tree ce73977ed641a66c1db9a96d0b2f8caab3a76e74
parent f0d4c96fdee9e43d3a6dafd0e10ee47680fdf98f
author Mike Frysinger <vapier@chromium.org> 1611168390 -0500
committer Robert Kolchmeyer <rkolchmeyer@google.com> 1618009859 -0700

cros_sdk: drop cgroups usage

In the bad old days before pid namespaces existed in the kernel, we
had problems with cbuildbot/cros_sdk leaking processes.  However, we
were able to use cpuset cgroups to keep track of all processes that
we spawned, and then destroy any dangling ones on exit.  So we used
that in cbuildbot & cros_sdk to avoid leaks.

Now that we've had the pid namespace logic in the tree for 7 years,
we should be able to assume that people have this enabled in their
kernels (as all modern distros do).  If they're using a weird setup
that doesn't have it, then they probably don't have cgroups either,
and they can get the leaking process behavior.

This allows us to delete cgroups usage from here to simplify.  It
also avoids having to fix the cgroups code to work with the new v2
layout that newer systemd versions are using.

BUG=None
TEST=`cros_sdk` works w/cgroupsv2 & systemd host

Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2640878
Reviewed-by: Chris McDonald <cjmcdonald@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Change-Id: I0e5eeda826638798abdc0ba80c313f4a154562ca