mm balloon: umount balloon_mnt when removing vb device

With CONFIG_BALLOON_COMPACTION=y the kernel will mount balloon_mnt for
balloon page migration when we probe a virtio_balloon device.  However
we do not unmount it when removing the device.  Fix this.

Fixes: b1123ea6d3b3 ("mm: balloon: use general non-lru movable page feature")
Link: http://lkml.kernel.org/r/1486531318-35189-1-git-send-email-xieyisheng1@huawei.com
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Gioh Kim <gi-oh.kim@profitbricks.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 181793f078524ae8c06751d4b03677a132b4a7c3..9d2738e9217f104ec0702245a2d9b48500924cf6 100644 (file)
--- 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);
 }