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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/mm/slub.c b/mm/slub.c
index fa28b1623644..202049a45764 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3042,13 +3042,15 @@ static int list_locations(struct kmem_cache *s, char *buf,
                         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);