Re: [PATCH -V10 3/9] mm/migrate: enable returning precise migrate_pages() success count

[Zi Yan]

On 15 Jul 2021, at 1:51, Huang Ying wrote:

> From: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
>
> Under normal circumstances, migrate_pages() returns the number of
> pages migrated.  In error conditions, it returns an error code.  When
> returning an error code, there is no way to know how many pages were
> migrated or not migrated.
>
> Make migrate_pages() return how many pages are demoted successfully
> for all cases, including when encountering errors.  Page reclaim
> behavior will depend on this in subsequent patches.
>
> Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
> Suggested-by: osalvador <osalvador@xxxxxxx> [optional parameter]
> Reviewed-by: Yang Shi <shy828301@xxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: Wei Xu <weixugc@xxxxxxxxxx>
> Cc: Zi Yan <ziy@xxxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: David Hildenbrand <david@xxxxxxxxxx>
>
> --
>
> Note: Yang Shi originally wrote the patch, thus the SoB.  There was
> also a Reviewed-by provided since there were some modifications made
> to this after the original work.
>
> Changes since 20210618:
>  * Reword some bits of the changelog/subject
>  * Allow callers to pass a NULL 'ret_succeeded'.  This ensures that
>    callers don't have to declare and pass a dummy variable.
>
> Changes since 20210302:
>  * Fix definition of CONFIG_MIGRATION=n stub migrate_pages().  Its
>    parameters were wrong, but oddly enough did not generate any
>    compile errors.
>
> Changes since 20200122:
>  * Fix migrate_pages() to manipulate nr_succeeded *value*
>    rather than the pointer.
> ---
>  include/linux/migrate.h |  5 +++--
>  mm/compaction.c         |  2 +-
>  mm/gup.c                |  2 +-
>  mm/memory-failure.c     |  2 +-
>  mm/memory_hotplug.c     |  2 +-
>  mm/mempolicy.c          |  4 ++--
>  mm/migrate.c            | 11 ++++++++---
>  mm/page_alloc.c         |  2 +-
>  8 files changed, 18 insertions(+), 12 deletions(-)
>
LGTM. Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>

—
Best Regards,
Yan, Zi

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