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=-15.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 6D8B4C4320A for ; Fri, 23 Jul 2021 02:33:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 508B960EB0 for ; Fri, 23 Jul 2021 02:33:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233281AbhGWBwb (ORCPT ); Thu, 22 Jul 2021 21:52:31 -0400 Received: from foss.arm.com ([217.140.110.172]:37662 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233166AbhGWBwa (ORCPT ); Thu, 22 Jul 2021 21:52:30 -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 1CDE9113E; Thu, 22 Jul 2021 19:33:04 -0700 (PDT) Received: from [10.163.66.36] (unknown [10.163.66.36]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6A6FD3F694; Thu, 22 Jul 2021 19:33:01 -0700 (PDT) Subject: Re: [PATCH v3 08/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in PMD modifying tests To: Gavin Shan , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org, akpm@linux-foundation.org, chuhu@redhat.com, shan.gavin@gmail.com References: <20210719130613.334901-1-gshan@redhat.com> <20210719130613.334901-9-gshan@redhat.com> <52a61d4a-f93d-af9e-4a34-d8ea7c476838@arm.com> <876f9722-c307-560d-5efd-3613c312c7bd@arm.com> <8d8daf85-0015-4221-aad5-5baa03e3f699@redhat.com> From: Anshuman Khandual Message-ID: <68b6ab2a-4b6d-a0b8-f753-01fdc165b24a@arm.com> Date: Fri, 23 Jul 2021 08:03:48 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <8d8daf85-0015-4221-aad5-5baa03e3f699@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/23/21 6:30 AM, Gavin Shan wrote: > Hi Anshuman, > > On 7/22/21 5:11 PM, Anshuman Khandual wrote: >> On 7/22/21 12:11 PM, Gavin Shan wrote: >>> On 7/22/21 3:45 PM, Anshuman Khandual wrote: >>>> On 7/19/21 6:36 PM, Gavin Shan wrote: >>>>> This uses struct pgtable_debug_args in PMD modifying tests. The allocated >>>>> huge page is used when set_pmd_at() is used. The corresponding tests >>>>> are skipped if the huge page doesn't exist. Besides, the unused variable >>>>> @pmd_aligned in debug_vm_pgtable() is dropped. >>>> >>>> Please dont drop @pmd_aligned just yet. >>>> >>> >>> We need do so. Otherwise, there is build warning to complain >>> something like 'unused variable' after this patch is applied. >>> >>>>> >>>>> Signed-off-by: Gavin Shan >>>>> --- >>>>>    mm/debug_vm_pgtable.c | 102 ++++++++++++++++++++---------------------- >>>>>    1 file changed, 48 insertions(+), 54 deletions(-) >>>>> >>>>> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c >>>>> index eb6dda88e0d9..cec3cbf99a6b 100644 >>>>> --- a/mm/debug_vm_pgtable.c >>>>> +++ b/mm/debug_vm_pgtable.c >>>>> @@ -213,54 +213,54 @@ static void __init pmd_basic_tests(struct pgtable_debug_args *args, int idx) >>>>>        WARN_ON(!pmd_bad(pmd_mkhuge(pmd))); >>>>>    } >>>>>    -static void __init pmd_advanced_tests(struct mm_struct *mm, >>>>> -                      struct vm_area_struct *vma, pmd_t *pmdp, >>>>> -                      unsigned long pfn, unsigned long vaddr, >>>>> -                      pgprot_t prot, pgtable_t pgtable) >>>>> +static void __init pmd_advanced_tests(struct pgtable_debug_args *args) >>>>>    { >>>>>        pmd_t pmd; >>>>> +    unsigned long vaddr = (args->vaddr & HPAGE_PMD_MASK); >>>>>          if (!has_transparent_hugepage()) >>>>>            return; >>>>>          pr_debug("Validating PMD advanced\n"); >>>>> -    /* Align the address wrt HPAGE_PMD_SIZE */ >>>>> -    vaddr &= HPAGE_PMD_MASK; >>>> >>>> Please just leave these unchanged. If has_transparent_hugepage() evaluates >>>> negative, it skips the masking operation. As mentioned earlier please avoid >>>> changing the test in any manner during these transition patches. >>>> >>> >>> Ok. >>> >>>>> +    if (args->pmd_pfn == ULONG_MAX) { >>>>> +        pr_debug("%s: Skipped\n", __func__); >>>>> +        return; >>>>> +    } >>>> >>>> Just return. Please dont call out "Skipped". >>>> >>> >>> Ok. >>> >>>>>    -    pgtable_trans_huge_deposit(mm, pmdp, pgtable); >>>>> +    pgtable_trans_huge_deposit(args->mm, args->pmdp, args->start_ptep); >>>>>    -    pmd = pfn_pmd(pfn, prot); >>>>> -    set_pmd_at(mm, vaddr, pmdp, pmd); >>>>> -    pmdp_set_wrprotect(mm, vaddr, pmdp); >>>>> -    pmd = READ_ONCE(*pmdp); >>>>> +    pmd = pfn_pmd(args->pmd_pfn, args->page_prot); >>>>> +    set_pmd_at(args->mm, vaddr, args->pmdp, pmd); >>>>> +    pmdp_set_wrprotect(args->mm, vaddr, args->pmdp); >>>>> +    pmd = READ_ONCE(*(args->pmdp)); >>>>>        WARN_ON(pmd_write(pmd)); >>>>> -    pmdp_huge_get_and_clear(mm, vaddr, pmdp); >>>>> -    pmd = READ_ONCE(*pmdp); >>>>> +    pmdp_huge_get_and_clear(args->mm, vaddr, args->pmdp); >>>>> +    pmd = READ_ONCE(*(args->pmdp)); >>>>>        WARN_ON(!pmd_none(pmd)); >>>>>    -    pmd = pfn_pmd(pfn, prot); >>>>> +    pmd = pfn_pmd(args->pmd_pfn, args->page_prot); >>>>>        pmd = pmd_wrprotect(pmd); >>>>>        pmd = pmd_mkclean(pmd); >>>>> -    set_pmd_at(mm, vaddr, pmdp, pmd); >>>>> +    set_pmd_at(args->mm, vaddr, args->pmdp, pmd); >>>>>        pmd = pmd_mkwrite(pmd); >>>>>        pmd = pmd_mkdirty(pmd); >>>>> -    pmdp_set_access_flags(vma, vaddr, pmdp, pmd, 1); >>>>> -    pmd = READ_ONCE(*pmdp); >>>>> +    pmdp_set_access_flags(args->vma, vaddr, args->pmdp, pmd, 1); >>>>> +    pmd = READ_ONCE(*(args->pmdp)); >>>>>        WARN_ON(!(pmd_write(pmd) && pmd_dirty(pmd))); >>>>> -    pmdp_huge_get_and_clear_full(vma, vaddr, pmdp, 1); >>>>> -    pmd = READ_ONCE(*pmdp); >>>>> +    pmdp_huge_get_and_clear_full(args->vma, vaddr, args->pmdp, 1); >>>>> +    pmd = READ_ONCE(*(args->pmdp)); >>>>>        WARN_ON(!pmd_none(pmd)); >>>>>    -    pmd = pmd_mkhuge(pfn_pmd(pfn, prot)); >>>>> +    pmd = pmd_mkhuge(pfn_pmd(args->pmd_pfn, args->page_prot)); >>>>>        pmd = pmd_mkyoung(pmd); >>>>> -    set_pmd_at(mm, vaddr, pmdp, pmd); >>>>> -    pmdp_test_and_clear_young(vma, vaddr, pmdp); >>>>> -    pmd = READ_ONCE(*pmdp); >>>>> +    set_pmd_at(args->mm, vaddr, args->pmdp, pmd); >>>>> +    pmdp_test_and_clear_young(args->vma, vaddr, args->pmdp); >>>>> +    pmd = READ_ONCE(*(args->pmdp)); >>>>>        WARN_ON(pmd_young(pmd)); >>>>>          /*  Clear the pte entries  */ >>>>> -    pmdp_huge_get_and_clear(mm, vaddr, pmdp); >>>>> -    pgtable = pgtable_trans_huge_withdraw(mm, pmdp); >>>>> +    pmdp_huge_get_and_clear(args->mm, vaddr, args->pmdp); >>>>> +    pgtable_trans_huge_withdraw(args->mm, args->pmdp); >>>>>    } >>>>>      static void __init pmd_leaf_tests(struct pgtable_debug_args *args) >>>>> @@ -417,12 +417,7 @@ static void __init pud_leaf_tests(struct pgtable_debug_args *args) { } >>>>>    #else  /* !CONFIG_TRANSPARENT_HUGEPAGE */ >>>>>    static void __init pmd_basic_tests(struct pgtable_debug_args *args, int idx) { } >>>>>    static void __init pud_basic_tests(struct pgtable_debug_args *args, int idx) { } >>>>> -static void __init