[PATCH] mm: memcg/slab: fix slab statistics in !SMP configuration

[Roman Gushchin]

Since ea426c2a7de8 ("mm: memcg: prepare for byte-sized vmstat items")
the write side of slab counters accepts a value in bytes and converts
it to pages. It happens in __mod_node_page_state().

However a non-SMP version of __mod_node_page_state() doesn't perform
this conversion. It leads to incorrect (unrealistically high) slab
counters values. Fix this by adding a similar conversion to the
non-SMP version of __mod_node_page_state().

Signed-off-by: Roman Gushchin <guro@xxxxxx>
Reported-by: Bastian Bittorf <bb@xxxxxx>
Fixes: ea426c2a7de8 ("mm: memcg: prepare for byte-sized vmstat items")
---
 include/linux/vmstat.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index d5431c1bf6e5..322dcbfcc933 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -312,6 +312,11 @@ static inline void __mod_zone_page_state(struct zone *zone,
 static inline void __mod_node_page_state(struct pglist_data *pgdat,
 			enum node_stat_item item, int delta)
 {
+	if (vmstat_item_in_bytes(item)) {
+		VM_WARN_ON_ONCE(delta & (PAGE_SIZE - 1));
+		delta >>= PAGE_SHIFT;
+	}
+
 	node_page_state_add(delta, pgdat, item);
 }
 
-- 
2.26.2