From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753090AbaBAXqW (ORCPT ); Sat, 1 Feb 2014 18:46:22 -0500 Received: from mail-pd0-f178.google.com ([209.85.192.178]:43713 "EHLO mail-pd0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751109AbaBAXqV (ORCPT ); Sat, 1 Feb 2014 18:46:21 -0500 Date: Sat, 1 Feb 2014 15:46:18 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Petr Tesarik cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Jiang Liu , Andrew Morton , Dave Hansen , linux-kernel@vger.kernel.org Subject: Re: [PATCHv2] x86: fix the initialization of physnode_map In-Reply-To: <20140201133019.32e56f86@hananiah.suse.cz> Message-ID: References: <20140201133019.32e56f86@hananiah.suse.cz> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 1 Feb 2014, Petr Tesarik wrote: > With DISCONTIGMEM, the mapping between a pfn and its owning node is > initialized using data provided by the BIOS. However, the initialization > may fail if the extents are not aligned to section boundary (64M). > > The symptom of this bug is an early boot failure in pfn_to_page(), > as it tries to access NODE_DATA(__nid) using index from an unitialized > element of the physnode_map[] array. > > While the bug is always present, it is more likely to be hit in kdump > kernels on large machines, because: > > 1. The memory map for a kdump kernel is specified as exactmap, and > exactmap is more likely to be unaligned. > > 2. Large reservations are more likely to span across a 64M boundary. > > Signed-off-by: Petr Tesarik Acked-by: David Rientjes