From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756954AbcEDJYE (ORCPT ); Wed, 4 May 2016 05:24:04 -0400 Received: from mail-wm0-f44.google.com ([74.125.82.44]:38358 "EHLO mail-wm0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751213AbcEDJYB (ORCPT ); Wed, 4 May 2016 05:24:01 -0400 Date: Wed, 4 May 2016 11:23:59 +0200 From: Michal Hocko To: Joonsoo Kim Cc: Andrew Morton , Vlastimil Babka , mgorman@techsingularity.net, Minchan Kim , Alexander Potapenko , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace Message-ID: <20160504092359.GH29978@dhcp22.suse.cz> References: <1462252984-8524-1-git-send-email-iamjoonsoo.kim@lge.com> <1462252984-8524-7-git-send-email-iamjoonsoo.kim@lge.com> <20160503085356.GD28039@dhcp22.suse.cz> <20160504021449.GA10256@js1304-P5Q-DELUXE> <20160504023500.GB10256@js1304-P5Q-DELUXE> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160504023500.GB10256@js1304-P5Q-DELUXE> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.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. -- Michal Hocko SUSE Labs