From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932180AbaHKT5W (ORCPT ); Mon, 11 Aug 2014 15:57:22 -0400 Received: from zimbra.brainity.com ([188.40.76.72]:34951 "EHLO zimbra.brainity.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754641AbaHKT5U (ORCPT ); Mon, 11 Aug 2014 15:57:20 -0400 X-Greylist: delayed 555 seconds by postgrey-1.27 at vger.kernel.org; Mon, 11 Aug 2014 15:57:19 EDT Date: Mon, 11 Aug 2014 21:48:02 +0200 (CEST) From: Daniel Walter To: Vivek Goyal Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, user-mode-linux-devel , Richard Weinberger Message-ID: <258676795.33655.1407786482432.JavaMail.root@0x90.at> In-Reply-To: <20140811184401.GE1863@redhat.com> Subject: Re: "resource: provide new functions to walk through resources" breaks UML MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [87.198.116.223] X-Mailer: Zimbra 7.2.0_GA_2669 (ZimbraWebClient - GC36 (Linux)/7.2.0_GA_2669) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- Original Message ----- > From: "Vivek Goyal" > To: "Richard Weinberger" > Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, "user-mode-linux-devel" > , sahne@0x90.at > Sent: Monday, August 11, 2014 7:44:01 PM > Subject: Re: "resource: provide new functions to walk through resources" breaks UML > > On Mon, Aug 11, 2014 at 02:25:56PM +0200, Richard Weinberger wrote: > > Hi Vivek, > > > > Am 11.08.2014 14:22, schrieb Vivek Goyal: > > > On Sun, Aug 10, 2014 at 06:56:14PM +0200, Richard Weinberger > > > wrote: > > >> Hi Vivek, > > >> > > >> Daniel Walter reported that UML is currently broken. > > >> The offending commit is: > > >> > > > > > > Hi Richard, > > > > > > Thanks for pointing it out. I will look into it. > > > > > > Would you have link to the report Daniel sent. I am interested in > > > looking at backtrace. > > > > he reported it on IRC to me. > > > > Here is a backtrace: > > RIP: 0033:[<0000000060039b9f>] > > RSP: 0000000081459da0 EFLAGS: 00010202 > > RAX: 0000000000000000 RBX: 00000000219b3fff RCX: 000000006010d1d9 > > RDX: 0000000000000001 RSI: 00000000602dfb94 RDI: 0000000081459df8 > > RBP: 0000000081459de0 R08: 00000000601b59f4 R09: ffffffff0000ff00 > > R10: ffffffff0000ff00 R11: 0000000081459e88 R12: 0000000081459df8 > > R13: 00000000219b3fff R14: 00000000602dfb94 R15: 0000000000000000 > > Kernel panic - not syncing: Segfault with no mm > > CPU: 0 PID: 1 Comm: swapper Not tainted 3.16.0-10454-g58d08e3 #13 > > Stack: > > 00000000 000080d0 81459df0 219b3fff > > 81459e70 6010d1d9 ffffffff 6033e010 > > 81459e50 6003a269 81459e30 00000000 > > Call Trace: > > [<6010d1d9>] ? kclist_add_private+0x0/0xe7 > > [<6003a269>] walk_system_ram_range+0x61/0xb7 > > [<6000e859>] ? proc_kcore_init+0x0/0xf1 > > [<6010d574>] kcore_update_ram+0x4c/0x168 > > [<6010d72e>] ? kclist_add+0x0/0x2e > > [<6000e943>] proc_kcore_init+0xea/0xf1 > > [<6000e859>] ? proc_kcore_init+0x0/0xf1 > > [<6000e859>] ? proc_kcore_init+0x0/0xf1 > > [<600189f0>] do_one_initcall+0x13c/0x204 > > [<6004ca46>] ? parse_args+0x1df/0x2e0 > > [<6004c82d>] ? parameq+0x0/0x3a > > [<601b5990>] ? strcpy+0x0/0x18 > > [<60001e1a>] kernel_init_freeable+0x240/0x31e > > [<6026f1c0>] kernel_init+0x12/0x148 > > [<60019fad>] new_thread_handler+0x81/0xa3 > > > > RIP is at kernel/resource.c:66. > > Hi Richard, > > Can you please give the attached patch a try and see if it fixes the > UML > issue. > > I noticed that previous code had a for() loop which will not execute > if p was null. I have resorted back to same code now. > > Thanks > Vivek > > > --- > kernel/resource.c | 11 ++++------- > 1 file changed, 4 insertions(+), 7 deletions(-) > > Index: linux-2.6/kernel/resource.c > =================================================================== > --- linux-2.6.orig/kernel/resource.c 2014-08-11 13:36:19.942423192 > -0400 > +++ linux-2.6/kernel/resource.c 2014-08-11 13:50:20.529387653 -0400 > @@ -351,15 +351,12 @@ static int find_next_iomem_res(struct re > end = res->end; > BUG_ON(start >= end); > > - read_lock(&resource_lock); > - > - if (first_level_children_only) { > - p = iomem_resource.child; > + if (first_level_children_only) > sibling_only = true; > - } else > - p = &iomem_resource; > > - while ((p = next_resource(p, sibling_only))) { > + read_lock(&resource_lock); > + > + for (p = iomem_resource.child; p; p = next_resource(p, > sibling_only)) { > if (p->flags != res->flags) > continue; > if (name && strcmp(p->name, name)) > Looks good to me, tested it on top of current HEAD (c8d6637d0497d62093dbba0694c7b3a80b79bfe1) for x86_64. Thanks, daniel