pmd_advanced_tests(struct mm_struct *mm, >>>>> -                      struct vm_area_struct *vma, pmd_t *pmdp, >>>>> -                      unsigned long pfn, unsigned long vaddr, >>>>> -                      pgprot_t prot, pgtable_t pgtable) >>>>> -{ >>>>> -} >>>>> +static void __init pmd_advanced_tests(struct pgtable_debug_args *args) { } >>>>>    static void __init pud_advanced_tests(struct mm_struct *mm, >>>>>                          struct vm_area_struct *vma, pud_t *pudp, >>>>>                          unsigned long pfn, unsigned long vaddr, >>>>> @@ -435,11 +430,11 @@ static void __init pmd_savedwrite_tests(struct pgtable_debug_args *args) { } >>>>>    #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ >>>>>      #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP >>>>> -static void __init pmd_huge_tests(pmd_t *pmdp, unsigned long pfn, pgprot_t prot) >>>>> +static void __init pmd_huge_tests(struct pgtable_debug_args *args) >>>>>    { >>>>>        pmd_t pmd; >>>>>    -    if (!arch_vmap_pmd_supported(prot)) >>>>> +    if (!arch_vmap_pmd_supported(args->page_prot)) >>>>>            return; >>>>>          pr_debug("Validating PMD huge\n"); >>>>> @@ -447,10 +442,11 @@ static void __init pmd_huge_tests(pmd_t *pmdp, unsigned long pfn, pgprot_t prot) >>>>>         * X86 defined pmd_set_huge() verifies that the given >>>>>         * PMD is not a populated non-leaf entry. >>>>>         */ >>>>> -    WRITE_ONCE(*pmdp, __pmd(0)); >>>>> -    WARN_ON(!pmd_set_huge(pmdp, __pfn_to_phys(pfn), prot)); >>>>> -    WARN_ON(!pmd_clear_huge(pmdp)); >>>>> -    pmd = READ_ONCE(*pmdp); >>>>> +    WRITE_ONCE(*(args->pmdp), __pmd(0)); >>>> >>>> Possible extra braces. >>>> >>> >>> Will drop it in v4, thanks! >>> >>>>> +    WARN_ON(!pmd_set_huge(args->pmdp, __pfn_to_phys(args->fixed_pmd_pfn), >>>>> +                  args->page_prot)); >>>> >>>> Dont break the line. >>>> >>> >>> Ok. >>> >>>>> +    WARN_ON(!pmd_clear_huge(args->pmdp)); >>>>> +    pmd = READ_ONCE(*(args->pmdp)); >>>>>        WARN_ON(!pmd_none(pmd)); >>>>>    } >>>>>    @@ -473,7 +469,7 @@ static void __init pud_huge_tests(pud_t *pudp, unsigned long pfn, pgprot_t prot) >>>>>        WARN_ON(!pud_none(pud)); >>>>>    } >>>>>    #else /* !CONFIG_HAVE_ARCH_HUGE_VMAP */ >>>>> -static void __init pmd_huge_tests(pmd_t *pmdp, unsigned long pfn, pgprot_t prot) { } >>>>> +static void __init pmd_huge_tests(struct pgtable_debug_args *args) { } >>>>>    static void __init pud_huge_tests(pud_t *pudp, unsigned long pfn, pgprot_t prot) { } >>>>>    #endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */ >>>>>    @@ -640,20 +636,19 @@ static void __init pte_clear_tests(struct pgtable_debug_args *args) >>>>>        WARN_ON(!pte_none(pte)); >>>>>    } >>>>>    -static void __init pmd_clear_tests(struct mm_struct *mm, pmd_t *pmdp) >>>>> +static void __init pmd_clear_tests(struct pgtable_debug_args *args) >>>>>    { >>>>> -    pmd_t pmd = READ_ONCE(*pmdp); >>>>> +    pmd_t pmd = READ_ONCE(*(args->pmdp)); >>>>>          pr_debug("Validating PMD clear\n"); >>>>>        pmd = __pmd(pmd_val(pmd) | RANDOM_ORVALUE); >>>>> -    WRITE_ONCE(*pmdp, pmd); >>>>> -    pmd_clear(pmdp); >>>>> -    pmd = READ_ONCE(*pmdp); >>>>> +    WRITE_ONCE(*(args->pmdp), pmd); >>>>> +    pmd_clear(args->pmdp); >>>>> +    pmd = READ_ONCE(*(args->pmdp)); >>>>>        WARN_ON(!pmd_none(pmd)); >>>>>    } >>>>>    -static void __init