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Re: [PATCH 3/6] mm/page_owner: copy last_migrate_reason in copy_page_owner()

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On 05/03/2016 07:23 AM, js1304@gmail.com wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>
> Currently, copy_page_owner() doesn't copy all the owner information.
> It skips last_migrate_reason because copy_page_owner() is used for
> migration and it will be properly set soon. But, following patch
> will use copy_page_owner() and this skip will cause the problem that
> allocated page has uninitialied last_migrate_reason. To prevent it,
> this patch also copy last_migrate_reason in copy_page_owner().

Hmm it's a corner case, but if the "new" page was dumped e.g. due to a 
bug during the migration, is the copied migrate reason from the "old" 
page actually meaningful? I'd say it might be misleading and it's 
simpler to just make sure it's initialized to -1.

> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> ---
>   mm/page_owner.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/mm/page_owner.c b/mm/page_owner.c
> index 792b56d..6693959 100644
> --- a/mm/page_owner.c
> +++ b/mm/page_owner.c
> @@ -101,6 +101,7 @@ void __copy_page_owner(struct page *oldpage, struct page *newpage)
>
>   	new_ext->order = old_ext->order;
>   	new_ext->gfp_mask = old_ext->gfp_mask;
> +	new_ext->last_migrate_reason = old_ext->last_migrate_reason;
>   	new_ext->nr_entries = old_ext->nr_entries;
>
>   	for (i = 0; i < ARRAY_SIZE(new_ext->trace_entries); i++)
>

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[PATCH 0/6] mm/page_owner: use tackdepot to store stacktrace js1304@gmail.com - 2016-05-03 07:30 +0200
  [PATCH 5/6] tools/vm/page_owner: increase temporary buffer size js1304@gmail.com - 2016-05-03 07:30 +0200
  [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace js1304@gmail.com - 2016-05-03 07:30 +0200
    Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace Michal Hocko <mhocko@kernel.org> - 2016-05-03 11:00 +0200
      Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace Joonsoo Kim <iamjoonsoo.kim@lge.com> - 2016-05-04 04:20 +0200
        Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace Joonsoo Kim <iamjoonsoo.kim@lge.com> - 2016-05-04 04:40 +0200
          Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace Michal Hocko <mhocko@kernel.org> - 2016-05-04 11:30 +0200
            Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace Joonsoo Kim <js1304@gmail.com> - 2016-05-04 17:40 +0200
        Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace Michal Hocko <mhocko@kernel.org> - 2016-05-04 11:30 +0200
          Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace Joonsoo Kim <js1304@gmail.com> - 2016-05-04 17:40 +0200
            Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace Joonsoo Kim <js1304@gmail.com> - 2016-05-04 17:50 +0200
              Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace Michal Hocko <mhocko@kernel.org> - 2016-05-04 21:50 +0200
            Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace Michal Hocko <mhocko@kernel.org> - 2016-05-04 21:50 +0200
              Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace Joonsoo Kim <js1304@gmail.com> - 2016-05-10 09:10 +0200
                Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace Michal Hocko <mhocko@kernel.org> - 2016-05-10 11:00 +0200
    Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace Vlastimil Babka <vbabka@suse.cz> - 2016-05-12 14:00 +0200
  [PATCH 3/6] mm/page_owner: copy last_migrate_reason in copy_page_owner() js1304@gmail.com - 2016-05-03 07:30 +0200
    Re: [PATCH 3/6] mm/page_owner: copy last_migrate_reason in  copy_page_owner() Vlastimil Babka <vbabka@suse.cz> - 2016-05-10 17:20 +0200
      Re: [PATCH 3/6] mm/page_owner: copy last_migrate_reason in  copy_page_owner() Joonsoo Kim <iamjoonsoo.kim@lge.com> - 2016-05-12 05:00 +0200
        Re: [PATCH 3/6] mm/page_owner: copy last_migrate_reason in  copy_page_owner() Vlastimil Babka <vbabka@suse.cz> - 2016-05-12 08:50 +0200
  [PATCH 4/6] mm/page_owner: introduce split_page_owner and replace manual handling js1304@gmail.com - 2016-05-03 07:30 +0200
    Re: [PATCH 4/6] mm/page_owner: introduce split_page_owner and replace  manual handling Vlastimil Babka <vbabka@suse.cz> - 2016-05-10 17:20 +0200
  [PATCH 2/6] mm/page_owner: initialize page owner without holding the zone lock js1304@gmail.com - 2016-05-03 07:30 +0200
    Re: [PATCH 2/6] mm/page_owner: initialize page owner without holding  the zone lock Vlastimil Babka <vbabka@suse.cz> - 2016-05-10 17:10 +0200
  [PATCH 1/6] mm/compaction: split freepages without holding the zone lock js1304@gmail.com - 2016-05-03 07:30 +0200
    Re: [PATCH 1/6] mm/compaction: split freepages without holding the  zone lock Vlastimil Babka <vbabka@suse.cz> - 2016-05-10 17:00 +0200
      Re: [PATCH 1/6] mm/compaction: split freepages without holding the  zone lock Joonsoo Kim <iamjoonsoo.kim@lge.com> - 2016-05-12 05:00 +0200

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