From patchwork Thu Dec 18 21:13:46 2008 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Brian King X-Patchwork-Id: 14733 X-Patchwork-Delegate: paulus@samba.org Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from ozlabs.org (localhost [127.0.0.1]) by ozlabs.org (Postfix) with ESMTP id E73784750A for ; Fri, 19 Dec 2008 08:15:22 +1100 (EST) X-Original-To: linuxppc-dev@ozlabs.org Delivered-To: linuxppc-dev@ozlabs.org Received: from e3.ny.us.ibm.com (e3.ny.us.ibm.com [32.97.182.143]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e3.ny.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id 93455DDF26 for ; Fri, 19 Dec 2008 08:14:54 +1100 (EST) Received: from d01relay02.pok.ibm.com (d01relay02.pok.ibm.com [9.56.227.234]) by e3.ny.us.ibm.com (8.13.1/8.13.1) with ESMTP id mBILDwY1029633 for ; Thu, 18 Dec 2008 16:13:58 -0500 Received: from d01av01.pok.ibm.com (d01av01.pok.ibm.com [9.56.224.215]) by d01relay02.pok.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id mBILEoIT193648 for ; Thu, 18 Dec 2008 16:14:50 -0500 Received: from d01av01.pok.ibm.com (loopback [127.0.0.1]) by d01av01.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id mBILEnhw017025 for ; Thu, 18 Dec 2008 16:14:50 -0500 Received: from localhost.localdomain (kastria.rchland.ibm.com [9.10.86.133] (may be forged)) by d01av01.pok.ibm.com (8.12.11.20060308/8.12.11) with ESMTP id mBILEmQY016988; Thu, 18 Dec 2008 16:14:49 -0500 Message-Id: <200812182114.mBILEmQY016988@d01av01.pok.ibm.com> Subject: [PATCH 1/2] powerpc: Disable Collaborative Memory Manager for kdump To: paulus@samba.org From: Brian King Date: Thu, 18 Dec 2008 15:13:46 -0600 Cc: brking@linux.vnet.ibm.com, linuxppc-dev@ozlabs.org X-BeenThere: linuxppc-dev@ozlabs.org X-Mailman-Version: 2.1.11 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@ozlabs.org Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@ozlabs.org When running Active Memory Sharing, the Collaborative Memory Manager (CMM) may mark some pages as "loaned" with the hypervisor. Periodically, the CMM will query the hypervisor for a loan request, which is a single signed value. When kexec'ing into a kdump kernel, the CMM driver in the kdump kernel is not aware of the pages the previous kernel had marked as "loaned", so the hypervisor and the CMM driver are out of sync. This results in the CMM driver getting a negative loan request, which can then get treated as a large unsigned value and can cause kdump to hang due to the CMM driver inflating too large. Since there really is no clean way for the CMM driver in the kdump kernel to clean this up, simply disable CMM in the kdump kernel. This fixes hangs we were seeing doing kdump with AMS. Signed-off-by: Brian King --- arch/powerpc/platforms/pseries/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN arch/powerpc/platforms/pseries/Kconfig~powerpc_cmm_no_kdump arch/powerpc/platforms/pseries/Kconfig --- linux-2.6/arch/powerpc/platforms/pseries/Kconfig~powerpc_cmm_no_kdump 2008-12-17 09:52:54.000000000 -0600 +++ linux-2.6-bjking1/arch/powerpc/platforms/pseries/Kconfig 2008-12-17 09:52:54.000000000 -0600 @@ -54,7 +54,7 @@ config PPC_SMLPAR config CMM tristate "Collaborative memory management" - depends on PPC_SMLPAR + depends on PPC_SMLPAR && !CRASH_DUMP default y help Select this option, if you want to enable the kernel interface