From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752655AbcELQi3 (ORCPT ); Thu, 12 May 2016 12:38:29 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:34554 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752613AbcELQi2 (ORCPT ); Thu, 12 May 2016 12:38:28 -0400 Date: Thu, 12 May 2016 18:38:25 +0200 From: Michal Hocko To: Tetsuo Handa Cc: hillf.zj@alibaba-inc.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v5] mm: Add memory allocation watchdog kernel thread. Message-ID: <20160512163824.GA4940@dhcp22.suse.cz> References: <004b01d1a9d1$3817fc10$a847f430$@alibaba-inc.com> <006e01d1a9d8$5c7a15f0$156e41d0$@alibaba-inc.com> <201605130009.EAJ35441.JLtFVOHFOSOMQF@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201605130009.EAJ35441.JLtFVOHFOSOMQF@I-love.SAKURA.ne.jp> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 13-05-16 00:09:07, Tetsuo Handa wrote: [...] > Michal, this version eliminated overhead of walking the process list > when nothing is wrong. You are aware of the possibility of > debug_show_all_locks() failing to report the culprit, aren't you? > So, what are unacceptable major problems for you? I do not remember complaining about anything unacceptable for this patch. I just thought it was way too large the last time I have looked at it. Johannes was suggesting to simply extend warn_alloc_failed to also report too many retries with some extended information as a more lightweight approach. It wouldn't give as much information as your watchdog but maybe it would be sufficient to figure out that something really bad is going on. Dunno but I would rather see a more lightweight debugging aid than a lot of code which sit basically unused most of the time. That being said I cannot comment on this particular version as I haven't checked it properly yet. -- Michal Hocko SUSE Labs