MFC r259407:

proc exit: don't take PROC_LOCK while freeing rlimits

Code wishing to check rlimits of some process should check whether it
is exiting first, which current consumers do.

sys/kern/kern_exit.c

@@ -387,10 +387,8 @@ exit1(struct thread *td, int rv)
 	/*
 	 * Release our limits structure.
 	 */
-	PROC_LOCK(p);
 	plim = p->p_limit;
 	p->p_limit = NULL;
-	PROC_UNLOCK(p);
 	lim_free(plim);
 
 	tidhash_remove(td);