common(vb);
+#ifdef CONFIG_BALLOON_COMPACTION
 	if (vb->vb_dev_info.inode)
 		iput(vb->vb_dev_info.inode);
+
+	kern_unmount(balloon_mnt);
+#endif
 	kfree(vb);
 }
 

-- 
1.7.12.4