diff --git a/libcontainer/cgroups/utils.go b/libcontainer/cgroups/utils.go index ea571ad9..9717acc7 100644 --- a/libcontainer/cgroups/utils.go +++ b/libcontainer/cgroups/utils.go @@ -14,6 +14,7 @@ import ( "time" units "github.com/docker/go-units" + "golang.org/x/sys/unix" ) const ( @@ -463,11 +464,40 @@ func WriteCgroupProc(dir string, pid int) error { return fmt.Errorf("no such directory for %s", CgroupProcesses) } - // Don't attach any pid to the cgroup if -1 is specified as a pid - if pid != -1 { - if err := ioutil.WriteFile(filepath.Join(dir, CgroupProcesses), []byte(strconv.Itoa(pid)), 0700); err != nil { - return fmt.Errorf("failed to write %v to %v: %v", pid, CgroupProcesses, err) - } + // Dont attach any pid to the cgroup if -1 is specified as a pid + if pid == -1 { + return nil + } + + cgroupProcessesFile, err := os.OpenFile(filepath.Join(dir, CgroupProcesses), os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0700) + if err != nil { + return fmt.Errorf("failed to write %v to %v: %v", pid, CgroupProcesses, err) + } + defer cgroupProcessesFile.Close() + + for i := 0; i < 5; i++ { + _, err = cgroupProcessesFile.WriteString(strconv.Itoa(pid)) + if err == nil { + return nil + } + + // EINVAL might mean that the task being added to cgroup.procs is in state + // TASK_NEW. We should attempt to do so again. + if isEINVAL(err) { + time.Sleep(30 * time.Millisecond) + continue + } + + return fmt.Errorf("failed to write %v to %v: %v", pid, CgroupProcesses, err) + } + return err +} + +func isEINVAL(err error) bool { + switch err := err.(type) { + case *os.PathError: + return err.Err == unix.EINVAL + default: + return false } - return nil }