From: Shengjing Zhu <i@zhsj.me>
Date: Sat, 28 Nov 2020 21:45:38 +0800
Subject: Only append Hugetlb in Subsystems list when available

Forwarded: https://github.com/containerd/cgroups/pull/187
---
 subsystem.go | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/subsystem.go b/subsystem.go
index f089ea4..b2f4185 100644
--- a/subsystem.go
+++ b/subsystem.go
@@ -18,6 +18,7 @@ package cgroups
 
 import (
 	"fmt"
+	"os"
 
 	v1 "github.com/containerd/cgroups/stats/v1"
 	specs "github.com/opencontainers/runtime-spec/specs-go"
@@ -46,7 +47,6 @@ const (
 // available on most linux systems
 func Subsystems() []Name {
 	n := []Name{
-		Hugetlb,
 		Freezer,
 		Pids,
 		NetCLS,
@@ -62,6 +62,9 @@ func Subsystems() []Name {
 	if !RunningInUserNS() {
 		n = append(n, Devices)
 	}
+	if _, err := os.Stat("/sys/kernel/mm/hugepages"); err == nil {
+		n = append(n, Hugetlb)
+	}
 	return n
 }