From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sipsolutions.net (s3.sipsolutions.net [168.119.38.16]) (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 E45AE4BD782; Thu, 1 Oct 2026 10:02:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=168.119.38.16 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790848925; cv=none; b=RtI1fHXmAS3q+gIxraOTQpnZaq4BOASHs9OtRCGO7QN6r5xPtVheCz3M2VqN+meqHOmlG62jIEfRxGs7gCcScJ+x/kVg8D0vm6go3pIgAomjCQBv0PmyhhAhoy4Cga4aNEa+1j63l5mZsMaeZS9pxVibMptIXiKsWA5Uvm1PmX8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790848925; c=relaxed/simple; bh=NHzN2YXmU8BLXeWCHs+b8V0pYB1gKOyCtkBAw3USOmI=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=JVWv9MWt2wX+oZBfv2cJ6bDN0irUZWTynX6rGvI6k5EjopZfwk152nSLzxboXdRh1lgfrT99FxuR+LPk1s4CoCyXlZwLVdmR3mv5+vBFaXAo/1hRYGZwvqCK8F4O9nxYWHQ3o42RtyaZ5QfD06F9WBKGxxxMm2GK7V7UIsav7Tc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=permerror header.from=sipsolutions.net; spf=pass smtp.mailfrom=sipsolutions.net; dkim=pass (2048-bit key) header.d=sipsolutions.net header.i=@sipsolutions.net header.b=J+9bbUt7; arc=none smtp.client-ip=168.119.38.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=permerror header.from=sipsolutions.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sipsolutions.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=sipsolutions.net header.i=@sipsolutions.net header.b="J+9bbUt7" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sipsolutions.net; s=mail; h=MIME-Version:Content-Transfer-Encoding: Content-Type:References:In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-To: Resent-Cc:Resent-Message-ID; bh=Qhjkz5LGIQ5OQf96jD8ObHxGuARoVZWuTiE3aF/pzBw=; t=1790848923; x=1792058523; b=J+9bbUt7NCRMVmDoA+WX+CejOgMkWb4zv3BPoGnZSkOshpI 9wYlhVfkAfrwH4xe0TTjexQX366zFoPm36psDG9WfRQUhFvinTBG30MQq2/px/QKNsgGSUXxigtBg oIaRdP9rzmq3rLJslCqJ5haCTkUGEyRIN41iIYPMPa+fKLiSPkHRPN7RTkPHGHTkAiD7CFPOKToUA oV+Q5i4NVECUftXjxrwZ71n20Y2viTmSeDhLzoHCpJ3shdTy8S9NZsH/r9B1gCvCUqk4w92YTK1/A CAcbyIl64s+M3BiqnXuG56FZg+3A8o3RM3tTP50E9/uYdStTu7wZjdqGTy+WSvXQ==; Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_X25519__ECDSA_SECP256R1_SHA256__AES_256_GCM:256) (Exim 4.98.2) (envelope-from ) id 1xCDbn-000000001cC-1VvD; Thu, 01 Oct 2026 12:01:47 +0200 Message-ID: <94759bed23f00d2044005e36be6f72f297e092f0.camel@sipsolutions.net> Subject: Re: [PATCH v4 1/2] selftests: run tests on nommu architecture From: Johannes Berg To: "Lorenzo Stoakes (ARM)" , "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 Date: Thu, 01 Oct 2026 12:01:45 +0200 In-Reply-To: References: <20260929235711.2287931-1-thehajime@gmail.com> <20260929235711.2287931-2-thehajime@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.2 (3.60.2-2.fc44) Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-malware-bazaar: not-scanned On Thu, 2026-10-01 at 09:42 +0100, Lorenzo Stoakes (ARM) wrote: > On Thu, Oct 01, 2026 at 09:08:33AM +0200, David Hildenbrand (Arm) wrote: > > On 9/30/26 01:57, Hajime Tazaki wrote: > > > Architectures lacking MMU don't support fork(2) syscall and only > > > vfork(2) is available with limitations. Thus, we cannot run kselftes= t > > > on nommu architecture as is. > > >=20 > > > This commit addresses this issue with the following changes: > > >=20 > > > - on test run stage, avoid calling timeout command when NOMMU=3D1 var= iable > > > 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. > > >=20 > > > So command line to build/execute tests for nommu should be like below= : > > >=20 > > > $ make ARCH=3Dum NOMMU=3D1 O=3Dbuild kselftest-all TARGETS=3Dnommu > > > $ make ARCH=3Dum NOMMU=3D1 O=3Dbuild kselftest-install TARGETS=3Dnom= mu > > > $ NOMMU=3D1 ./build/kselftest/kselftest_install/run_kselftest.sh -p = \ > > > -c nommu > >=20 > > Is there a way we could derive that from the environment in one of thes= e cases? >=20 > I thought maybe uname could help but our LLM overlords tell me no. Hajime originally wanted uname to indicate it, but that caused regressions elsewhere, so we dropped that commit. I guess we could put _something_ back? > It pointed at something though. >=20 > In fs/proc/meminfo.c: >=20 > #ifndef CONFIG_MMU > show_val_kb(m, "MmapCopy: ", > (unsigned long)atomic_long_read(&mmap_pages_allocated)); > #endif >=20 > So MmapCopy in /proc/meminfo tells us definitively, weirdly enough. Hyrum's law and all that, but I guess it's not highly likely to (want to) change :) johannes