[PATCH v4 06/14] mm/ksm: Break COW PTE before modify shared PTE

Chih-En Lin
2023-02-07T03:53:52Z

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 dd02780c387f..ce3887d3b04c 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1045,7 +1045,7 @@ 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;
@@ -1163,6 +1163,8 @@ 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, vma, mm, addr,
addr + PAGE_SIZE);
--
2.34.1