From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751837AbdGZMT5 (ORCPT ); Wed, 26 Jul 2017 08:19:57 -0400 Received: from mx2.suse.de ([195.135.220.15]:57606 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751714AbdGZMT4 (ORCPT ); Wed, 26 Jul 2017 08:19:56 -0400 Date: Wed, 26 Jul 2017 14:19:52 +0200 From: Michal Hocko To: Heiko Carstens Cc: Andrew Morton , linux-mm@kvack.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Andre Wild , KAMEZAWA Hiroyuki , Thomas Gleixner , Vlastimil Babka Subject: Re: [PATCH] mm: take memory hotplug lock within numa_zonelist_order_handler() Message-ID: <20170726121952.GN2981@dhcp22.suse.cz> References: <20170726111738.38768-1-heiko.carstens@de.ibm.com> <20170726113112.GJ2981@dhcp22.suse.cz> <20170726114812.GH3218@osiris> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170726114812.GH3218@osiris> 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 26-07-17 13:48:12, Heiko Carstens wrote: > On Wed, Jul 26, 2017 at 01:31:12PM +0200, Michal Hocko wrote: > > On Wed 26-07-17 13:17:38, Heiko Carstens wrote: > > [...] > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > > index 6d30e914afb6..fc32aa81f359 100644 > > > --- a/mm/page_alloc.c > > > +++ b/mm/page_alloc.c > > > @@ -4891,9 +4891,11 @@ int numa_zonelist_order_handler(struct ctl_table *table, int write, > > > NUMA_ZONELIST_ORDER_LEN); > > > user_zonelist_order = oldval; > > > } else if (oldval != user_zonelist_order) { > > > + mem_hotplug_begin(); > > > mutex_lock(&zonelists_mutex); > > > build_all_zonelists(NULL, NULL); > > > mutex_unlock(&zonelists_mutex); > > > + mem_hotplug_done(); > > > } > > > } > > > out: > > > > Please note that this code has been removed by > > http://lkml.kernel.org/r/20170721143915.14161-2-mhocko@kernel.org. It > > will get to linux-next as soon as Andrew releases a new version mmotm > > tree. > > We still would need something for 4.13, no? If this presents a real problem then yes. Has this happened in a real workload or during some artificial test? I mean the code has been like that for ages and nobody noticed/reported any problems. That being said, I do not have anything against your patch. It is trivial to rebase mine on top of yours. I am just not sure it is worth the code churn. E.g. do you think this patch is a stable backport material? -- Michal Hocko SUSE Labs