On 8/25/2021 2:46 AM, Christoph Hellwig wrote:

On Tue, Aug 24, 2021 at 10:48:17PM -0500, Alex Sierra wrote:

quoted

  		} else {
-			if (!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM))
+			if (!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM) &&
+			    !(migrate->flags & MIGRATE_VMA_SELECT_IOMEM))
  				goto next;
  			pfn = pte_pfn(pte);
  			if (is_zero_pfn(pfn)) {

.. also how is this going to work for the device public memory?  That
should be pte_special() an thus fail vm_normal_page.

Perhaps we're missing something, as we're not doing any special marking 
for the device public pfn/entries.
pfn_valid return true, pte_special return false and pfn_t_devmap return 
false on these pages. Same as system pages.
That's the reason vm_normal_page returns the page correctly through 
pfn_to_page helper.

Regards,
Alex S.