Re: v2.6.31-rc6: BUG: unable to handle kernel NULL pointer dereference at 0000000000000008

["Zhang, Yanmin" <yanmin_zhang@linux.intel.com>]

On Thu, 2009-08-20 at 17:23 +0800, Xiaotian Feng wrote:
> I got following on 2.6.31-rc5 and rc6 .....
I didn't run into such issues on my 2 stoakley machines and 1 Nehalem machine.
Perhaps kernel config bypasses this issue. What's the kernel config file you used?

> 
> ------------[ cut here ]------------
> kernel BUG at kernel/workqueue.c:287!
> invalid opcode: 0000 [#1] SMP
> last sysfs file: /sys/devices/pci0000:00/0000:00:19.0/irq
> CPU 2
> Modules linked in: fuse sco bridge stp llc bnep l2cap bluetooth sunrpc
> ip6t_REJECT nf_conntrack_ipv6 ip6table_filter ip6_tables ipv6
> dm_multipath uinput radeon snd_hda_codec_analog ttm drm snd_hda_intel
> i2c_algo_bit i2c_i801 snd_hda_codec snd_hwdep snd_pcm wmi dcdbas
> i2c_core ppdev parport_pc parport snd_timer e1000e snd soundcore
> snd_page_alloc iTCO_wdt iTCO_vendor_support pcspkr serio_raw
> ata_generic pata_acpi [last unloaded: speedstep_lib]
> Pid: 17, comm: events/2 Not tainted 2.6.31-rc5 #51 OptiPlex 760
> RIP: 0010:[<ffffffff81060941>]  [<ffffffff81060941>] worker_thread+0x1bc/0x31d
> RSP: 0000:ffff88022ec61de0  EFLAGS: 00010286
> RAX: ffff88021200d238 RBX: ffff88003598ec00 RCX: 000000000000009f
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff88022edf22f0
> RBP: ffff88022ec61eb0 R08: 0000000000000000 R09: ffff88003598ec00
> R10: 0000000000000000 R11: 0000000000000000 R12: ffff88021200d230
> R13: ffff88003598ec40 R14: 0000000000000000 R15: ffff88003598ec50
> FS:  0000000000000000(0000) GS:ffff8800357b8000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
> CR2: 0000000001af7aa8 CR3: 00000001fd0d3000 CR4: 00000000000406e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> Process events/2 (pid: 17, threadinfo ffff88022ec60000, task ffff88022edf22f0)
> Stack:
>  ffffffff81060945 ffffffff81415f34 ffff88022ec61e00 ffff88022ec61e20
> <0> ffff88022ec61e20 ffffffff810739bb ffff88021200d238 ffff88022edf22f0
> <0> 0000000000000000 0000000000000000 0000000000000000 0000000000000000
> Call Trace:
>  [<ffffffff81060945>] ? worker_thread+0x1c0/0x31d
>  [<ffffffff81415f34>] ? thread_return+0x3e/0xaf
>  [<ffffffff810739bb>] ? lock_release_holdtime+0x2c/0x11d
>  [<ffffffff8106549e>] ? autoremove_wake_function+0x0/0x39
>  [<ffffffff81060785>] ? worker_thread+0x0/0x31d
>  [<ffffffff8106513c>] kthread+0x8a/0x92
>  [<ffffffff81012d4a>] child_rip+0xa/0x20
>  [<ffffffff810126d0>] ? restore_args+0x0/0x30
>  [<ffffffff810650b2>] ? kthread+0x0/0x92
>  [<ffffffff81012d40>] ? child_rip+0x0/0x20
> Code: 08 48 89 31 48 89 52 08 48 89 12 48 89 85 60 ff ff ff e8 66 74
> 3b 00 48 8b 85 60 ff ff ff 48 8b 50 f8 48 83 e2 fc 48 39 d3 74 04 <0f>
> 0b eb fe f0 80 60 f8 fe 48 8b bb a8 00 00 00 45 31 c9 31 c9
> RIP  [<ffffffff81060941>] worker_thread+0x1bc/0x31d
>  RSP <ffff88022ec61de0>
> ---[ end trace 4d8a59030f36f167 ]---
> 
> 
> 
> On Thu, Aug 20, 2009 at 3:33 PM, Eric W. Biederman
> <ebiederm@xmission.com> wrote:
> >
> > Xiaotian Feng <xtfeng@gmail.com> writes:
> >
> > > On Thu, Aug 20, 2009 at 2:07 PM, Eric W. Biederman <ebiederm@xmission.com>
> > > wrote:
> > >
> > >
> > >     ebiederm@xmission.com (Eric W. Biederman) writes:
> > >
> > >     > I'm not certain who I should route this too, but I just had 2.6.31-rc6
> > >     > fall over on me.  I don't know how reproducible this will be but
> > >     > I have a full crash dump if someone is interested in looking into this.
> > >
> > >     Looks like I was wrong.  This is appears trivial to reproduce,
> > >     I have just reproduced it two more times in a row.  I think
> > >     the problem is pty related.
> > >
> > >     I was looking into a change in behavior on 2.6.31-rc6 where
> > >     data was being lost, and it appears one variant of my test program
> > >     kills the kernel.
> > >
> > >     The following program run as an unprivileged user causes a kernel
> > >     panic in about a minute:
> > >
> > >     aka
> > >
> > >     while :; do ./KernelTtyTest ; done
> > >
> > >
> > > oops.... It panics my x86_64 machine.....
> >
> > I guess I forgot to mention that detail.  Thanks for confirming this
> > bug isn't just me.
> >
> > Eric