pmd_populate_tests(struct mm_struct *mm, pmd_t *pmdp, >>>>> -                      pgtable_t pgtable) >>>>> +static void __init pmd_populate_tests(struct pgtable_debug_args *args) >>>>>    { >>>>>        pmd_t pmd; >>>>>    @@ -662,8 +657,8 @@ static void __init pmd_populate_tests(struct mm_struct *mm, pmd_t *pmdp, >>>>>         * This entry points to next level page table page. >>>>>         * Hence this must not qualify as pmd_bad(). >>>>>         */ >>>>> -    pmd_populate(mm, pmdp, pgtable); >>>>> -    pmd = READ_ONCE(*pmdp); >>>>> +    pmd_populate(args->mm, args->pmdp, args->start_ptep); >>>>> +    pmd = READ_ONCE(*(args->pmdp)); >>>>>        WARN_ON(pmd_bad(pmd)); >>>>>    } >>>>>    @@ -1159,7 +1154,7 @@ static int __init debug_vm_pgtable(void) >>>>>        pgtable_t saved_ptep; >>>>>        pgprot_t prot; >>>>>        phys_addr_t paddr; >>>>> -    unsigned long vaddr, pmd_aligned; >>>>> +    unsigned long vaddr; >>>>>        unsigned long pud_aligned; >>>>>        spinlock_t *ptl = NULL; >>>>>        int idx, ret; >>>>> @@ -1194,7 +1189,6 @@ static int __init debug_vm_pgtable(void) >>>>>         */ >>>>>        paddr = __pa_symbol(&start_kernel); >>>>>    -    pmd_aligned = (paddr & PMD_MASK) >> PAGE_SHIFT; >>>> >>>> Please dont drop these just yet and wait until [PATCH 11/12]. >>>> >>> >>> Otherwise, it causes build warning: 'unused variable'. >> >> Why ? Just the evaluation of 'pmd_aligned' from 'paddr' should >> be enough to avoid such warning. 'pmd_aligned' need not be used >> afterwards. >> > > It's not enough to avoid the warning. I apply the patches till > this one (PATCH[v3 08/12]) and have additional code to keep > @pmd_aligned, then I run into build warning as below: > > diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c > index cec3cbf99a6b..961c9bb6fc7c 100644 > --- a/mm/debug_vm_pgtable.c > +++ b/mm/debug_vm_pgtable.c > @@ -1154,7 +1154,7 @@ static int __init debug_vm_pgtable(void) >         pgtable_t saved_ptep; >         pgprot_t prot; >         phys_addr_t paddr; > -       unsigned long vaddr; > +       unsigned long vaddr, pmd_aligned; >         unsigned long pud_aligned; >         spinlock_t *ptl = NULL; >         int idx, ret; > @@ -1189,6 +1189,7 @@ static int __init debug_vm_pgtable(void) >          */ >         paddr = __pa_symbol(&start_kernel); >   > +       pmd_aligned = (paddr & PMD_MASK) >> PAGE_SHIFT; >         pud_aligned = (paddr & PUD_MASK) >> PAGE_SHIFT; >   >         pgdp = pgd_offset(mm, vaddr); > > [gwshan@gshan l]$ make W=1 mm/debug_vm_pgtable.o >      : > mm/debug_vm_pgtable.c: In function ‘debug_vm_pgtable’: > mm/debug_vm_pgtable.c:1157:23: warning: variable ‘pmd_aligned’ set but not used [-Wunused-but-set-variable] >  1157 |  unsigned long vaddr, pmd_aligned; >       |                       ^~~~~~~~~~~ > > > By the way, 0-day is trying to build kernel with "W=1". It means the > build warnings will be reported by 0-day if the unused variables aren't > dropped from individual patches. It makes the review a bit harder. However, It is not about keeping the review process simple. But rather the proposed patch changing as much what is really required and nothing else. > we still need to keep each individual patch complete to make 'git bisect' > friendly. With W=1 if this throws up a build error, I guess we dont have choice here. We need to keep the build clean for each individual patch applies.