Re: [PATCH v5 2/4] selftests: cgroup: Add dmem selftest coverage

[Eric Chanudet <echanude@redhat.com>]

On Mon, Jul 06, 2026 at 02:06:41PM +0200, Albert Esteve wrote:
> Currently, tools/testing/selftests/cgroup/ does not include
> a dmem-specific test binary. This leaves dmem charge and
> limit behavior largely unvalidated in kselftest coverage.
> 
> Add test_dmem and wire it into the cgroup selftests Makefile.
> The new test exercises dmem controller behavior through the
> dmem_selftest debugfs interface for the dmem_selftest region.
> 
> The test adds three complementary checks:
> - test_dmem_max creates a nested hierarchy with per-leaf
>   dmem.max values and verifies that over-limit charges
>   fail while in-limit charges succeed in dmem.current.
> - test_dmem_min and test_dmem_low verify that charging
>   from a cgroup with the corresponding protection knob
>   set updates dmem.current as expected.
> - test_dmem_charge_byte_granularity validates accounting
>   bounds for non-page-aligned charge sizes and
>   uncharge-to-zero behavior.
> 
> This provides deterministic userspace coverage for dmem
> accounting and hard-limit enforcement using a test helper
> module, without requiring subsystem-specific production
> drivers.
> 
> Signed-off-by: Albert Esteve <aesteve@redhat.com>

Reviewed-by: Eric Chanudet <echanude@redhat.com>

-- 
Eric Chanudet