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=-7.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 54587C2D0EE for ; Sun, 29 Mar 2020 14:22:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3446B20733 for ; Sun, 29 Mar 2020 14:22:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728160AbgC2OWL (ORCPT ); Sun, 29 Mar 2020 10:22:11 -0400 Received: from foss.arm.com ([217.140.110.172]:58914 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727488AbgC2OWL (ORCPT ); Sun, 29 Mar 2020 10:22:11 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A5D9C31B; Sun, 29 Mar 2020 07:22:10 -0700 (PDT) Received: from [10.163.1.70] (unknown [10.163.1.70]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 542D63F68F; Sun, 29 Mar 2020 07:22:01 -0700 (PDT) From: Anshuman Khandual Subject: Re: [PATCH V2 0/3] mm/debug: Add more arch page table helper tests To: Christophe Leroy , linux-mm@kvack.org Cc: Jonathan Corbet , Andrew Morton , Mike Rapoport , Vineet Gupta , Catalin Marinas , Will Deacon , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , "Kirill A . Shutemov" , Paul Walmsley , Palmer Dabbelt , linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-riscv@lists.infradead.org, x86@kernel.org, linux-doc@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org References: <1585027375-9997-1-git-send-email-anshuman.khandual@arm.com> <2bb4badc-2b7a-e15d-a99b-b1bd38c9d9bf@arm.com> <9675882f-0ec5-5e46-551f-dd3aa38bf8d8@arm.com> Message-ID: Date: Sun, 29 Mar 2020 19:51:54 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On 03/27/2020 12:30 PM, Christophe Leroy wrote: > > > On 03/27/2020 06:46 AM, Anshuman Khandual wrote: >> >> On 03/26/2020 08:53 PM, Christophe Leroy wrote: >>> >>> >>> Le 26/03/2020 à 03:23, Anshuman Khandual a écrit : >>>> >>>> >>>> On 03/24/2020 10:52 AM, Anshuman Khandual wrote: >>>>> This series adds more arch page table helper tests. The new tests here are >>>>> either related to core memory functions and advanced arch pgtable helpers. >>>>> This also creates a documentation file enlisting all expected semantics as >>>>> suggested by Mike Rapoport (https://lkml.org/lkml/2020/1/30/40). >>>>> >>>>> This series has been tested on arm64 and x86 platforms. >>>> >>>> If folks can test these patches out on remaining ARCH_HAS_DEBUG_VM_PGTABLE >>>> enabled platforms i.e s390, arc, powerpc (32 and 64), that will be really >>>> appreciated. Thank you. >>>> >>> >>> On powerpc 8xx (PPC32), I get: >>> >>> [   53.338368] debug_vm_pgtable: debug_vm_pgtable: Validating architecture page table helpers >>> [   53.347403] ------------[ cut here ]------------ >>> [   53.351832] WARNING: CPU: 0 PID: 1 at mm/debug_vm_pgtable.c:647 debug_vm_pgtable+0x280/0x3f4 >> >> mm/debug_vm_pgtable.c:647 ? >> >> With the following commits in place >> >> 53a8338ce (HEAD) Documentation/mm: Add descriptions for arch page table helper >> 5d4913fc1 mm/debug: Add tests validating arch advanced page table helpers >> bcaf120a7 mm/debug: Add tests validating arch page table helpers for core features >> d6ed5a4a5 x86/memory: Drop pud_mknotpresent() >> 0739d1f8d mm/debug: Add tests validating architecture page table helpers >> 16fbf79b0 (tag: v5.6-rc7) Linux 5.6-rc7 > > I have: > > facaa5eb5909 (HEAD -> helpers0) mm/debug: Add tests validating arch advanced page table helpers > 6389fed515fc mm/debug: Add tests validating arch page table helpers for core features > dc14ecc8b94e mm/debug: add tests validating architecture page table helpers > c6624071c338 (origin/merge, merge) Automatic merge of branches 'master', 'next' and 'fixes' into merge > 58e05c5508e6 Automatic merge of branches 'master', 'next' and 'fixes' into merge > 1b649e0bcae7 (origin/master, origin/HEAD) Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net > > origin is https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git > > I can't see your last patch in powerpc mailing list (https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=166237) My bad, did not update the last patch with required lists (will fix). > >> >> mm/debug_vm_pgtable.c:647 is here. > > Line 647 is: > >     WARN_ON(!pte_same(pte, __swp_entry_to_pte(swp))); Both set of definitions suggest that the last three bits (if present) on the PTE will be discarded during PTE->SWP->PTE conversion which might be leading to this mismatch and subsequent failure. arch/powerpc/include/asm/nohash/32/pgtable.h arch/powerpc/include/asm/book3s/32/pgtable.h #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) >> 3 }) #define __swp_entry_to_pte(x) ((pte_t) { (x).val << 3 }) Also there are some more architectures (microblaze, sh, etc) where these conversions are not always preserving. On powerpc64, it sets back _PAGE_PTE irrespective of whether the bit was originally set or not. Probably it is wrong to expect that PTE->SWP->PTE conversion will be always preserving. So wondering if it is worth changing this test to accommodate all such architectures or just drop it instead. > > >> >> #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION >> static void __init pmd_swap_tests(unsigned long pfn, pgprot_t prot) >> { >>          swp_entry_t swp; >>          pmd_t pmd;  -----------------------------> Line #647 >> >>          pmd = pfn_pmd(pfn, prot); >>          swp = __pmd_to_swp_entry(pmd); >>          WARN_ON(!pmd_same(pmd, __swp_entry_to_pmd(swp))); >> } >> #else >> static void __init pmd_swap_tests(unsigned long pfn, pgprot_t prot) { } >> #end >> >> Did I miss something ? >> > > [...] > >> Could you please point me to the exact test which is failing ? >> >>> [   53.519778] Freeing unused kernel memory: 608K >>> >>> >> So I assume that the system should have come till runtime just fine apart from >> the above warning message because. >> > > Yes it boots fine otherwise. Cool, that is good to know. > > Christophe >