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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,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 B2F9AC2D0E9 for ; Thu, 26 Mar 2020 02:18:43 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 544E520719 for ; Thu, 26 Mar 2020 02:18:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 544E520719 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9D9D16B000A; Wed, 25 Mar 2020 22:18:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 987F36B000C; Wed, 25 Mar 2020 22:18:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 877236B000D; Wed, 25 Mar 2020 22:18:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0069.hostedemail.com [216.40.44.69]) by kanga.kvack.org (Postfix) with ESMTP id 6BF836B000A for ; Wed, 25 Mar 2020 22:18:42 -0400 (EDT) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 576BE180AD815 for ; Thu, 26 Mar 2020 02:18:42 +0000 (UTC) X-FDA: 76635904884.03.face83_11b4cb0f0fa33 X-HE-Tag: face83_11b4cb0f0fa33 X-Filterd-Recvd-Size: 13363 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf26.hostedemail.com (Postfix) with ESMTP for ; Thu, 26 Mar 2020 02:18:41 +0000 (UTC) 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 7ADDF1FB; Wed, 25 Mar 2020 19:18:40 -0700 (PDT) Received: from [10.163.1.31] (unknown [10.163.1.31]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A5A9D3F52E; Wed, 25 Mar 2020 19:18:32 -0700 (PDT) From: Anshuman Khandual Subject: Re: [PATCH V2 1/3] mm/debug: Add tests validating arch page table helpers for core features To: Zi Yan Cc: linux-mm@kvack.org, christophe.leroy@c-s.fr, 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-arch@vger.kernel.org, linux-kernel@vger.kernel.org References: <1585027375-9997-1-git-send-email-anshuman.khandual@arm.com> <1585027375-9997-2-git-send-email-anshuman.khandual@arm.com> <89E72C74-A32F-4A5B-B5F3-8A63428507A5@nvidia.com> Message-ID: <5b188e44-73d5-673c-8df1-f2c42b556cf9@arm.com> Date: Thu, 26 Mar 2020 07:48:26 +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: <89E72C74-A32F-4A5B-B5F3-8A63428507A5@nvidia.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US 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: On 03/24/2020 06:59 PM, Zi Yan wrote: > On 24 Mar 2020, at 1:22, Anshuman Khandual wrote: >=20 >> This adds new tests validating arch page table helpers for these follo= wing >> core memory features. These tests create and test specific mapping typ= es at >> various page table levels. >> >> 1. SPECIAL mapping >> 2. PROTNONE mapping >> 3. DEVMAP mapping >> 4. SOFTDIRTY mapping >> 5. SWAP mapping >> 6. MIGRATION mapping >> 7. HUGETLB mapping >> 8. THP mapping >> >> Cc: Andrew Morton >> Cc: Mike Rapoport >> Cc: Vineet Gupta >> Cc: Catalin Marinas >> Cc: Will Deacon >> Cc: Benjamin Herrenschmidt >> Cc: Paul Mackerras >> Cc: Michael Ellerman >> Cc: Heiko Carstens >> Cc: Vasily Gorbik >> Cc: Christian Borntraeger >> Cc: Thomas Gleixner >> Cc: Ingo Molnar >> Cc: Borislav Petkov >> Cc: "H. Peter Anvin" >> Cc: Kirill A. Shutemov >> Cc: Paul Walmsley >> Cc: Palmer Dabbelt >> Cc: linux-snps-arc@lists.infradead.org >> Cc: linux-arm-kernel@lists.infradead.org >> Cc: linuxppc-dev@lists.ozlabs.org >> Cc: linux-s390@vger.kernel.org >> Cc: linux-riscv@lists.infradead.org >> Cc: x86@kernel.org >> Cc: linux-arch@vger.kernel.org >> Cc: linux-kernel@vger.kernel.org >> Suggested-by: Catalin Marinas >> Signed-off-by: Anshuman Khandual >> --- >> mm/debug_vm_pgtable.c | 291 +++++++++++++++++++++++++++++++++++++++++= - >> 1 file changed, 290 insertions(+), 1 deletion(-) >> >> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c >> index 98990a515268..15055a8f6478 100644 >> --- a/mm/debug_vm_pgtable.c >> +++ b/mm/debug_vm_pgtable.c >> @@ -289,6 +289,267 @@ static void __init pmd_populate_tests(struct mm_= struct *mm, pmd_t *pmdp, >> WARN_ON(pmd_bad(pmd)); >> } >> >> +static void __init pte_special_tests(unsigned long pfn, pgprot_t prot= ) >> +{ >> + pte_t pte =3D pfn_pte(pfn, prot); >> + >> + if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) >> + return; >> + >> + WARN_ON(!pte_special(pte_mkspecial(pte))); >> +} >> + >> +static