From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752329Ab3CAVnY (ORCPT ); Fri, 1 Mar 2013 16:43:24 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:52622 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751804Ab3CAVnX (ORCPT ); Fri, 1 Mar 2013 16:43:23 -0500 Date: Fri, 1 Mar 2013 13:43:21 -0800 From: Andrew Morton To: Jan Kara Cc: "Paul E. McKenney" , LKML Subject: Re: [PATCH v3] printk: Avoid softlockups in console_unlock() Message-Id: <20130301134321.85e18987.akpm@linux-foundation.org> In-Reply-To: <20130301103027.GC26128@quack.suse.cz> References: <1361927819-1570-1-git-send-email-jack@suse.cz> <20130227175945.GC3336@linux.vnet.ibm.com> <20130301103027.GC26128@quack.suse.cz> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; 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 Fri, 1 Mar 2013 11:30:27 +0100 Jan Kara wrote: > > If a CPU remains in your loop where you invoke rcu_cpu_stall_reset(), > > there is no indication of the stall. Now, I do understand why having > > RCU add a CPU stall warning into the mix would be very bad, but it > > would be good to have some sort of indication that there is stalling. > > Perhaps a counter visible in sysfs? Whatever it is, at least some way > > of diagnosing the stall condition would be very good. > I see. If others (Andrew, ping?) are OK with the rest of the patch, I can > extend it and add a counter of printk() breaks we had to make. That looks > like a good idea. hmpf, spose so. It sound lke the world's least interesting counter but perhaps it will look more interesting when we see its sparkly documentation.