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b=di+7PMDPHKJfCpsQmjVBUEbvXlQaZKb3l1YLxpWKXFvWrDrILEJQmo2eEwwMqWiQ8 3VtqnaEz0JXZZncs8PraIMpk3NIunXnWyDCqt//xeQu4IopzhXaHUWU6Xoy3GWVI+7 s9HuO+Xht7BpCV8TZf5SuXjSRTmpfgUPkO0aW21lYqDwX3vWR92tkUT1ywm9s6MVBj 4r7stbb/zFTi59pT0dBR3+NTuMEQQsX0avCLwwHTxxxqneTZxvVqHZjg+iV38KlDXS HaF+XUuViD3b9+EpFbB1weCL89MBtsC7Hr25gFh6A02REt3u/GO5SxShPGCtPdBaW5 WHKXpUuewxP+g== Date: Tue, 25 Aug 2026 14:12:52 +0100 From: "Lorenzo Stoakes (ARM)" To: "David Hildenbrand (Arm)" Cc: Hajime Tazaki , linux-mm@kvack.org, liam@infradead.org, rbm@suse.com, akpm@linux-foundation.org, luto@amacapital.net, brendan.jackman@linux.dev, 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 v2 0/2] support kselftest on nommu platform Message-ID: References: <20260825015945.141739-1-thehajime@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Stat-Signature: wc1jedqbgbz8mgq7man9ts7ijciprnjy X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: C8E21100009 X-HE-Tag: 1787663581-361417 X-HE-Meta: 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 cMOQsEac PC98tBjhGXHqoiN//J2ySakjdCK2KkcGDvSezUPl/rFv7aSDohij+ZTIwDt+06RbgmLGHgwkx/54qexuk+UFv25DWSdF0PA+uQQ1DObytrOVH11/XmvF6tZq4Fejuu9LzA1Ln72tNe0PYbMF9UBruD4PYdVrLSjMEjzhSu3yE3vO1wXGtBH9BcbvLg1wn9l27DpMiQjf2e5bRVtEh8o1X+2XJC7e7pZT2vDX2EOfJGB6SQnLT8URFrvKutAj95mra8ssJke6uRTXihJcbKjPl8m4phCG0Vk5YpsVq8whhHyE761I= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Aug 25, 2026 at 10:37:41AM +0200, David Hildenbrand (Arm) wrote: > On 8/25/26 03:59, Hajime Tazaki wrote: > > We add an ability to execute kselftest on nommu platforms. > > > > Currently there are several issues if we wish to run kselftests on nommu > > targets: > > > > - it cannot compile/build test binaries because the current files mainly > > assume to build with glibc, > > - some of the tests are not able to run on nommu targets as there are no > > fork(2) syscall. > > > > The first issue can be avoided if we can build static PIE binaries (if > > targets support it), but in our case (build on ubuntu/glibc and run on > > alpine/musl-libc), it fails to invoke due to lack of the GNU ifunc > > mechanism. Thus, we need to cross-compile with musl toolchain, which > > needs to be solved the first issue. > > > > The second issue is the lack of fork(2) syscall on those platforms. > > Especially the test harness helper (kselftest_harness.h) uses the > > syscall, which cannot be simply with vfork(2). `timeout` command used > > in `runner.sh` never works for nommu platform as it uses fork(2). > > > > nommu component in the mm subsystem has several known issues and having > > test cases should help this situation, thus this patchset is very first > > step toward enriching test environment which has not been well tested > > for a while. The test cases is implemented based on the document > > (Documentation/admin-guide/mm/nommu-mmap.rst). > > > > So, for the first step, nommu targets only support low-level API of > > kselftests (kselftest.h), and implement tests in a new target, > > TARGETS=mm/nommu. Other targets are currently not even able to build > > due to toolchain issues but will be addressed once the initial > > introduction which mainly focuses on nommu test will be settled. > > > > The patch was initially combined with other patches but is decoupled to > > only focus on test framework and testcases. > > > > - rfc: > > https://lore.kernel.org/linux-mm/20260813063401.1786548-1-thehajime@gmail.com/ > > > > Hajime Tazaki (2): > > selftests: run tests on nommu architecture > > selftests/mm: add nommu mmap and mremap behavior tests > > > > Documentation/dev-tools/kselftest.rst | 14 + > > tools/testing/selftests/Makefile | 1 + > > tools/testing/selftests/kselftest/runner.sh | 9 +- > > tools/testing/selftests/kselftest_harness.h | 4 + > > tools/testing/selftests/lib.mk | 8 + > > tools/testing/selftests/mm/nommu/Makefile | 7 + > > .../selftests/mm/nommu/nommu_mmap_test.c | 265 +++++++++++++ > > .../selftests/mm/nommu/nommu_mremap_test.c | 353 ++++++++++++++++++ > > That's odd. > > tools/testing/selftests/mm > > itself should know which tests can be built and ran on nommu. nommu-only tests > can be placed in mm/nommu, but I would expect tools/testing/selftests/mm's > Makefile and run script to compile and run only selftests that are supported on > the given platform. I mean I think at this point with mm/nommu/nommu_xxx.c it'd make more sense to simply have selftests/nommu/ + update the mm makefile to not build stuff that's broken on nommu there. That way positively nommu-stuff is put in its own place and what's broken on mm specific to nommu can be fixed there. I'd rather isolate them clearly rather than having them live in a subdirectory of mm. > > -- > Cheers, > > David -- Cheers, Lorenzo