Merge pull request containers#11648 from giuseppe/raise-move-process-…

…to-scope-only-with-cgroupv2

utils: raise warning only on cgroupv2

utils/utils.go

@@ -12,6 +12,7 @@ import (
 	"sync"
 
 	"github.com/containers/podman/v3/libpod/define"
+	"github.com/containers/podman/v3/pkg/cgroups"
 	"github.com/containers/storage/pkg/archive"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
@@ -190,7 +191,11 @@ func moveProcessToScope(pidPath, slice, scope string) error {
 func MovePauseProcessToScope(pausePidPath string) {
 	err := moveProcessToScope(pausePidPath, "user.slice", "podman-pause.scope")
 	if err != nil {
-		if RunsOnSystemd() {
+		unified, err := cgroups.IsCgroup2UnifiedMode()
+		if err != nil {
+			logrus.Warnf("Failed to detect if running with cgroup unified: %v", err)
+		}
+		if RunsOnSystemd() && unified {
 			logrus.Warnf("Failed to add pause process to systemd sandbox cgroup: %v", err)
 		} else {
 			logrus.Debugf("Failed to add pause process to systemd sandbox cgroup: %v", err)

utils/utils_supported.go

@@ -47,10 +47,10 @@ func RunUnderSystemdScope(pid int, slice string, unitName string) error {
 		// 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
+				if err := moveUnderCgroup(cgroup, "", []uint32{uint32(pid)}); err == nil {
+					return nil
 				}
-				return nil
+				// On errors return the original error message we got from StartTransientUnit.
 			}
 		}
 		return err