Re: [PATCH -V8 04/10] mm/migrate: make migrate_pages() return nr_succeeded

[Oscar Salvador]

On Fri, Jun 18, 2021 at 02:15:31PM +0800, Huang Ying wrote:
> From: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
> 
> The migrate_pages() returns the number of pages that were not migrated,
> or an error code.  When returning an error code, there is no way to know
> how many pages were migrated or not migrated.
> 
> In the following patch, migrate_pages() is used to demote pages to PMEM
> node, we need account how many pages are reclaimed (demoted) since page
> reclaim behavior depends on this.  Add *nr_succeeded parameter to make
> migrate_pages() return how many pages are demoted successfully for all
> cases.
> 
> Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
> Reviewed-by: Yang Shi <shy828301@xxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: Wei Xu <weixugc@xxxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: David Hildenbrand <david@xxxxxxxxxx>
> Cc: osalvador <osalvador@xxxxxxx>

I thought we all agreed on making nr_succeed an optional argument [1].
It reduced the churn quite a lot.

[1] https://patchwork.kernel.org/comment/24104453/


-- 
Oscar Salvador
SUSE L3