On 5/13/22 09:07, Baolin Wang wrote: > Now we use huge_ptep_get() to get the pte value of a hugetlb page, > however it will only return one specific pte value for the CONT-PTE > or CONT-PMD size hugetlb on ARM64 system, which can contain seravel A small nit. s/seravel/several > continuous pte or pmd entries with same page table attributes. And it > will not take into account the subpages' dirty or young bits of a > CONT-PTE/PMD size hugetlb page. > > So the huge_ptep_get() is inconsistent with huge_ptep_get_and_clear(), > which already takes account the dirty or young bits for any subpages > in this CONT-PTE/PMD size hugetlb [1]. Meanwhile we can miss dirty or > young flags statistics for hugetlb pages with current huge_ptep_get(), > such as the gather_hugetlb_stats() function, and CONT-PTE/PMD hugetlb > monitoring with DAMON. > > Thus define an ARM64 specific huge_ptep_get() implementation, that will > take into account any subpages' dirty or young bits for CONT-PTE/PMD size > hugetlb page, for those functions that want to check the dirty and young > flags of a hugetlb page. > > [1] https://lore.kernel.org/linux-mm/85bd80b4-b4fd-0d3f-a2e5-149559f2f387@xxxxxxxxxx/ Might be worth mentioning that arm64 now enables __HAVE_ARCH_HUGE_PTEP_GET. > > Suggested-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> > Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx> > Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> > --- > arch/arm64/include/asm/hugetlb.h | 2 ++ > arch/arm64/mm/hugetlbpage.c | 24 ++++++++++++++++++++++++ > 2 files changed, 26 insertions(+) > > diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h > index 616b2ca..1fd2846 100644 > --- a/arch/arm64/include/asm/hugetlb.h > +++ b/arch/arm64/include/asm/hugetlb.h > @@ -44,6 +44,8 @@ extern pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, > #define __HAVE_ARCH_HUGE_PTE_CLEAR > extern void huge_pte_clear(struct mm_struct *mm, unsigned long addr, > pte_t *ptep, unsigned long sz); > +#define __HAVE_ARCH_HUGE_PTEP_GET > +extern pte_t huge_ptep_get(pte_t *ptep); > extern void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr, > pte_t *ptep, pte_t pte, unsigned long sz); > #define set_huge_swap_pte_at set_huge_swap_pte_at > diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c > index 9553851..9a3f7f1 100644 > --- a/arch/arm64/mm/hugetlbpage.c > +++ b/arch/arm64/mm/hugetlbpage.c > @@ -158,6 +158,30 @@ static inline int num_contig_ptes(unsigned long size, size_t *pgsize) > return contig_ptes; > } > > +pte_t huge_ptep_get(pte_t *ptep) > +{ > + int ncontig, i; > + size_t pgsize; > + pte_t orig_pte = ptep_get(ptep); > + > + if (!pte_present(orig_pte) || !pte_cont(orig_pte)) > + return orig_pte; > + > + ncontig = num_contig_ptes(page_size(pte_page(orig_pte)), &pgsize); Hmm, I guess there is no better way of deriving page size here. Please drop the extra line here. > + > + for (i = 0; i < ncontig; i++, ptep++) { > + pte_t pte = ptep_get(ptep); > + > + if (pte_dirty(pte)) > + orig_pte = pte_mkdirty(orig_pte); > + > + if (pte_young(pte)) > + orig_pte = pte_mkyoung(orig_pte); > + } Please drop the extra line here. > + > + return orig_pte; > +} > + > /* > * Changing some bits of contiguous entries requires us to follow a > * Break-Before-Make approach, breaking the whole contiguous set Otherwise LGTM. With those small changes accommodated, Reviewed-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
