From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752676AbeAWVA5 (ORCPT ); Tue, 23 Jan 2018 16:00:57 -0500 Received: from mail.kernel.org ([198.145.29.99]:35588 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932092AbeAWVA4 (ORCPT ); Tue, 23 Jan 2018 16:00:56 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6B89921781 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=rostedt@goodmis.org Date: Tue, 23 Jan 2018 16:00:54 -0500 From: Steven Rostedt To: Tejun Heo Cc: Rik van Riel , Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, kernel-team@fb.com, Sergey Senozhatsky , Petr Mladek Subject: Re: [PATCH] lockdep: Avoid triggering hardlockup from debug_show_all_locks() Message-ID: <20180123160054.325ff326@gandalf.local.home> In-Reply-To: <20180123205706.GH1771050@devbig577.frc2.facebook.com> References: <20180122220055.GB1771050@devbig577.frc2.facebook.com> <1516734237.31954.17.camel@fb.com> <20180123205706.GH1771050@devbig577.frc2.facebook.com> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.31; x86_64-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 On Tue, 23 Jan 2018 12:57:06 -0800 Tejun Heo wrote: > Yeah, it's ridiculous how often printk ends up escalating otherwise > recoverable situations into system crashes. I don't know what the > right answer is. For spurious NMI hardlockups, maybe auditing debug > paths and adding touch_nmi_watchdog() would be enough but that also is > a pretty leaky approach. What about if every printk were to touch NMI watchdog? NMI watchdog is really there for when the system locks up. If the system is locked up doing printk, at least we see what is happening, and not a total freeze. -- Steve