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Subject: Re: [PATCH v4 09/12] mm/debug_vm_pgtable: Use struct
 pgtable_debug_args in PUD modifying tests
To:     Gavin Shan <gshan@redhat.com>, linux-mm@kvack.org
Cc:     linux-kernel@vger.kernel.org, gerald.schaefer@linux.ibm.com,
        aneesh.kumar@linux.ibm.com, christophe.leroy@csgroup.eu,
        cai@lca.pw, catalin.marinas@arm.com, will@kernel.org,
        akpm@linux-foundation.org, chuhu@redhat.com, shan.gavin@gmail.com
References: <20210727061401.592616-1-gshan@redhat.com>
 <20210727061401.592616-10-gshan@redhat.com>
From:   Anshuman Khandual <anshuman.khandual@arm.com>
Message-ID: <5c9d9868-8185-aa21-ee2f-d8b3810e3781@arm.com>
Date:   Thu, 29 Jul 2021 11:14:36 +0530
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On 7/27/21 11:43 AM, Gavin Shan wrote:
> This uses struct pgtable_debug_args in PUD modifying tests. The allocated
> huge page is used when set_pud_at() is used. The corresponding tests
> are skipped if the huge page doesn't exist. Besides, the following unused
> variables in debug_vm_pgtable() are dropped: @prot, @paddr, @pud_aligned.
> 
> Signed-off-by: Gavin Shan <gshan@redhat.com>
> ---
>  mm/debug_vm_pgtable.c | 126 ++++++++++++++++--------------------------
>  1 file changed, 48 insertions(+), 78 deletions(-)
> 
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index 2a7c810b56b4..863871e70268 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -337,55 +337,56 @@ static void __init pud_basic_tests(struct pgtable_debug_args *args, int idx)
>  	WARN_ON(!pud_bad(pud_mkhuge(pud)));
>  }
>  
> -static void __init pud_advanced_tests(struct mm_struct *mm,
> -				      struct vm_area_struct *vma, pud_t *pudp,
> -				      unsigned long pfn, unsigned long vaddr,
> -				      pgprot_t prot)
> +static void __init pud_advanced_tests(struct pgtable_debug_args *args)
>  {
> +	unsigned long vaddr = args->vaddr;
>  	pud_t pud;
>  
>  	if (!has_transparent_hugepage())
>  		return;
>  
> +	if (args->pud_pfn == ULONG_MAX)
> +		return;
> +
>  	pr_debug("Validating PUD advanced\n");
>  	/* Align the address wrt HPAGE_PUD_SIZE */
>  	vaddr &= HPAGE_PUD_MASK;
>  
> -	pud = pfn_pud(pfn, prot);
> -	set_pud_at(mm, vaddr, pudp, pud);
> -	pudp_set_wrprotect(mm, vaddr, pudp);
> -	pud = READ_ONCE(*pudp);
> +	pud = pfn_pud(args->pud_pfn, args->page_prot);
> +	set_pud_at(args->mm, vaddr, args->pudp, pud);
> +	pudp_set_wrprotect(args->mm, vaddr, args->pudp);
> +	pud = READ_ONCE(*args->pudp);
>  	WARN_ON(pud_write(pud));
>  
>  #ifndef __PAGETABLE_PMD_FOLDED
> -	pudp_huge_get_and_clear(mm, vaddr, pudp);
> -	pud = READ_ONCE(*pudp);
> +	pudp_huge_get_and_clear(args->mm, vaddr, args->pudp);
> +	pud = READ_ONCE(*args->pudp);
>  	WARN_ON(!pud_none(pud));
>  #endif /* __PAGETABLE_PMD_FOLDED */
> -	pud = pfn_pud(pfn, prot);
> +	pud = pfn_pud(args->pud_pfn, args->page_prot);
>  	pud = pud_wrprotect(pud);
>  	pud = pud_mkclean(pud);
> -	set_pud_at(mm, vaddr, pudp, pud);
> +	set_pud_at(args->mm, vaddr, args->pudp, pud);
>  	pud = pud_mkwrite(pud);
>  	pud = pud_mkdirty(pud);
> -	pudp_set_access_flags(vma, vaddr, pudp, pud, 1);
> -	pud = READ_ONCE(*pudp);
> +	pudp_set_access_flags(args->vma, vaddr, args->pudp, pud, 1);
> +	pud = READ_ONCE(*args->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);
> +	pudp_huge_get_and_clear_full(args->mm, vaddr, args->pudp, 1);
> +	pud = READ_ONCE(*args->pudp);
>  	WARN_ON(!pud_none(pud));
>  #endif /* __PAGETABLE_PMD_FOLDED */
>  
> -	pud = pfn_pud(pfn, prot);
> +	pud = pfn_pud(args->pud_pfn, args->page_prot);
>  	pud = pud_mkyoung(pud);
> -	set_pud_at(mm, vaddr, pudp, pud);
> -	pudp_test_and_clear_young(vma, vaddr, pudp);
> -	pud = READ_ONCE(*pudp);
> +	set_pud_at(args->mm, vaddr, args->pudp, pud);
> +	pudp_test_and_clear_young(args->vma, vaddr, args->pudp);
> +	pud = READ_ONCE(*args->pudp);
>  	WARN_ON(pud_young(pud));
>  
