From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752325AbdGDKxr (ORCPT ); Tue, 4 Jul 2017 06:53:47 -0400 Received: from mx2.suse.de ([195.135.220.15]:45218 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751845AbdGDKxp (ORCPT ); Tue, 4 Jul 2017 06:53:45 -0400 Date: Tue, 4 Jul 2017 12:53:42 +0200 From: Michal Hocko To: Vlastimil Babka Cc: Joonsoo Kim , Yang Shi , Mel Gorman , Andrew Morton , linux-mm@kvack.org, LKML Subject: Re: "mm: use early_pfn_to_nid in page_ext_init" broken on some configurations? Message-ID: <20170704105342.GJ14722@dhcp22.suse.cz> References: <20170630141847.GN22917@dhcp22.suse.cz> <54336b9a-6dc7-890f-1900-c4188fb6cf1a@suse.cz> <20170704052304.GC28589@js1304-desktop> <45268b53-88dc-4129-725c-df5849e494db@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <45268b53-88dc-4129-725c-df5849e494db@suse.cz> 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 Tue 04-07-17 11:39:57, Vlastimil Babka wrote: > On 07/04/2017 07:23 AM, Joonsoo Kim wrote: > > On Mon, Jul 03, 2017 at 04:18:01PM +0200, Vlastimil Babka wrote: > >> allocated" looks much more sane there. But there's a warning nevertheless. > > > > Warning would comes from the fact that drain_all_pages() is called > > before mm_percpu_wq is initialised. We could remove WARN_ON_ONCE() and add > > drain_local_page(zone) to fix the problem. > > Wouldn't that still leave some period during boot where kernel already > runs on multiple CPU's, but mm_percpu_wq is not yet initialized and > somebody tries to use it? We want to catch such cases, right? I haven't checked the boot sequence but if we know that we need mm_percpu_wq initialized earlier than moving it should be not a big deal I guess. -- Michal Hocko SUSE Labs