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From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	mgorman@techsingularity.net, Minchan Kim <minchan@kernel.org>,
	Alexander Potapenko <glider@google.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/6] mm/page_owner: copy last_migrate_reason in copy_page_owner()
Date: Thu, 12 May 2016 11:58:58 +0900	[thread overview]
Message-ID: <20160512025858.GC8215@js1304-P5Q-DELUXE> (raw)
In-Reply-To: <5731FA88.2060701@suse.cz>

On Tue, May 10, 2016 at 05:13:12PM +0200, Vlastimil Babka wrote:
> 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.

Hmm... if it is the case, other fields are also misleading. I think
that we can tolerate this corner case and keeping function semantic as
function name suggests is better practice.

Thanks.

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  reply	other threads:[~2016-05-12  2:58 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-03  5:22 [PATCH 0/6] mm/page_owner: use tackdepot to store stacktrace js1304
2016-05-03  5:22 ` [PATCH 1/6] mm/compaction: split freepages without holding the zone lock js1304
2016-05-10 14:56   ` Vlastimil Babka
2016-05-12  2:51     ` Joonsoo Kim
2016-05-03  5:23 ` [PATCH 2/6] mm/page_owner: initialize page owner " js1304
2016-05-10 15:00   ` Vlastimil Babka
2016-05-03  5:23 ` [PATCH 3/6] mm/page_owner: copy last_migrate_reason in copy_page_owner() js1304
2016-05-10 15:13   ` Vlastimil Babka
2016-05-12  2:58     ` Joonsoo Kim [this message]
2016-05-12  6:48       ` Vlastimil Babka
2016-05-03  5:23 ` [PATCH 4/6] mm/page_owner: introduce split_page_owner and replace manual handling js1304
2016-05-10 15:14   ` Vlastimil Babka
2016-05-03  5:23 ` [PATCH 5/6] tools/vm/page_owner: increase temporary buffer size js1304
2016-05-03  5:23 ` [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace js1304
2016-05-03  8:53   ` Michal Hocko
2016-05-04  2:14     ` Joonsoo Kim
2016-05-04  2:35       ` Joonsoo Kim
2016-05-04  9:23         ` Michal Hocko
2016-05-04 15:31           ` Joonsoo Kim
2016-05-04  9:21       ` Michal Hocko
2016-05-04 15:30         ` Joonsoo Kim
2016-05-04 15:45           ` Joonsoo Kim
2016-05-04 19:41             ` Michal Hocko
2016-05-04 19:40           ` Michal Hocko
2016-05-10  7:07             ` Joonsoo Kim
2016-05-10  8:57               ` Michal Hocko
2016-05-12 11:57   ` Vlastimil Babka

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