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Message-ID: <8997bf56-ff67-060d-c25b-91e11f31e88a@arm.com>
Date: Thu, 22 Jul 2021 11:09:25 +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 09/12] mm/debug_vm_pgtable: Use struct
pgtable_debug_args in PUD modifying tests
On 7/19/21 6:36 PM, 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.
Please dont drop @prot, @paddr, @pud_aligned just yet.
>
> Signed-off-by: Gavin Shan <gshan@...hat.com>
> ---
> mm/debug_vm_pgtable.c | 130 ++++++++++++++++--------------------------
> 1 file changed, 50 insertions(+), 80 deletions(-)
>
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index cec3cbf99a6b..57b7ead0708b 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -338,55 +338,55 @@ 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 & HPAGE_PUD_MASK);
> pud_t pud;
>
> if (!has_transparent_hugepage())
> return;
>
> pr_debug("Validating PUD advanced\n");
> - /* Align the address wrt HPAGE_PUD_SIZE */
> - vaddr &= HPAGE_PUD_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.
> + if (args->pud_pfn == ULONG_MAX) {
> + pr_debug("%s: Skipped\n", __func__);
Just return. Please dont call out "Skipped". Applicable for all transition
patches here.
> + return;
> + }
>
> - 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));
Seems like an extra braces while de-referencing arg->pudp. Could these be
dropped. Just 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)
> @@ -406,24 +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) { }
> @@ -450,11 +440,11 @@ 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");
> @@ -462,15 +452,16 @@ 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));
Please dont break the line, we could go upto 100 width. Please do
the same for the entire series. Improves the readability.
> + 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(void)
> @@ -492,27 +483,26 @@ static void __init pgd_basic_tests(void)
> }
>
> #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");
> @@ -520,16 +510,13 @@ 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
> @@ -1152,10 +1139,7 @@ static int __init debug_vm_pgtable(void)
> pud_t *pudp, *saved_pudp;
> pmd_t *pmdp, *saved_pmdp, pmd;
> 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;
>
> @@ -1164,7 +1148,6 @@ static int __init debug_vm_pgtable(void)
> if (ret)
> return ret;
>
> - prot = vm_get_page_prot(VMFLAGS);
Please dont drop these just yet and wait until [PATCH 11/12].
> vaddr = get_random_vaddr();
> mm = mm_alloc();
> if (!mm) {
> @@ -1178,19 +1161,6 @@ 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.
> - */
Please move this comment as is to the right place inside init_args()
in the first patch itself. If possible all comments should be moved
during the first patch and just the code remains till [PATCH 11/12].
> - paddr = __pa_symbol(&start_kernel);
> -
> - pud_aligned = (paddr & PUD_MASK) >> PAGE_SHIFT;
> -
Please dont drop these just yet and wait until [PATCH 11/12].
> pgdp = pgd_offset(mm, vaddr);
> p4dp = p4d_alloc(mm, pgdp, vaddr);
> pudp = pud_alloc(mm, p4dp, vaddr);
> @@ -1282,11 +1252,11 @@ 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);
>
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