From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751670AbbFVRY2 (ORCPT ); Mon, 22 Jun 2015 13:24:28 -0400 Received: from mail.skyhub.de ([78.46.96.112]:56874 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751420AbbFVRYT (ORCPT ); Mon, 22 Jun 2015 13:24:19 -0400 Date: Mon, 22 Jun 2015 19:24:00 +0200 From: Borislav Petkov To: Andy Lutomirski Cc: Kees Cook , "Paul E. McKenney" , "linux-kernel@vger.kernel.org" , Oleg Nesterov , Denys Vlasenko , Brian Gerst , =?utf-8?B?RnLDqWTDqXJpYw==?= Weisbecker , X86 ML , Rik van Riel Subject: Re: [PATCH v2 03/14] notifiers: Assert that RCU is watching in notify_die Message-ID: <20150622172400.GD20244@pd.tnic> References: <20150622113649.GB20244@pd.tnic> <20150622163333.GC20244@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 22, 2015 at 10:03:30AM -0700, Andy Lutomirski wrote: > The rcu_lockdep_assert should be merely a warning, not a full OOPS. It is still pretty huge, see below. > I think that, if rcu_lockdep_assert hangs, then we should fix that > rather than avoiding debugging checks. The RCU assertion firing might be unrelated to the oops happening and could prevent us from seeing the real splat. [ 0.048815] [ 0.050493] =============================== [ 0.052005] [ INFO: suspicious RCU usage. ] [ 0.056007] 4.1.0-rc8+ #4 Not tainted [ 0.060005] ------------------------------- [ 0.064005] arch/x86/kernel/cpu/amd.c:677 BOINK! [ 0.066758] [ 0.066758] other info that might help us debug this: [ 0.066758] [ 0.068006] [ 0.068006] rcu_scheduler_active = 0, debug_locks = 0 [ 0.072005] no locks held by swapper/0/0. [ 0.076005] [ 0.076005] stack backtrace: [ 0.080006] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.1.0-rc8+ #4 [ 0.083331] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014 [ 0.084021] 0000000000000000 ffffffff81967eb8 ffffffff816709c7 0000000000000000 [ 0.092005] ffffffff81975580 ffffffff81967ee8 ffffffff8109e8cd 0000000000000000 [ 0.097227] ffffffff81a3aec0 ffffffff81cad9c0 ffffffff81cb42c0 ffffffff81967f38 [ 0.104005] Call Trace: [ 0.106021] [] dump_stack+0x4f/0x7b [ 0.108007] [] lockdep_rcu_suspicious+0xfd/0x130 [ 0.112007] [] init_amd+0x34/0x560 [ 0.116007] [] identify_cpu+0x242/0x3b0 [ 0.119068] [] identify_boot_cpu+0x10/0x7e [ 0.120006] [] check_bugs+0x9/0x2d [ 0.124007] [] start_kernel+0x40e/0x425 [ 0.128007] [] x86_64_start_reservations+0x2a/0x2c [ 0.132009] [] x86_64_start_kernel+0xeb/0xef -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in Please read the FAQ at http://www.tux.org/lkml/