cgroup.go: avoid panic on nil interface

linrl3 · linrl3 · commit d55de5d2af9a · 2021-09-09T20:43:14.000+08:00
Signed-off-by: linrl3 &lt;linrunlong@bytedance.com&gt;
diff --git a/cgroup.go b/cgroup.go
@@ -327,6 +327,9 @@ func (c *cgroup) processes(subsystem Name, recursive bool, pType procType) ([]Pr
 	if err != nil {
 		return nil, err
 	}
+	if s == nil {
+		return nil, fmt.Errorf("cgroups: %s doesn't exist in %s subsystem", sp, subsystem)
+	}
 	path := s.(pather).Path(sp)
 	var processes []Process
 	err = filepath.Walk(path, func(p string, info os.FileInfo, err error) error {
