Re: [PATCH v3] mm/migrate_device: Try to handle swapcache pages

[Mika Penttilä]

Hi,


On 7.6.2023 17.10, Christoph Hellwig wrote:
> On Tue, Jun 06, 2023 at 08:01:49AM +0300, mpenttil@xxxxxxxxxx wrote:
> > From: Mika Penttilä <mpenttil@xxxxxxxxxx>
> >
> > Migrating file pages and swapcache pages into device memory is not supported.
> > The decision is done based on page_mapping(). For now, swapcache pages are not migrated.
>
> Please fix the commit log formatting, it should not exceed 7 lines.
>
> >   		if (is_device_private_page(newpage) ||
> >   		    is_device_coherent_page(newpage)) {
> > -			/*
> > -			 * For now only support anonymous memory migrating to
> > -			 * device private or coherent memory.
> > -			 */
> > +
> >   			if (mapping) {
>
> Very nitpicky, but this empty line looks odd.  Also isn't the comment
> still (mostly) correct given that file backed memory is still not
> supported?

Yes the comment is mostly correct and moved a few lines lower, 
complemented with a comment about the swap cache.

> > +				/*
> > +				 * For now only support anonymous memory migrating to
> > +				 * device private or coherent memory.
> > +				 *
> > +				 * Try to get rid of swap cache if possible.
> > +				 *
> > +				 */
> > +				if (!folio_test_anon(folio) || !folio_free_swap(folio)) {
>
> Please avoid the overly long lines.

Thanks,
Mika