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Fix read "max" value for cgroup v2 #2837

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merged 2 commits into from
Mar 26, 2021
Merged

Fix read "max" value for cgroup v2 #2837

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cf79551
helpers: simplify cgroup v2 memory stats
giuseppe Mar 24, 2021
7bd9ea7
helpers: handle cgroup v2 "max" value
giuseppe Mar 24, 2021
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32 changes: 6 additions & 26 deletions container/common/helpers.go
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Original file line number Diff line number Diff line change
Expand Up @@ -17,9 +17,9 @@ package common
import (
"fmt"
"io/ioutil"
"math"
"os"
"path"
"path/filepath"
"strconv"
"strings"
"time"
Expand Down Expand Up @@ -50,25 +50,6 @@ func DebugInfo(watches map[string][]string) map[string][]string {
return out
}

// findFileInAncestorDir returns the path to the parent directory that contains the specified file.
// "" is returned if the lookup reaches the limit.
func findFileInAncestorDir(current, file, limit string) (string, error) {
for {
fpath := path.Join(current, file)
_, err := os.Stat(fpath)
if err == nil {
return current, nil
}
if !os.IsNotExist(err) {
return "", err
}
if current == limit {
return "", nil
}
current = filepath.Dir(current)
}
}

var bootTime = func() time.Time {
now := time.Now()
var sysinfo unix.Sysinfo_t
Expand Down Expand Up @@ -165,11 +146,7 @@ func GetSpec(cgroupPaths map[string]string, machineInfoFactory info.MachineInfoF
spec.Memory.Reservation = readUInt64(memoryRoot, "memory.soft_limit_in_bytes")
}
} else {
memoryRoot, err := findFileInAncestorDir(memoryRoot, "memory.max", "/sys/fs/cgroup")
if err != nil {
return spec, err
}
if memoryRoot != "" {
if utils.FileExists(path.Join(memoryRoot, "memory.max")) {
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👍

spec.HasMemory = true
spec.Memory.Reservation = readUInt64(memoryRoot, "memory.high")
spec.Memory.Limit = readUInt64(memoryRoot, "memory.max")
Expand Down Expand Up @@ -226,7 +203,10 @@ func readString(dirpath string, file string) string {

func readUInt64(dirpath string, file string) uint64 {
out := readString(dirpath, file)
if out == "" || out == "max" {
if out == "max" {
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Why have you decided to change behaviour for out == ""?

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for out == "" I've left the same behavior there was before 2ccad4b

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Of course, my bad!

return math.MaxUint64
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@odinuge odinuge Mar 24, 2021 •
edited
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nit: The max value for cgroup v1 is 9223372036854771712 (max signed integer rounded to nearest page, at least on x86). So to be correct it should be something like this I guess:

Suggested change
return math.MaxUint64
return math.MaxInt64^0xFFF

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I am fine with changing it, but would it be a problem with cgroup v1? "max" is used only on cgroup v2

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I don't remember where this value is used, but I just thought it was nice with the same value for both cgroup v2. If you try to write MaxInt64^0xFFF + 0x1 you get max on cgroup v2, and 9223372036854771712 on v1. 9223372036854771712 is also default on v1.

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Edit: This is used for more than the memory limits, and my above comments only apply to those. Hmm

}
if out == "" {
return 0
}

Expand Down