[PATCH v3 06/14] mm/ksm: Break COW PTE before modify shared PTE
From: Chih-En Lin
Date: Tue Dec 20 2022 - 02:26:43 EST
Break COW PTE before merge the page that reside in COW-ed PTE.
Signed-off-by: Chih-En Lin <shiyn.lin@xxxxxxxxx>
---
mm/ksm.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/ksm.c b/mm/ksm.c
index c19fcca9bc03d..896a14c44a858 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1017,7 +1017,7 @@ 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;
@@ -1136,6 +1136,8 @@ 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) < 0)
+ goto out;
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, addr,
addr + PAGE_SIZE);
--
2.37.3