Kubernetes Submit Queue 89e433fca1 Merge pull request #59404 from ohmystack/docker-mem-swap ...

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dockertools: disable MemorySwap on Linux

In this commit, set `MemorySwap` the same with `Memory` to prevent using swap on Linux.

**What this PR does / why we need it**:

In #39731, @pires tried to disable swap on Linux by setting `MemorySwap` to 0.
However, according to [Docker's docs](https://docs.docker.com/config/containers/resource_constraints/#--memory-swap-details), setting `MemorySwap` to 0 is treated as unset, and its [default behavior](https://github.com/moby/moby/blob/v17.05.0-ce/daemon/daemon_unix.go#L266-L269) is to set to twice the size of `Memory`, which can still cause the container to use the swap.

**Which issue(s) this PR fixes** :

This issue was mentioned in this comment: https://github.com/kubernetes/kubernetes/issues/7294#issuecomment-362722637

**Special notes for your reviewer**:

1. For the case on Windows, we can still use the 0 because [Windows does not support `MemorySwap`](https://github.com/moby/moby/blob/v17.05.0-ce/daemon/daemon_windows.go#L185-L187).
2. There is another place using the `DefaultMemorySwap()` is for [sandbox](https://github.com/kubernetes/kubernetes/blob/v1.9.2/pkg/kubelet/dockershim/docker_sandbox.go#L505).
Maybe setting the sandbox's `MemorySwap` to 0 is fine. I didn't change that.

**Release note**:

```release-note
dockertools: disable memory swap on Linux.
```

2018-02-26 21:34:42 -08:00

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