xen/gntdev: Fix partial gntdev_mmap() cleanup

When cleaning up after a partially successful gntdev_mmap(), unmap the
successfully mapped grant pages otherwise Xen will kill the domain if
in debug mode (Attempt to implicitly unmap a granted PTE) or Linux will
kill the process and emit "BUG: Bad page map in process" if Xen is in
release mode.

This is only needed when use_ptemod is true because gntdev_put_map()
will unmap grant pages itself when use_ptemod is false.

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index d3391a1e3796..bd56653b9bbc 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -1071,8 +1071,10 @@ unlock_out:
 out_unlock_put:
         mutex_unlock(&priv->lock);
 out_put_map:
-        if (use_ptemod)
+        if (use_ptemod) {
                 map->vma = NULL;
+                unmap_grant_pages(map, 0, map->count);
+        }
         gntdev_put_map(priv, map);
         return err;
 }