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@xxxxxxxxxx/
Might be worth mentioning that arm64 now enables __HAVE_ARCH_HUGE_PTEP_GET.
Sure.
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.
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@xxxxxxx>
Thanks for reviewing.
