This is observed by code review only but not any real report.
When we turn off swapping we could have lost the bits stored in the swap
ptes. The new rmap-exclusive bit is fine since that turned into a page
flag, but not for soft-dirty and uffd-wp. Add them.
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
---
mm/swapfile.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 9398e915b36b..eaea7a1f000b 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1783,7 +1783,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
{
struct page *swapcache;
spinlock_t *ptl;
- pte_t *pte;
+ pte_t *pte, newpte;
int ret = 1;
swapcache = page;
@@ -1821,8 +1821,12 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
page_add_new_anon_rmap(page, vma, addr);
lru_cache_add_inactive_or_unevictable(page, vma);
}
- set_pte_at(vma->vm_mm, addr, pte,
- pte_mkold(mk_pte(page, vma->vm_page_prot)));
+ new_pte = pte_mkold(mk_pte(page, vma->vm_page_prot));
+ if (pte_swp_soft_dirty(*pte))
+ pte = pte_mksoft_dirty(new_pte);
+ if (pte_swp_uffd_wp(*pte))
+ pte = pte_mkuffd_wp(new_pte);
+ set_pte_at(vma->vm_mm, addr, pte, new_pte);
swap_free(entry);
out:
pte_unmap_unlock(pte, ptl);
--
2.32.0
--4l5E6+oouBxra33V--
