From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 31012 invoked by alias); 27 May 2009 17:45:35 -0000 Received: (qmail 30995 invoked by uid 22791); 27 May 2009 17:45:32 -0000 X-SWARE-Spam-Status: No, hits=-0.1 required=5.0 tests=BAYES_20,J_CHICKENPOX_73,SPF_PASS X-Spam-Check-By: sourceware.org Received: from e4.ny.us.ibm.com (HELO e4.ny.us.ibm.com) (32.97.182.144) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Wed, 27 May 2009 17:45:23 +0000 Received: from d01relay02.pok.ibm.com (d01relay02.pok.ibm.com [9.56.227.234]) by e4.ny.us.ibm.com (8.13.1/8.13.1) with ESMTP id n4RHenWC026623 for ; Wed, 27 May 2009 13:40:49 -0400 Received: from d01av03.pok.ibm.com (d01av03.pok.ibm.com [9.56.224.217]) by d01relay02.pok.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n4RHjK3D181276 for ; Wed, 27 May 2009 13:45:20 -0400 Received: from d01av03.pok.ibm.com (loopback [127.0.0.1]) by d01av03.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n4RHjKg1023774 for ; Wed, 27 May 2009 13:45:20 -0400 Received: from [9.65.0.6] (sig-9-65-0-6.mts.ibm.com [9.65.0.6]) by d01av03.pok.ibm.com (8.12.11.20060308/8.12.11) with ESMTP id n4RHjIqR023690; Wed, 27 May 2009 13:45:19 -0400 Message-ID: <4A1D697D.3090309@us.ibm.com> Date: Wed, 27 May 2009 17:45:00 -0000 From: Darren Hart User-Agent: Thunderbird 2.0.0.21 (X11/20090318) MIME-Version: 1.0 To: Jim Keniston CC: Kiran , systemtap@sources.redhat.com, sripathi@in.ibm.com Subject: Re: BUG: [preempt-rt] scheduling while atomic: stapio References: <1242812648.13247.12.camel@kiran-laptop> <1242836214.3481.10.camel@dyn9047018094.beaverton.ibm.com> In-Reply-To: <1242836214.3481.10.camel@dyn9047018094.beaverton.ibm.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2009-q2/txt/msg00714.txt.bz2 Jim Keniston wrote: > On Wed, 2009-05-20 at 15:14 +0530, Kiran wrote: >> Hi, Hi Josh, Sorry for the delay in responding, I'm on paternity leave right now, so I'm experiencing high email response latency ;-) >> >> I am getting the following bug report in dmesg when I run pfaults.stp I presume that is a page fault tapset of some sort? >> script in the systemtap.examples/memory. I am using systemtap-0.9.7 and >> kernel version is 2.6.29-rt4. > > The first thing that comes to mind is that spinlocks are different in > (at least some) real-time kernels. They can give up and sleep after a > while. If you want spinlocks that are guaranteed not to sleep, you have > to use the raw_* versions of the spinlock functions. Just the declaration actually, the functions are the same. -- Darren > That's about the > extent of my (mis)information on the subject. I'm cc-ing an RT guy > (Darren) in case he can help. > > Jim Keniston > >> BUG: scheduling while atomic: stapio/0x00000001/26142, CPU#3 >> Modules linked in: stap_246f93f30a500769142af9987624737a_5072 ipv6 >> autofs4 i2c_dev i2c_core hidp rfcomm l2cap bluetooth sunrpc dm_mirror >> dm_region_hash dm_log dm_multipath scsi_dh dm_mod video output sbs >> sbshc battery ac parport_pc lp parport sg bnx2 serio_raw button shpchp >> k8temp hwmon pcspkr mptsas mptscsih scsi_transport_sas mptbase sd_mod >> scsi_mod ext3 jbd mbcache uhci_hcd ohci_hcd ehci_hcd [last unloaded: >> stap_8455b451d15976a5e16919831aef7e51_3974] >> Pid: 26142, comm: stapio Not tainted 2.6.29.1-rt4 #1 >> Call Trace: >> [] __schedule_bug+0x6f/0x8a >> [] __schedule+0x9f/0x94a >> [] schedule+0x1d/0x46 >> [] schedule_timeout+0x37/0x1a9 >> [] ? check_preempt_wakeup+0x138/0x16e >> [] wait_for_common+0xcb/0x159 >> [] ? default_wake_function+0x0/0x38 >> [] wait_for_completion+0x2b/0x41 >> [] __synchronize_sched+0x57/0x72 >> [] ? wakeme_after_rcu+0x0/0x36 >> [] ? srcu_readers_active_idx+0x5e/0x89 >> [] synchronize_srcu+0x6f/0x96 >> [] srcu_notifier_chain_unregister+0x60/0x82 >> [] cpufreq_unregister_notifier+0x35/0x5c >> [] _stp_kill_time+0xb6/0xbd [stap_246f93f30a500769142af9987624737a_5072] >> [] probe_1391+0x3c/0xa8 [stap_246f93f30a500769142af9987624737a_5072] >> [] enter_end_probe+0x14a/0x1e3 [stap_246f93f30a500769142af9987624737a_5072] >> [] _stp_cleanup_and_exit+0x2df/0x2f8 [stap_246f93f30a500769142af9987624737a_5072] >> [] _stp_ctl_write_cmd+0x460/0x7f8 [stap_246f93f30a500769142af9987624737a_5072] >> [] ? __wake_up+0x4d/0x6e >> [] ? tty_ldisc_deref+0x74/0x8f >> [] ? security_file_permission+0x24/0x3a >> [] vfs_write+0xc1/0x180 >> [] sys_write+0x56/0x93 >> [] system_call_fastpath+0x16/0x1b >> >> Could someone please provide pointers on the cause of this bug? >> >> >> > -- Darren Hart IBM Linux Technology Center Real-Time Linux Team