Re: [PATCH v1 5/7] mm/pagewalk: add walk_page_range_vma()

[David Hildenbrand]

On 05.10.22 22:42, Peter Xu wrote:
> On Fri, Sep 30, 2022 at 04:19:29PM +0200, David Hildenbrand wrote:
> > +int walk_page_range_vma(struct vm_area_struct *vma, unsigned long start,
> > +			unsigned long end, const struct mm_walk_ops *ops,
> > +			void *private)
> > +{
> > +	struct mm_walk walk = {
> > +		.ops		= ops,
> > +		.mm		= vma->vm_mm,
> > +		.vma		= vma,
> > +		.private	= private,
> > +	};
> > +	int err;
> > +
> > +	if (start >= end || !walk.mm)
> > +		return -EINVAL;
> > +	if (start < vma->vm_start || end > vma->vm_end)
> > +		return -EINVAL;
> > +
> > +	mmap_assert_locked(walk.mm);
> > +
> > +	err = walk_page_test(start, end, &walk);
>
> According to test_walk():
>
>   * @test_walk:		caller specific callback function to determine whether
>   *			we walk over the current vma or not. Returning 0 means
>   *			"do page table walk over the current vma", returning
>   *			a negative value means "abort current page table walk
>   *			right now" and returning 1 means "skip the current vma"
>
> Since this helper has vma passed in, not sure whether this is needed at
> all?

I kept it because walk_page_vma() similarly has it -- walk_page_vma() 
walks the whole VMA range.

I do agree that it's kind of weird to have it like that. All users of 
walk_page_vma() don't use it, so we can just get rid of it there as 
well. Might make the walk slightly faster.

> walk_page_vma_range() sounds slightly better to me as it does look more
> like an extension of walk_page_vma(), rather than sister version of
> walk_page_range_novma() (which works for "no backing VMA" case).  But no
> strong opinion.

I matched that to walk_page_range_novma(). Now we have

walk_page_range
walk_page_vma
walk_page_range_novma
walk_page_range_vma


--
Thanks,

David / dhildenb