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Date: Thu, 26 Mar 2009 09:49:56 -0400 (EDT)
From: Steven Rostedt <rostedt@goodmis.org>
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To: Frederic Weisbecker <fweisbec@gmail.com>
cc: Maneesh Soni <maneesh@in.ibm.com>, linux-kernel@vger.kernel.org,
       mingo@elte.hu
Subject: Re: [-tip] ftrace: oops at probe_wakeup_sched_switch+0xd1/0x1ae
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On Thu, 26 Mar 2009, Frederic Weisbecker wrote:

> On Thu, Mar 26, 2009 at 05:58:07PM +0530, Maneesh Soni wrote:
> > 
> > I hit the below oops while playing with "wakeup" tracer. Just enabled
> > tracing and ran "while true; do cat trace; done" on a 8-way systems with
> > -tip at commit 9e25bacc221318a29d37425e054c01047edad7f5.
> > 
> > 
> > Attached the .config.
> > 
> > Thanks
> > Maneesh
> > 
> > BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
> > IP: [<ffffffff802d2258>] probe_wakeup_sched_switch+0xd1/0x1ae
> > PGD 219147067 PUD 1e449e067 PMD 0 
> > Oops: 0000 [#1] SMP 
> > last sysfs file: /sys/devices/pci0000:0c/0000:0c:00.0/irq
> > CPU 5 
> > Modules linked in: autofs4 hidp rfcomm l2cap bluetooth iptable_filter ip_tables ip6t_REJECT xt_tcpudp ip6table_filter ip6_tables x_tables ipv6 dm_mirror dm_region_hash dm_log dm_multipath scsi_dh dm_mod sbs sbshc battery ac parport_pc lp parport sg sr_mod ide_cd_mod cdrom serio_raw acpi_memhotplug button tg3 libphy i2c_piix4 i2c_core pcspkr usb_storage uhci_hcd ohci_hcd ehci_hcd aacraid sd_mod scsi_mod ext3 jbd
> > Pid: 5937, comm: cat Not tainted 2.6.29-tip-test #1 eserver xSeries 366-[88632RA]-
> > RIP: 0010:[<ffffffff802d2258>]  [<ffffffff802d2258>] probe_wakeup_sched_switch+0xd1/0x1ae
> > RSP: 0000:ffff8801cf4cdea0  EFLAGS: 00010046
> > RAX: 0000000000000000 RBX: ffff88022f232820 RCX: 0000000000000046
> > RDX: ffff8800281989a0 RSI: ffffffff8020d56d RDI: ffffffff811de480
> > RBP: ffff8801cf4cded0 R08: 0000000000000000 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000046
> > R13: 0000000000000000 R14: ffff8801e4471820 R15: 0000000000000005
> > FS:  00007f607411c6e0(0000) GS:ffff88002818b000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> > CR2: 0000000000000008 CR3: 00000001da19a000 CR4: 00000000000006e0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> > Process cat (pid: 5937, threadinfo ffff8801cf4cc000, task ffff8801e4471820)
> > Stack:
> >  ffff8800281989a0 ffff8802191e14b0 ffff88002819dd40 00007fff7c130640
> >  0000000000000000 ffff88002819dd40 ffff8801cf4cdf70 ffffffff806f8264
> >  0000000000000002 ffff8801cf4cdf48 ffff8801e4471820 ffff88022f232820
> > Call Trace:
> >  [<ffffffff806f8264>] schedule+0xd99/0x10f9
> >  [<ffffffff806fb61b>] ? trace_hardirqs_on_thunk+0x3a/0x3c
> >  [<ffffffff8020d56d>] retint_careful+0x12/0x2e
> > Code: f2 83 3d 1b b0 9f 00 00 74 77 48 3b 1d a2 de f2 00 75 6e 48 8b 4d 00 48 8b 3d 8d de f2 00 45 89 e8 48 8b 01 48 8b 71 08 4c 89 e1 <48> 8b 50 08 e8 f7 9f ff ff 48 8b 3d 70 de f2 00 45 89 e8 48 89 
> > RIP  [<ffffffff802d2258>] probe_wakeup_sched_switch+0xd1/0x1ae
> >  RSP <ffff8801cf4cdea0>
> > CR2: 0000000000000008
> > ---[ end trace ab11daa90bb147ba ]---
> > 
> 
> 
> 
> I've tested the same config and ran your script with wakeup tracer but nothing
> weird happened.
> Though I've tested on UP so may be I should try on SMP.

Yeah, that may make a difference ;-)

-- Steve
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