Re: [PATCH v5 0/4] cgroup: dmem: add selftest helper, coverage, and VM runner

[Michal Koutný]

Hello Albert.

On Mon, Jul 06, 2026 at 02:06:39PM +0200, Albert Esteve <aesteve@xxxxxxxxxx> wrote:
> Hi all,
> 
> This small series adds practical test coverage for the dmem
> cgroup controller.
> 
> The motivation came from following the recent dmem API discussion in
> thread [1]. That discussion considered changing the dmem API and
> adding a new knob. Currently there are no dedicated tests covering
> dmem behaviour, which makes such changes riskier.
> 
> Adding selftests has an additional challenge: dmem charging paths
> are driver-driven today, so regression testing is harder unless a
> suitable driver is present in the test environment.
> 
> This series addresses that by adding:
> - a kernel-side selftest helper module to trigger charge/uncharge
>   from userspace in a controlled way,
> - cgroup selftests covering dmem accounting and protection semantics
>   (including dmem.max enforcement and byte-granularity checks),
> - a virtme-based VM runner for repeatable execution of the dmem tests.
> 
> The goal is to make dmem behavior easier to validate when evolving the API
> and implementation, while keeping tests deterministic and driver-independent.

Thanks for the dmem selftesting. I'll respond to first two patches
individually. I find the wrapper scripts in the last two a bit of an
overkill for the selftest (as it adds dependency on particular VM
environment, I'd keep the simplicity of selftests such that wherever
they are executed (w/out wrappers), there they run (be it a physical
machine or a VM). At most, I'd consider a simple wrapper that'd load
ensure the test module is loaded.

Thanks,
Michal

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