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

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

[Christoph Hellwig]

On Tue, Jun 06, 2023 at 08:01:49AM +0300, mpenttil@redhat.com wrote:
> From: Mika Penttilä <mpenttil@redhat.com>
> 
> 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?

> +				/*
> +				 * 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.

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@redhat.com wrote:
>> From: Mika Penttilä <mpenttil@redhat.com>
>>
>> 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

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

[Mika Penttilä]

On 7.6.2023 17.10, Christoph Hellwig wrote:
> On Tue, Jun 06, 2023 at 08:01:49AM +0300, mpenttil@redhat.com wrote:
>> From: Mika Penttilä <mpenttil@redhat.com>
>>
>> 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.

Not sure what you mean should not exceed 7 lines..?

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

[Christoph Hellwig]

On Wed, Jun 07, 2023 at 07:06:06PM +0300, Mika Penttilä wrote:
> 
> 
> On 7.6.2023 17.10, Christoph Hellwig wrote:
> > On Tue, Jun 06, 2023 at 08:01:49AM +0300, mpenttil@redhat.com wrote:
> > > From: Mika Penttilä <mpenttil@redhat.com>
> > > 
> > > 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.
> 
> Not sure what you mean should not exceed 7 lines..?

Sorry, this should be 73.