From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C6010CA5FA5 for ; Thu, 1 Oct 2026 10:02:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:MIME-Version: Content-Transfer-Encoding:Content-Type:References:In-Reply-To:Date:Cc:To:From :Subject:Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Qhjkz5LGIQ5OQf96jD8ObHxGuARoVZWuTiE3aF/pzBw=; b=kC3zodh+ykPjUBBVU9X/JRyVA8 yINjFvonnF2WaZppratni/MnAB7TVHe9hqOxp8JvTPihRBsGobKSI+hqQH3xrF5CckumkmEHsnuPA Wj7/3aPjdP6tGGucCohn20hWtg2DZpgy6JeAz11LjDqrtdoWH2K4yGeFwm0cH6LIpbtTuCgiApaoj coK+NUCMBXdCVOf+dVC041Lu7ZvTfkWr8SvtDKQrHYuG8n0d3RB5awNFZdyxqjB0ZCokqaWFUYGkS mJUT2ddmwDawWFcJG8VzaT40TrQUGu0jIx8aRn9ttIRAoL7bF4ot9emapwM/CWa5NmiwKcV5OEBev PtFNT6KA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xCDc6-00000008Si1-1qCy; Thu, 01 Oct 2026 10:02:06 +0000 Received: from s3.sipsolutions.net ([2a01:4f8:242:246e::2] helo=sipsolutions.net) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xCDc4-00000008Sgh-18YL for linux-um@lists.infradead.org; Thu, 01 Oct 2026 10:02:05 +0000 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=1790848924; x=1792058524; b=q9xORyBFdeqEevl/UX33zAnMfcWG+XBCs5zegiqKHUZH6Ju 5wCCPwNMmHnsfcaTDHVt6H51pwxv29XEOmgzf1o7RRbqrpc6gtj6DVGRbAjM5pfFfyTwtnnvOr41G s6X7yJgUvYp+Jy7/3gWhw3U4Lxdb0Rb762GsBOtbSKS9uuC86yUyWN9avQ1MYuLnTuhEAynaTQzis VZ7aGtsVm0ZThmo9laJAY2ojuiP48G+a0FLTQ0sBtH8N6Gao5BvBePl77iq2HXttXMXaFdjRaUgFu b2u31x7BlhVL1pWxqHabR/VId0z+3qX1Rb4gvrsgjyfoD6bV3j/vrkqpfdvUOXMA==; 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) MIME-Version: 1.0 X-malware-bazaar: not-scanned X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261001_030204_321815_FF13DF27 X-CRM114-Status: GOOD ( 16.09 ) X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org 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