From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759330Ab2GLWgB (ORCPT ); Thu, 12 Jul 2012 18:36:01 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:58752 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759297Ab2GLWf4 (ORCPT ); Thu, 12 Jul 2012 18:35:56 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg KH , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Steven Rostedt , Benjamin Herrenschmidt Subject: [ 006/187] powerpc/ftrace: Do not trace restore_interrupts() Date: Thu, 12 Jul 2012 15:32:42 -0700 Message-Id: <20120712191522.827473614@linuxfoundation.org> X-Mailer: git-send-email 1.7.10.1.362.g242cab3 In-Reply-To: <20120712191522.742634173@linuxfoundation.org> References: <20120712192421.GA28926@kroah.com> <20120712191522.742634173@linuxfoundation.org> User-Agent: quilt/0.60-20.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Greg KH 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Steven Rostedt commit 2d773aa4810d4a612d1c879faacc38594cc3f841 upstream. As I was adding code that affects all archs, I started testing function tracer against PPC64 and found that it currently locks up with 3.4 kernel. I figured it was due to tracing a function that shouldn't be, so I went through the following process to bisect to find the culprit: cat /debug/tracing/available_filter_functions > t num=`wc -l t` sed -ne "1,${num}p" t > t1 let num=num+1 sed -ne "${num},$p" t > t2 cat t1 > /debug/tracing/set_ftrace_filter echo function /debug/tracing/current_tracer It finally came down to this function: restore_interrupts() I'm not sure why this locks up the system. It just seems to prevent scheduling from occurring. Interrupts seem to still work, as I can ping the box. But all user processes freeze. When restore_interrupts() is not traced, function tracing works fine. Signed-off-by: Steven Rostedt Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kernel/irq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/powerpc/kernel/irq.c +++ b/arch/powerpc/kernel/irq.c @@ -277,7 +277,7 @@ EXPORT_SYMBOL(arch_local_irq_restore); * NOTE: This is called with interrupts hard disabled but not marked * as such in paca->irq_happened, so we need to resync this. */ -void restore_interrupts(void) +void notrace restore_interrupts(void) { if (irqs_disabled()) { local_paca->irq_happened |= PACA_IRQ_HARD_DIS;