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Message-ID: <876f9722-c307-560d-5efd-3613c312c7bd@arm.com>
Date: Thu, 22 Jul 2021 12:41:26 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: Gavin Shan <gshan@...hat.com>, linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org, catalin.marinas@....com,
will@...nel.org, akpm@...ux-foundation.org, chuhu@...hat.com,
shan.gavin@...il.com
Subject: Re: [PATCH v3 08/12] mm/debug_vm_pgtable: Use struct
pgtable_debug_args in PMD modifying tests
On 7/22/21 12:11 PM, Gavin Shan wrote:
> Hi Anshuman,
>
> 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 <gshan@...hat.com>
>>> ---
>>> 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.
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