Index: sys/arch/amd64/conf/GENERIC.MP
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/arch/amd64/conf/GENERIC.MP,v
diff -u -p -u -p -r1.16 GENERIC.MP
--- sys/arch/amd64/conf/GENERIC.MP	9 Feb 2021 14:06:19 -0000	1.16
+++ sys/arch/amd64/conf/GENERIC.MP	26 Jan 2025 00:15:32 -0000
@@ -4,6 +4,6 @@ include "arch/amd64/conf/GENERIC"
 
 option	MULTIPROCESSOR
 #option	MP_LOCKDEBUG
-#option	WITNESS
+option	WITNESS
 
 cpu*		at mainbus?
Index: sys/arch/arm64/conf/GENERIC.MP
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/arch/arm64/conf/GENERIC.MP,v
diff -u -p -u -p -r1.5 GENERIC.MP
--- sys/arch/arm64/conf/GENERIC.MP	1 Jul 2018 21:05:07 -0000	1.5
+++ sys/arch/arm64/conf/GENERIC.MP	26 Jan 2025 00:15:32 -0000
@@ -4,6 +4,6 @@ include "arch/arm64/conf/GENERIC"
 
 option	MULTIPROCESSOR
 #option	MP_LOCKDEBUG
-#option	WITNESS
+option	WITNESS
 
 cpu*		at mainbus?
Index: sys/arch/i386/conf/GENERIC.MP
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/arch/i386/conf/GENERIC.MP,v
diff -u -p -u -p -r1.11 GENERIC.MP
--- sys/arch/i386/conf/GENERIC.MP	3 Jun 2018 05:18:33 -0000	1.11
+++ sys/arch/i386/conf/GENERIC.MP	26 Jan 2025 00:15:32 -0000
@@ -7,6 +7,6 @@ include "arch/i386/conf/GENERIC"
 
 option		MULTIPROCESSOR	# Multiple processor support
 #option		MP_LOCKDEBUG
-#option		WITNESS
+option		WITNESS
 
 cpu*		at mainbus?
Index: sys/arch/macppc/conf/GENERIC.MP
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/arch/macppc/conf/GENERIC.MP,v
diff -u -p -u -p -r1.2 GENERIC.MP
--- sys/arch/macppc/conf/GENERIC.MP	15 Apr 2020 08:09:33 -0000	1.2
+++ sys/arch/macppc/conf/GENERIC.MP	26 Jan 2025 00:15:32 -0000
@@ -4,6 +4,6 @@ include "arch/macppc/conf/GENERIC"
 
 option	MULTIPROCESSOR
 #option	MP_LOCKDEBUG
-#option	WITNESS
+option	WITNESS
 
 cpu*	at mainbus?
Index: sys/arch/powerpc64/conf/GENERIC.MP
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/arch/powerpc64/conf/GENERIC.MP,v
diff -u -p -u -p -r1.1 GENERIC.MP
--- sys/arch/powerpc64/conf/GENERIC.MP	21 Jul 2020 21:38:31 -0000	1.1
+++ sys/arch/powerpc64/conf/GENERIC.MP	26 Jan 2025 00:15:32 -0000
@@ -4,6 +4,6 @@ include "arch/powerpc64/conf/GENERIC"
 
 option	MULTIPROCESSOR
 #option	MP_LOCKDEBUG
-#option	WITNESS
+option	WITNESS
 
 cpu*		at mainbus?
Index: sys/arch/riscv64/conf/GENERIC.MP
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/arch/riscv64/conf/GENERIC.MP,v
diff -u -p -u -p -r1.1 GENERIC.MP
--- sys/arch/riscv64/conf/GENERIC.MP	29 Jun 2021 21:27:52 -0000	1.1
+++ sys/arch/riscv64/conf/GENERIC.MP	26 Jan 2025 00:15:32 -0000
@@ -4,6 +4,6 @@ include "arch/riscv64/conf/GENERIC"
 
 option	MULTIPROCESSOR
 #option	MP_LOCKDEBUG
-#option	WITNESS
+option	WITNESS
 
 cpu*		at mainbus?
Index: sys/netinet6/nd6.c
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/netinet6/nd6.c,v
diff -u -p -u -p -r1.283 nd6.c
--- sys/netinet6/nd6.c	4 Sep 2024 07:54:52 -0000	1.283
+++ sys/netinet6/nd6.c	26 Jan 2025 00:15:30 -0000
@@ -709,21 +709,25 @@ nd6_nud_hint(struct rtentry *rt)
 	struct llinfo_nd6 *ln;
 	struct ifnet *ifp;
 
-	NET_ASSERT_LOCKED_EXCLUSIVE();
-
-	ifp = if_get(rt->rt_ifidx);
-	if (ifp == NULL)
-		return;
+	NET_ASSERT_LOCKED();
 
 	if ((rt->rt_flags & RTF_GATEWAY) != 0 ||
 	    (rt->rt_flags & RTF_LLINFO) == 0 ||
-	    rt->rt_llinfo == NULL || rt->rt_gateway == NULL ||
+	    rt->rt_gateway == NULL ||
 	    rt->rt_gateway->sa_family != AF_LINK) {
 		/* This is not a host route. */
-		goto out;
+		return;
 	}
 
+	ifp = if_get(rt->rt_ifidx);
+	if (ifp == NULL)
+		return;
+
+	mtx_enter(&nd6_mtx);
+
 	ln = (struct llinfo_nd6 *)rt->rt_llinfo;
+	if (ln == NULL)
+		goto out;
 	if (ln->ln_state < ND6_LLINFO_REACHABLE)
 		goto out;
 
@@ -739,6 +743,7 @@ nd6_nud_hint(struct rtentry *rt)
 	if (!ND6_LLINFO_PERMANENT(ln))
 		nd6_llinfo_settimer(ln, ifp->if_nd->reachable);
 out:
+	mtx_leave(&nd6_mtx);
 	if_put(ifp);
 }