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=-12.6 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,USER_AGENT_SANE_1 autolearn=ham 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 E9FA6C433E1 for ; Thu, 20 Aug 2020 14:33:19 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A48B32076E for ; Thu, 20 Aug 2020 14:33:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A48B32076E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=csgroup.eu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 371428D0009; Thu, 20 Aug 2020 10:33:19 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 321F78D0002; Thu, 20 Aug 2020 10:33:19 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2378B8D0009; Thu, 20 Aug 2020 10:33:19 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0210.hostedemail.com [216.40.44.210]) by kanga.kvack.org (Postfix) with ESMTP id 0D9C88D0002 for ; Thu, 20 Aug 2020 10:33:19 -0400 (EDT) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 65D20180ACF86 for ; Thu, 20 Aug 2020 14:33:18 +0000 (UTC) X-FDA: 77171189676.13.rate49_0c019ec27031 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin13.hostedemail.com (Postfix) with ESMTP id B88DE1814063F for ; Thu, 20 Aug 2020 14:33:11 +0000 (UTC) X-HE-Tag: rate49_0c019ec27031 X-Filterd-Recvd-Size: 6648 Received: from pegase1.c-s.fr (pegase1.c-s.fr [93.17.236.30]) by imf46.hostedemail.com (Postfix) with ESMTP for ; Thu, 20 Aug 2020 14:33:09 +0000 (UTC) Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 4BXRvk3Rf6z9vD3m; Thu, 20 Aug 2020 16:33:06 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id nQSbO1N6odEA; Thu, 20 Aug 2020 16:33:06 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 4BXRvk2SGBz9vD3l; Thu, 20 Aug 2020 16:33:06 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id F21BE8B860; Thu, 20 Aug 2020 16:33:07 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id ru8Mj5dwt87n; Thu, 20 Aug 2020 16:33:07 +0200 (CEST) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 831998B764; Thu, 20 Aug 2020 16:33:07 +0200 (CEST) Subject: Re: [PATCH v2 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 Cc: linuxppc-dev@lists.ozlabs.org, Anshuman Khandual References: <20200819130107.478414-1-aneesh.kumar@linux.ibm.com> <20200819130107.478414-8-aneesh.kumar@linux.ibm.com> From: Christophe Leroy Message-ID: Date: Thu, 20 Aug 2020 16:32:54 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <20200819130107.478414-8-aneesh.kumar@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr X-Rspamd-Queue-Id: B88DE1814063F X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 Content-Transfer-Encoding: quoted-printable 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: Le 19/08/2020 =C3=A0 15:01, Aneesh Kumar K.V a =C3=A9crit=C2=A0: > 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 locati= ons > that are not a valid PTE. >=20 > Signed-off-by: Aneesh Kumar K.V > --- > mm/debug_vm_pgtable.c | 35 +++++++++++++++-------------------- > 1 file changed, 15 insertions(+), 20 deletions(-) >=20 > diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c > index 76f4c713e5a3..9c7e2c9cfc76 100644 > --- a/mm/debug_vm_pgtable.c > +++ b/mm/debug_vm_pgtable.c > @@ -74,15 +74,18 @@ static void __init pte_advanced_tests(struct mm_str= uct *mm, > { > pte_t pte =3D pfn_pte(pfn, prot); > =20 > + /* > + * 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 =3D pfn_pte(pfn, prot); > set_pte_at(mm, vaddr, ptep, pte); > ptep_set_wrprotect(mm, vaddr, ptep); > pte =3D ptep_get(ptep); > WARN_ON(pte_write(pte)); > - > - pte =3D pfn_pte(pfn, prot); > - set_pte_at(mm, vaddr, ptep, pte); > ptep_get_and_clear(mm, vaddr, ptep); > pte =3D ptep_get(ptep); > WARN_ON(!pte_none(pte)); > @@ -96,13 +99,11 @@ static void __init pte_advanced_tests(struct mm_str= uct *mm, > ptep_set_access_flags(vma, vaddr, ptep, pte, 1); > pte =3D ptep_get(ptep); > WARN_ON(!(pte_write(pte) && pte_dirty(pte))); > - > - pte =3D pfn_pte(pfn, prot); > - set_pte_at(mm, vaddr, ptep, pte); > ptep_get_and_clear_full(mm, vaddr, ptep, 1); > pte =3D ptep_get(ptep); > WARN_ON(!pte_none(pte)); > =20 > + pte =3D pfn_pte(pfn, prot); > pte =3D pte_mkyoung(pte); > set_pte_at(mm, vaddr, ptep, pte); > ptep_test_and_clear_young(vma, vaddr, ptep); > @@ -164,9 +165,6 @@ static void __init pmd_advanced_tests(struct mm_str= uct *mm, > pmdp_set_wrprotect(mm, vaddr, pmdp); > pmd =3D READ_ONCE(*pmdp); > WARN_ON(pmd_write(pmd)); > - > - pmd =3D pmd_mkhuge(pfn_pmd(pfn, prot)); > - set_pmd_at(mm, vaddr, pmdp, pmd); > pmdp_huge_get_and_clear(mm, vaddr, pmdp); > pmd =3D READ_ONCE(*pmdp); > WARN_ON(!pmd_none(pmd)); > @@ -180,13 +178,11 @@ static void __init pmd_advanced_tests(struct mm_s= truct *mm, > pmdp_set_access_flags(vma, vaddr, pmdp, pmd, 1); > pmd =3D READ_ONCE(*pmdp); > WARN_ON(!(pmd_write(pmd) && pmd_dirty(pmd))); > - > - pmd =3D pmd_mkhuge(pfn_pmd(pfn, prot)); > - set_pmd_at(mm, vaddr, pmdp, pmd); > pmdp_huge_get_and_clear_full(vma, vaddr, pmdp, 1); > pmd =3D READ_ONCE(*pmdp); > WARN_ON(!pmd_none(pmd)); > =20 > + pmd =3D pmd_mkhuge(pfn_pmd(pfn, prot)); > pmd =3D pmd_mkyoung(pmd); > set_pmd_at(mm, vaddr, pmdp, pmd); > pmdp_test_and_clear_young(vma, vaddr, pmdp); > @@ -283,18 +279,10 @@ static void __init pud_advanced_tests(struct mm_s= truct *mm, > WARN_ON(pud_write(pud)); > =20 > #ifndef __PAGETABLE_PMD_FOLDED Same as below, once set_put_at() is gone, I don't think this #ifndef=20 __PAGETABLE_PMD_FOLDED is still need, should be possible to replace by=20 'if (mm_pmd_folded())' > - > - pud =3D pud_mkhuge(pfn_pud(pfn, prot)); > - set_pud_at(mm, vaddr, pudp, pud); > pudp_huge_get_and_clear(mm, vaddr, pudp); > pud =3D READ_ONCE(*pudp); > WARN_ON(!pud_none(pud)); > =20 > - pud =3D pud_mkhuge(pfn_pud(pfn, prot)); > - set_pud_at(mm, vaddr, pudp, pud); > - pudp_huge_get_and_clear_full(mm, vaddr, pudp, 1); > - pud =3D READ_ONCE(*pudp); > - WARN_ON(!pud_none(pud)); > #endif /* __PAGETABLE_PMD_FOLDED */ > =20 > pud =3D pud_mkhuge(pfn_pud(pfn, prot)); > @@ -307,6 +295,13 @@ static void __init pud_advanced_tests(struct mm_st= ruct *mm, > pud =3D READ_ONCE(*pudp); > WARN_ON(!(pud_write(pud) && pud_dirty(pud))); > =20 > +#ifndef __PAGETABLE_PMD_FOLDED > + pudp_huge_get_and_clear_full(vma, vaddr, pudp, 1); > + pud =3D READ_ONCE(*pudp); > + WARN_ON(!pud_none(pud)); > +#endif /* __PAGETABLE_PMD_FOLDED */ pudp_huge_get_and_clear_full() and pud_none() are always defined, I=20 think this #ifndef can be replaced by an 'if (mm_pmd_folded())' > + > + pud =3D pud_mkhuge(pfn_pud(pfn, prot)); > pud =3D pud_mkyoung(pud); > set_pud_at(mm, vaddr, pudp, pud); > pudp_test_and_clear_young(vma, vaddr, pudp); >=20 Christophe