It is not possible set memory.swappiness -1 on old kernel

[caiolima]

I am trying run runc start with the Docker's busybox image but I am getting the following error:

WARN[0000] signal: killed                               
FATA[0000] Container start failed: [10] System error: no such directory for memory.swappiness. 

My config.json is:

{
        "ociVersion": "0.3.0-dev",
        "platform": {
                "os": "linux",
                "arch": "amd64"
        },
        "process": {
                "terminal": true,
                "user": {
                        "uid": 0,
                        "gid": 0
                },
                "args": [
                        "sh"
                ],
                "env": [
                        "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
                        "TERM=xterm"
                ],
                "cwd": "/"
        },
        "root": {
                "path": "rootfs",
                "readonly": true
        },
        "hostname": "shell",
        "mounts": [
                {
                        "name": "proc",
                        "path": "/proc"
                },
                {
                        "name": "dev",
                        "path": "/dev"
                },
                {
                        "name": "devpts",
                        "path": "/dev/pts"
                },
                {
                        "name": "shm",
                        "path": "/dev/shm"
                },
                {
                        "name": "mqueue",
                        "path": "/dev/mqueue"
                },
                {
                        "name": "sysfs",
                        "path": "/sys"
                },
                {
                        "name": "cgroup",
                        "path": "/sys/fs/cgroup"
                }
        ],
        "linux": {
                "capabilities": [
                        "CAP_AUDIT_WRITE",
                        "CAP_KILL",
                        "CAP_NET_BIND_SERVICE"
                ]
        }
}

and my runtime.js is:

{
        "mounts": {
                "cgroup": {
                        "type": "cgroup",
                        "source": "cgroup",
                        "options": [
                                "nosuid",
                                "noexec",
                                "nodev",
                                "relatime",
                                "ro"
                        ]
                },
                "dev": {
                        "type": "tmpfs",
                        "source": "tmpfs",
                        "options": [
                                "nosuid",
                                "strictatime",
                                "mode=755",
                                "size=65536k"
                        ]
                },
                "devpts": {
                        "type": "devpts",
                        "source": "devpts",
                        "options": [
                                "nosuid",
                                "noexec",
                                "newinstance",
                                "ptmxmode=0666",
                                "mode=0620",
                                "gid=5"
                        ]
                },
                "mqueue": {
                        "type": "mqueue",
                        "source": "mqueue",
                        "options": [
                                "nosuid",
                                "noexec",
                                "nodev"
                        ]
                },
                "proc": {
                        "type": "proc",
                        "source": "proc"
                },
                "shm": {
                        "type": "tmpfs",
                        "source": "shm",
                        "options": [
                                "nosuid",
                                "noexec",
                                "nodev",
                                "mode=1777",
                                "size=65536k"
                        ]
                },
                "sysfs": {
                        "type": "sysfs",
                        "source": "sysfs",
                        "options": [
                                "nosuid",
                                "noexec",
                                "nodev"
                        ]
                }
        },
        "hooks": {},
        "linux": {
                "rlimits": [
                        {
                                "type": "RLIMIT_NOFILE",
                                "hard": 1024,
                                "soft": 1024
                        }
                ],
                "resources": {
                        "memory": {
                                "kernelTCP": null
                        }
                },
                "namespaces": [
                        {
                                "type": "pid"
                        },
                        {
                                "type": "network"
                        },
                        {
                                "type": "ipc"
                        },
                        {
                                "type": "uts"
                        },
                        {
                                "type": "mount"
                        }
                ],
                "devices": [
                        {
                                "path": "/dev/null",
                                "type": 99,
                                "major": 1,
                                "minor": 3,
                                "permissions": "rwm",
                                "fileMode": 438,
                                "uid": 0,
                                "gid": 0
                        },
                        {
                                "path": "/dev/random",
                                "type": 99,
                                "major": 1,
                                "minor": 8,
                                "permissions": "rwm",
                                "fileMode": 438,
                                "uid": 0,
                                "gid": 0
                        },
                        {
                                "path": "/dev/full",
                                "type": 99,
                                "major": 1,
                                "minor": 7,
                                "permissions": "rwm",
                                "fileMode": 438,
                                "uid": 0,
                                "gid": 0
                        },
                        {
                                "path": "/dev/tty",
                                "type": 99,
                                "major": 5,
                                "minor": 0,
                                "permissions": "rwm",
                                "fileMode": 438,
                                "uid": 0,
                                "gid": 0
                        },
                        {
                                "path": "/dev/zero",
                                "type": 99,
                                "major": 1,
                                "minor": 5,
                                "permissions": "rwm",
                                "fileMode": 438,
                                "uid": 0,
                                "gid": 0
                        },
                        {
                                "path": "/dev/urandom",
                                "type": 99,
                                "major": 1,
                                "minor": 9,
                                "permissions": "rwm",
                                "fileMode": 438,
                                "uid": 0,
                                "gid": 0
                        }
                ],
                "apparmorProfile": "",
                "selinuxProcessLabel": "",
                "seccomp": {
                        "defaultAction": "SCMP_ACT_ALLOW",
                        "architectures": null,
                        "syscalls": []
                }
        }
}

Also, my Linux environment is:

Linux debian 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt11-1+deb8u6 (2015-11-09) x86_64 GNU/Linux

Following the documentation trying to disable the Swappiness, I tried set it to -1 but I got the following error:

json: cannot unmarshal number -1 into Go value of type uint64

Inspecting the opencontainers/specs PRs, I have found this discussion #233 indicating the not int64 usage to solve it. Thus, there is no way to support disable swappiness on old kernels?

Also, since specs changed, there are a lot of "-1" usage to consider Swappiness disabeld like this one.

I think we need to think in a new way to handle this case instead of using the swappiness == -1. What do you think?

[hqhq]

Can you try the latest runc? For now, if there is no swappiness in your config, it means unlimited, which is the same as the former swappiness=-1 but more reasonable.

And "-1" usage is implementation detail for OCI compliant implementations which should not be considered by users.

[caiolima]

I have tried it with the latest runc. But the problem is because of this swappiness definition on https://github.com/vishh/specs/blob/488f174af95fd3a38fee3e4dbd33802c13498dd7/runtime_config_linux.go#L164

I have changed it to int64 and it was possible run the container without swappiness. What I think it is a good chang on implementation is to add a new spec/config field called enable_swappiness: true for example.

[crosbymichael]

This should not be an issue with the 0.0.8 release of runc. The swap files are nullable now.