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authorGiuseppe Scrivano <gscrivan@redhat.com>2020-12-02 22:07:55 +0100
committerGiuseppe Scrivano <gscrivan@redhat.com>2020-12-03 10:03:39 +0100
commit9a33e064a16c2d281d1946c8efa89599624e7a70 (patch)
tree97d46809546945eac7a7421e7904bdc2aeed87e4
parent9c5fe954cca8b4bcb8f552645e1f52a5d9824134 (diff)
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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 <gscrivan@redhat.com>
-rw-r--r--utils/utils_supported.go45
1 files 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)
+ }
}
}
}