From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from e28smtp03.in.ibm.com ([122.248.162.3]) by canuck.infradead.org with esmtps (Exim 4.72 #1 (Red Hat Linux)) id 1PxCwR-0001rb-MK for kexec@lists.infradead.org; Wed, 09 Mar 2011 06:32:16 +0000 Received: from d28relay03.in.ibm.com (d28relay03.in.ibm.com [9.184.220.60]) by e28smtp03.in.ibm.com (8.14.4/8.13.1) with ESMTP id p296W8xa030902 for ; Wed, 9 Mar 2011 12:02:08 +0530 Received: from d28av04.in.ibm.com (d28av04.in.ibm.com [9.184.220.66]) by d28relay03.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p296W8AE872636 for ; Wed, 9 Mar 2011 12:02:08 +0530 Received: from d28av04.in.ibm.com (loopback [127.0.0.1]) by d28av04.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p296W7xw009096 for ; Wed, 9 Mar 2011 17:32:07 +1100 Message-ID: <4D771EE6.5050404@linux.vnet.ibm.com> Date: Wed, 09 Mar 2011 12:02:06 +0530 From: Mahesh Jagannath Salgaonkar MIME-Version: 1.0 Subject: Re: [PATCH 1/2] kdump: Allow shrinking of kdump region to be overridden References: <20100825002258.GD28360@kryten> In-Reply-To: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=twosheds.infradead.org@lists.infradead.org To: "Eric W. Biederman" Cc: linuxppc-dev@ozlabs.org, akpm@linux-foundation.org, kexec@lists.infradead.org, Anton Blanchard , linux-kernel@vger.kernel.org On 08/25/2010 06:07 AM, Eric W. Biederman wrote: > Anton Blanchard writes: > >> On ppc64 the crashkernel region almost always overlaps an area of firmware. >> This works fine except when using the sysfs interface to reduce the kdump >> region. If we free the firmware area we are guaranteed to crash. > > That is ppc64 bug. firmware should not be in the reserved region. Any > random kernel like thing can be put in to that region at any valid > address and the fact that shrinking the region frees your firmware means > that using that region could also stomp your firmware (which I assume > would be a bad thing). The issue only happens while shrinking the region using sysfs interface. We already have checks in kexec for not to stomp over on the firmware overlap area while loading capture kernel. Currently we do a top-down allocation for the firmware region which means it sits at the top of the RMO, right in the middle of the crashdump region. We can not move the crashkernel region beyond firmware region because kernel needs its some of memory in RMO region. > > So please fix the ppc64 reservation. > > Eric > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e28smtp01.in.ibm.com (e28smtp01.in.ibm.com [122.248.162.1]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e28smtp01.in.ibm.com", Issuer "GeoTrust SSL CA" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id 6A129B70EE for ; Wed, 9 Mar 2011 17:32:11 +1100 (EST) Received: from d28relay05.in.ibm.com (d28relay05.in.ibm.com [9.184.220.62]) by e28smtp01.in.ibm.com (8.14.4/8.13.1) with ESMTP id p296W9eL013127 for ; Wed, 9 Mar 2011 12:02:09 +0530 Received: from d28av04.in.ibm.com (d28av04.in.ibm.com [9.184.220.66]) by d28relay05.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p296W8Mb2748468 for ; Wed, 9 Mar 2011 12:02:08 +0530 Received: from d28av04.in.ibm.com (loopback [127.0.0.1]) by d28av04.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p296W700009096 for ; Wed, 9 Mar 2011 17:32:08 +1100 Message-ID: <4D771EE6.5050404@linux.vnet.ibm.com> Date: Wed, 09 Mar 2011 12:02:06 +0530 From: Mahesh Jagannath Salgaonkar MIME-Version: 1.0 To: "Eric W. Biederman" Subject: Re: [PATCH 1/2] kdump: Allow shrinking of kdump region to be overridden References: <20100825002258.GD28360@kryten> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Cc: linuxppc-dev@ozlabs.org, akpm@linux-foundation.org, kexec@lists.infradead.org, Anton Blanchard , linux-kernel@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 08/25/2010 06:07 AM, Eric W. Biederman wrote: > Anton Blanchard writes: > >> On ppc64 the crashkernel region almost always overlaps an area of firmware. >> This works fine except when using the sysfs interface to reduce the kdump >> region. If we free the firmware area we are guaranteed to crash. > > That is ppc64 bug. firmware should not be in the reserved region. Any > random kernel like thing can be put in to that region at any valid > address and the fact that shrinking the region frees your firmware means > that using that region could also stomp your firmware (which I assume > would be a bad thing). The issue only happens while shrinking the region using sysfs interface. We already have checks in kexec for not to stomp over on the firmware overlap area while loading capture kernel. Currently we do a top-down allocation for the firmware region which means it sits at the top of the RMO, right in the middle of the crashdump region. We can not move the crashkernel region beyond firmware region because kernel needs its some of memory in RMO region. > > So please fix the ppc64 reservation. > > Eric > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752746Ab1CIGcQ (ORCPT ); Wed, 9 Mar 2011 01:32:16 -0500 Received: from e28smtp02.in.ibm.com ([122.248.162.2]:41813 "EHLO e28smtp02.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751164Ab1CIGcP (ORCPT ); Wed, 9 Mar 2011 01:32:15 -0500 Message-ID: <4D771EE6.5050404@linux.vnet.ibm.com> Date: Wed, 09 Mar 2011 12:02:06 +0530 From: Mahesh Jagannath Salgaonkar User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.15) Gecko/20101027 Fedora/3.0.10-1.fc12 Thunderbird/3.0.10 MIME-Version: 1.0 To: "Eric W. Biederman" CC: Anton Blanchard , akpm@linux-foundation.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org Subject: Re: [PATCH 1/2] kdump: Allow shrinking of kdump region to be overridden References: <20100825002258.GD28360@kryten> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/25/2010 06:07 AM, Eric W. Biederman wrote: > Anton Blanchard writes: > >> On ppc64 the crashkernel region almost always overlaps an area of firmware. >> This works fine except when using the sysfs interface to reduce the kdump >> region. If we free the firmware area we are guaranteed to crash. > > That is ppc64 bug. firmware should not be in the reserved region. Any > random kernel like thing can be put in to that region at any valid > address and the fact that shrinking the region frees your firmware means > that using that region could also stomp your firmware (which I assume > would be a bad thing). The issue only happens while shrinking the region using sysfs interface. We already have checks in kexec for not to stomp over on the firmware overlap area while loading capture kernel. Currently we do a top-down allocation for the firmware region which means it sits at the top of the RMO, right in the middle of the crashdump region. We can not move the crashkernel region beyond firmware region because kernel needs its some of memory in RMO region. > > So please fix the ppc64 reservation. > > Eric > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev