3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ross Lagerwall <ross.lagerw...@citrix.com>


[ Upstream commit cf2acf66ad43abb39735568f55e1f85f9844e990 ]

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.lagerw...@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrov...@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrov...@oracle.com>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/xen/gntdev.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -817,8 +817,10 @@ 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;
 }


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