Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753709Ab2FSXAE (ORCPT ); Tue, 19 Jun 2012 19:00:04 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:37174 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751251Ab2FSXAD (ORCPT ); Tue, 19 Jun 2012 19:00:03 -0400 Date: Tue, 19 Jun 2012 16:00:01 -0700 From: Andrew Morton To: "Pearson, Greg" Cc: "tj@kernel.org" , "hpa@linux.intel.com" , "shangw@linux.vnet.ibm.com" , "mingo@elte.hu" , "yinghai@kernel.org" , "benh@kernel.crashing.org" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v4] mm/memblock: fix overlapping allocation when doubling reserved array Message-Id: <20120619160001.0c58c7be.akpm@linux-foundation.org> In-Reply-To: <4FE0FE9B.8020401@hp.com> References: <1340063278-31601-1-git-send-email-greg.pearson@hp.com> <20120619151435.10c16aed.akpm@linux-foundation.org> <4FE0FE9B.8020401@hp.com> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1780 Lines: 38 On Tue, 19 Jun 2012 22:35:08 +0000 "Pearson, Greg" wrote: > On 06/19/2012 04:14 PM, Andrew Morton wrote: > > On Mon, 18 Jun 2012 17:47:58 -0600 > > Greg Pearson wrote: > > > >> The __alloc_memory_core_early() routine will ask memblock for a range > >> of memory then try to reserve it. If the reserved region array lacks > >> space for the new range, memblock_double_array() is called to allocate > >> more space for the array. If memblock is used to allocate memory for > >> the new array it can end up using a range that overlaps with the range > >> originally allocated in __alloc_memory_core_early(), leading to possible > >> data corruption. > > OK, but we have no information about whether it *does* lead to data > > corruption. Are there workloads which trigger this? End users who are > > experiencing problems? > > > > See, I (and others) need to work out whether this patch should be > > included in 3.5 or even earlier kernels. To do that we often need the > > developer to tell us what the impact of the bug is upon users. Please > > always include this info when fixing bugs. > > Andrew, > > I'm currently working on a prototype system that exhibits the data > corruption problem when doubling the reserved array while booting the > system. This system will be a released product in the future. OK. I guess we can slip this fix into 3.5. Do you think it should be backported? I guess "yes", as you will probably want to run 3.4 or earlier kernels on that machine. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/