Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763060Ab3ECJ7i (ORCPT ); Fri, 3 May 2013 05:59:38 -0400 Received: from www.linutronix.de ([62.245.132.108]:44311 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762989Ab3ECJ7f (ORCPT ); Fri, 3 May 2013 05:59:35 -0400 Message-ID: <51838A84.90500@linutronix.de> Date: Fri, 03 May 2013 11:59:32 +0200 From: Sebastian Andrzej Siewior User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.12) Gecko/20130116 Icedove/10.0.12 MIME-Version: 1.0 To: Steven Rostedt CC: Clark Williams , linux-rt-users , Thomas Gleixner , LKML Subject: Re: Suspend resume problem (WAS Re: [ANNOUNCE] 3.8.10-rt6) References: <20130429201202.GB7979@linutronix.de> <20130429161925.2a6ea78a@riff.lan> <20130430170948.GB4688@linutronix.de> <1367345295.30667.68.camel@gandalf.local.home> In-Reply-To: <1367345295.30667.68.camel@gandalf.local.home> X-Enigmail-Version: 1.4.1 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1199 Lines: 33 On 04/30/2013 08:08 PM, Steven Rostedt wrote: >> This NMI releated deadlock is a problem which should also trigger >> mainline, right? > > Well, yeah, as sending out a NMI stack dump is sorta the last resort, > and is dangerous to do printks from NMI context. So we did bad and we upgrade to bad and dangerous. >> >> Now, the time jump on the other hand is the real issue here and is >> RT-only. It looks like we get a big number of timer updates via >> tick_do_update_jiffies64() because according to ktime_get() that much >> time really passed by. > > As the NMI dump only happens because of the time jump, which as you > said, is -rt only, I wouldn't say that the NMI deadlock is a mainline > bug. The reason for the NMI was a bug in the -RT tree but if something else triggers that NMI we have a good chance to deadlock. What about a try_lock() and leave after 50 usecs of trying and not getting it in the in_nmi() case? > -- Steve Sebastian -- 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/