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

@@ -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