diff --git a/runsc/cgroup/cgroup.go b/runsc/cgroup/cgroup.go index 13c6a16a0..e9ae59a92 100644 --- a/runsc/cgroup/cgroup.go +++ b/runsc/cgroup/cgroup.go @@ -203,6 +203,19 @@ func LoadPaths(pid string) (map[string]string, error) { } func loadPathsHelper(cgroup io.Reader) (map[string]string, error) { + // For nested containers, in /proc/self/cgroup we see paths from host, + // which don't exist in container, so recover the container paths here by + // double-checking with /proc/pid/mountinfo + mountinfo, err := os.Open("/proc/self/mountinfo") + if err != nil { + return nil, err + } + defer mountinfo.Close() + + return loadPathsHelperWithMountinfo(cgroup, mountinfo) +} + +func loadPathsHelperWithMountinfo(cgroup, mountinfo io.Reader) (map[string]string, error) { paths := make(map[string]string) scanner := bufio.NewScanner(cgroup) @@ -225,6 +238,31 @@ func loadPathsHelper(cgroup io.Reader) (map[string]string, error) { if err := scanner.Err(); err != nil { return nil, err } + + mfScanner := bufio.NewScanner(mountinfo) + for mfScanner.Scan() { + txt := mfScanner.Text() + fields := strings.Fields(txt) + if len(fields) < 9 || fields[len(fields)-3] != "cgroup" { + continue + } + for _, opt := range strings.Split(fields[len(fields)-1], ",") { + // Remove prefix for cgroups with no controller, eg. systemd. + opt = strings.TrimPrefix(opt, "name=") + if cgroupPath, ok := paths[opt]; ok { + root := fields[3] + relCgroupPath, err := filepath.Rel(root, cgroupPath) + if err != nil { + return nil, err + } + paths[opt] = relCgroupPath + } + } + } + if err := mfScanner.Err(); err != nil { + return nil, err + } + return paths, nil }