void __init pte_protnone_tests(unsigned long pfn, pgprot_t pro= t) >> +{ >> + pte_t pte =3D pfn_pte(pfn, prot); >> + >> + if (!IS_ENABLED(CONFIG_NUMA_BALANCING)) >> + return; >> + >> + WARN_ON(!pte_protnone(pte)); >> + WARN_ON(!pte_present(pte)); >> +} >> + >> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE >> +static void __init pmd_protnone_tests(unsigned long pfn, pgprot_t pro= t) >> +{ >> + pmd_t pmd =3D pfn_pmd(pfn, prot); >> + >> + if (!IS_ENABLED(CONFIG_NUMA_BALANCING)) >> + return; >> + >> + WARN_ON(!pmd_protnone(pmd)); >> + WARN_ON(!pmd_present(pmd)); >> +} >> +#else >> +static void __init pmd_protnone_tests(unsigned long pfn, pgprot_t pro= t) { } >> +#endif >> + >> +#ifdef CONFIG_ARCH_HAS_PTE_DEVMAP >> +static void __init pte_devmap_tests(unsigned long pfn, pgprot_t prot) >> +{ >> + pte_t pte =3D pfn_pte(pfn, prot); >> + >> + WARN_ON(!pte_devmap(pte_mkdevmap(pte))); >> +} >> + >> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE >> +static void __init pmd_devmap_tests(unsigned long pfn, pgprot_t prot) >> +{ >> + pmd_t pmd =3D pfn_pmd(pfn, prot); >> + >> + WARN_ON(!pmd_devmap(pmd_mkdevmap(pmd))); >> +} >> + >> +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD >> +static void __init pud_devmap_tests(unsigned long pfn, pgprot_t prot) >> +{ >> + pud_t pud =3D pfn_pud(pfn, prot); >> + >> + WARN_ON(!pud_devmap(pud_mkdevmap(pud))); >> +} >> +#else >> +static void __init pud_devmap_tests(unsigned long pfn, pgprot_t prot)= { } >> +#endif >> +#else >> +static void __init pmd_devmap_tests(unsigned long pfn, pgprot_t prot)= { } >> +static void __init pud_devmap_tests(unsigned long pfn, pgprot_t prot)= { } >> +#endif >> +#else >> +static void __init pte_devmap_tests(unsigned long pfn, pgprot_t prot)= { } >> +static void __init pmd_devmap_tests(unsigned long pfn, pgprot_t prot)= { } >> +static void __init pud_devmap_tests(unsigned long pfn, pgprot_t prot)= { } >> +#endif >> + >> +static void __init pte_soft_dirty_tests(unsigned long pfn, pgprot_t p= rot) >> +{ >> + pte_t pte =3D pfn_pte(pfn, prot); >> + >> + if (!IS_ENABLED(CONFIG_HAVE_ARCH_SOFT_DIRTY)) >> + return; >> + >> + WARN_ON(!pte_soft_dirty(pte_mksoft_dirty(pte))); >> + WARN_ON(pte_soft_dirty(pte_clear_soft_dirty(pte))); >> +} >> + >> +static void __init pte_swap_soft_dirty_tests(unsigned long pfn, pgpro= t_t prot) >> +{ >> + pte_t pte =3D pfn_pte(pfn, prot); >> + >> + if (!IS_ENABLED(CONFIG_HAVE_ARCH_SOFT_DIRTY)) >> + return; >> + >> + WARN_ON(!pte_swp_soft_dirty(pte_swp_mksoft_dirty(pte))); >> + WARN_ON(pte_swp_soft_dirty(pte_swp_clear_soft_dirty(pte))); >> +} >> + >> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE >> +static void __init pmd_soft_dirty_tests(unsigned long pfn, pgprot_t p= rot) >> +{ >> + pmd_t pmd =3D pfn_pmd(pfn, prot); >> + >> + if (!IS_ENABLED(CONFIG_HAVE_ARCH_SOFT_DIRTY)) >> + return; >> + >> + WARN_ON(!pmd_soft_dirty(pmd_mksoft_dirty(pmd))); >> + WARN_ON(pmd_soft_dirty(pmd_clear_soft_dirty(pmd))); >> +} >> + >> +static void __init pmd_swap_soft_dirty_tests(unsigned long pfn, pgpro= t_t prot) >> +{ >> + pmd_t pmd =3D pfn_pmd(pfn, prot); >> + >> + if (!IS_ENABLED(CONFIG_HAVE_ARCH_SOFT_DIRTY) || >> + !IS_ENABLED(CONFIG_ARCH_ENABLE_THP_MIGRATION)) >> + return; >> + >> + WARN_ON(!pmd_swp_soft_dirty(pmd_swp_mksoft_dirty(pmd))); >> + WARN_ON(pmd_swp_soft_dirty(pmd_swp_clear_soft_dirty(pmd))); >> +} >> +#else >> +static void __init pmd_soft_dirty_tests(unsigned long pfn, pgprot_t p= rot) { } >> +static void __init pmd_swap_soft_dirty_tests(unsigned long pfn, pgpro= t_t prot) >> +{ >> +} >> +#endif >> + >> +static void __init pte_swap_tests(unsigned long pfn, pgprot_t prot) >> +{ >> + swp_entry_t swp; >> + pte_t pte; >> + >> + pte =3D pfn_pte(pfn, prot); >> + swp =3D __pte_to_swp_entry(pte); >> + WARN_ON(!pte_same(pte, __swp_entry_to_pte(swp))); >> +} >> + >> +#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; >> + >> + pmd =3D pfn_pmd(pfn, prot); >> + swp =3D __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) {= } >> +#endif >> + >> +static void __init swap_migration_tests(void) >> +{ >> + struct page *page; >> + swp_entry_t swp; >> + >> + if (!IS_ENABLED(CONFIG_MIGRATION)) >> + return; >> + /* >> + * swap_migration_tests() requires a dedicated page as it needs to >> + * be locked before creating a migration entry from it. Locking the >> + * page that actually maps kernel text ('start_kernel') can be real >> + * problematic. Lets allocate a dedicated page explicitly for this >> + * purpose that will be freed subsequently. >> + */ >> + page =3D alloc_page(GFP_KERNEL); >> + if (!page) { >> + pr_err("page allocation failed\n"); >> + return; >> + } >> + >> + /* >> + * make_migration_entry() expects given page to be >> + * locked, otherwise it stumbles upon a BUG_ON(). >> + */ >> + __SetPageLocked(page); >> + swp =3D make_migration_entry(page, 1); >> + WARN_ON(!is_migration_entry(swp)); >> + WARN_ON(!is_write_migration_entry(swp)); >> + >> + make_migration_entry_read(&swp); >> + WARN_ON(!is_migration_entry(swp)); >> + WARN_ON(is_write_migration_entry(swp)); >> + >> + swp =3D make_migration_entry(page, 0); >> + WARN_ON(!is_migration_entry(swp)); >> + WARN_ON(is_write_migration_entry(swp)); >> + __ClearPageLocked(page); >> + __free_page(page); >> +} >> + >> +#ifdef CONFIG_HUGETLB_PAGE >> +static void __init hugetlb_basic_tests(unsigned long pfn, pgprot_t pr= ot) >> +{ >> + struct page *page; >> + pte_t pte; >> + >> + /* >> + * Accessing the page associated with the pfn is safe here, >> + * as it was previously derived from a real kernel symbol. >> + */ >> + page =3D pfn_to_page(pfn); >> + pte =3D mk_huge_pte(page, prot); >> + >> + WARN_ON(!huge_pte_dirty(huge_pte_mkdirty(pte))); >> + WARN_ON(!huge_pte_write(huge_pte_mkwrite(huge_pte_wrprotect(pte)))); >> + WARN_ON(huge_pte_write(huge_pte_wrprotect(huge_pte_mkwrite(pte)))); >> + >> +#ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB >> + pte =3D pfn_pte(pfn, prot); >> + >> + WARN_ON(!pte_huge(pte_mkhuge(pte))); >> +#endif >> +} >> +#else >> +static void __init hugetlb_basic_tests(unsigned long pfn, pgprot_t pr= ot) { } >> +#endif >> + >> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE >> +static void __init pmd_thp_tests(unsigned long pfn, pgprot_t prot) >> +{ >> + pmd_t pmd; >> + >> + /* >> + * pmd_trans_huge() and pmd_present() must return positive >> + * after MMU invalidation with pmd_mknotpresent(). >> + */ >> + pmd =3D pfn_pmd(pfn, prot); >> + WARN_ON(!pmd_trans_huge(pmd_mkhuge(pmd))); >> + >> +#ifndef __HAVE_ARCH_PMDP_INVALIDATE >> + WARN_ON(!pmd_trans_huge(pmd_mknotpresent(pmd_mkhuge(pmd)))); >> + WARN_ON(!pmd_present(pmd_mknotpresent(pmd_mkhuge(pmd)))); >> +#endif >=20 > I think we need a better comment here, because requiring pmd_trans_huge= () and > pmd_present() returning true after pmd_mknotpresent() is not straightfo= rward. Thats right. >=20 > According to Andrea Arcangeli=E2=80=99s email (https://lore.kernel.org/= linux-mm/20181017020930.GN30832@redhat.com/), > This behavior is an optimization for transparent huge page. > pmd_trans_huge() must be true if pmd_page() returns you a valid THP to = avoid > taking the pmd_lock when others walk over non transhuge pmds (i.e. ther= e are no > THP allocated). Especially when we split a THP, removing the present bi= t from > the pmd, pmd_trans_huge() still needs to return true. pmd_present() sho= uld > be true whenever pmd_trans_huge() returns true. Sure, will modify the existing comment here like this. /* * pmd_trans_huge() and pmd_present() must return positive after * MMU invalidation with pmd_mknotpresent(). This behavior is an * optimization for transparent huge page. pmd_trans_huge() must * be true if pmd_page() returns a valid THP to avoid taking the * pmd_lock when others walk over non transhuge pmds (i.e. there * are no THP allocated). Especially when splitting a THP and * removing the present bit from the pmd, pmd_trans_huge() still * needs to return true. pmd_present() should be true whenever * pmd_trans_huge() returns true. */ >=20 > I think it is also worth either putting Andres=E2=80=99s email or the l= ink to it > in the rst file in your 3rd patch. It is a good documentation for this = special > case. Makes sense. Will update Andrea's email link in the .rst file as well. >=20 > =E2=80=94 > Best Regards, > Yan Zi >=20