Index: kern/kern_sysctl.c
===================================================================
--- kern/kern_sysctl.c	(revision 249327)
+++ kern/kern_sysctl.c	(working copy)
@@ -1406,7 +1406,7 @@ static int
 sysctl_root(SYSCTL_HANDLER_ARGS)
 {
 	struct sysctl_oid *oid;
-	int error, indx, lvl;
+	int error, indx, lvl, giantlocked;
 
 	SYSCTL_ASSERT_XLOCKED();
 
@@ -1488,10 +1488,13 @@ sysctl_root(SYSCTL_HANDLER_ARGS)
 	oid->oid_running++;
 	SYSCTL_XUNLOCK();
 
-	if (!(oid->oid_kind & CTLFLAG_MPSAFE))
+	if (!(oid->oid_kind & CTLFLAG_MPSAFE)) {
+		giantlocked = 1;
 		mtx_lock(&Giant);
+	} else
+		giantlocked = 0;
 	error = oid->oid_handler(oid, arg1, arg2, req);
-	if (!(oid->oid_kind & CTLFLAG_MPSAFE))
+	if (giantlocked)
 		mtx_unlock(&Giant);
 
 	KFAIL_POINT_ERROR(_debug_fail_point, sysctl_running, error);