From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx118.postini.com [74.125.245.118]) by kanga.kvack.org (Postfix) with SMTP id 0C1F26B0062 for ; Wed, 20 Jun 2012 11:21:58 -0400 (EDT) From: "Pearson, Greg" Subject: Re: [PATCH v4] mm/memblock: fix overlapping allocation when doubling reserved array Date: Wed, 20 Jun 2012 15:21:24 +0000 Message-ID: <4FE1EA73.2030300@hp.com> References: <1340063278-31601-1-git-send-email-greg.pearson@hp.com> <20120619151435.10c16aed.akpm@linux-foundation.org> <4FE0FE9B.8020401@hp.com> <20120619160001.0c58c7be.akpm@linux-foundation.org> In-Reply-To: <20120619160001.0c58c7be.akpm@linux-foundation.org> Content-Language: en-US Content-Type: text/plain; charset="iso-8859-1" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton 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" On 06/19/2012 05:00 PM, Andrew Morton wrote: > 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 possib= le >>>> 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. > Having the fix in 3.4 would be good for us, as we do plan to test on the=20 latest stable kernel. If there is anything I can do to help with that please let me know. Thanks -- Greg= -- 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