[PATCH v4 12/14] fs/proc: Support COW PTE with clear_refs_write

Chih-En Lin
2023-02-07T03:55:04Z

Before clearing the entry in COW-ed PTE, break COW PTE first.

Signed-off-by: Chih-En Lin <shiyn.lin@gmail.com>
---
fs/proc/task_mmu.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index af1c49ae11b1..94958422aede 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1196,6 +1196,11 @@ static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr,
if (pmd_trans_unstable(pmd))
return 0;

+ /* Only break COW when we modify the soft-dirty bit. */
+ if (cp->type == CLEAR_REFS_SOFT_DIRTY &&
+ break_cow_pte(vma, pmd, addr))
+ return 0;
+
pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
for (; addr != end; pte++, addr += PAGE_SIZE) {
ptent = *pte;
--
2.34.1