From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755935AbbBPPHl (ORCPT ); Mon, 16 Feb 2015 10:07:41 -0500 Received: from casper.infradead.org ([85.118.1.10]:56095 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754621AbbBPPHk (ORCPT ); Mon, 16 Feb 2015 10:07:40 -0500 Date: Mon, 16 Feb 2015 16:07:33 +0100 From: Peter Zijlstra To: Steven Rostedt Cc: Frederic Weisbecker , Huang Ying , Ingo Molnar , LKML , LKP ML Subject: Re: [LKP] [sched] BUG: kernel boot hang Message-ID: <20150216150733.GD5029@twins.programming.kicks-ass.net> References: <1423986208.5538.5.camel@intel.com> <20150215154620.GC8838@lerouge> <20150215131807.30c1808c@grimm.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150215131807.30c1808c@grimm.local.home> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Feb 15, 2015 at 01:18:07PM -0500, Steven Rostedt wrote: > On Sun, 15 Feb 2015 16:46:22 +0100 > Frederic Weisbecker wrote: > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > > index c017a5f..a6d4d6c 100644 > > --- a/kernel/sched/core.c > > +++ b/kernel/sched/core.c > > @@ -2879,7 +2879,7 @@ void __sched schedule_preempt_disabled(void) > > preempt_disable(); > > } > > > > -static void preempt_schedule_common(void) > > +static void __sched notrace preempt_schedule_common(void) > > { > > do { > > preempt_count_add(PREEMPT_ACTIVE); > > Ah, since I added better recursion protection code in function tracer > this didn't break that. But unfortunately, function graph tracer > doesn't have that protection. > > If it traces between preempt_schedule() and where it sets > PREEMPT_ACTIVE, it can indeed go into an infinite recursion. Yeah, > preempt_schedule_common() should be notrace, at least until we change > function_graph to have that recursion protection. > > Acked-by: Steven Rostedt Can someone shoot me a proper patch with Changelog and such? From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============3169424997967974966==" MIME-Version: 1.0 From: Peter Zijlstra To: lkp@lists.01.org Subject: Re: [sched] BUG: kernel boot hang Date: Mon, 16 Feb 2015 16:07:33 +0100 Message-ID: <20150216150733.GD5029@twins.programming.kicks-ass.net> In-Reply-To: <20150215131807.30c1808c@grimm.local.home> List-Id: --===============3169424997967974966== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable On Sun, Feb 15, 2015 at 01:18:07PM -0500, Steven Rostedt wrote: > On Sun, 15 Feb 2015 16:46:22 +0100 > Frederic Weisbecker wrote: > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > > index c017a5f..a6d4d6c 100644 > > --- a/kernel/sched/core.c > > +++ b/kernel/sched/core.c > > @@ -2879,7 +2879,7 @@ void __sched schedule_preempt_disabled(void) > > preempt_disable(); > > } > > = > > -static void preempt_schedule_common(void) > > +static void __sched notrace preempt_schedule_common(void) > > { > > do { > > preempt_count_add(PREEMPT_ACTIVE); > = > Ah, since I added better recursion protection code in function tracer > this didn't break that. But unfortunately, function graph tracer > doesn't have that protection. > = > If it traces between preempt_schedule() and where it sets > PREEMPT_ACTIVE, it can indeed go into an infinite recursion. Yeah, > preempt_schedule_common() should be notrace, at least until we change > function_graph to have that recursion protection. > = > Acked-by: Steven Rostedt Can someone shoot me a proper patch with Changelog and such? --===============3169424997967974966==--