Messages in this thread Patch in this message | | | Subject | Re: [PATCH v3 08/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in PMD modifying tests | From | Gavin Shan <> | Date | Fri, 23 Jul 2021 11:00:15 +1000 |
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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 <gshan@redhat.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. >
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, we still need to keep each individual patch complete to make 'git bisect' friendly.
Thanks, Gavin
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