cgroupv2: fix fs2 driver default path

When the cgroupv2 fs driver is used without setting cgroupsPath, it picks up a path from /proc/self/cgroup. On a host with systemd, such a path can look like (examples from my machines): - /user.slice/user-1000.slice/session-4.scope - /user.slice/user-1000.slice/[email protected]/gnome-launched-xfce4-terminal.desktop-4260.scope - /user.slice/user-1000.slice/[email protected]/gnome-terminal-server.service This cgroup already contains processes in it, which prevents to enable controllers for a sub-cgroup (writing to cgroup.subtree_control fails with EBUSY or EOPNOTSUPP). Obviously, a parent cgroup (which does not contain tasks) should be used. Fixes opencontainers/runc/issues/2298 Signed-off-by: Kir Kolyshkin <[email protected]>
dims · Apr 9, 2020 · 63b8a6e · 63b8a6e
1 parent 8586adc
commit 63b8a6e
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/libcontainer/cgroups/fs2/defaultpath.go b/libcontainer/cgroups/fs2/defaultpath.go
@@ -48,6 +48,11 @@ func defaultDirPath(c *configs.Cgroup) (string, error) {
 	if err != nil {
 		return "", err
 	}
+	// The current user scope most probably has tasks in it already,
+	// making it impossible to enable controllers for its sub-cgroup.
+	// A parent cgroup (with no tasks in it) is what we need.
+	ownCgroup = filepath.Dir(ownCgroup)
+
 	return _defaultDirPath(UnifiedMountpoint, cgPath, cgParent, cgName, ownCgroup)
 }