Index: kern/kern_sig.c
===================================================================
RCS file: /cvsroot/src/sys/kern/kern_sig.c,v
retrieving revision 1.349
diff -p -u -r1.349 kern_sig.c
--- kern/kern_sig.c	28 May 2018 14:07:37 -0000	1.349
+++ kern/kern_sig.c	13 Sep 2018 01:25:30 -0000
@@ -1758,7 +1758,10 @@ issignal(struct lwp *l)
 			/*
 			 * Don't take default actions on system processes.
 			 */
-			if (p->p_pid <= 1) {
+			if (p->p_pid <= 1 &&
+			    signo != SIGILL &&
+			    signo != SIGSEGV &&
+			    signo != SIGBUS) {
 #ifdef DIAGNOSTIC
 				/*
 				 * Are you sure you want to ignore SIGSEGV
Index: kern/subr_lockdebug.c
===================================================================
RCS file: /cvsroot/src/sys/kern/subr_lockdebug.c,v
retrieving revision 1.66
diff -p -u -r1.66 subr_lockdebug.c
--- kern/subr_lockdebug.c	3 Sep 2018 16:29:35 -0000	1.66
+++ kern/subr_lockdebug.c	13 Sep 2018 01:25:30 -0000
@@ -1016,20 +1016,21 @@ lockdebug_abort(const char *func, size_t
 #endif	/* LOCKDEBUG */
 
 	/*
-	 * Complain first on the occurrance only.  Otherwise proceeed to
-	 * panic where we will `rendezvous' with other CPUs if the machine
-	 * is going down in flames.
+	 * Don't make the situation worse if the system is already going
+	 * down in flames.  Once a panic is triggered, lockdebug state
+	 * becomes stale and cannot be trusted.
 	 */
-	if (atomic_inc_uint_nv(&ld_panic) == 1) {
-		printf_nolog("%s error: %s,%zu: %s\n\n"
-		    "lock address : %#018lx\n"
-		    "current cpu  : %18d\n"
-		    "current lwp  : %#018lx\n",
-		    ops->lo_name, func, line, msg, (long)lock,
-		    (int)cpu_index(curcpu()), (long)curlwp);
-		(*ops->lo_dump)(lock);
-		printf_nolog("\n");
-	}
+	if (atomic_inc_uint_nv(&ld_panic) > 1)
+		return;
+
+	printf_nolog("%s error: %s,%zu: %s\n\n"
+	    "lock address : %#018lx\n"
+	    "current cpu  : %18d\n"
+	    "current lwp  : %#018lx\n",
+	    ops->lo_name, func, line, msg, (long)lock,
+	    (int)cpu_index(curcpu()), (long)curlwp);
+	(*ops->lo_dump)(lock);
+	printf_nolog("\n");
 
 	panic("lock error: %s: %s,%zu: %s: lock %p cpu %d lwp %p",
 	    ops->lo_name, func, line, msg, lock, cpu_index(curcpu()), curlwp);
Index: ddb/db_command.c
===================================================================
RCS file: /cvsroot/src/sys/ddb/db_command.c,v
retrieving revision 1.156
diff -p -u -r1.156 db_command.c
--- ddb/db_command.c	13 Aug 2018 03:20:19 -0000	1.156
+++ ddb/db_command.c	13 Sep 2018 01:25:30 -0000
@@ -1353,9 +1353,7 @@ db_reboot_cmd(db_expr_t addr, bool have_
 	 */
 	db_recover = 0;
 	/* Avoid all mutex errors */
-#ifdef LOCKDEBUG
 	lockdebug_dismiss();
-#endif
 	panicstr = "reboot forced via kernel debugger";
 	cpu_reboot((int)bootflags, NULL);
 #else	/* _KERNEL */