From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751843AbdHPLRh (ORCPT ); Wed, 16 Aug 2017 07:17:37 -0400 Received: from mx2.suse.de ([195.135.220.15]:37305 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751287AbdHPLRf (ORCPT ); Wed, 16 Aug 2017 07:17:35 -0400 Date: Wed, 16 Aug 2017 13:17:32 +0200 From: Michal Hocko To: Chen Yu Cc: linux-mm@kvack.org, linux-pm@vger.kernel.org, Andrew Morton , Vlastimil Babka , Mel Gorman , linux-kernel@vger.kernel.org, "Rafael J. Wysocki" , Len Brown , Dan Williams Subject: Re: [PATCH][RFC] PM / Hibernate: Feed NMI wathdog when creating snapshot Message-ID: <20170816111731.GA32161@dhcp22.suse.cz> References: <1502731156-24903-1-git-send-email-yu.c.chen@intel.com> <20170815124119.GG29067@dhcp22.suse.cz> <20170815160107.GA2541@yu-desktop-1.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170815160107.GA2541@yu-desktop-1.sh.intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 16-08-17 00:01:08, Chen Yu wrote: > Hi Michal, > On Tue, Aug 15, 2017 at 02:41:19PM +0200, Michal Hocko wrote: [...] > > Moreover why don't you need to touch_nmi_watchdog in the loop over all > > pfns in the zone (right above this loop)? > As the NMI was triggered when checking the free_list rather than in the loop over > all pfns, it seems that the former has more possibility to catch a NMI if the > latter has already taken too much time. But yes, a safer way is to feed dog > in the latter too. I'll modify the code according to your suggestion. This is a wrong approach IMHO. The whole thing has IRQ disabled. -- Michal Hocko SUSE Labs