From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938956AbXGTXnV (ORCPT ); Fri, 20 Jul 2007 19:43:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756044AbXGTXnO (ORCPT ); Fri, 20 Jul 2007 19:43:14 -0400 Received: from nz-out-0506.google.com ([64.233.162.230]:31806 "EHLO nz-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755623AbXGTXnN (ORCPT ); Fri, 20 Jul 2007 19:43:13 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=EkmLic6Vdi9GJ02P6Dh3AgdkAf4cGjkx4zuTHcBcXHUxlbxK2UTfoOGAQ1pCkj+F3in27L20lfPJbjbYnYvWevCwusPVwZhjplwyIGviZSv/qf6ES/epLPHSSC3Y1KnskOI4ShxZLv8tH10w3jg6+A0BnPobhA2wocl3CDeKsdc= Message-ID: Date: Sat, 21 Jul 2007 05:13:12 +0530 From: "Satyam Sharma" To: "Greg KH" Subject: Re: [broken-out-2007-07-20-00-22] kernel bug at kernel/params:570 Cc: "Andrew Morton" , rdunlap@xenotime.net, "Michal Piotrowski" , LKML In-Reply-To: <20070720231052.GA19752@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <6bffcb0e0707200932p2b905e21g7970172ca7eb4da7@mail.gmail.com> <20070720225047.GA17520@suse.de> <20070720155912.079c5a27.akpm@linux-foundation.org> <20070720231052.GA19752@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 7/21/07, Greg KH wrote: > On Fri, Jul 20, 2007 at 03:59:12PM -0700, Andrew Morton wrote: > > On Fri, 20 Jul 2007 15:50:47 -0700 > > Greg KH wrote: > > > > > On Fri, Jul 20, 2007 at 06:32:21PM +0200, Michal Piotrowski wrote: > > > > Hi Greg, > > > > > > > > This looks like a sysfs bug > > > > http://www.stardust.webpages.pl/files/tbf/bitis-gabonica/ > > > > broken-out-2007-07-20-00-22/00003.jpg > > > > > > > > l *kernel_param_sysfs_setup+0x75 > > > > 0xc13c0894 is in kernel_param_sysfs_setup (kernel/params.c:570). > > > > 565 mk->mod = THIS_MODULE; > > > > 566 kobj_set_kset_s(mk, module_subsys); > > > > 567 kobject_set_name(&mk->kobj, name); > > > > 568 kobject_init(&mk->kobj); > > > > 569 ret = kobject_add(&mk->kobj); > > > > 570 BUG_ON(ret < 0); > > > > 571 param_sysfs_setup(mk, kparam, num_params, name_skip); > > > > 572 kobject_uevent(&mk->kobj, KOBJ_ADD); > > > > 573 } > > > > 574 > > > > > > > > http://www.stardust.webpages.pl/files/tbf/bitis-gabonica/broken-out-2007-07-20-00-22/mm-config > > > > > > What kernel version is this happening on? The -mm tree? Can you try > > > Linus's tree instead? > > > > > > It looks like there was some needed information right before the first > > > stack dump, showing exactly what kobject was trying to be added that was > > > already present. Odds are this is a kernel parameter with the same name > > > as a duplicate one within the same module, I don't think that's an -EEXIST. I think what we have here is kobject_add() exiting with -EINVAL. (kobject attempted to be registered with no name!) [ The first trace on that screen shows: kobject_shadow_add+0x5b/0x189. That's the WARN_ON(1) at lib/kobject.c:176. If it was a EEXIST case, we would've seen an offset in kobject_shadow_add closer to 0x189, because the dump_stack() for EEXIST is barely 4 instructions before we return from that function. ] > > > but the trick is going to be > > > trying to figure out what module is causing this. So I'd guess we want to search for a module that's passing a kobject * to kobject_add() such that !kobj->k_name is true. > > > So it's not a sysfs bug, but rather a driver issue that this is > > > catching. > > > > In that case a BUG was way too harsh treatment, and in fact directly > > contributed to our inability to debug the bug! > > > > Can we wind that back a bit? Add some useful printks and then recover > > in some fashion? > [...] > So I'm guessing he was trying to catch something specific here. Considering that: (1) This isn't a bug that should bring down the kernel that hard, and, (2) kobject_shadow_add() seems to be dumping enough stacks and printing printk's on errors already, I'd suggest to just get rid of the BUG_ON() in kernel_param_sysfs_setup() Satyam