SLUB: Fix behavior if the text output of list_locations overflows PAGE_SIZE

If slabs are allocated or freed from a large set of call sites (typical
for the kmalloc area) then we may create more output than fits into
a single PAGE and sysfs only gives us one page. The output should be
truncated. This patch fixes the checks to do the truncation properly.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.22-rc4-mm2/mm/slub.c
===================================================================
--- linux-2.6.22-rc4-mm2.orig/mm/slub.c	2007-06-18 14:57:41.000000000 -0700
+++ linux-2.6.22-rc4-mm2/mm/slub.c	2007-06-18 14:57:45.000000000 -0700
@@ -3112,13 +3112,15 @@ static int list_locations(struct kmem_ca
 			n += sprintf(buf + n, " pid=%ld",
 				l->min_pid);
 
-		if (num_online_cpus() > 1 && !cpus_empty(l->cpus)) {
+		if (num_online_cpus() > 1 && !cpus_empty(l->cpus) &&
+				n < PAGE_SIZE - 60) {
 			n += sprintf(buf + n, " cpus=");
 			n += cpulist_scnprintf(buf + n, PAGE_SIZE - n - 50,
 					l->cpus);
 		}
 
-		if (num_online_nodes() > 1 && !nodes_empty(l->nodes)) {
+		if (num_online_nodes() > 1 && !nodes_empty(l->nodes) &&
+				n < PAGE_SIZE - 60) {
 			n += sprintf(buf + n, " nodes=");
 			n += nodelist_scnprintf(buf + n, PAGE_SIZE - n - 50,
 					l->nodes);