[096/143] mm: restore node stat checking in /proc/sys/vm/stat_refresh

Commit Message

Andrew Morton May 5, 2021, 1:37 a.m. UTC

From: Hugh Dickins <[e-mail]>
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
<[e-mail]> for tangentially pointing this out.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Hugh Dickins <[e-mail]>
Cc: Roman Gushchin <[e-mail]>
Cc: Johannes Weiner <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Vlastimil Babka <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/vmstat.c |    8 ++++++++
 1 file changed, 8 insertions(+)

Patch

--- 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)