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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D22E4C32771 for ; Tue, 28 Jan 2020 02:11:57 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8FC112173E for ; Tue, 28 Jan 2020 02:11:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lca.pw header.i=@lca.pw header.b="jZmBH73p" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8FC112173E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lca.pw Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1B4DA6B0006; Mon, 27 Jan 2020 21:11:57 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 13DD26B0007; Mon, 27 Jan 2020 21:11:57 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 006836B0008; Mon, 27 Jan 2020 21:11:56 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0113.hostedemail.com [216.40.44.113]) by kanga.kvack.org (Postfix) with ESMTP id DBB256B0006 for ; Mon, 27 Jan 2020 21:11:56 -0500 (EST) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id A2F9C2C8F for ; Tue, 28 Jan 2020 02:11:56 +0000 (UTC) X-FDA: 76425417432.06.start24_4b195a943db43 X-HE-Tag: start24_4b195a943db43 X-Filterd-Recvd-Size: 6483 Received: from mail-qv1-f68.google.com (mail-qv1-f68.google.com [209.85.219.68]) by imf17.hostedemail.com (Postfix) with ESMTP for ; Tue, 28 Jan 2020 02:11:55 +0000 (UTC) Received: by mail-qv1-f68.google.com with SMTP id dc14so5537949qvb.9 for ; Mon, 27 Jan 2020 18:11:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lca.pw; s=google; h=content-transfer-encoding:from:mime-version:subject:date:message-id :references:cc:in-reply-to:to; bh=7Y+cJY1xhd0yBpcec7AzD+9evfVDrwqprX0erT9gNQ8=; b=jZmBH73pillRBQpbX84TZ57nVUbP8l/pwzyrT6F1TLbL143seIWhzMHM+f433HkTJ5 4+74y+cXEGlf05IjEqB0rGqFVcscYw+GLhSFsx8WaySmYsTRfGWpPzerjlys6mf9W6z9 7MQu28uGR+vExcu4XcFzxZsCEsEyIZnW5XYihpKw20TjtS/g7K7vcnSmLO9Y2I2ACMbR UKd7mEwngqjuWYnzl9qMnEhgnX2KVdsQpg9XPqLIZZY/9EZaReISvH0tgX5LHWCxTzuH Sdb0djgaeTc7Y2XT2pWCZ+vec+pYHc73GLTjZ8LH4FVsFHxU1dJtwXiD8faH/K6Piqjx Qz+Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:content-transfer-encoding:from:mime-version :subject:date:message-id:references:cc:in-reply-to:to; bh=7Y+cJY1xhd0yBpcec7AzD+9evfVDrwqprX0erT9gNQ8=; b=ZZecyDMh3hPNov6RQ3fVDqqBL4Eb8pSi2/DxE5outUZVAKTa8+U4e60UXZ/zZTlHdd PvOa704vra21Nrs/NPmNHAepaY8kmtuEuVR5ZDbVRDOZUiTglZwNjH9MzsOPchLRjdBI kyDESjqwIb5pI/i+8q3smKprxnkpZ/b2dVrjHpDmM06XhihqFFD5lHt0A1YOTIcOM1CM YxIcSR4l68YdjgV+AqSFE31PeJn3E7hYHtiPiAkzOoDLnhhAKhVueiNSeJUwrhdXz7py dr6f89CwD270ogvE4Bcd6LaT61Z1R1138y6hJbyYyYfnyVB85ciQXDlMje0XTAmWLNOm 7U3A== X-Gm-Message-State: APjAAAXpXRXxL+fKMRtLZrUKw7zJ92TS+e5qOrfVaWcn2KC0YIsfh+Vh HiSQAuvgrahn2HHdMzJ+Uf+WyA== X-Google-Smtp-Source: APXvYqzg/cYWhjYHl3Ki3ZAih+ex/42KJTx6ZAw8WelCuco+qFvVUewpgAxMMsdmClIjS/CcngZCgg== X-Received: by 2002:a05:6214:9d2:: with SMTP id dp18mr19624941qvb.98.1580177515237; Mon, 27 Jan 2020 18:11:55 -0800 (PST) Received: from [192.168.1.183] (pool-71-184-117-43.bstnma.fios.verizon.net. [71.184.117.43]) by smtp.gmail.com with ESMTPSA id m21sm11036189qka.117.2020.01.27.18.11.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 27 Jan 2020 18:11:54 -0800 (PST) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: Qian Cai Mime-Version: 1.0 (1.0) Subject: Re: [PATCH V12] mm/debug: Add tests validating architecture page table helpers Date: Mon, 27 Jan 2020 21:11:53 -0500 Message-Id: <14882A91-17DE-4ABD-ABF2-08E7CCEDF660@lca.pw> References: <1580174873-18117-1-git-send-email-anshuman.khandual@arm.com> Cc: linux-mm@kvack.org, Andrew Morton , Vlastimil Babka , Greg Kroah-Hartman , Thomas Gleixner , Mike Rapoport , Jason Gunthorpe , Dan Williams , Peter Zijlstra , Michal Hocko , Mark Rutland , Mark Brown , Steven Price , Ard Biesheuvel , Masahiro Yamada , Kees Cook , Tetsuo Handa , Matthew Wilcox , Sri Krishna chowdary , Dave Hansen , Russell King - ARM Linux , Michael Ellerman , Paul Mackerras , Martin Schwidefsky , Heiko Carstens , "David S. Miller" , Vineet Gupta , James Hogan , Paul Burton , Ralf Baechle , "Kirill A . Shutemov" , Gerald Schaefer , Christophe Leroy , Ingo Molnar , linux-snps-arc@lists.infradead.org, linux-mips@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <1580174873-18117-1-git-send-email-anshuman.khandual@arm.com> To: Anshuman Khandual X-Mailer: iPhone Mail (17C54) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > On Jan 27, 2020, at 8:28 PM, Anshuman Khandual = wrote: >=20 > This adds tests which will validate architecture page table helpers and > other accessors in their compliance with expected generic MM semantics. > This will help various architectures in validating changes to existing > page table helpers or addition of new ones. >=20 > This test covers basic page table entry transformations including but not > limited to old, young, dirty, clean, write, write protect etc at various > level along with populating intermediate entries with next page table page= > and validating them. >=20 > Test page table pages are allocated from system memory with required size > and alignments. The mapped pfns at page table levels are derived from a > real pfn representing a valid kernel text symbol. This test gets called > right after page_alloc_init_late(). >=20 > This gets build and run when CONFIG_DEBUG_VM_PGTABLE is selected along wit= h > CONFIG_VM_DEBUG. Architectures willing to subscribe this test also need to= > select CONFIG_ARCH_HAS_DEBUG_VM_PGTABLE which for now is limited to x86 an= d > arm64. Going forward, other architectures too can enable this after fixing= > build or runtime problems (if any) with their page table helpers. What=E2=80=99s the value of this block of new code? It only supports x86 and= arm64 which are supposed to be good now. Did those tests ever find any regr= ession or this is almost only useful for new architectures which only happen= ed once in a few years? The worry if not many people will use this config an= d code those that much in the future because it is inefficient to find bugs,= it will simply be rotten like a few other debugging options out there we ha= ve in the mainline that will be a pain to remove later on.=