mm: fix off-by-one bug in print_nodes_state()

/sys/devices/system/node/{online,possible} outputs a garbage byte
because print_nodes_state() returns content size + 1.  To fix the bug,
the patch changes the use of cpuset_sprintf_cpulist to follow the use at
other places, which is clearer and safer.

This bug was introduced in v2.6.24 (commit bde631a5: "mm: add node
states sysfs class attributeS").
Signed-off-by: Ryota Ozaki <ozaki.ryota@gmail.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/base/node.c

@@ -592,11 +592,9 @@ static ssize_t print_nodes_state(enum node_states state, char *buf)
 {
 	int n;
 
-	n = nodelist_scnprintf(buf, PAGE_SIZE, node_states[state]);
-	if (n > 0 && PAGE_SIZE > n + 1) {
-		*(buf + n++) = '\n';
-		*(buf + n++) = '\0';
-	}
+	n = nodelist_scnprintf(buf, PAGE_SIZE-2, node_states[state]);
+	buf[n++] = '\n';
+	buf[n] = '\0';
 	return n;
 }