From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753767Ab1IFSIa (ORCPT ); Tue, 6 Sep 2011 14:08:30 -0400 Received: from mail-gy0-f174.google.com ([209.85.160.174]:34773 "EHLO mail-gy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753542Ab1IFSI1 (ORCPT ); Tue, 6 Sep 2011 14:08:27 -0400 Date: Tue, 6 Sep 2011 15:08:19 -0300 From: Arnaldo Carvalho de Melo To: Peter Zijlstra Cc: Thomas Gleixner , linux-kernel Subject: Re: [PATCH -rt] sched: teach migrate_disable about atomic contexts Message-ID: <20110906180819.GA5365@ghostprotocols.net> References: <1314967297.1301.14.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1314967297.1301.14.camel@twins> X-Url: http://acmel.wordpress.com 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 Em Fri, Sep 02, 2011 at 02:41:37PM +0200, Peter Zijlstra escreveu: > Subject: sched: teach migrate_disable about atomic contexts > From: Peter Zijlstra > Date: Fri Sep 02 14:29:27 CEST 2011 > > [] spin_bug+0x94/0xa8 > [] do_raw_spin_lock+0x43/0xea > [] _raw_spin_lock_irqsave+0x6b/0x85 > [] ? migrate_disable+0x75/0x12d > [] ? pin_current_cpu+0x36/0xb0 > [] migrate_disable+0x75/0x12d > [] pagefault_disable+0xe/0x1f > [] copy_from_user_nmi+0x74/0xe6 > [] perf_callchain_user+0xf3/0x135 > > Now clearly we can't go around taking locks from NMI context, cure > this by short-circuiting migrate_disable() when we're in an atomic > context already. > > Add some extra debugging to avoid things like: > > preempt_disable() > migrate_disable(); > > preempt_enable(); > migrate_enable(); > > Signed-off-by: Peter Zijlstra > Link: http://lkml.kernel.org/n/tip-wbot4vsmwhi8vmbf83hsclk6@git.kernel.org Now I can collect callchains with perf on linux RT, thanks. Tested-by: Arnaldo Carvalho de Melo - Arnaldo