From: Oleg Nesterov <oleg@tv-sign.ru>

This is for testing in -mm tree only.  Ensure that we really do not use pid ==
0.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 kernel/pid.c |    1 +
 1 file changed, 1 insertion(+)

diff -puN kernel/pid.c~pidhash-temporary-debug-checks kernel/pid.c
--- a/kernel/pid.c~pidhash-temporary-debug-checks
+++ a/kernel/pid.c
@@ -240,6 +240,7 @@ struct pid * fastcall find_pid(int nr)
 
 	hlist_for_each_entry_rcu(pid, elem,
 			&pid_hash[pid_hashfn(nr)], pid_chain) {
+		WARN_ON(!pid->nr); /* to be removed soon */
 		if (pid->nr == nr)
 			return pid;
 	}
_