From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755487Ab1KWNSJ (ORCPT ); Wed, 23 Nov 2011 08:18:09 -0500 Received: from mtagate3.uk.ibm.com ([194.196.100.163]:53570 "EHLO mtagate3.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755145Ab1KWNSI (ORCPT ); Wed, 23 Nov 2011 08:18:08 -0500 Message-ID: <1322054283.10119.11.camel@br98xy6r> Subject: [PATCH v2] kdump: crashk_res init check for /sys/kernel/kexec_crash_size From: Michael Holzheu Reply-To: holzheu@linux.vnet.ibm.com To: akpm@linux-foundation.org Cc: Simon Horman , heiko.carstens@de.ibm.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, "Eric W. Biederman" , schwidefsky@de.ibm.com, akpm@linux-foundation.org, Vivek Goyal Date: Wed, 23 Nov 2011 14:18:03 +0100 In-Reply-To: <20111123102214.GA4914@verge.net.au> References: <1322043068.10119.7.camel@br98xy6r> <20111123102214.GA4914@verge.net.au> Organization: IBM Content-Type: text/plain; charset="us-ascii" X-Mailer: Evolution 3.2.0- Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Michael Holzheu Currently it is possible to set the crash_size via the sysfs /sys/kernel/kexec_crash_size even if no crash kernel memory has been defined with the "crashkernel" parameter. In this case "crashk_res" is not initialized and crashk_res.start = crashk_res.end = 0. Unfortunately resource_size(&crashk_res) returns 1 in this case. This breaks the s390 implementation of crash_(un)map_reserved_pages(). To fix the problem the correct "old_size" is now calculated in crash_shrink_memory(). "old_size is set to "0" if crashk_res is not initialized. With this change crash_shrink_memory() will do nothing, when "crashk_res" is not initialized. It will return "0" for "echo 0 > /sys/kernel/kexec_crash_size" and -EINVAL for "echo [not zero] > /sys/kernel/kexec_crash_size". In addition to that this patch also simplifies the "ret = -EINVAL" vs. "ret = 0" logic as suggested by Simon Horman. Cc: Simon Horman Signed-off-by: Michael Holzheu --- kernel/kexec.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -1131,7 +1131,7 @@ void __weak crash_free_reserved_phys_ran int crash_shrink_memory(unsigned long new_size) { int ret = 0; - unsigned long start, end; + unsigned long start, end, old_size; mutex_lock(&kexec_mutex); @@ -1141,11 +1141,9 @@ int crash_shrink_memory(unsigned long ne } start = crashk_res.start; end = crashk_res.end; - - if (new_size >= end - start + 1) { - ret = -EINVAL; - if (new_size == end - start + 1) - ret = 0; + old_size = (end == 0) ? 0 : end - start + 1; + if (new_size >= old_size) { + ret = (new_size == old_size) ? 0 : -EINVAL; goto unlock; }