Gitlab CI job report no space error

I am using gitlab runner 11.0.2 on ubuntu 16.04.Docker 18.09.3
I have this config in config.toml file

tls_verify = false
image = “gcc”
memory = “512m”
privileged = false
disable_cache = false
volumes = ["/cache"]
shm_size = 0
pull_policy = “never”

I set memory max to 512MB.But every time gitlab runner launch a docker container, /run with tmpfs will take some memory, and don’t release the memory when job finished. So if there is no space in /run, Gitlab runner will report error. Like this

root@gitlab-runner:/etc/gitlab-runner# df -h
Filesystem Size Used Avail Use% Mounted on
udev 2.0G 0 2.0G 0% /dev
tmpfs 396M 396M 40k 100% /run
/dev/vda1 40G 18G 20G 47% /
tmpfs 2.0G 0 2.0G 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 2.0G 0 2.0G 0% /sys/fs/cgroup
tmpfs 396M 0 396M 0% /run/user/0

When I don’t set memory limit in config.toml file, /run space will not be eat.
How can I resolve this problem?

Any help?