zoneinfo: 'per-node stats' sections seem to confuse the parser #386
Description
On RHEL 8.3 and 8.4 kernels there seems to be a parsing issue in node-exporter 1.1.2's zoneinfo collector which is based on procfs.
Example:
# uname -a
Linux rhel83 4.18.0-240.15.1.el8_3.x86_64 #1 SMP Wed Feb 3 03:12:15 EST 2021 x86_64 x86_64 x86_64 GNU/Linux
# grep -E '(managed|^Node)' /proc/zoneinfo
Node 0, zone DMA
managed 3840
Node 0, zone DMA32
managed 580234
Node 0, zone Normal
managed 45882525
Node 0, zone Movable
managed 0
Node 0, zone Device
managed 0
Node 1, zone DMA
managed 0
Node 1, zone DMA32
managed 0
Node 1, zone Normal
managed 46688852
Node 1, zone Movable
managed 0
Node 1, zone Device
managed 0
# curl -o metrics http://localhost:9100/metrics
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 151k 0 151k 0 0 3360k 0 --:--:-- --:--:-- --:--:-- 3360k
# grep node_zoneinfo_managed metrics
# HELP node_zoneinfo_managed_pages Present pages managed by the buddy system
# TYPE node_zoneinfo_managed_pages gauge
node_zoneinfo_managed_pages{node="0",zone=""} 3840
node_zoneinfo_managed_pages{node="0",zone="DMA32"} 580234
node_zoneinfo_managed_pages{node="0",zone="Device"} 0
node_zoneinfo_managed_pages{node="0",zone="Movable"} 0
node_zoneinfo_managed_pages{node="0",zone="Normal"} 4.5882525e+07
node_zoneinfo_managed_pages{node="1",zone=""} 4.6688852e+07
node_zoneinfo_managed_pages{node="1",zone="DMA"} 0
node_zoneinfo_managed_pages{node="1",zone="DMA32"} 0
node_zoneinfo_managed_pages{node="1",zone="Device"} 0
node_zoneinfo_managed_pages{node="1",zone="Movable"} 0
Notice, there's not even a zone="Normal" label for node 1 or a zone="DMA" label for node 0!
From a quick look I suspect this is caused by the "per-node stats" lines of /proc/zoneinfo. The parser resets zoneinfoElement.Zone when it sees such a line (the following numbers are from a different run):
[...]
Node 0, zone Normal
pages free 47098578
min 2448054
low 3060067
high 3672080
spanned 49545216
present 49545216
managed 46373028
protection: (0, 0, 0, 0, 0)
[...]
Node 1, zone Normal
per-node stats <<<<<<<<<<<<<<<<<<<<<<<<<<<<<
nr_inactive_anon 1947
[...]
nr_kernel_misc_reclaimable 0
pages free 48669597
min 2464943
low 3081178
high 3697413
spanned 50331648
present 50331648
managed 46692949
protection: (0, 0, 0, 0, 0)
func parseZoneinfo(zoneinfoData []byte) ([]Zoneinfo, error) {
zoneinfo := []Zoneinfo{}
zoneinfoBlocks := bytes.Split(zoneinfoData, []byte("\nNode"))
for _, block := range zoneinfoBlocks {
var zoneinfoElement Zoneinfo
lines := strings.Split(string(block), "\n")
for _, line := range lines {
if nodeZone := nodeZoneRE.FindStringSubmatch(line); nodeZone != nil {
zoneinfoElement.Node = nodeZone[1]
zoneinfoElement.Zone = nodeZone[2]
continue
}
if strings.HasPrefix(strings.TrimSpace(line), "per-node stats") {
zoneinfoElement.Zone = ""
continue
}