Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752746AbbFANG1 (ORCPT ); Mon, 1 Jun 2015 09:06:27 -0400 Received: from cantor2.suse.de ([195.135.220.15]:49746 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751357AbbFANGT (ORCPT ); Mon, 1 Jun 2015 09:06:19 -0400 Date: Mon, 1 Jun 2015 15:06:16 +0200 From: Jan Kara To: Andrew Morton Cc: Petr Mladek , Frederic Weisbecker , Steven Rostedt , Dave Anderson , "Paul E. McKenney" , Kay Sievers , Jiri Kosina , Michal Hocko , Jan Kara , linux-kernel@vger.kernel.org, Wang Long , peifeiyue@huawei.com, dzickus@redhat.com, morgan.wang@huawei.com, sasha.levin@oracle.com Subject: Re: [PATCH 00/10] printk: Avoid deadlock in NMI + vprintk_emit() cleanup Message-ID: <20150601130616.GE20288@quack.suse.cz> References: <1432557993-20458-1-git-send-email-pmladek@suse.cz> <20150529135045.09d87c7ab98bf26dec95c8b3@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150529135045.09d87c7ab98bf26dec95c8b3@linux-foundation.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1280 Lines: 30 On Fri 29-05-15 13:50:45, Andrew Morton wrote: > On Mon, 25 May 2015 14:46:23 +0200 Petr Mladek wrote: > > > The main source of deadlocks caused by printk() in NMI context has been > > solved by the commit a9edc88093287 ("x86/nmi: Perform a safe NMI stack > > trace on all CPUs"). > > > > But there are still few warnings printed in the NMI code that could > > case a deadlock. For example, see the freeze discussed at > > https://lkml.org/lkml/2015/5/20/481 > > I'm not (yet) convinced that we want the entire patchset btw. Do we > really want to try to semi-support printk from NMI? With a rather > nasty set of hacks? > > Why not just delete the offending printks? And what about WARN_ONs and BUG_ONs? Delete as well? Or just don't print anything when we are in NMI? I agree that NMI is so problematic context that restricting printk there makes some sence. OTOH propagating information from NMI to user is useful as well so I'm somewhat undecided. Honza -- Jan Kara SUSE Labs, CR -- 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/