Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759405Ab2FAUXG (ORCPT ); Fri, 1 Jun 2012 16:23:06 -0400 Received: from mga11.intel.com ([192.55.52.93]:29519 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759247Ab2FAUXE (ORCPT ); Fri, 1 Jun 2012 16:23:04 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="173797059" Date: Fri, 1 Jun 2012 21:38:44 +0100 From: Alan Cox To: Linus Torvalds Cc: Eric Dumazet , "linux-kernel@vger.kernel.org" , Jens Axboe Subject: Re: [PATCH] tty: add lockdep annotations Message-ID: <20120601213844.3abdae5e@bob.linux.org.uk> In-Reply-To: References: <4FC6189B.9080909@fusionio.com> <1338402812.2760.413.camel@edumazet-glaptop> <4FC66D3D.6080509@fusionio.com> <1338404902.2760.451.camel@edumazet-glaptop> <1338410107.2760.544.camel@edumazet-glaptop> <1338456918.2760.1318.camel@edumazet-glaptop> <1338574627.2760.1545.camel@edumazet-glaptop> Organization: Intel X-Mailer: Claws Mail 3.8.0 (GTK+ 2.24.8; x86_64-redhat-linux-gnu) Organisation: Intel Corporation UK Ltd, registered no. 1134945 (England), Registered office Pipers Way, Swindon, SN3 1RJ 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: 1554 Lines: 43 On Fri, 1 Jun 2012 11:51:13 -0700 Linus Torvalds wrote: > On Fri, Jun 1, 2012 at 11:17 AM, Eric Dumazet > wrote: > > > > About 10% of boots on my machine, and this looks like (hand written) > > > > general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC > > ... > > RIP : tty_shutdown+0x15/)x70 > > Ok, DEBUG_PAGEALLOC and with that offset fairly early in tty_shutdown, > it's almost certainly one of the accesses in the > > tty->driver->ops->remove > > chain when it does the (inlined) > > tty_driver_remove_tty(tty->driver, tty); > > you could check which one it is at that offset 0x15, but I think both > the ops and the driver structures should be statically allocated, so I > suspect it's the "tty" itself that is already freed. Might be worth checking tty->magic in queue_release_one_tty and the entry to release_one_tty You can also turn on TTY_PARANOIA_CHECK defines which may show more but can also be mistriggered in a few cases. What distro setup is this and is it booting to run level 3 or 5. I'm just wondering which paths you hit. Some of the distros do weird stuff (notably Fedora is totally broken on the console management) and that might be hiding a race or two in saner cases where you get more console hangups. Alan -- 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/