[PATCH] Prevent max_threads from exceeding PID_MAX

["Patrick O'Rourke" <porourke@egenera.com>]

It is possible on large memory systems that the default process limits
can exceed PID_MAX.  This will allow a non-root user to consume all pids
resulting in the kernel to basically hang in get_pid().

The following patch to fork_init() will prevent max_threads from exceeding
PID_MAX.

Pat

--- linux-2.4.19-pre2-x/kernel/fork.c	Mon Feb 25 14:38:13 2002
+++ linux-2.4.19-pre2/kernel/fork.c	Wed Mar  6 09:15:17 2002
@@ -74,6 +74,11 @@
 	 */
 	max_threads = mempages / (THREAD_SIZE/PAGE_SIZE) / 8;
 
+	/* don't let threads go beyond PID_MAX */
+	if (max_threads > PID_MAX) {
+		max_threads = PID_MAX;
+	}
+
 	init_task.rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
 	init_task.rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
 }