Now, if the pte is dirty _PAGE_DIRTY but without _PAGE_MODIFIED, after
pte_modify() we lose _PAGE_DIRTY, then pte_dirty() returns false. So
we need _PAGE_MODIFIED to record _PAGE_DIRTY here.

The new modification involves checking whether the original PTE has the
_PAGE_DIRTY flag. If it exists, the _PAGE_MODIFIED bit is set, ensuring
that the pte_dirty interface can return accurate information.

Co-developed-by: Liupu Wang <wangliupu@loongson.cn>
Signed-off-by: Liupu Wang <wangliupu@loongson.cn>
Signed-off-by: Tianyang Zhang <zhangtianyang@loongson.cn>
---
 arch/loongarch/include/asm/pgtable.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h
index bd128696e96d..e0b92fe850b3 100644
--- a/arch/loongarch/include/asm/pgtable.h
+++ b/arch/loongarch/include/asm/pgtable.h
@@ -424,6 +424,9 @@ static inline unsigned long pte_accessible(struct mm_struct *mm, pte_t a)
 
 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 {
+	if (pte_val(pte) & _PAGE_DIRTY)
+		pte_val(pte) |= _PAGE_MODIFIED;
+
 	return __pte((pte_val(pte) & _PAGE_CHG_MASK) |
 		     (pgprot_val(newprot) & ~_PAGE_CHG_MASK));
 }
@@ -547,6 +550,9 @@ static inline struct page *pmd_page(pmd_t pmd)
 
 static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
 {
+	if (pmd_val(pmd) & _PAGE_DIRTY)
+		pmd_val(pmd) |= _PAGE_MODIFIED;
+
 	pmd_val(pmd) = (pmd_val(pmd) & _HPAGE_CHG_MASK) |
 				(pgprot_val(newprot) & ~_HPAGE_CHG_MASK);
 	return pmd;
-- 
2.41.0

Applied, thanks.

Huacai

On Fri, Nov 7, 2025 at 11:58 AM Tianyang Zhang
<zhangtianyang@loongson.cn> wrote:
>
> Now, if the pte is dirty _PAGE_DIRTY but without _PAGE_MODIFIED, after
> pte_modify() we lose _PAGE_DIRTY, then pte_dirty() returns false. So
> we need _PAGE_MODIFIED to record _PAGE_DIRTY here.
>
> The new modification involves checking whether the original PTE has the
> _PAGE_DIRTY flag. If it exists, the _PAGE_MODIFIED bit is set, ensuring
> that the pte_dirty interface can return accurate information.
>
> Co-developed-by: Liupu Wang <wangliupu@loongson.cn>
> Signed-off-by: Liupu Wang <wangliupu@loongson.cn>
> Signed-off-by: Tianyang Zhang <zhangtianyang@loongson.cn>
> ---
>  arch/loongarch/include/asm/pgtable.h | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h
> index bd128696e96d..e0b92fe850b3 100644
> --- a/arch/loongarch/include/asm/pgtable.h
> +++ b/arch/loongarch/include/asm/pgtable.h
> @@ -424,6 +424,9 @@ static inline unsigned long pte_accessible(struct mm_struct *mm, pte_t a)
>
>  static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
>  {
> +       if (pte_val(pte) & _PAGE_DIRTY)
> +               pte_val(pte) |= _PAGE_MODIFIED;
> +
>         return __pte((pte_val(pte) & _PAGE_CHG_MASK) |
>                      (pgprot_val(newprot) & ~_PAGE_CHG_MASK));
>  }
> @@ -547,6 +550,9 @@ static inline struct page *pmd_page(pmd_t pmd)
>
>  static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
>  {
> +       if (pmd_val(pmd) & _PAGE_DIRTY)
> +               pmd_val(pmd) |= _PAGE_MODIFIED;
> +
>         pmd_val(pmd) = (pmd_val(pmd) & _HPAGE_CHG_MASK) |
>                                 (pgprot_val(newprot) & ~_HPAGE_CHG_MASK);
>         return pmd;
> --
> 2.41.0
>
>