[PATCH AUTOSEL 4.9 15/17] mm/vmstat.c: assert that vmstat_text is in sync with stat_items_size

[Sasha Levin]

From: Jann Horn <jannh@xxxxxxxxxx>

[ Upstream commit f0ecf25a093fc0589f0a6bc4c1ea068bbb67d220 ]

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@xxxxxxxxxx
Signed-off-by: Jann Horn <jannh@xxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Acked-by: Roman Gushchin <guro@xxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Christoph Lameter <clameter@xxxxxxx>
Cc: Kemi Wang <kemi.wang@xxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 mm/vmstat.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 5e6a4d76659d..2bab38d5570c 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1484,6 +1484,8 @@ 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)
-- 
2.17.1