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    Subject[PATCH v2 06/44] mm/mmap: convert brk to use vma iterator
    Date
    From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>

    Use the vma iterator API for the brk() system call. This will provide
    type safety at compile time.

    Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
    ---
    mm/mmap.c | 47 +++++++++++++++++++++++------------------------
    1 file changed, 23 insertions(+), 24 deletions(-)

    diff --git a/mm/mmap.c b/mm/mmap.c
    index 9318f2ac8a6e..4a6f42ab3560 100644
    --- a/mm/mmap.c
    +++ b/mm/mmap.c
    @@ -239,10 +239,10 @@ static int check_brk_limits(unsigned long addr, unsigned long len)

    return mlock_future_check(current->mm, current->mm->def_flags, len);
    }
    -static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
    +static int do_brk_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
    unsigned long newbrk, unsigned long oldbrk,
    struct list_head *uf);
    -static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *brkvma,
    +static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *brkvma,
    unsigned long addr, unsigned long request, unsigned long flags);
    SYSCALL_DEFINE1(brk, unsigned long, brk)
    {
    @@ -253,7 +253,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
    bool populate;
    bool downgraded = false;
    LIST_HEAD(uf);
    - MA_STATE(mas, &mm->mm_mt, 0, 0);
    + struct vma_iterator vmi;

    if (mmap_write_lock_killable(mm))
    return -EINTR;
    @@ -301,8 +301,8 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
    int ret;

    /* Search one past newbrk */
    - mas_set(&mas, newbrk);
    - brkvma = mas_find(&mas, oldbrk);
    + vma_iter_init(&vmi, mm, newbrk);
    + brkvma = vma_find(&vmi, oldbrk);
    if (!brkvma || brkvma->vm_start >= oldbrk)
    goto out; /* mapping intersects with an existing non-brk vma. */
    /*
    @@ -311,7 +311,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
    * before calling do_brk_munmap().
    */
    mm->brk = brk;
    - ret = do_brk_munmap(&mas, brkvma, newbrk, oldbrk, &uf);
    + ret = do_brk_munmap(&vmi, brkvma, newbrk, oldbrk, &uf);
    if (ret == 1) {
    downgraded = true;
    goto success;
    @@ -329,14 +329,14 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
    * Only check if the next VMA is within the stack_guard_gap of the
    * expansion area
    */
    - mas_set(&mas, oldbrk);
    - next = mas_find(&mas, newbrk - 1 + PAGE_SIZE + stack_guard_gap);
    + vma_iter_init(&vmi, mm, oldbrk);
    + next = vma_find(&vmi, newbrk + PAGE_SIZE + stack_guard_gap);
    if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
    goto out;

    - brkvma = mas_prev(&mas, mm->start_brk);
    + brkvma = vma_prev_limit(&vmi, mm->start_brk);
    /* Ok, looks good - let it rip. */
    - if (do_brk_flags(&mas, brkvma, oldbrk, newbrk - oldbrk, 0) < 0)
    + if (do_brk_flags(&vmi, brkvma, oldbrk, newbrk - oldbrk, 0) < 0)
    goto out;

    mm->brk = brk;
    @@ -2963,7 +2963,7 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,

    /*
    * brk_munmap() - Unmap a parital vma.
    - * @mas: The maple tree state.
    + * @vmi: The vma iterator
    * @vma: The vma to be modified
    * @newbrk: the start of the address to unmap
    * @oldbrk: The end of the address to unmap
    @@ -2973,7 +2973,7 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
    * unmaps a partial VMA mapping. Does not handle alignment, downgrades lock if
    * possible.
    */
    -static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
    +static int do_brk_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
    unsigned long newbrk, unsigned long oldbrk,
    struct list_head *uf)
    {
    @@ -2981,14 +2981,14 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
    int ret;

    arch_unmap(mm, newbrk, oldbrk);
    - ret = do_mas_align_munmap(mas, vma, mm, newbrk, oldbrk, uf, true);
    + ret = do_mas_align_munmap(&vmi->mas, vma, mm, newbrk, oldbrk, uf, true);
    validate_mm_mt(mm);
    return ret;
    }

    /*
    * do_brk_flags() - Increase the brk vma if the flags match.
    - * @mas: The maple tree state.
    + * @vmi: The vma iterator
    * @addr: The start address
    * @len: The length of the increase
    * @vma: The vma,
    @@ -2998,7 +2998,7 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
    * do not match then create a new anonymous VMA. Eventually we may be able to
    * do some brk-specific accounting here.
    */
    -static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
    +static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
    unsigned long addr, unsigned long len, unsigned long flags)
    {
    struct mm_struct *mm = current->mm;
    @@ -3025,8 +3025,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
    if (vma && vma->vm_end == addr && !vma_policy(vma) &&
    can_vma_merge_after(vma, flags, NULL, NULL,
    addr >> PAGE_SHIFT, NULL_VM_UFFD_CTX, NULL)) {
    - mas_set_range(mas, vma->vm_start, addr + len - 1);
    - if (mas_preallocate(mas, vma, GFP_KERNEL))
    + if (vma_iter_prealloc(vmi, vma))
    goto unacct_fail;

    vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0);
    @@ -3036,7 +3035,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
    }
    vma->vm_end = addr + len;
    vma->vm_flags |= VM_SOFTDIRTY;
    - mas_store_prealloc(mas, vma);
    + vma_iter_store(vmi, vma);

    if (vma->anon_vma) {
    anon_vma_interval_tree_post_update_vma(vma);
    @@ -3057,8 +3056,8 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
    vma->vm_pgoff = addr >> PAGE_SHIFT;
    vma->vm_flags = flags;
    vma->vm_page_prot = vm_get_page_prot(flags);
    - mas_set_range(mas, vma->vm_start, addr + len - 1);
    - if (mas_store_gfp(mas, vma, GFP_KERNEL))
    + mas_set_range(&vmi->mas, vma->vm_start, vma->vm_end - 1);
    + if (vma_iter_store_gfp(vmi, vma, GFP_KERNEL))
    goto mas_store_fail;

    mm->map_count++;
    @@ -3087,7 +3086,7 @@ int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
    int ret;
    bool populate;
    LIST_HEAD(uf);
    - MA_STATE(mas, &mm->mm_mt, addr, addr);
    + VMA_ITERATOR(vmi, mm, addr);

    len = PAGE_ALIGN(request);
    if (len < request)
    @@ -3106,12 +3105,12 @@ int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
    if (ret)
    goto limits_failed;

    - ret = do_mas_munmap(&mas, mm, addr, len, &uf, 0);
    + ret = do_mas_munmap(&vmi.mas, mm, addr, len, &uf, 0);
    if (ret)
    goto munmap_failed;

    - vma = mas_prev(&mas, 0);
    - ret = do_brk_flags(&mas, vma, addr, len, flags);
    + vma = vma_prev(&vmi);
    + ret = do_brk_flags(&vmi, vma, addr, len, flags);
    populate = ((mm->def_flags & VM_LOCKED) != 0);
    mmap_write_unlock(mm);
    userfaultfd_unmap_complete(mm, &uf);
    --
    2.35.1
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