Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759781AbYFIO6R (ORCPT ); Mon, 9 Jun 2008 10:58:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754430AbYFIO6H (ORCPT ); Mon, 9 Jun 2008 10:58:07 -0400 Received: from mtagate8.uk.ibm.com ([195.212.29.141]:36917 "EHLO mtagate8.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753982AbYFIO6E (ORCPT ); Mon, 9 Jun 2008 10:58:04 -0400 Date: Mon, 9 Jun 2008 16:57:57 +0200 From: Cornelia Huck To: "Vegard Nossum" Cc: "Adrian Bunk" , "Andrew Morton" , "Ingo Molnar" , linux-kernel@vger.kernel.org, "Jens Axboe" , "Greg Kroah-Hartman" , "Linus Torvalds" , "Rafael J. Wysocki" , "Kay Sievers" , "Neil Brown" , "Mariusz Kozlowski" , "Dave Young" Subject: Re: [bug, 2.6.26-rc4/rc5] sporadic bootup crashes in blk_lookup_devt()/prepare_namespace() Message-ID: <20080609165757.184724ff@gondolin.boeblingen.de.ibm.com> In-Reply-To: <19f34abd0806090728s3b3fdbeq7dd3d31d02c8f28e@mail.gmail.com> References: <20080609080312.GA32458@elte.hu> <20080609020623.b6727f2b.akpm@linux-foundation.org> <19f34abd0806090209l541d93c6jaba2704314b34418@mail.gmail.com> <20080609133426.GB20194@cs181133002.pp.htv.fi> <19f34abd0806090658v54f3a912n2ed30ad6cc20d00@mail.gmail.com> <19f34abd0806090728s3b3fdbeq7dd3d31d02c8f28e@mail.gmail.com> Organization: IBM Deutschland Entwicklung GmbH Vorsitzender des Aufsichtsrats: Martin Jetter =?ISO-8859-15?Q?Gesch=E4ftsf=FChrung:?= Herbert Kircher Sitz der Gesellschaft: =?ISO-8859-15?Q?B=F6blingen?= Registergericht: Amtsgericht Stuttgart, HRB 243294 X-Mailer: Claws Mail 3.4.0 (GTK+ 2.12.10; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1854 Lines: 42 On Mon, 9 Jun 2008 16:28:09 +0200, "Vegard Nossum" wrote: > On 6/9/08, Vegard Nossum wrote: > > It seems that this list (block_class.devices) is protected by > > block_class_lock in block/genhd.c. This list is only ever modified by > > device_add() and device_del() in drivers/base/core.c. Both of those > > are (only) protected by dev->class->sem, however. Is there a locking > > mismatch here? But none of the locking code here seems to be changed > > in years... > > I think this seems correct. > > Everywhere else where we traverse the struct class->devices list, they > have down(&class->sem); first and up(&class->sem); afterwards. > > Commit fd04897bb20be29d60f7e426a053545aebeaa61a even has this hunk: > @@ -177,8 +177,7 @@ struct class { > struct list_head devices; > struct list_head interfaces; > struct kset class_dirs; > - struct semaphore sem; /* locks both the children and interface > - > + struct semaphore sem; /* locks children, devices, interfaces */ > struct class_attribute * class_attrs; > struct class_device_attribute * class_dev_attrs; > struct device_attribute * dev_attrs; > > > So why doesn't block/genhd.c do this too? It seems to me that the > mutex locking here is simply a remnant of old code that happened to > not crash in most cases by chance. > Does this crash happen with the conversion to the class iterator functions (should be in linux-next) as well? They take the class mutex... -- 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/