From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from stravinsky.debian.org (stravinsky.debian.org [82.195.75.108]) (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 1101D21A95D; Mon, 16 Mar 2026 16:02:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=82.195.75.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773676977; cv=none; b=MxBIMgSNHPCY0zzXZfmswEBu+lXnEytS++czllS4RpaOSbmeREZ4jwo0lf0YCplh2XWJchj3pjZeSMyAyh9HCkb0/ZiWuftaJlbPjZNeAP7LZwU+QLiP2vse3UzeFJvealQigw0+IELtfQRDVyt2QRiFmHVKFKypjvUXAEjEzCw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773676977; c=relaxed/simple; bh=iH4ZmIE7get/TI4IYPCISY4ctgd+qoJ3FkNVlSbJAoo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ATN3VRpY/BdJOrVBxLikf41QxVWIViHsDZ8bxi0Ig1JvXNUtcThR3e/JCafzIESQ//Jvfkw90ZSaaxEYSzZrU6hkoiJzJMIK/AUVJGfcEC+VyFhXpRuFzpN+ps1+8oJ3imitz7Uz51e/Zu2Vs/UmGTQvwFeIGZuF0ISq5Txo7W8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org; spf=none smtp.mailfrom=debian.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b=vZzqMjx+; arc=none smtp.client-ip=82.195.75.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=debian.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b="vZzqMjx+" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Reply-To:Content-ID:Content-Description; bh=RPhGdp8fS2iuoiGh9J6Zs2sMJGA6LuqofK+hwfYa/c4=; b=vZzqMjx+Q8KfhCEsnw3DRTL4ld m39k9jPQmfZqhTm3Ikq3r/0OvExw8PYxYd79qiuIaC75ra3iTFpCiMEzAWx5BkH8LMInmwCYDH5/l NMYJVctNa7QW8e2VbCtqIXclWbtot6UU6hCgVR6/w9c4mEjLsJFIvgbBuu0rJJ9OraH+N46rfkMXV ued/6MZJDtNN5xGhj/ZOeCv+0W8UxBinKrBE1/G924FzyIOlbcbnbOw9XTa3ozbltP+0knw+H0o6t tTj6rJZSzdoSnrh7iGsvE8iQH1wVu4OSoz+RWRylJThICWqPRzygOyHTgiXrS++JK14EAblugBuGE VMy4q2ew==; Received: from authenticated user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.94.2) (envelope-from ) id 1w2AOz-002E9E-13; Mon, 16 Mar 2026 16:02:43 +0000 Date: Mon, 16 Mar 2026 09:02:33 -0700 From: Breno Leitao To: "David Hildenbrand (Arm)" Cc: "Lorenzo Stoakes (Oracle)" , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH] selftests/mm: add THP sysfs interface test Message-ID: References: <20260309-thp_selftest_v2-v1-1-a00cef41da44@debian.org> <9cb63c24-eaff-4954-97d5-2a422a0401fc@lucifer.local> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Debian-User: leitao On Mon, Mar 16, 2026 at 03:44:14PM +0100, David Hildenbrand (Arm) wrote: > On 3/16/26 14:47, Breno Leitao wrote: > > On Mon, Mar 16, 2026 at 12:55:13PM +0000, Lorenzo Stoakes (Oracle) wrote: > >> On Mon, Mar 09, 2026 at 05:00:34AM -0700, Breno Leitao wrote: > >>> Add a shell-based selftest that exercises the full set of THP sysfs > >>> knobs: enabled (global and per-size anon), defrag, use_zero_page, > >>> hpage_pmd_size, shmem_enabled (global and per-size), shrink_underused, > >>> khugepaged/ tunables, and per-size stats files. > >>> > >>> Each writable knob is tested for valid writes, invalid-input rejection, > >>> idempotent writes, and mode transitions where applicable. All original > >>> values are saved before testing and restored afterwards. > >>> > >>> The test uses the kselftest KTAP framework (ktap_helpers.sh) for > >>> structured TAP 13 output, making results parseable by the kselftest > >>> harness. The test plan is printed at the end since the number of test > >>> points is dynamic (depends on available hugepage sizes and sysfs files). > >>> > >>> This is particularly useful for validating the refactoring of > >>> enabled_store() and anon_enabled_store() to use sysfs_match_string() > >>> and the new change_enabled()/change_anon_orders() helpers. > >>> > >>> Signed-off-by: Breno Leitao > >> > >> The test is broken locally for me, returning error code 127. > >> > >> I do appreciate the effort here, so I'm sorry to push back negatively, but I > >> feel a bash script here is pretty janky, and frankly if any of these interfaces > >> were as broken as this it'd be a major failure that would surely get picked up > >> far sooner elsewhere. > >> > >> So while I think this might be useful as a local test for your sysfs interface > >> changes, I don't think this is really suited to the mm selftests. > > > > That is totally fine. This test is what I have been using to test the > > changes, and I decide to share it in case someone find it useful. > > > > Let's drop it. > > Out of interest, to we know why the test is failing for Lorenzo? I really don't know, but, it sounds like ktap was not found? Then the first early-exit path hit: ktap_skip_all "..." # undefined → returns 127 exit "$KSFT_SKIP" # expands to: exit "" → exits with last $? = 127 > I agree that the test is a bit excessive, in particular when it comes to > invalid/idempotent values etc. I could see some value for testing > whether setting the modes keeps working, but also then I wonder if that > is really something we'll be changing frequently (and that breaks easily). yea, I make it very excessive, because there were some intrinsics in those sysfs that I was gettingit wrong when doing the intial conversion. So, the test is something that I trust now, and I found it useful when finding regressiosn. Is is something that will chagne frequently? probably not! That said, would you like to have a simplified/different version of this test?