diff mbox series

[v4,2/5] mm/swapfile: Fix lost swap bits in unuse_pte()

Message ID 20220519125030.21486-3-linmiaohe@huawei.com (mailing list archive)
State New
Headers show
Series A few fixup patches for mm | expand

Commit Message

Miaohe Lin May 19, 2022, 12:50 p.m. UTC 
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@redhat.com>
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
---
 mm/swapfile.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 226c7d3ba896..0beeaffc7dee 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1774,7 +1774,7 @@  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;
@@ -1823,8 +1823,12 @@  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))
+		new_pte = pte_mksoft_dirty(new_pte);
+	if (pte_swp_uffd_wp(*pte))
+		new_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);