From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx167.postini.com [74.125.245.167]) by kanga.kvack.org (Postfix) with SMTP id 3CB0B6B0062 for ; Tue, 19 Jun 2012 18:37:36 -0400 (EDT) From: "Pearson, Greg" Subject: Re: [PATCH v4] mm/memblock: fix overlapping allocation when doubling reserved array Date: Tue, 19 Jun 2012 22:35:08 +0000 Message-ID: <4FE0FE9B.8020401@hp.com> References: <1340063278-31601-1-git-send-email-greg.pearson@hp.com> <20120619151435.10c16aed.akpm@linux-foundation.org> In-Reply-To: <20120619151435.10c16aed.akpm@linux-foundation.org> Content-Language: en-US Content-Type: text/plain; charset="iso-8859-1" Content-ID: <3177E2BB60E9DF4792AAA88EEC01117A@Compaq.com> 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 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=20 corruption problem when doubling the reserved array while booting the=20 system. This system will be a released product in the future. I'll=20 remember to include this information in the patch next time. 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