It's nice to know where did the authorization process stop.

Index: openpam_dispatch.c
===================================================================
--- openpam_dispatch.c	(wersja 382)
+++ openpam_dispatch.c	(kopia robocza)
@@ -153,7 +153,8 @@
 			err = r;
 		if ((chain->flag == PAM_REQUIRED ||
 		    chain->flag == PAM_BINDING) && !fail) {
-			openpam_log(PAM_LOG_DEBUG, "required module failed");
+			openpam_log(PAM_LOG_DEBUG, "required module (%s)"
+			    " failed", chain->module->path);
 			fail = 1;
 			err = r;
 		}
@@ -163,7 +164,8 @@
 		 * immediately.
 		 */
 		if (chain->flag == PAM_REQUISITE) {
-			openpam_log(PAM_LOG_DEBUG, "requisite module failed");
+			openpam_log(PAM_LOG_DEBUG, "requisite module (%s)"
+			    " failed", chain->module->path);
 			fail = 1;
 			break;
 		}