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=-13.9 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 94BE9C43461 for ; Fri, 4 Sep 2020 05:37:08 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4448A206F2 for ; Fri, 4 Sep 2020 05:37:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4448A206F2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4BjRJK5sMGzDrJl for ; Fri, 4 Sep 2020 15:37:05 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=arm.com (client-ip=217.140.110.172; helo=foss.arm.com; envelope-from=anshuman.khandual@arm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=arm.com Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lists.ozlabs.org (Postfix) with ESMTP id 4BjRG50bKyzDrHb for ; Fri, 4 Sep 2020 15:35:07 +1000 (AEST) 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 6ABDC101E; Thu, 3 Sep 2020 22:35:06 -0700 (PDT) Received: from [10.163.70.23] (unknown [10.163.70.23]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8C1CB3F71F; Thu, 3 Sep 2020 22:35:04 -0700 (PDT) Subject: Re: [PATCH v4 07/13] mm/debug_vm_pgtable/set_pte/pmd/pud: Don't use set_*_at to update an existing pte entry To: "Aneesh Kumar K.V" , linux-mm@kvack.org, akpm@linux-foundation.org References: <20200902114222.181353-1-aneesh.kumar@linux.ibm.com> <20200902114222.181353-8-aneesh.kumar@linux.ibm.com> From: Anshuman Khandual Message-ID: Date: Fri, 4 Sep 2020 11:04:32 +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: <20200902114222.181353-8-aneesh.kumar@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 09/02/2020 05:12 PM, Aneesh Kumar K.V wrote: > set_pte_at() should not be used to set a pte entry at locations that > already holds a valid pte entry. Architectures like ppc64 don't do TLB > invalidate in set_pte_at() and hence expect it to be used to set locations > that are not a valid PTE. > > Signed-off-by: Aneesh Kumar K.V > --- > mm/debug_vm_pgtable.c | 35 +++++++++++++++-------------------- > 1 file changed, 15 insertions(+), 20 deletions(-) > > diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c > index 9cafed39c236..de333871f407 100644 > --- a/mm/debug_vm_pgtable.c > +++ b/mm/debug_vm_pgtable.c > @@ -79,15 +79,18 @@ static void __init pte_advanced_tests(struct mm_struct *mm, > { > pte_t pte = pfn_pte(pfn, prot); > > + /* > + * Architectures optimize set_pte_at by avoiding TLB flush. > + * This requires set_pte_at to be not used to update an > + * existing pte entry. Clear pte before we do set_pte_at > + */ > + > pr_debug("Validating PTE advanced\n"); > pte = pfn_pte(pfn, prot); > set_pte_at(mm, vaddr, ptep, pte); > ptep_set_wrprotect(mm, vaddr, ptep); > pte = ptep_get(ptep); > WARN_ON(pte_write(pte)); > - > - pte = pfn_pte(pfn, prot); > - set_pte_at(mm, vaddr, ptep, pte); > ptep_get_and_clear(mm, vaddr, ptep); > pte = ptep_get(ptep); > WARN_ON(!pte_none(pte)); > @@ -101,13 +104,11 @@ static void __init pte_advanced_tests(struct mm_struct *mm, > ptep_set_access_flags(vma, vaddr, ptep, pte, 1); > pte = ptep_get(ptep); > WARN_ON(!(pte_write(pte) && pte_dirty(pte))); > - > - pte = pfn_pte(pfn, prot); > - set_pte_at(mm, vaddr, ptep, pte); > ptep_get_and_clear_full(mm, vaddr, ptep, 1); > pte = ptep_get(ptep); > WARN_ON(!pte_none(pte)); > > + pte = pfn_pte(pfn, prot); > pte = pte_mkyoung(pte); > set_pte_at(mm, vaddr, ptep, pte); > ptep_test_and_clear_young(vma, vaddr, ptep); > @@ -169,9 +170,6 @@ static void __init pmd_advanced_tests(struct mm_struct *mm, > pmdp_set_wrprotect(mm, vaddr, pmdp); > pmd = READ_ONCE(*pmdp); > WARN_ON(pmd_write(pmd)); > - > - pmd = pmd_mkhuge(pfn_pmd(pfn, prot)); > - set_pmd_at(mm, vaddr, pmdp, pmd); > pmdp_huge_get_and_clear(mm, vaddr, pmdp); > pmd = READ_ONCE(*pmdp); > WARN_ON(!pmd_none(pmd)); > @@ -185,13 +183,11 @@ static void __init pmd_advanced_tests(struct mm_struct *mm, > pmdp_set_access_flags(vma, vaddr, pmdp, pmd, 1); > pmd = READ_ONCE(*pmdp); > WARN_ON(!(pmd_write(pmd) && pmd_dirty(pmd))); > - > - pmd = pmd_mkhuge(pfn_pmd(pfn, prot)); > - set_pmd_at(mm, vaddr, pmdp, pmd); > pmdp_huge_get_and_clear_full(vma, vaddr, pmdp, 1); > pmd = READ_ONCE(*pmdp); > WARN_ON(!pmd_none(pmd)); > > + pmd = pmd_mkhuge(pfn_pmd(pfn, prot)); > pmd = pmd_mkyoung(pmd); > set_pmd_at(mm, vaddr, pmdp, pmd); > pmdp_test_and_clear_young(vma, vaddr, pmdp); > @@ -292,17 +288,9 @@ static void __init pud_advanced_tests(struct mm_struct *mm, > WARN_ON(pud_write(pud)); > > #ifndef __PAGETABLE_PMD_FOLDED > - pud = pud_mkhuge(pfn_pud(pfn, prot)); > - set_pud_at(mm, vaddr, pudp, pud); > pudp_huge_get_and_clear(mm, vaddr, pudp); > pud = READ_ONCE(*pudp); > WARN_ON(!pud_none(pud)); > - > - pud = pud_mkhuge(pfn_pud(pfn, prot)); > - set_pud_at(mm, vaddr, pudp, pud); > - pudp_huge_get_and_clear_full(mm, vaddr, pudp, 1); > - pud = READ_ONCE(*pudp); > - WARN_ON(!pud_none(pud)); > #endif /* __PAGETABLE_PMD_FOLDED */ > > pud = pud_mkhuge(pfn_pud(pfn, prot)); > @@ -315,6 +303,13 @@ static void __init pud_advanced_tests(struct mm_struct *mm, > pud = READ_ONCE(*pudp); > WARN_ON(!(pud_write(pud) && pud_dirty(pud))); > > +#ifndef __PAGETABLE_PMD_FOLDED > + pudp_huge_get_and_clear_full(mm, vaddr, pudp, 1); > + pud = READ_ONCE(*pudp); > + WARN_ON(!pud_none(pud)); > +#endif /* __PAGETABLE_PMD_FOLDED */ > + > + pud = pud_mkhuge(pfn_pud(pfn, prot)); > pud = pud_mkyoung(pud); > set_pud_at(mm, vaddr, pudp, pud); > pudp_test_and_clear_young(vma, vaddr, pudp); > Reviewed-by: Anshuman Khandual