reduce m_start() cost...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c
index 7be26f0..1a81373 100644
--- a/fs/proc_namespace.c
+++ b/fs/proc_namespace.c
@@ -267,6 +267,7 @@
 	p->root = root;
 	p->m.poll_event = ns->event;
 	p->show = show;
+	p->cached_event = ~0ULL;
 
 	return 0;