Re: [RFC PATCH v3 2/3] mm: Add PUD level pagetable account

Baolin Wang
2022-07-01T08:04:25Z

On 6/30/2022 10:17 PM, Mike Rapoport wrote:
> On Thu, Jun 30, 2022 at 07:11:15PM +0800, Baolin Wang wrote:
>> Now the PUD level ptes are always protected by mm->page_table_lock,
>> which means no split pagetable lock needed. So the generic PUD level
>> pagetable pages allocation will not call pgtable_pte_page_ctor/dtor(),
>> that means we will miss to account PUD level pagetable pages.
>>
>> Adding pagetable account by calling pgtable_page_inc() or
>> pgtable_page_dec() when allocating or freeing PUD level pagetable
>> pages to help to get an accurate pagetable accounting.
>>
>> Moreover this patch will also mark the PUD level pagetable with PG_table
>> flag, which will help to do sanity validation in unpoison_memory() and
>> get more accurate pagetable accounting by /proc/kpageflags interface.
>>
>> Meanwhile converting the architectures with using generic PUD pagatable
>> allocation to add corresponding pgtable_page_inc() or pgtable_page_dec()
>> to account PUD level pagetable.
>>
>> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>> ---
>> arch/arm64/include/asm/tlb.h | 5 ++++-
>> arch/loongarch/include/asm/pgalloc.h | 11 ++++++++---
>> arch/mips/include/asm/pgalloc.h | 11 ++++++++---
>> arch/s390/include/asm/tlb.h | 1 +
>> arch/x86/mm/pgtable.c | 5 ++++-
>> include/asm-generic/pgalloc.h | 12 ++++++++++--
>> 6 files changed, 35 insertions(+), 10 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h
>> index c995d1f..1772df9 100644
>> --- a/arch/arm64/include/asm/tlb.h
>> +++ b/arch/arm64/include/asm/tlb.h
>> @@ -94,7 +94,10 @@ static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
>> static inline void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pudp,
>> unsigned long addr)
>> {
>> - tlb_remove_table(tlb, virt_to_page(pudp));
>> + struct page *page = virt_to_page(pudp);
>> +
>> + pgtable_page_dec(page);
>
> Using pgtable_pud_page_ctor() and pgtable_pud_page_dtor() would be
> consistent with what we currently have for PTEs and PMDs.
>
> This applies to all the additions of pgtable_page_dec() and
> pgtable_page_inc().

OK. I can add pgtable_pud_page_ctor() and pgtable_pud_page_dtor()
helpers to keep consistent, which are just wrappers of
pgtable_page_inc() and pgtable_page_dec().

>
>> + tlb_remove_table(tlb, page);
>> }
>> #endif
>>
>> diff --git a/arch/loongarch/include/asm/pgalloc.h b/arch/loongarch/include/asm/pgalloc.h
>> index b0a57b2..19bfe14 100644
>> --- a/arch/loongarch/include/asm/pgalloc.h
>> +++ b/arch/loongarch/include/asm/pgalloc.h
>> @@ -89,10 +89,15 @@ static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
>> static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long address)
>> {
>> pud_t *pud;
>> + struct page *page;
>>
>> - pud = (pud_t *) __get_free_pages(GFP_KERNEL, PUD_ORDER);
>> - if (pud)
>> - pud_init((unsigned long)pud, (unsigned long)invalid_pmd_table);
>> + page = alloc_pages(GFP_KERNEL, PUD_ORDER);
>> + if (!page)
>> + return NULL;
>> +
>> + pgtable_page_inc(page);
>> + pud = (pud_t *)page_address(page);
>> + pud_init((unsigned long)pud, (unsigned long)invalid_pmd_table);
>> return pud;
>> }
>>
>> diff --git a/arch/mips/include/asm/pgalloc.h b/arch/mips/include/asm/pgalloc.h
>> index 867e9c3..990f614 100644
>> --- a/arch/mips/include/asm/pgalloc.h
>> +++ b/arch/mips/include/asm/pgalloc.h
>> @@ -89,11 +89,16 @@ static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
>>
>> static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long address)
>> {
>> + struct page *page;
>> pud_t *pud;
>>
>> - pud = (pud_t *) __get_free_pages(GFP_KERNEL, PUD_ORDER);
>> - if (pud)
>> - pud_init((unsigned long)pud, (unsigned long)invalid_pmd_table);
>> + page = alloc_pages(GFP_KERNEL, PUD_ORDER);
>> + if (!page)
>> + return NULL;
>> +
>> + pgtable_page_inc(page);
>> + pud = (pud_t *)page_address(page);
>> + pud_init((unsigned long)pud, (unsigned long)invalid_pmd_table);
>> return pud;
>> }
>>
>> diff --git a/arch/s390/include/asm/tlb.h b/arch/s390/include/asm/tlb.h
>> index fe6407f..744e2d7 100644
>> --- a/arch/s390/include/asm/tlb.h
>> +++ b/arch/s390/include/asm/tlb.h
>> @@ -125,6 +125,7 @@ static inline void pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
>> {
>> if (mm_pud_folded(tlb->mm))
>> return;
>> + pgtable_page_dec(virt_to_page(pud));
>> tlb->mm->context.flush_mm = 1;
>> tlb->freed_tables = 1;
>> tlb->cleared_p4ds = 1;
>> diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
>> index a932d77..5e46e31 100644
>> --- a/arch/x86/mm/pgtable.c
>> +++ b/arch/x86/mm/pgtable.c
>> @@ -76,8 +76,11 @@ void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
>> #if CONFIG_PGTABLE_LEVELS > 3
>> void ___pud_free_tlb(struct mmu_gather *tlb, pud_t *pud)
>> {
>> + struct page *page = virt_to_page(pud);
>> +
>> + pgtable_page_dec(page);
>> paravirt_release_pud(__pa(pud) >> PAGE_SHIFT);
>> - paravirt_tlb_remove_table(tlb, virt_to_page(pud));
>> + paravirt_tlb_remove_table(tlb, page);
>> }
>>
>> #if CONFIG_PGTABLE_LEVELS > 4
>> diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h
>> index 977bea1..11350f7 100644
>> --- a/include/asm-generic/pgalloc.h
>> +++ b/include/asm-generic/pgalloc.h
>> @@ -149,11 +149,16 @@ static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
>>
>> static inline pud_t *__pud_alloc_one(struct mm_struct *mm, unsigned long addr)
>> {
>> + struct page *page;
>> gfp_t gfp = GFP_PGTABLE_USER;
>>
>> if (mm == &init_mm)
>> gfp = GFP_PGTABLE_KERNEL;
>> - return (pud_t *)get_zeroed_page(gfp);
>> + page = alloc_pages(gfp, 0);
>> + if (!page)
>> + return NULL;
>> + pgtable_page_inc(page);
>> + return (pud_t *)page_address(page);
>> }
>>
>> #ifndef __HAVE_ARCH_PUD_ALLOC_ONE
>> @@ -174,8 +179,11 @@ static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long addr)
>>
>> static inline void __pud_free(struct mm_struct *mm, pud_t *pud)
>> {
>> + struct page *page = virt_to_page(pud);
>> +
>> BUG_ON((unsigned long)pud & (PAGE_SIZE-1));
>> - free_page((unsigned long)pud);
>> + pgtable_page_dec(page);
>> + __free_page(page);
>> }
>>
>> #ifndef __HAVE_ARCH_PUD_FREE
>> --
>> 1.8.3.1
>>
>