This is a note to let you know that I've just added the patch titled
mm/rmap: fixup copying of soft dirty and uffd ptes
to the 5.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-rmap-fixup-copying-of-soft-dirty-and-uffd-ptes.patch
and it can be found in the queue-5.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ad7df764b7e1c7dc64e016da7ada2e3e1bb90700 Mon Sep 17 00:00:00 2001
From: Alistair Popple <alistair@xxxxxxxxxxxx>
Date: Fri, 4 Sep 2020 16:36:01 -0700
Subject: mm/rmap: fixup copying of soft dirty and uffd ptes
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From: Alistair Popple <alistair@xxxxxxxxxxxx>
commit ad7df764b7e1c7dc64e016da7ada2e3e1bb90700 upstream.
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 <alistair@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Peter Xu <peterx@xxxxxxxxxx>
Cc: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Cc: Alistair Popple <alistair@xxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200825064232.10023-2-alistair@xxxxxxxxxxxx
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 15 +++++++++++----
mm/rmap.c | 9 +++++++--
2 files changed, 18 insertions(+), 6 deletions(-)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2330,10 +2330,17 @@ 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);
/*
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1511,9 +1511,14 @@ static bool try_to_unmap_one(struct page
*/
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);
/*
Patches currently in stable-queue which might be from alistair@xxxxxxxxxxxx are
queue-5.8/mm-rmap-fixup-copying-of-soft-dirty-and-uffd-ptes.patch
