From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754210AbcFGLjO (ORCPT ); Tue, 7 Jun 2016 07:39:14 -0400 Received: from ozlabs.org ([103.22.144.67]:33110 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752023AbcFGLjM (ORCPT ); Tue, 7 Jun 2016 07:39:12 -0400 Message-ID: <1465299544.16285.3.camel@ellerman.id.au> Subject: Re: powerpc/nvram: Fix an incorrect partition merge From: Michael Ellerman To: xinhui , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Cc: Andrzej Hajda , Christophe Jaillet , Hari Bathini , Paul Mackerras , tglx@linutronix.de, Nathan Fontenot Date: Tue, 07 Jun 2016 21:39:04 +1000 In-Reply-To: <57550AB2.8090500@linux.vnet.ibm.com> References: <3rLj4P6Swcz9t6B@ozlabs.org> <57550AB2.8090500@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.16.5-1ubuntu3.1 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2016-06-06 at 13:31 +0800, xinhui wrote: > On 2016年06月03日 19:47, Michael Ellerman wrote: > > On Thu, 2015-10-12 at 07:30:02 UTC, xinhui wrote: > > > From: Pan Xinhui > > > > > > When we merge two contiguous partitions whose signatures are marked > > > NVRAM_SIG_FREE, We need update prev's length and checksum, then write it > > > to nvram, not cur's. So lets fix this mistake now. > > > > > > Also use memset instead of strncpy to set the partition's name. It's > > > more readable if we want to fill up with duplicate chars . > > > > Does this ever happen in practice? ie. should we backport the fix to stable > > kernels? > > I did not see that nvram warning in practice. BUT I suggest to backport it to stable kernel. :) > > Let me recall the story. :) > In past days, I was using pstore to keep some kernel logs. and sometimes I found my own logs and the panic logs did not show. > pstore use a fixed-address reserved memory In x86 while nvram instead in ppc. > > Then I spent some days to review the nvram codes. > And worked out three patches to fix all issues that I found in nvram. BUT looks like I only sent out two of them. :) > I lost the third patch maybe... OK. > > Has it always been broken? > > no. after nvram partition corruption hit, all nvram partitions will be erased and re-alloc after the second machine reboot. > I don't know who does it but i guess it is the firmware. :) Actually I meant has the code always contained the bug, or was it added recently. cheers