Apply by doing:
	cd /usr/src/sys/kern
	patch -p0 < 010_profil.patch

And then rebuild your kernel.

--- kern_exec.c.orig	Mon Aug  9 11:50:57 1999
+++ kern_exec.c	Mon Aug  9 11:51:11 1999
@@ -434,6 +434,7 @@
 	    ((char *)PS_STRINGS) - szsigcode, szsigcode))
 		goto exec_abort;
 
+	stopprofclock(p);	/* stop profiling */
 	fdcloseexec(p);		/* handle close on exec */
 	execsigs(p);		/* reset catched signals */