> -	pudp_huge_get_and_clear(mm, vaddr, pudp);
> +	pudp_huge_get_and_clear(args->mm, vaddr, args->pudp);
>  }
>  
>  static void __init pud_leaf_tests(struct pgtable_debug_args *args)
> @@ -405,24 +406,14 @@ static void __init pud_leaf_tests(struct pgtable_debug_args *args)
>  }
>  #else  /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
>  static void __init pud_basic_tests(struct pgtable_debug_args *args, int idx) { }
> -static void __init pud_advanced_tests(struct mm_struct *mm,
> -				      struct vm_area_struct *vma, pud_t *pudp,
> -				      unsigned long pfn, unsigned long vaddr,
> -				      pgprot_t prot)
> -{
> -}
> +static void __init pud_advanced_tests(struct pgtable_debug_args *args) { }
>  static void __init pud_leaf_tests(struct pgtable_debug_args *args) { }
>  #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
>  #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 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,
> -				      pgprot_t prot)
> -{
> -}
> +static void __init pud_advanced_tests(struct pgtable_debug_args *args) { }
>  static void __init pmd_leaf_tests(struct pgtable_debug_args *args) { }
>  static void __init pud_leaf_tests(struct pgtable_debug_args *args) { }
>  static void __init pmd_savedwrite_tests(struct pgtable_debug_args *args) { }
> @@ -448,11 +439,11 @@ static void __init pmd_huge_tests(struct pgtable_debug_args *args)
>  	WARN_ON(!pmd_none(pmd));
>  }
>  
> -static void __init pud_huge_tests(pud_t *pudp, unsigned long pfn, pgprot_t prot)
> +static void __init pud_huge_tests(struct pgtable_debug_args *args)
>  {
>  	pud_t pud;
>  
> -	if (!arch_vmap_pud_supported(prot))
> +	if (!arch_vmap_pud_supported(args->page_prot))
>  		return;
>  
>  	pr_debug("Validating PUD huge\n");
> @@ -460,15 +451,15 @@ static void __init pud_huge_tests(pud_t *pudp, unsigned long pfn, pgprot_t prot)
>  	 * X86 defined pud_set_huge() verifies that the given
>  	 * PUD is not a populated non-leaf entry.
>  	 */
> -	WRITE_ONCE(*pudp, __pud(0));
> -	WARN_ON(!pud_set_huge(pudp, __pfn_to_phys(pfn), prot));
> -	WARN_ON(!pud_clear_huge(pudp));
> -	pud = READ_ONCE(*pudp);
> +	WRITE_ONCE(*args->pudp, __pud(0));
> +	WARN_ON(!pud_set_huge(args->pudp, __pfn_to_phys(args->fixed_pud_pfn), args->page_prot));
> +	WARN_ON(!pud_clear_huge(args->pudp));
> +	pud = READ_ONCE(*args->pudp);
>  	WARN_ON(!pud_none(pud));
>  }
>  #else /* !CONFIG_HAVE_ARCH_HUGE_VMAP */
>  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) { }
> +static void __init pud_huge_tests(struct pgtable_debug_args *args) { }
>  #endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */
>  
>  static void __init p4d_basic_tests(struct pgtable_debug_args *args)
> @@ -490,27 +481,26 @@ static void __init pgd_basic_tests(struct pgtable_debug_args *args)
>  }
>  
>  #ifndef __PAGETABLE_PUD_FOLDED
> -static void __init pud_clear_tests(struct mm_struct *mm, pud_t *pudp)
> +static void __init pud_clear_tests(struct pgtable_debug_args *args)
>  {
> -	pud_t pud = READ_ONCE(*pudp);
> +	pud_t pud = READ_ONCE(*args->pudp);
>  
> -	if (mm_pmd_folded(mm))
> +	if (mm_pmd_folded(args->mm))
>  		return;
>  
>  	pr_debug("Validating PUD clear\n");
>  	pud = __pud(pud_val(pud) | RANDOM_ORVALUE);
> -	WRITE_ONCE(*pudp, pud);
> -	pud_clear(pudp);
> -	pud = READ_ONCE(*pudp);
> +	WRITE_ONCE(*args->pudp, pud);
> +	pud_clear(args->pudp);
> +	pud = READ_ONCE(*args->pudp);
>  	WARN_ON(!pud_none(pud));
>  }
>  
> -static void __init pud_populate_tests(struct mm_struct *mm, pud_t *pudp,
> -				      pmd_t *pmdp)
> +static void __init pud_populate_tests(struct pgtable_debug_args *args)
>  {
>  	pud_t pud;
>  
> -	if (mm_pmd_folded(mm))
> +	if (mm_pmd_folded(args->mm))
>  		return;
>  
>  	pr_debug("Validating PUD populate\n");
> @@ -518,16 +508,13 @@ static void __init pud_populate_tests(struct mm_struct *mm, pud_t *pudp,
>  	 * This entry points to next level page table page.
