From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 865C9463B6F; Tue, 25 Aug 2026 13:13:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787663588; cv=none; b=o2D/LJf9IgJL62UBU0LkXI+AYfa4g5X1PlgKdtGueOvWjqf4EvYSPP1fWILaNr88j8H3MShlsdMpJfA3MhL3fg7GcunIvzi+j2BLjrgvEYcWnBRcpsy75Xg6/tJ9+hNh3qDup9WJfNGkyVP7dC+DfPMduMa4+cViW3oty4orKG4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787663588; c=relaxed/simple; bh=hhEO4/3KevWWjpuvVW/uNLA0iV7xOfcX6lnr9uAtHbI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=rV4lWp28qcO4yvTFk6RDjrEeFV8/5M2NhlIEny0eKk1jhgIcTQBU2RWdjQKp101L1G8/f1er8AuqkBBwip6z28TyBmBXxgNB3b3RhHco/M8vuzCZUBfz+RkAP4uQEhnKVFTeb7va2E+RIDuWnKsX09UxFUbp0iknuF81rbRcx9w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=di+7PMDP; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="di+7PMDP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A0FF81F00A3A; Tue, 25 Aug 2026 13:12:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787663580; bh=y1ooUZqu3n0X6AHMc52e/9cK3btR11yvm1f2GPiErVs=; h=Date:From:To:Cc:Subject:References:In-Reply-To; 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> Precedence: bulk X-Mailing-List: linux-doc@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: 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