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    SubjectRe: [PATCH v3] mm/mmap: Don't unlock VMAs in remap_file_pages()
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    On 24.02.21 00:50, Liam Howlett wrote:
    > Since this call uses MAP_FIXED, do_mmap() will munlock the necessary
    > range. There is also an error in the loop test expression which will
    > evaluate as false and the loop body has never execute.
    >
    > Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
    > Acked-by: Hugh Dickins <hughd@google.com>
    > ---
    > mm/mmap.c | 18 +-----------------
    > 1 file changed, 1 insertion(+), 17 deletions(-)
    >
    > diff --git a/mm/mmap.c b/mm/mmap.c
    > index dc7206032387c..e22b048733269 100644
    > --- a/mm/mmap.c
    > +++ b/mm/mmap.c
    > @@ -3025,25 +3025,9 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
    >
    > flags &= MAP_NONBLOCK;
    > flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
    > - if (vma->vm_flags & VM_LOCKED) {
    > - struct vm_area_struct *tmp;
    > + if (vma->vm_flags & VM_LOCKED)
    > flags |= MAP_LOCKED;
    >
    > - /* drop PG_Mlocked flag for over-mapped range */
    > - for (tmp = vma; tmp->vm_start >= start + size;
    > - tmp = tmp->vm_next) {
    > - /*
    > - * Split pmd and munlock page on the border
    > - * of the range.
    > - */
    > - vma_adjust_trans_huge(tmp, start, start + size, 0);
    > -
    > - munlock_vma_pages_range(tmp,
    > - max(tmp->vm_start, start),
    > - min(tmp->vm_end, start + size));
    > - }
    > - }
    > -
    > file = get_file(vma->vm_file);
    > ret = do_mmap(vma->vm_file, start, size,
    > prot, flags, pgoff, &populate, NULL);
    >

    Reviewed-by: David Hildenbrand <david@redhat.com>

    --
    Thanks,

    David / dhildenb

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