From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932132AbXGZHvg (ORCPT ); Thu, 26 Jul 2007 03:51:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758164AbXGZHvN (ORCPT ); Thu, 26 Jul 2007 03:51:13 -0400 Received: from ausmtp04.au.ibm.com ([202.81.18.152]:48937 "EHLO ausmtp04.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755006AbXGZHvL (ORCPT ); Thu, 26 Jul 2007 03:51:11 -0400 Date: Thu, 26 Jul 2007 13:19:57 +0530 To: Ingo Molnar Cc: Arjan van de Ven , linux@bohmer.net, LKML , RT-Users , mathieu.desnoyers@polymtl.ca Subject: Re: [Question] Hooks for scheduler tracing (CFS) Message-ID: <20070726074957.GA19398@in.ibm.com> Reply-To: Ankita Garg References: <3efb10970707161246se06ab22i32872cfe6fa4f2f6@mail.gmail.com> <1184615557.2698.3.camel@laptopd505.fenrus.org> <20070726072858.GC13061@in.ibm.com> <20070726073520.GA12206@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070726073520.GA12206@elte.hu> User-Agent: Mutt/1.5.13 (2006-08-11) From: ankita@in.ibm.com (Ankita Garg) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 26, 2007 at 09:35:20AM +0200, Ingo Molnar wrote: > > * Ankita Garg wrote: > > > The probe point did get triggered, and soon after that I had the > > following in dmesg, leading to system hang... > > > > BUG: scheduling while atomic: softirq-rcu/3/0x00000004/52, CPU#3 > > > > Call Trace: > > <#DB> [] __schedule_bug+0x4b/0x4f > > [] __sched_text_start+0xcc/0xaaa > > [] dump_trace+0x248/0x25d > > [] print_traces+0x9/0xb > > [] show_trace+0x5c/0x64 > > [] schedule+0xe4/0x104 > > [] rt_spin_lock_slowlock+0xfc/0x19e > > [] __rt_spin_lock+0x1f/0x21 > > [] rt_spin_lock+0x9/0xb > > [] > > :stap_c1a10b1292b5f87a563f56d89ddfc765_606:_stp_print_flush+0x5f/0xdf > > [] > > :stap_c1a10b1292b5f87a563f56d89ddfc765_606:probe_1493+0x1f6/0x257 > > [] > > I'd suggest to not put a probe into a preempt-off section - put it to > the beginning and to the end of schedule() to capture context-switches. > _stp_print_flush() is in the systemtap-generated module, right? Maybe > the problem is resolved by changing that spinlock to use raw_spinlock_t > / DEFINE_RAW_SPIN_LOCK. Yes, _stp_print_flush is in the systemtap-generated kprobe module. Placing the probe at the beginning of schedule() also has the same effect. Will try by changing the spinlock to raw_spinlock_t... > > > Ingo -- Regards, Ankita Garg (ankita@in.ibm.com) Linux Technology Center IBM India Systems & Technology Labs, Bangalore, India