>  	 * Hence this must not qualify as pud_bad().
>  	 */
> -	pud_populate(mm, pudp, pmdp);
> -	pud = READ_ONCE(*pudp);
> +	pud_populate(args->mm, args->pudp, args->start_pmdp);
> +	pud = READ_ONCE(*args->pudp);
>  	WARN_ON(pud_bad(pud));
>  }
>  #else  /* !__PAGETABLE_PUD_FOLDED */
> -static void __init pud_clear_tests(struct mm_struct *mm, pud_t *pudp) { }
> -static void __init pud_populate_tests(struct mm_struct *mm, pud_t *pudp,
> -				      pmd_t *pmdp)
> -{
> -}
> +static void __init pud_clear_tests(struct pgtable_debug_args *args) { }
> +static void __init pud_populate_tests(struct pgtable_debug_args *args) { }
>  #endif /* PAGETABLE_PUD_FOLDED */
>  
>  #ifndef __PAGETABLE_P4D_FOLDED
> @@ -1230,10 +1217,7 @@ static int __init debug_vm_pgtable(void)
>  	pmd_t *pmdp, *saved_pmdp, pmd;
>  	pte_t *ptep;
>  	pgtable_t saved_ptep;
> -	pgprot_t prot;
> -	phys_addr_t paddr;
>  	unsigned long vaddr;
> -	unsigned long pud_aligned;
>  	spinlock_t *ptl = NULL;
>  	int idx, ret;
>  
> @@ -1242,7 +1226,6 @@ static int __init debug_vm_pgtable(void)
>  	if (ret)
>  		return ret;
>  
> -	prot = vm_get_page_prot(VMFLAGS);
>  	vaddr = get_random_vaddr();
>  	mm = mm_alloc();
>  	if (!mm) {
> @@ -1256,19 +1239,6 @@ static int __init debug_vm_pgtable(void)
>  		return 1;
>  	}
>  
> -	/*
> -	 * PFN for mapping at PTE level is determined from a standard kernel
> -	 * text symbol. But pfns for higher page table levels are derived by
> -	 * masking lower bits of this real pfn. These derived pfns might not
> -	 * exist on the platform but that does not really matter as pfn_pxx()
> -	 * helpers will still create appropriate entries for the test. This
> -	 * helps avoid large memory block allocations to be used for mapping
> -	 * at higher page table levels.
> -	 */
> -	paddr = __pa_symbol(&start_kernel);
> -
> -	pud_aligned = (paddr & PUD_MASK) >> PAGE_SHIFT;
> -
>  	pgdp = pgd_offset(mm, vaddr);
>  	p4dp = p4d_alloc(mm, pgdp, vaddr);
>  	pudp = pud_alloc(mm, p4dp, vaddr);
> @@ -1361,11 +1331,11 @@ static int __init debug_vm_pgtable(void)
>  	pmd_populate_tests(&args);
>  	spin_unlock(ptl);
>  
> -	ptl = pud_lock(mm, pudp);
> -	pud_clear_tests(mm, pudp);
> -	pud_advanced_tests(mm, vma, pudp, pud_aligned, vaddr, prot);
> -	pud_huge_tests(pudp, pud_aligned, prot);
> -	pud_populate_tests(mm, pudp, saved_pmdp);
> +	ptl = pud_lock(args.mm, args.pudp);
> +	pud_clear_tests(&args);
> +	pud_advanced_tests(&args);
> +	pud_huge_tests(&args);
> +	pud_populate_tests(&args);
>  	spin_unlock(ptl);
>  
>  	spin_lock(&mm->page_table_lock);
> 

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>