From: Tianyang Zhang Date: Sun, 9 Nov 2025 08:02:01 +0000 (+0800) Subject: LoongArch: Let {pte,pmd}_modify() record the status of _PAGE_DIRTY X-Git-Tag: v6.18-rc6~36^2~10 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a073d637c8cfbfbab39b7272226a3fbf3b887580;p=thirdparty%2Fkernel%2Flinux.git LoongArch: Let {pte,pmd}_modify() record the status of _PAGE_DIRTY Now if the PTE/PMD is dirty with _PAGE_DIRTY but without _PAGE_MODIFIED, after {pte,pmd}_modify() we lose _PAGE_DIRTY, then {pte,pmd}_dirty() return false and lead to data loss. This can happen in certain scenarios such as HW PTW doesn't set _PAGE_MODIFIED automatically, so here we need _PAGE_MODIFIED to record the dirty status (_PAGE_DIRTY). The new modification involves checking whether the original PTE/PMD has the _PAGE_DIRTY flag. If it exists, the _PAGE_MODIFIED bit is also set, ensuring that the {pte,pmd}_dirty() interface can always return accurate information. Cc: stable@vger.kernel.org Co-developed-by: Liupu Wang Signed-off-by: Liupu Wang Signed-off-by: Tianyang Zhang --- diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h index bd128696e96d0..03fb60432fde7 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)); } @@ -547,9 +550,11 @@ static inline struct page *pmd_page(pmd_t pmd) static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot) { - pmd_val(pmd) = (pmd_val(pmd) & _HPAGE_CHG_MASK) | - (pgprot_val(newprot) & ~_HPAGE_CHG_MASK); - return pmd; + if (pmd_val(pmd) & _PAGE_DIRTY) + pmd_val(pmd) |= _PAGE_MODIFIED; + + return __pmd((pmd_val(pmd) & _HPAGE_CHG_MASK) | + (pgprot_val(newprot) & ~_HPAGE_CHG_MASK)); } static inline pmd_t pmd_mkinvalid(pmd_t pmd)