Commit ebdf8321 authored Sep 04, 2020 by Alistair Popple Committed by Linus Torvalds Sep 05, 2020

mm/migrate: fixup setting UFFD_WP flag



Commit f45ec5ff ("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: f45ec5ff ("userfaultfd: wp: support swap and page migration")
Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Link: https://lkml.kernel.org/r/20200825064232.10023-1-alistair@popple.id.au


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 7867fd7c

mm/migrate.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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);
		}
		}

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