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author | James Houghton <jthoughton@google.com> | 2023-01-05 02:19:10 +0300 |
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committer | Andrew Morton <akpm@linux-foundation.org> | 2023-01-12 03:14:20 +0300 |
commit | b30c14cd61025eeea2f2e8569606cd167ba9ad2d (patch) | |
tree | f29fb344382f3e1b97a7f17e69fadace848aae85 /scripts | |
parent | a1193de562f54c7c9f60ca9f2db96e50a7608de1 (diff) | |
download | linux-b30c14cd61025eeea2f2e8569606cd167ba9ad2d.tar.xz |
hugetlb: unshare some PMDs when splitting VMAs
PMD sharing can only be done in PUD_SIZE-aligned pieces of VMAs; however,
it is possible that HugeTLB VMAs are split without unsharing the PMDs
first.
Without this fix, it is possible to hit the uffd-wp-related WARN_ON_ONCE
in hugetlb_change_protection [1]. The key there is that
hugetlb_unshare_all_pmds will not attempt to unshare PMDs in
non-PUD_SIZE-aligned sections of the VMA.
It might seem ideal to unshare in hugetlb_vm_op_open, but we need to
unshare in both the new and old VMAs, so unsharing in hugetlb_vm_op_split
seems natural.
[1]: https://lore.kernel.org/linux-mm/CADrL8HVeOkj0QH5VZZbRzybNE8CG-tEGFshnA+bG9nMgcWtBSg@mail.gmail.com/
Link: https://lkml.kernel.org/r/20230104231910.1464197-1-jthoughton@google.com
Fixes: 6dfeaff93be1 ("hugetlb/userfaultfd: unshare all pmds for hugetlbfs when register wp")
Signed-off-by: James Houghton <jthoughton@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'scripts')
0 files changed, 0 insertions, 0 deletions