Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756843AbaFROlN (ORCPT ); Wed, 18 Jun 2014 10:41:13 -0400 Received: from cantor2.suse.de ([195.135.220.15]:45568 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752303AbaFROlM (ORCPT ); Wed, 18 Jun 2014 10:41:12 -0400 Date: Wed, 18 Jun 2014 16:41:09 +0200 (CEST) From: Jiri Kosina To: "Paul E. McKenney" cc: Linus Torvalds , Frederic Weisbecker , Petr Mladek , Andrew Morton , Steven Rostedt , Dave Anderson , Kay Sievers , Michal Hocko , Jan Kara , Linux Kernel Mailing List Subject: Re: [RFC PATCH 00/11] printk: safe printing in NMI context In-Reply-To: <20140618143612.GC4669@linux.vnet.ibm.com> Message-ID: References: <1399626665-29817-1-git-send-email-pmladek@suse.cz> <20140529000909.GC6507@localhost.localdomain> <20140610164641.GD1951@localhost.localdomain> <20140618143612.GC4669@linux.vnet.ibm.com> User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 18 Jun 2014, Paul E. McKenney wrote: > > - both RCU stall detector and 'echo l > sysrq-trigger' can (and we've > > seen it happening for real) cause a complete, undebuggable, silent hang > > of machine (deadlock in NMI context) > > I could easily add an option to RCU to allow people to tell it not to > use NMIs to dump the stack. Would that help? Well, that would make unfortunately the information provided by RCU stall detector rather useless ... workqueue-based stack dumping is very unlikely to point its finger to the real offender, as it'd be coming way too late. Thanks, -- Jiri Kosina SUSE Labs -- 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/