From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753573Ab1KWKWV (ORCPT ); Wed, 23 Nov 2011 05:22:21 -0500 Received: from kirsty.vergenet.net ([202.4.237.240]:42778 "EHLO kirsty.vergenet.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752469Ab1KWKWU (ORCPT ); Wed, 23 Nov 2011 05:22:20 -0500 Date: Wed, 23 Nov 2011 19:22:15 +0900 From: Simon Horman To: Michael Holzheu Cc: akpm@linux-foundation.org, heiko.carstens@de.ibm.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, "Eric W. Biederman" , schwidefsky@de.ibm.com, Vivek Goyal Subject: Re: [PATCH] kdump: crashk_res init check for /sys/kernel/kexec_crash_size Message-ID: <20111123102214.GA4914@verge.net.au> References: <1322043068.10119.7.camel@br98xy6r> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1322043068.10119.7.camel@br98xy6r> Organisation: Horms Solutions Ltd. User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 23, 2011 at 11:11:08AM +0100, Michael Holzheu wrote: > 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". > > Signed-off-by: Michael Holzheu > --- > kernel/kexec.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 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); > > @@ -1141,10 +1141,10 @@ int crash_shrink_memory(unsigned long ne > } > start = crashk_res.start; > end = crashk_res.end; > - > - if (new_size >= end - start + 1) { > + old_size = (end == 0) ? 0 : end - start + 1; > + if (new_size >= old_size) { > ret = -EINVAL; > - if (new_size == end - start + 1) > + if (new_size == old_size) > ret = 0; I wonder if while we are here we could clean up the logic above a little. To my mind both ret = new_size == old_size ? 0 : -EINVAL; and if (new_size == old_size) ret = 0; else ret = -EINVAL; are easier on the eyes than the current logic. > goto unlock; > } But I am happy with the patch without my above suggestion. Reviewed-by-by: Simon Horman