lxc-download ubuntu: Failed to mount cgroup at /sys/fs/cgroup/systemd

If I start ubuntu containers I get this log:
Failed to mount cgroup at /sys/fs/cgroup/systemd: Operation not permitted
[!!!!!!] Failed to mount API filesystems, freezing.
Freezing execution.

With Alpine 3.5.2 (same settings), it is working.

Grsecurity settings:
kernel.grsecurity.chroot_caps = 0
kernel.grsecurity.chroot_deny_chmod = 0
kernel.grsecurity.chroot_deny_pivot = 0
kernel.grsecurity.chroot_deny_chroot = 0
kernel.grsecurity.chroot_deny_mount = 0
kernel.grsecurity.chroot_deny_mknod = 0

(from redmine: issue id 7342, created on 2017-05-29)

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