mm/vmstat.c: assert that vmstat_text is in sync with stat_items_size

Having two gigantic arrays that must manually be kept in sync, including
ifdefs, isn't exactly robust.  To make it easier to catch such issues in
the future, add a BUILD_BUG_ON().

Link: http://lkml.kernel.org/r/20181001143138.95119-3-jannh@google.com
Signed-off-by: Jann Horn <jannh@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Kemi Wang <kemi.wang@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/vmstat.c b/mm/vmstat.c
index dab5343..6038ce5 100644 (file)
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1665,6 +1665,8 @@ static void *vmstat_start(struct seq_file *m, loff_t *pos)
        stat_items_size += sizeof(struct vm_event_state);
 #endif
 
+       BUILD_BUG_ON(stat_items_size !=
+                    ARRAY_SIZE(vmstat_text) * sizeof(unsigned long));
        v = kmalloc(stat_items_size, GFP_KERNEL);
        m->private = v;
        if (!v)