linux-kernel - Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace

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Message-ID: <CAAmzW4PGnWDz265KLTQFq0LDnuht_V2YXOWMUxHgnfaz1DKswQ@mail.gmail.com>
Date:	Thu, 5 May 2016 00:31:32 +0900
From:	Joonsoo Kim <js1304@...il.com>
To:	Michal Hocko <mhocko@...nel.org>
Cc:	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Vlastimil Babka <vbabka@...e.cz>,
	Mel Gorman <mgorman@...hsingularity.net>,
	Minchan Kim <minchan@...nel.org>,
	Alexander Potapenko <glider@...gle.com>,
	Linux Memory Management List <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace

2016-05-04 18:23 GMT+09:00 Michal Hocko <mhocko@...nel.org>:
> On Wed 04-05-16 11:35:00, Joonsoo Kim wrote:
> [...]
>> Oops... I think more deeply and change my mind. In recursion case,
>> stack is consumed more than 1KB and it would be a problem. I think
>> that best approach is using preallocated per cpu entry. It will also
>> close recursion detection issue by paying interrupt on/off overhead.
>
> I was thinking about per-cpu solution as well but the thing is that the
> stackdepot will allocate and until you drop __GFP_DIRECT_RECLAIM then
> per-cpu is not safe. I haven't checked the implamentation of
> depot_save_stack but I assume it will not schedule in other places.

I will think more.

Thanks for review!

Thanks.