From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752787AbbIOIxI (ORCPT ); Tue, 15 Sep 2015 04:53:08 -0400 Received: from metis.ext.pengutronix.de ([92.198.50.35]:48012 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752612AbbIOIxF convert rfc822-to-8bit (ORCPT ); Tue, 15 Sep 2015 04:53:05 -0400 From: Juergen Borleis Organization: Pengutronix e.K. To: Thomas Gleixner Subject: Re: PowerPC: massive "scheduling while atomic" reports Date: Tue, 15 Sep 2015 10:53:15 +0200 User-Agent: KMail/1.9.10 (enterprise35 0.20100827.1168748) Cc: "linux-rt-users" , LKML References: <201509101106.56931.jbe@pengutronix.de> In-Reply-To: X-KMail-QuotePrefix: > MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <201509151053.16563.jbe@pengutronix.de> X-SA-Exim-Connect-IP: 2001:67c:670:201:5054:ff:fe8d:eefb X-SA-Exim-Mail-From: jbe@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Thomas, On Tuesday 15 September 2015 00:05:31 Thomas Gleixner wrote: > Please CC lkml on bug reports for RT. Okay. > > When running the system at least every other boot this kernel spits out > > massive "scheduling while atomic" reports. > > I doubt that this only happens on every other boot. This is a > systematic failure. That was one of the confusing things: we booted the machine and got a bunch off "scheduling while atomic" reports and we re-booted it and it was silent. That's why we thought it might be a race instead of a systematic failure. > [...] > If you encounter such a 'confusing' problem the next time, then look > out for commonalities, AKA patterns. 99% of all problems can be > decoded via patterns. And if you look at the other call chains you'll > find more instances of those pte_*_lock() calls, which all end up in > kmap_atomic(). Sounds easy. But we stared with two developers on the code and the bug traces and were lost in the code. Seems you are in a pole position due to your experience with the RT preempt code. The good news: I tried your suggested change on my system and reboot it again and again since an hour now and no more "scheduling while atomic" reports occur. \o/ Thank you very much Juergen -- Pengutronix e.K.                              | Juergen Borleis             | Industrial Linux Solutions                    | http://www.pengutronix.de/  |