mm/hugetlb: fix uffd-wp during fork()

Patch series "mm/hugetlb: More fixes around uffd-wp vs fork() / RO pins",
v2.


This patch (of 6):

There're a bunch of things that were wrong:

  - Reading uffd-wp bit from a swap entry should use pte_swp_uffd_wp()
    rather than huge_pte_uffd_wp().

  - When copying over a pte, we should drop uffd-wp bit when
    !EVENT_FORK (aka, when !userfaultfd_wp(dst_vma)).

  - When doing early CoW for private hugetlb (e.g. when the parent page was
    pinned), uffd-wp bit should be properly carried over if necessary.

No bug reported probably because most people do not even care about these
corner cases, but they are still bugs and can be exposed by the recent unit
tests introduced, so fix all of them in one shot.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: bc70fbf269fd ("mm/hugetlb: handle uffd-wp during fork()")
Signed-off-by: Peter Xu <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Axel Rasmussen <[email protected]>
Cc: Mika Penttilä <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Nadav Amit <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions