On 21.04.22 14:53, Miaohe Lin wrote: > 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. > > Suggested-by: Peter Xu <peterx@xxxxxxxxxx> > Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx> > --- > mm/swapfile.c | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 95b63f69f388..332ccfc76142 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, new_pte; > int ret = 1; > > swapcache = page; > @@ -1832,8 +1832,14 @@ 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)) > + new_pte = pte_mksoft_dirty(new_pte); > + if (pte_swp_uffd_wp(*pte)) { > + new_pte = pte_mkuffd_wp(new_pte); > + new_pte = pte_wrprotect(new_pte); The wrprotect shouldn't be necessary, we don't do a pte_mkwrite(). Note that in do_swap_page() we might have done a maybe_mkwrite(pte_mkdirty(pte)), which is why the pte_wrprotect() is required there. -- Thanks, David / dhildenb