Description

When using plugin.RuntimeRuncV2, LoadProcess will not error if the process does not exist. Instead, it will return a process with status unknown. When using plugin.RuntimeLinuxV1, LoadProcess will return an error instead.

Steps to reproduce the issue:

1. Create a container and task.
2. Try to LoadProcess on the task with a process ID that does not exist.

Describe the results you received:
LoadProcess returns a process with status unknown.

Describe the results you expected:
LoadProcess returns a not found error.

Output of containerd --version:

containerd containerd.io 1.3.7 8fba4e9a7d01810a393d5d25a3621dc101981175

(We observed this on 1.4.1 too).

Any other relevant information:

We have prepared a gist that exposes the problem.

/cc @georgethebeatle @kieron-dev @danail-branekov @mnitchev