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    Subject[PATCH v13 57/70] mm/mlock: use vma iterator and maple state instead of vma linked list
    Date
    From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

    Handle overflow checking in count_mm_mlocked_page_nr() differently.

    Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
    Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
    ---
    mm/mlock.c | 35 +++++++++++++++++++----------------
    1 file changed, 19 insertions(+), 16 deletions(-)

    diff --git a/mm/mlock.c b/mm/mlock.c
    index b14e929084cc..43d19a1f28eb 100644
    --- a/mm/mlock.c
    +++ b/mm/mlock.c
    @@ -471,6 +471,7 @@ static int apply_vma_lock_flags(unsigned long start, size_t len,
    unsigned long nstart, end, tmp;
    struct vm_area_struct *vma, *prev;
    int error;
    + MA_STATE(mas, &current->mm->mm_mt, start, start);

    VM_BUG_ON(offset_in_page(start));
    VM_BUG_ON(len != PAGE_ALIGN(len));
    @@ -479,13 +480,14 @@ static int apply_vma_lock_flags(unsigned long start, size_t len,
    return -EINVAL;
    if (end == start)
    return 0;
    - vma = find_vma(current->mm, start);
    - if (!vma || vma->vm_start > start)
    + vma = mas_walk(&mas);
    + if (!vma)
    return -ENOMEM;

    - prev = vma->vm_prev;
    if (start > vma->vm_start)
    prev = vma;
    + else
    + prev = mas_prev(&mas, 0);

    for (nstart = start ; ; ) {
    vm_flags_t newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
    @@ -505,7 +507,7 @@ static int apply_vma_lock_flags(unsigned long start, size_t len,
    if (nstart >= end)
    break;

    - vma = prev->vm_next;
    + vma = find_vma(prev->vm_mm, prev->vm_end);
    if (!vma || vma->vm_start != nstart) {
    error = -ENOMEM;
    break;
    @@ -526,24 +528,23 @@ static unsigned long count_mm_mlocked_page_nr(struct mm_struct *mm,
    {
    struct vm_area_struct *vma;
    unsigned long count = 0;
    + unsigned long end;
    + VMA_ITERATOR(vmi, mm, start);

    if (mm == NULL)
    mm = current->mm;

    - vma = find_vma(mm, start);
    - if (vma == NULL)
    - return 0;
    -
    - for (; vma ; vma = vma->vm_next) {
    - if (start >= vma->vm_end)
    - continue;
    - if (start + len <= vma->vm_start)
    - break;
    + /* Don't overflow past ULONG_MAX */
    + if (unlikely(ULONG_MAX - len < start))
    + end = ULONG_MAX;
    + else
    + end = start + len;
    + for_each_vma_range(vmi, vma, end) {
    if (vma->vm_flags & VM_LOCKED) {
    if (start > vma->vm_start)
    count -= (start - vma->vm_start);
    - if (start + len < vma->vm_end) {
    - count += start + len - vma->vm_start;
    + if (end < vma->vm_end) {
    + count += end - vma->vm_start;
    break;
    }
    count += vma->vm_end - vma->vm_start;
    @@ -659,6 +660,7 @@ SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
    */
    static int apply_mlockall_flags(int flags)
    {
    + MA_STATE(mas, &current->mm->mm_mt, 0, 0);
    struct vm_area_struct *vma, *prev = NULL;
    vm_flags_t to_add = 0;

    @@ -679,7 +681,7 @@ static int apply_mlockall_flags(int flags)
    to_add |= VM_LOCKONFAULT;
    }

    - for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
    + mas_for_each(&mas, vma, ULONG_MAX) {
    vm_flags_t newflags;

    newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
    @@ -687,6 +689,7 @@ static int apply_mlockall_flags(int flags)

    /* Ignore errors */
    mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
    + mas_pause(&mas);
    cond_resched();
    }
    out:
    --
    2.35.1
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