drm/i915: check for -EINVAL from vm_insert_pfn

Indicates something is wrong with the mapping; and apparently triggers
in current kernels.

Signed-off-by: Jesse Barnes <jbarnes@virtuosugeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0abccb7..9f4eceb 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1072,6 +1072,7 @@
 	case -EAGAIN:
 		return VM_FAULT_OOM;
 	case -EFAULT:
+	case -EINVAL:
 		return VM_FAULT_SIGBUS;
 	default:
 		return VM_FAULT_NOPAGE;