From: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: mm: restore node stat checking in /proc/sys/vm/stat_refresh
v4.7 52b6f46bc163 ("mm: /proc/sys/vm/stat_refresh to force vmstat update")
introduced vmstat_refresh(), with its vmstat underflow checking; then v4.8
75ef71840539 ("mm, vmstat: add infrastructure for per-node vmstats") split
NR_VM_NODE_STAT_ITEMS out of NR_VM_ZONE_STAT_ITEMS without updating
vmstat_refresh(): so it has been missing out much of the vmstat underflow
checking ever since. Reinstate it. Thanks to Roman Gushchin
<guro@xxxxxx> for tangentially pointing this out.
Link: https://lkml.kernel.org/r/alpine.LSU.2.11.2102251502240.13363@eggly.anvils
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Roman Gushchin <guro@xxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmstat.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/mm/vmstat.c~mm-restore-node-stat-checking-in-proc-sys-vm-stat_refresh
+++ a/mm/vmstat.c
@@ -1875,6 +1875,14 @@ int vmstat_refresh(struct ctl_table *tab
}
}
#endif
+ for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
+ val = atomic_long_read(&vm_node_stat[i]);
+ if (val < 0) {
+ pr_warn("%s: %s %ld\n",
+ __func__, node_stat_name(i), val);
+ err = -EINVAL;
+ }
+ }
if (err)
return err;
if (write)
_
