Re: [PATCHv2 1/2] mm/memory: Do not populate page table entries beyond i_size

[David Hildenbrand]

On 24.10.25 21:32, Kirill A. Shutemov wrote:
> On Fri, Oct 24, 2025, at 16:42, David Hildenbrand wrote:
> > On 23.10.25 11:32, Kiryl Shutsemau wrote:
> > >    	addr0 = addr - start * PAGE_SIZE;
> > >    	if (folio_within_vma(folio, vmf->vma) &&
> > > -	    (addr0 & PMD_MASK) == ((addr0 + folio_size(folio) - 1) & PMD_MASK)) {
> > > +	    (addr0 & PMD_MASK) == ((addr0 + folio_size(folio) - 1) & PMD_MASK) &&
> >
> > Isn't this just testing whether addr0 is aligned to folio_size(folio)?
> > (given that we don't support folios > PMD_SIZE), like
> >
> > 	IS_ALIGNED(addr0, folio_size(folio))
>
> Actually, no. VMA can be not aligned to folio_size().

Ah, I missed that we can also have folio sizes besides PMD_SIZE here.

So it's all about testing whether the complete folio would be mapped by 
a single page table.

(a helper would be nice, but cannot immediately come up with a good name)

--
Cheers

David / dhildenb