diff --git a/libcontainer/cgroups/utils.go b/libcontainer/cgroups/utils.go index a05945cba6c..d404647c8c0 100644 --- a/libcontainer/cgroups/utils.go +++ b/libcontainer/cgroups/utils.go @@ -251,27 +251,39 @@ again: // RemovePath aims to remove cgroup path. It does so recursively, // by removing any subdirectories (sub-cgroups) first. func RemovePath(path string) error { - // Try the fast path first. + // Try the fast path first; don't retry on EBUSY yet. if err := rmdir(path, false); err == nil { return nil } + // There are many reasons why rmdir can fail, including: + // 1. cgroup have existing sub-cgroups; + // 2. cgroup (still) have some processes (that are about to vanish); + // 3. lack of permission (one example is read-only /sys/fs/cgroup mount, + // in which case rmdir returns EROFS even for for a non-existent path, + // see issue 4518). + // + // Using os.ReadDir here kills two birds with one stone: check if + // the directory exists (handling scenario 3 above), and use + // directory contents to remove sub-cgroups (handling scenario 1). infos, err := os.ReadDir(path) - if err != nil && !os.IsNotExist(err) { + if err != nil { + if os.IsNotExist(err) { + return nil + } return err } + // Let's remove sub-cgroups, if any. for _, info := range infos { if info.IsDir() { - // We should remove subcgroup first. if err = RemovePath(filepath.Join(path, info.Name())); err != nil { - break + return err } } } - if err == nil { - err = rmdir(path, true) - } - return err + // Finally, try rmdir again, this time with retries on EBUSY, + // which may help with scenario 2 above. + return rmdir(path, true) } // RemovePaths iterates over the provided paths removing them.