linux-kernel - Re: [BUG -rt] scheduling while atomic in -rt git tree

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Message-ID: <alpine.DEB.1.10.0902011512360.30993@gandalf.stny.rr.com>
Date:	Sun, 1 Feb 2009 15:15:34 -0500 (EST)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Luis Henriques <henrix@...o.pt>
cc:	linux-rt-users <linux-rt-users@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [BUG -rt] scheduling while atomic in -rt git tree


Thanks, but I'm going to bring the -rt tree back to making all 
local_bh_disable into nops, and then investigate all the areas that might 
need a true bh disable, and do preempt_disable for rt.

This is the major cause of these scheduling while atomic bugs. Any time 
you see a '| preempt count: 00000101 ]' where you have the 0xff00 bits 
set, is a local_bh_disable bug.

Right now I'm investigating a bug that I get with the local_bh_disable as 
nops, and this is why I have not released it yet.

The old -rt trees had local_bh_disable as a nop.

-- Steve


On Sun, 1 Feb 2009, Luis Henriques wrote:

> Hi,
> 
> I am using an x86_64 and getting the following log while executing the master in
> the -rt git tree:
> 
> [   28.182621] BUG: scheduling while atomic: sirq-net-rx/0/8/0x00000101, CPU#0
> [   28.182744] Modules linked in: parport_pc ppdev parport ipv6 powernow_k8
> cpufreq_stats cpufreq_conservative cpufreq_ondemand freq_table cpufreq_powersave
> cpufreq_userspace af_packet sbp2 loop joydev arc4 snd_hda_intel ecb snd_pcm
> snd_page_alloc uvcvideo snd_hwdep ath5k snd_seq compat_ioctl32 mac80211 psmouse
> snd_timer videodev snd_seq_device k8temp v4l1_compat led_class snd soundcore
> cfg80211 rfkill input_polldev battery video output ac button evdev ext3 jbd
> mbcache sg sr_mod cdrom ide_pci_generic ide_core ata_generic sd_mod pata_acpi
> ohci1394 ahci ehci_hcd pata_atiixp ohci_hcd ieee1394 libata usbcore scsi_mod
> r8169 mii thermal processor fan
> [   28.186632] Pid: 8, comm: sirq-net-rx/0 Tainted: G        W
> 2.6.28-rt-00209-g82e0a07 #1
> [   28.186747] Call Trace:
> [   28.186831]  [<ffffffff80455cb4>] ? netif_receive_skb+0x2c4/0x590
> [   28.186938]  [<ffffffff80242795>] __schedule_bug+0x85/0x90
> [   28.187033]  [<ffffffff804ead38>] thread_return+0x142/0x70a
> [   28.187127]  [<ffffffff8020c3c8>] ? ftrace_call+0x5/0x2b
> [   28.187218]  [<ffffffff8024f42f>] ksoftirqd+0x1df/0x270
> [   28.187306]  [<ffffffff8024f250>] ? ksoftirqd+0x0/0x270
> [   28.187395]  [<ffffffff802621de>] kthread+0x4e/0x90
> [   28.187481]  [<ffffffff8020d639>] child_rip+0xa/0x11
> [   28.187569]  [<ffffffff802408d9>] ? finish_task_switch+0x59/0x130
> [   28.187663]  [<ffffffff804ed1ab>] ? _spin_unlock_irq+0x1b/0x40
> [   28.187753]  [<ffffffff8020cb25>] ? restore_args+0x0/0x30
> [   28.187842]  [<ffffffff80262190>] ? kthread+0x0/0x90
> [   28.187929]  [<ffffffff8020d62f>] ? child_rip+0x0/0x11
> [   28.188034] ---------------------------
> [   28.188111] | preempt count: 00000101 ]
> [   28.188189] | 2-level deep critical section nesting:
> [   28.188272] ----------------------------------------
> [   28.188356] .. [<ffffffff804a9c16>] .... icmp_send+0xc6/0x6a0
> [   28.188497] .....[<ffffffff804a9c16>] ..   ( <= icmp_send+0xc6/0x6a0)
> [   28.188639] .. [<ffffffff804ea7ac>] .... schedule+0x2c/0x476
> [   28.188777] .....[<ffffffff8024f42f>] ..   ( <= ksoftirqd+0x1df/0x270)
> [   28.188918] 
> 
> Can also provide my config file if needed.
> 
> -- 
> Luis Henriques
> 
> 
--
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