| Message ID | de60e44dc6fa7991889320a7dfc9ee7ea38f01d8.1652411252.git.baolin.wang@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Implement arm64 specific huge_ptep_get() | expand |
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@oracle.com/ Might be worth mentioning that arm64 now enables __HAVE_ARCH_HUGE_PTEP_GET. > > Suggested-by: Muchun Song <songmuchun@bytedance.com> > Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> > Reviewed-by: Muchun Song <songmuchun@bytedance.com> > --- > 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@arm.com>
在 5/13/2022 7:03 PM, Anshuman Khandual 写道: > > > 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 Will fix. > >> 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@oracle.com/ > > Might be worth mentioning that arm64 now enables __HAVE_ARCH_HUGE_PTEP_GET. Sure. > >> >> Suggested-by: Muchun Song <songmuchun@bytedance.com> >> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> >> Reviewed-by: Muchun Song <songmuchun@bytedance.com> >> --- >> 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. OK. > >> + >> + 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. Sure. > >> + >> + 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@arm.com> Thanks for reviewing.
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); + + 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); + } + + return orig_pte; +} + /* * Changing some bits of contiguous entries requires us to follow a * Break-Before-Make approach, breaking the whole contiguous set