Re: [mm 4.15-rc8] Random oopses under memory pressure.

[Dave Hansen]

On 01/18/2018 05:12 AM, Kirill A. Shutemov wrote:
> -		if (pte_page(*pvmw->pte) - pvmw->page >=
> -				hpage_nr_pages(pvmw->page)) {

Is ->pte guaranteed to map a page which is within the same section as
pvmw->page?  Otherwise, with sparsemem (non-vmemmap), the pointer
arithmetic won't work.

WARN_ON_ONCE(page_to_section(pvmw->page) !=
	     page_to_section(pte_page(*pvmw->pte));

Will detect that.