From ad7df764b7e1c7dc64e016da7ada2e3e1bb90700 Mon Sep 17 00:00:00 2001 From: Alistair Popple Date: Fri, 4 Sep 2020 16:36:01 -0700 Subject: mm/rmap: fixup copying of soft dirty and uffd ptes MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit During memory migration a pte is temporarily replaced with a migration swap pte. Some pte bits from the existing mapping such as the soft-dirty and uffd write-protect bits are preserved by copying these to the temporary migration swap pte. However these bits are not stored at the same location for swap and non-swap ptes. Therefore testing these bits requires using the appropriate helper function for the given pte type. Unfortunately several code locations were found where the wrong helper function is being used to test soft_dirty and uffd_wp bits which leads to them getting incorrectly set or cleared during page-migration. Fix these by using the correct tests based on pte type. Fixes: a5430dda8a3a ("mm/migrate: support un-addressable ZONE_DEVICE page in migration") Fixes: 8c3328f1f36a ("mm/migrate: migrate_vma() unmap page from vma while collecting pages") Fixes: f45ec5ff16a7 ("userfaultfd: wp: support swap and page migration") Signed-off-by: Alistair Popple Signed-off-by: Andrew Morton Reviewed-by: Peter Xu Cc: Jérôme Glisse Cc: John Hubbard Cc: Ralph Campbell Cc: Alistair Popple Cc: Link: https://lkml.kernel.org/r/20200825064232.10023-2-alistair@popple.id.au Signed-off-by: Linus Torvalds --- mm/migrate.c | 15 +++++++++++---- mm/rmap.c | 9 +++++++-- 2 files changed, 18 insertions(+), 6 deletions(-) (limited to 'mm') diff --git a/mm/migrate.c b/mm/migrate.c index ddb64253fe3e..12f63806d0ac 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -2427,10 +2427,17 @@ again: entry = make_migration_entry(page, mpfn & MIGRATE_PFN_WRITE); swp_pte = swp_entry_to_pte(entry); - if (pte_soft_dirty(pte)) - swp_pte = pte_swp_mksoft_dirty(swp_pte); - if (pte_uffd_wp(pte)) - swp_pte = pte_swp_mkuffd_wp(swp_pte); + if (pte_present(pte)) { + if (pte_soft_dirty(pte)) + swp_pte = pte_swp_mksoft_dirty(swp_pte); + if (pte_uffd_wp(pte)) + swp_pte = pte_swp_mkuffd_wp(swp_pte); + } else { + if (pte_swp_soft_dirty(pte)) + swp_pte = pte_swp_mksoft_dirty(swp_pte); + if (pte_swp_uffd_wp(pte)) + swp_pte = pte_swp_mkuffd_wp(swp_pte); + } set_pte_at(mm, addr, ptep, swp_pte); /* diff --git a/mm/rmap.c b/mm/rmap.c index 83cc459edc40..9425260774a1 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1511,9 +1511,14 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, */ entry = make_migration_entry(page, 0); swp_pte = swp_entry_to_pte(entry); - if (pte_soft_dirty(pteval)) + + /* + * pteval maps a zone device page and is therefore + * a swap pte. + */ + if (pte_swp_soft_dirty(pteval)) swp_pte = pte_swp_mksoft_dirty(swp_pte); - if (pte_uffd_wp(pteval)) + if (pte_swp_uffd_wp(pteval)) swp_pte = pte_swp_mkuffd_wp(swp_pte); set_pte_at(mm, pvmw.address, pvmw.pte, swp_pte); /* -- cgit v1.2.3