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Subject: [PATCH v5 08/17] mm/ksm: Break COW PTE before modify shared PTE
Date:   Fri, 14 Apr 2023 22:23:32 +0800
Message-Id: <20230414142341.354556-9-shiyn.lin@gmail.com>
In-Reply-To: <20230414142341.354556-1-shiyn.lin@gmail.com>
References: <20230414142341.354556-1-shiyn.lin@gmail.com>
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Break COW PTE before merge the page that reside in COW-ed PTE.

Signed-off-by: Chih-En Lin <shiyn.lin@gmail.com>
---
 mm/ksm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/ksm.c b/mm/ksm.c
index 2b8d30068cbb..963ef4d0085d 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1052,7 +1052,7 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
 			      pte_t *orig_pte)
 {
 	struct mm_struct *mm = vma->vm_mm;
-	DEFINE_PAGE_VMA_WALK(pvmw, page, vma, 0, 0);
+	DEFINE_PAGE_VMA_WALK(pvmw, page, vma, 0, PVMW_BREAK_COW_PTE);
 	int swapped;
 	int err = -EFAULT;
 	struct mmu_notifier_range range;
@@ -1169,6 +1169,8 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
 	barrier();
 	if (!pmd_present(pmde) || pmd_trans_huge(pmde))
 		goto out;
+	if (break_cow_pte(vma, pmd, addr))
+		goto out;
 
 	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, addr,
 				addr + PAGE_SIZE);
-- 
2.34.1