From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1752454AbdF3OTC (ORCPT <rfc822;w@1wt.eu>);
        Fri, 30 Jun 2017 10:19:02 -0400
Received: from mx2.suse.de ([195.135.220.15]:43210 "EHLO mx1.suse.de"
        rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP
        id S1751668AbdF3OTB (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Fri, 30 Jun 2017 10:19:01 -0400
Date: Fri, 30 Jun 2017 16:18:47 +0200
From: Michal Hocko <mhocko@kernel.org>
To: Yang Shi <yang.shi@linaro.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        Andrew Morton <akpm@linux-foundation.org>,
        Vlastimil Babka <vbabka@suse.cz>, linux-mm@kvack.org,
        LKML <linux-kernel@vger.kernel.org>
Subject: "mm: use early_pfn_to_nid in page_ext_init" broken on some
 configurations?
Message-ID: <20170630141847.GN22917@dhcp22.suse.cz>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

fe53ca54270a ("mm: use early_pfn_to_nid in page_ext_init") seem
to silently depend on CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID resp.
CONFIG_HAVE_MEMBLOCK_NODE_MAP. early_pfn_to_nid is returning zero with
!defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID) && !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
I am not sure how widely is this used but such a code is tricky. I see
how catching early allocations during defered initialization might be
useful but a subtly broken code sounds like a problem to me.  So is
fe53ca54270a worth this or we should revert it?
-- 
Michal Hocko
SUSE Labs