From 9a33e064a16c2d281d1946c8efa89599624e7a70 Mon Sep 17 00:00:00 2001 From: Giuseppe Scrivano Date: Wed, 2 Dec 2020 22:07:55 +0100 Subject: podman, exec: move conmon to the correct cgroup move the conmon process to the conmon cgroup also on exec. The previous implementation would fail to move the conmon process as the systemd unit already exists so its creation would fail. When the unit cannot be created, attempt to directly join the cgroup instead. Signed-off-by: Giuseppe Scrivano --- utils/utils_supported.go | 45 ++++++++++++++++++++++++++++++++++++--------- 1 file changed, 36 insertions(+), 9 deletions(-) diff --git a/utils/utils_supported.go b/utils/utils_supported.go index bcaa2c61a..e6978ca6f 100644 --- a/utils/utils_supported.go +++ b/utils/utils_supported.go @@ -43,6 +43,15 @@ func RunUnderSystemdScope(pid int, slice string, unitName string) error { ch := make(chan string) _, err = conn.StartTransientUnit(unitName, "replace", properties, ch) if err != nil { + // On errors check if the cgroup already exists, if it does move the process there + if props, err := conn.GetUnitTypeProperties(unitName, "Scope"); err == nil { + if cgroup, ok := props["ControlGroup"].(string); ok && cgroup != "" { + if err := moveUnderCgroup(cgroup, "", []uint32{uint32(pid)}); err != nil { + return err + } + return nil + } + } return err } defer conn.Close() @@ -101,6 +110,13 @@ func GetCgroupProcess(pid int) (string, error) { // MoveUnderCgroupSubtree moves the PID under a cgroup subtree. func MoveUnderCgroupSubtree(subtree string) error { + return moveUnderCgroup("", subtree, nil) +} + +// moveUnderCgroup moves a group of processes to a new cgroup. +// If cgroup is the empty string, then the current calling process cgroup is used. +// If processes is empty, then the processes from the current cgroup are moved. +func moveUnderCgroup(cgroup, subtree string, processes []uint32) error { procFile := "/proc/self/cgroup" f, err := os.Open(procFile) if err != nil { @@ -140,13 +156,12 @@ func MoveUnderCgroupSubtree(subtree string) error { cgroupRoot = filepath.Join(cgroupRoot, controller) } - processes, err := ioutil.ReadFile(filepath.Join(cgroupRoot, parts[2], "cgroup.procs")) - if err != nil { - return err + parentCgroup := cgroup + if parentCgroup == "" { + parentCgroup = parts[2] } - - newCgroup := filepath.Join(cgroupRoot, parts[2], subtree) - if err := os.Mkdir(newCgroup, 0755); err != nil { + newCgroup := filepath.Join(cgroupRoot, parentCgroup, subtree) + if err := os.Mkdir(newCgroup, 0755); err != nil && !os.IsExist(err) { return err } @@ -156,9 +171,21 @@ func MoveUnderCgroupSubtree(subtree string) error { } defer f.Close() - for _, pid := range bytes.Split(processes, []byte("\n")) { - if _, err := f.Write(pid); err != nil { - logrus.Warnf("Cannot move process %s to cgroup %q", pid, newCgroup) + if len(processes) > 0 { + for _, pid := range processes { + if _, err := f.Write([]byte(fmt.Sprintf("%d\n", pid))); err != nil { + logrus.Warnf("Cannot move process %d to cgroup %q", pid, newCgroup) + } + } + } else { + processesData, err := ioutil.ReadFile(filepath.Join(cgroupRoot, parts[2], "cgroup.procs")) + if err != nil { + return err + } + for _, pid := range bytes.Split(processesData, []byte("\n")) { + if _, err := f.Write(pid); err != nil { + logrus.Warnf("Cannot move process %d to cgroup %q", pid, newCgroup) + } } } } -- cgit v1.2.3-54-g00ecf