commit 9a0599dd upstream.

Fix the case where the ttm pointer may be NULL causing
a NULL pointer dereference.
Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Thomas Hellström <thellstrom@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>