Re: [PATCH v4 1/5] mm: add mkwrite param to vm_insert_mixed()

Jan Kara
2017-07-24T11:25:35Z

> @@ -1658,14 +1658,28 @@ static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
> if (!pte)
> goto out;
> retval = -EBUSY;
> - if (!pte_none(*pte))
> - goto out_unlock;
> + if (!pte_none(*pte)) {
> + if (mkwrite) {
> + if (WARN_ON_ONCE(pte_pfn(*pte) != pfn_t_to_pfn(pfn)))

Is the WARN_ON_ONCE() really appropriate here? Your testcase with private
mappings has triggered this situation if I'm right...

Otherwise the patch looks good to me.

Honza

--
Jan Kara <jack@suse.com>
SUSE Labs, CR