Re: [PATCH v1 3/9] mm/vma: Add limits to unmap_region() for vmas

[Suren Baghdasaryan <surenb@google.com>]

On Tue, Sep 9, 2025 at 12:10 PM Liam R. Howlett <Liam.Howlett@oracle.com> wrote:
>
> Add a limit to the vma search instead of using the start and end of the
> one passed in.

Would be good to explain why this is needed. I'm sure I'll find the
answer in the later patches though.


>
> No functional changes intended.
>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>

Reviewed-by: Suren Baghdasaryan <surenb@google.com>

> ---
>  mm/vma.c | 6 ++++--
>  mm/vma.h | 1 +
>  2 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/mm/vma.c b/mm/vma.c
> index abe0da33c8446..a648e0555c873 100644
> --- a/mm/vma.c
> +++ b/mm/vma.c
> @@ -474,6 +474,7 @@ void remove_vma(struct vm_area_struct *vma)
>   * Called with the mm semaphore held.
>   */
>  void unmap_region(struct ma_state *mas, struct vm_area_struct *vma,
> +               unsigned long vma_min, unsigned long vma_max,
>                 struct vm_area_struct *prev, struct vm_area_struct *next)
>  {
>         struct mm_struct *mm = vma->vm_mm;
> @@ -481,7 +482,7 @@ void unmap_region(struct ma_state *mas, struct vm_area_struct *vma,
>
>         tlb_gather_mmu(&tlb, mm);
>         update_hiwater_rss(mm);
> -       unmap_vmas(&tlb, mas, vma, vma->vm_start, vma->vm_end, vma->vm_end,
> +       unmap_vmas(&tlb, mas, vma, vma_min, vma_max, vma_max,
>                    /* mm_wr_locked = */ true);
>         mas_set(mas, vma->vm_end);
>         free_pgtables(&tlb, mas, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
> @@ -2417,7 +2418,8 @@ static int __mmap_new_file_vma(struct mmap_state *map,
>
>                 vma_iter_set(vmi, vma->vm_end);
>                 /* Undo any partial mapping done by a device driver. */
> -               unmap_region(&vmi->mas, vma, map->prev, map->next);
> +               unmap_region(&vmi->mas, vma, vma->vm_start, vma->vm_end,
> +                            map->prev, map->next);
>
>                 return error;
>         }
> diff --git a/mm/vma.h b/mm/vma.h
> index 9183fe5490090..a9d0cef684ddb 100644
> --- a/mm/vma.h
> +++ b/mm/vma.h
> @@ -261,6 +261,7 @@ int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm,
>  void remove_vma(struct vm_area_struct *vma);
>
>  void unmap_region(struct ma_state *mas, struct vm_area_struct *vma,
> +               unsigned long min, unsigned long max,
>                 struct vm_area_struct *prev, struct vm_area_struct *next);
>
>  /* We are about to modify the VMA's flags. */
> --
> 2.47.2
>