Re: [PATCH v2] mm: page_isolation: avoid unsafe folio reads while scanning compound pages

[Andrew Morton]

On Tue, 02 Jun 2026 11:02:41 -0400 Zi Yan <ziy@xxxxxxxxxx> wrote:

> > -		*step = folio_nr_pages(folio) - folio_page_idx(folio, page);
> > +		nr_pages = 1UL << order;
> > +		pfn = page_to_pfn(page);
> > +		*step = (pfn | (nr_pages - 1)) + 1 - pfn;
> >  		return false;
> >  	}
> 
> LGTM. Thanks.
> 
> Just a comment, order can be dropped and use
> nr_pages = compound_nr(&folio->page) instead:
> 1. order > MAX_FOLIO_ORDER -> nr_pages > MAX_FOLIO_NR_PAGES
> 2. PAGE_SIZE << order -> PAGE_SIZE * nr_pages.
> But it is not worth a new version.
> 
> Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>

Thanks, I queued this.

What are we to make of Sashiko's question?
https://sashiko.dev/#/patchset/20260602130755.38794-1-kaitao.cheng@xxxxxxxxx