From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755579Ab1KWNfE (ORCPT ); Wed, 23 Nov 2011 08:35:04 -0500 Received: from mx1.redhat.com ([209.132.183.28]:4274 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755445Ab1KWNfC (ORCPT ); Wed, 23 Nov 2011 08:35:02 -0500 Message-ID: <4ECCF669.6080007@redhat.com> Date: Wed, 23 Nov 2011 21:34:33 +0800 From: Dave Young User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.15) Gecko/20110323 Thunderbird/3.1.9 MIME-Version: 1.0 To: holzheu@linux.vnet.ibm.com CC: akpm@linux-foundation.org, heiko.carstens@de.ibm.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Simon Horman , "Eric W. Biederman" , schwidefsky@de.ibm.com, Vivek Goyal Subject: Re: [PATCH v2] kdump: crashk_res init check for /sys/kernel/kexec_crash_size References: <1322043068.10119.7.camel@br98xy6r> <20111123102214.GA4914@verge.net.au> <1322054283.10119.11.camel@br98xy6r> In-Reply-To: <1322054283.10119.11.camel@br98xy6r> 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 11/23/2011 09:18 PM, 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". > > 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; Sorry for jump in a little late, instead of introduce a new variable, why not add something like: if (!end) return -EINVAL; > > 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; > } > > > > > _______________________________________________ > kexec mailing list > kexec@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec -- Thanks Dave