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Tue, 29 Sep 2026 16:57:16 -0700 (PDT) Received: from ikb-h07-29-noble.in.iijlab.net ([202.214.97.5]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3a4ca4498f1sm265230a91.11.2026.09.29.16.57.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Sep 2026 16:57:15 -0700 (PDT) Received: by ikb-h07-29-noble.in.iijlab.net (Postfix, from userid 1010) id A488B16DC6A2; Wed, 30 Sep 2026 08:57:14 +0900 (JST) From: Hajime Tazaki To: linux-mm@kvack.org, liam@infradead.org, rbm@suse.com, akpm@linux-foundation.org, luto@amacapital.net, brendan.jackman@linux.dev, david@kernel.org, liuhangbin@gmail.com, corbet@lwn.net, kees@kernel.org, ljs@kernel.org, broonie@kernel.org, mhocko@suse.com, rppt@kernel.org, shuah@kernel.org, surenb@google.com, vbabka@kernel.org, wad@chromium.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-um@lists.infradead.org Cc: geert@linux-m68k.org, daniel@thingy.jp, Hajime Tazaki Subject: [PATCH v4 1/2] selftests: run tests on nommu architecture Date: Wed, 30 Sep 2026 08:57:10 +0900 Message-ID: <20260929235711.2287931-2-thehajime@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260929235711.2287931-1-thehajime@gmail.com> References: <20260929235711.2287931-1-thehajime@gmail.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Architectures lacking MMU don't support fork(2) syscall and only vfork(2) is available with limitations. Thus, we cannot run kselftest on nommu architecture as is. This commit addresses this issue with the following changes: - on test run stage, avoid calling timeout command when NOMMU=1 variable added to environmental variable, since timeout command uses fork syscall which nommu platform doesn't support. - describe the difference of nommu tests in the document. So command line to build/execute tests for nommu should be like below: $ make ARCH=um NOMMU=1 O=build kselftest-all TARGETS=nommu $ make ARCH=um NOMMU=1 O=build kselftest-install TARGETS=nommu $ NOMMU=1 ./build/kselftest/kselftest_install/run_kselftest.sh -p \ -c nommu Cc: Shuah Khan Cc: Jonathan Corbet Cc: Kees Cook Cc: Andy Lutomirski Cc: Will Drewry Cc: Mark Brown Cc: Brendan Jackman Cc: Hangbin Liu Cc: "Ricardo B. Marliere" Cc: linux-kselftest@vger.kernel.org Cc: linux-um@lists.infradead.org Cc: linux-mm@kvack.org Cc: linux-doc@vger.kernel.org Closes: https://sashiko.dev/#/patchset/20260813063401.1786548-1-thehajime%40gmail.com Signed-off-by: Hajime Tazaki -- v3 => v4 - fix typos in commit message v2 => v3 - remove unnecessary modification - new target is moved from TARGETS=mm/nommu to TARGETS=nommu - rename CONFIG_NOMMU to NOMMU to avoid confusion to kernel config rfc => v2 - reformat ktap header, reported by Sashiko review - https://lore.kernel.org/linux-mm/20260825015945.141739-2-thehajime@gmail.com/ rfc: https://lore.kernel.org/linux-mm/20260813063401.1786548-1-thehajime@gmail.com/ --- Documentation/dev-tools/kselftest.rst | 14 ++++++++++++++ tools/testing/selftests/kselftest/runner.sh | 6 +++++- 2 files changed, 19 insertions(+), 1 deletion(-) diff --git a/Documentation/dev-tools/kselftest.rst b/Documentation/dev-tools/kselftest.rst index 64c0ec7428a2..c35b819947b7 100644 --- a/Documentation/dev-tools/kselftest.rst +++ b/Documentation/dev-tools/kselftest.rst @@ -230,6 +230,20 @@ section:: .. _tar's auto-compress: https://www.gnu.org/software/tar/manual/html_node/gzip.html#auto_002dcompress +Build and test on nommu target +============================== + +If you (cross-)build kselftests for nommu targets, or run tests on nommu targets, use +``NOMMU=1`` as a make variable/environment setting to tell build system to do the additional +checks. These nommu targets may differ in several ways, such as not supporting fork(2) or +using musl or another libc. Set this variable to apply the necessary build and test adjustments. + +:: + + $ make ARCH=um NOMMU=1 O=build kselftest-all TARGETS=nommu # <= build-only + $ make ARCH=um NOMMU=1 O=build kselftest-install TARGETS=nommu + $ NOMMU=1 ./build/kselftest/kselftest_install/run_kselftest.sh -p -c nommu + Contributing new tests ====================== diff --git a/tools/testing/selftests/kselftest/runner.sh b/tools/testing/selftests/kselftest/runner.sh index 311811dc55a0..ee2c1f0403d9 100644 --- a/tools/testing/selftests/kselftest/runner.sh +++ b/tools/testing/selftests/kselftest/runner.sh @@ -38,8 +38,12 @@ tap_prefix() tap_timeout() { + # nommu doesn't support timeout command (missing fork(2)) + if [ "$NOMMU" = "1" ] ; then + echo "timeout isn't supported for NOMMU" + $1 # Make sure tests will time out if utility is available. - if [ -x /usr/bin/timeout ] ; then + elif [ -x /usr/bin/timeout ] ; then /usr/bin/timeout --foreground "$kselftest_timeout" \ /usr/bin/timeout "$kselftest_timeout" $1 else -- 2.43.0