From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f200.google.com (mail-wr0-f200.google.com [209.85.128.200]) by kanga.kvack.org (Postfix) with ESMTP id 92B9E2802FE for ; Fri, 30 Jun 2017 10:18:51 -0400 (EDT) Received: by mail-wr0-f200.google.com with SMTP id z1so38459802wrz.10 for ; Fri, 30 Jun 2017 07:18:51 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id p91si6107862wrc.257.2017.06.30.07.18.49 for (version=TLS1 cipher=AES128-SHA bits=128/128); Fri, 30 Jun 2017 07:18:50 -0700 (PDT) Date: Fri, 30 Jun 2017 16:18:47 +0200 From: Michal Hocko 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 Sender: owner-linux-mm@kvack.org List-ID: To: Yang Shi Cc: Joonsoo Kim , Mel Gorman , Andrew Morton , Vlastimil Babka , linux-mm@kvack.org, LKML 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org