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[100.17.17.231]) by smtp.gmail.com with ESMTPSA id ada2fe7eead31-744d6a3eb8esm3409363137.3.2026.07.09.06.31.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Jul 2026 06:31:23 -0700 (PDT) Date: Thu, 9 Jul 2026 09:31:22 -0400 From: Eric Chanudet To: Albert Esteve Cc: Tejun Heo , Johannes Weiner , Michal =?utf-8?Q?Koutn=C3=BD?= , Shuah Khan , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v5 2/4] selftests: cgroup: Add dmem selftest coverage Message-ID: References: <20260706-kunit_cgroups-v5-0-6c42c8753468@redhat.com> <20260706-kunit_cgroups-v5-2-6c42c8753468@redhat.com> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260706-kunit_cgroups-v5-2-6c42c8753468@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 Reviewed-by: Eric Chanudet -- Eric Chanudet