Re: [PATCH v4 15/66] mm: Convert vma_lookup() to use the Maple Tree

[Vlastimil Babka]

Re: subject. It already uses the Maple Tree via find_vma(). So more accurate
would be e.g. "to use mtree_load()"?

Note there's also the side-effect of not using vmacache anymore (which is
still used in find_vma()), thus again potentially biasing results of later
vmacache removal. But seems like vma_lookup() is not used from hotpaths, so
it should be fine.

On 12/1/21 15:29, Liam Howlett wrote:
> From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
> 
> Unlike the rbtree, the Maple Tree will return a NULL if there's
> nothing at a particular address.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>

> ---
>  include/linux/mm.h | 7 +------
>  1 file changed, 1 insertion(+), 6 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 4d5ab70b1f6d..c28bd97a4ecd 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2845,12 +2845,7 @@ struct vm_area_struct *find_vma_intersection(struct mm_struct *mm,
>  static inline
>  struct vm_area_struct *vma_lookup(struct mm_struct *mm, unsigned long addr)
>  {
> -	struct vm_area_struct *vma = find_vma(mm, addr);
> -
> -	if (vma && addr < vma->vm_start)
> -		vma = NULL;
> -
> -	return vma;
> +	return mtree_load(&mm->mm_mt, addr);
>  }
>  
>  static inline unsigned long vm_start_gap(struct vm_area_struct *vma)