From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932954Ab3LDRdM (ORCPT ); Wed, 4 Dec 2013 12:33:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:62392 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932683Ab3LDRdJ (ORCPT ); Wed, 4 Dec 2013 12:33:09 -0500 Date: Wed, 4 Dec 2013 12:32:39 -0500 From: Vivek Goyal To: Baoquan He Cc: linux-kernel@vger.kernel.org, kexec@lists.infradead.org, mjg59@srcf.ucam.org, greg@kroah.com, ebiederm@xmission.com, hpa@zytor.com Subject: Re: [PATCH 4/6] kexec: A new system call, kexec_file_load, for in kernel kexec Message-ID: <20131204173238.GD19087@redhat.com> References: <1384969851-7251-1-git-send-email-vgoyal@redhat.com> <1384969851-7251-5-git-send-email-vgoyal@redhat.com> <20131204015657.GD3298@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131204015657.GD3298@localhost.localdomain> 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, Dec 04, 2013 at 09:56:57AM +0800, Baoquan He wrote: > On 11/20/13 at 12:50pm, Vivek Goyal wrote: > > + * that kexec_mutex is held. > > + */ > > I think kexec_add_buffer is guaranteed to be called before allocating > control pages, why not updating image->control_page after each time > kexec_add_buffer is called. Then when control page is needed, effective > address in crash_kernel region can be given. This can be a little more > efficient. image->control_page controls the lowest address available for control pages in crash kernel region. When we do kexec_add_buffer, we don't necessarily know whether there is an empty page available between segments or not. Also, existing logic for kexec does not update the image->control_page when segments are being copied. So I think this does not offer any huge benefits and it is not performance critical path. I will just leave it as it is. Thanks Vivek