Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753894AbbGJIyZ (ORCPT ); Fri, 10 Jul 2015 04:54:25 -0400 Received: from e06smtp15.uk.ibm.com ([195.75.94.111]:48117 "EHLO e06smtp15.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753504AbbGJIyU (ORCPT ); Fri, 10 Jul 2015 04:54:20 -0400 X-Helo: d06dlp01.portsmouth.uk.ibm.com X-MailFrom: holzheu@linux.vnet.ibm.com X-RcptTo: linux-s390@vger.kernel.org Date: Fri, 10 Jul 2015 10:54:13 +0200 From: Michael Holzheu To: Minfei Huang Cc: ebiederm@xmission.com, vgoyal@redhat.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, linux390@de.ibm.com, linux-s390@vger.kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4] kexec: Make a pair of map and unmap reserved pages when kdump fails to start Message-ID: <20150710105413.04e1db00@holzheu> In-Reply-To: <1436505137-4364-1-git-send-email-mnfhuang@gmail.com> References: <1436505137-4364-1-git-send-email-mnfhuang@gmail.com> Organization: IBM X-Mailer: Claws Mail 3.8.0 (GTK+ 2.24.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15071008-0021-0000-0000-0000048DD546 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3428 Lines: 115 On Fri, 10 Jul 2015 13:12:17 +0800 Minfei Huang wrote: > For some arch, kexec shall map the reserved pages, then use them, when > we try to start the kdump service. > > Now kexec will never unmap the reserved pages, once it fails to continue > starting the kdump service. So we make a pair of map/unmap reserved > pages whatever kexec fails or not in code path. > > In order to make code readable, wrap a new function __kexec_load which > contains all of the logic to deal with the image loading. > > Signed-off-by: Minfei Huang > --- > v3: > - reconstruct the patch, wrap a new function to deal with the code logic, based on Vivek and Michael's patch > v2: > - replace the "failure" label with "fail_unmap_pages" > v1: > - reconstruct the patch code > --- > kernel/kexec.c | 112 ++++++++++++++++++++++++++++++++------------------------- > 1 file changed, 63 insertions(+), 49 deletions(-) > > diff --git a/kernel/kexec.c b/kernel/kexec.c > index a785c10..2232c90 100644 > --- a/kernel/kexec.c > +++ b/kernel/kexec.c > @@ -1247,10 +1247,71 @@ int kexec_load_disabled; > > static DEFINE_MUTEX(kexec_mutex); > > +static int __kexec_load(unsigned long entry, unsigned long nr_segments, > + struct kexec_segment __user *segments, > + unsigned long flags) > +{ > + int result = 0; > + struct kimage **dest_image, *image; > + > + dest_image = &kexec_image; > + > + if (flags & KEXEC_ON_CRASH) > + dest_image = &kexec_crash_image; > + > + if (nr_segments == 0) { > + /* Install the new kernel, and Uninstall the old */ > + image = xchg(dest_image, image); > + kimage_free(image); Well this is wrong and should probably be: if (nr_segments == 0) { /* Uninstall image */ image = xchg(dest_image, NULL); kimage_free(image); > + } else { > + unsigned long i; > + > + if (flags & KEXEC_ON_CRASH) { > + /* [snip] > + result = kimage_load_segment(image, &image->segment[i]); > + if (result) > + goto failure_unmap_mem; > + } > + > + kimage_terminate(image); > + > + /* Install the new kernel, and Uninstall the old */ Perhaps fix the comment: Remove superfluous blank and lowercase "uninstall"? > + image = xchg(dest_image, image); > + > +failure_unmap_mem: > + if (flags & KEXEC_ON_CRASH) > + crash_unmap_reserved_pages(); > + kimage_free(image); Here the update patch: --- diff --git a/kernel/kexec.c b/kernel/kexec.c index e686a39..2f5b4aa 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -1249,8 +1249,8 @@ static int __kexec_load(unsigned long entry, unsigned long nr_segments, dest_image = &kexec_crash_image; if (nr_segments == 0) { - /* Install the new kernel, and Uninstall the old */ - image = xchg(dest_image, image); + /* Uninstall image */ + image = xchg(dest_image, NULL); kimage_free(image); } else { unsigned long i; @@ -1287,7 +1287,7 @@ static int __kexec_load(unsigned long entry, unsigned long nr_segments, kimage_terminate(image); - /* Install the new kernel, and Uninstall the old */ + /* Install the new kernel, and uninstall the old */ image = xchg(dest_image, image); failure_unmap_mem: -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/