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b=DJaay7PGP72R0tGkgyP+Oia4imEuYm8t8qR2pXFgrg9WILqzSl7Vjhp2rqDjHKhux uDvrW2JpIyiASNUHIEFPZCnwPdOnC86ajBo8MeUmgKWcO1RGq3jtrAcpsqaC2H/gSN YN8/cyXRUqo+vKyymEyDaWP/qu79jZshTmfGQWuhHsZgZlrxlBA4TpI5fBeUFX/zP9 Q5IWXT00yBQBnN09zoLUi1pomgDek0CrQ7diRBg3IxLLnE22BgtzKyel6+XVNdLMUg BUbrKXD6vrPDCndd/xW8t3MDQHdtA92TFc5Ucd4FjBjsCfi2hMUSQGyF4YZtKTsPIl GRMJ5Vp+/rHuA== Date: Mon, 28 Sep 2026 12:03:58 +0100 From: "Lorenzo Stoakes (ARM)" To: Hajime Tazaki Cc: 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, 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, geert@linux-m68k.org, daniel@thingy.jp Subject: Re: [PATCH v3 2/3] selftests: run tests on nommu architecture Message-ID: References: <20260926010819.604346-1-thehajime@gmail.com> <20260926010819.604346-3-thehajime@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260926010819.604346-3-thehajime@gmail.com> X-Stat-Signature: a5haowxywz39kf6zhefmbxo46yddimkh X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 294291C000D X-HE-Tag: 1790593447-129854 X-HE-Meta: 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 9ikFVRvj 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, Sep 26, 2026 at 10:08:18AM +0900, Hajime Tazaki wrote: > Architectures lacks MMU doesn'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 LGTM so: Reviewed-by: Lorenzo Stoakes (ARM) > > -- > > 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 8fc1018d6fec..95b5ebb8bbb9 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 > -- Cheers, Lorenzo