On Mon, Aug 24, 2020 at 06:31:27PM +1000, Alistair Popple wrote:
Commit f45ec5ff16a75 ("userfaultfd: wp: support swap and page migration") introduced support for tracking the uffd wp bit during page migration. However the non-swap PTE variant was used to set the flag for zone device private pages which are a type of swap page.
This leads to corruption of the swap offset if the original PTE has the uffd_wp flag set.
Fixes: f45ec5ff16a75 ("userfaultfd: wp: support swap and page migration") Signed-off-by: Alistair Popple alistair@popple.id.au Cc: stable@vger.kernel.org
mm/migrate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/migrate.c b/mm/migrate.c index 34a842a8eb6a..ddb64253fe3e 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -251,7 +251,7 @@ static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma, entry = make_device_private_entry(new, pte_write(pte)); pte = swp_entry_to_pte(entry); if (pte_swp_uffd_wp(*pvmw.pte))
pte = pte_mkuffd_wp(pte);
pte = pte_swp_mkuffd_wp(pte); }
Looks correct... thanks!
Reviewed-by: Peter Xu peterx@redhat.com