Re: [Xen-devel] Re: 2.6.38 x86_64 domU null pointer in xennet_alloc_rx_buffers

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Mon, May 23, 2011 at 09:19:54AM -0700, retsyx wrote:
> Here is a similar kernel panic on a 32-bit system. I can get this to
> consistently happen when the panicked machine is being used a PPTP server.
> The panic is triggered instantly when a particular PPTP client attempts to
> establish a tunnel (encryption is off BTW):

Great.

Do you have a step-by-step instruction on how to reproduce this failure?
The more details the better.

> 
> 
> BUG: unable to handle kernel NULL pointer dereference at   (null)
> IP: [<c0193144>] page_address+0x14/0xe0
> *pdpt = 000000001eaf3007 *pde = 0000000000000000 
> Oops: 0000 [#1] SMP 
> last sysfs file: /sys/kernel/uevent_seqnum
> Modules linked in:
> 
> Pid: 0, comm: swapper Not tainted 2.6.38.3-linode32 #1  
> EIP: 0061:[<c0193144>] EFLAGS: 00010286 CPU: 0
> EIP is at page_address+0x14/0xe0
> EAX: 00000000 EBX: 00000000 ECX: 00000251 EDX: 00000250
> ESI: 00000250 EDI: de6b7980 EBP: 20411000 ESP: df40feb4
>  DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0069
> Process swapper (pid: 0, ti=df40e000 task=c079df20 task.ti=c0788000)
> Stack:
>  deb58340 00000250 de6b7980 20411000 c049e742 00000000 000000d0 dee8a000
>  00d02280 deb58be4 00000010 deb58000 deb59010 000000c0 deb58340 00000001
>  deb58340 de6af8d8 c049fcff 00000000 00000001 df40ff9c dfbba380 df40ff78
> Call Trace:
>  [<c049e742>] ? xennet_alloc_rx_buffers+0x1c2/0x300
>  [<c049fcff>] ? xennet_poll+0x4df/0xc20
>  [<c04fc43a>] ? net_rx_action+0x9a/0x130
>  [<c01380ec>] ? __do_softirq+0x7c/0x130
>  [<c0138070>] ? __do_softirq+0x0/0x130
>  <IRQ> 
>  [<c0137fe5>] ? irq_exit+0x65/0x70
>  [<c043a03d>] ? xen_evtchn_do_upcall+0x1d/0x30
>  [<c0109487>] ? xen_do_upcall+0x7/0xc
>  [<c01013a7>] ? hypercall_page+0x3a7/0x1010
>  [<c0105b8f>] ? xen_safe_halt+0xf/0x20
>  [<c010f66f>] ? default_idle+0x2f/0x60
>  [<c0107ed2>] ? cpu_idle+0x42/0x70
>  [<c07ca8ac>] ? start_kernel+0x2da/0x2df
>  [<c07ca410>] ? unknown_bootoption+0x0/0x190
>  [<c07cdaa5>] ? xen_start_kernel+0x530/0x538
> Code: 89 c2 b8 2c 1e 85 c0 e9 3f ff ff ff 0f 0b eb fe 8d b4 26 00 00 00 00
> 83 ec 10 89 1c 24 89 c3 89 74 24 04 89 7c 24 08 89 6c 24 0c <8b> 00 c1 e8 1e
> 69 c0 80 03 00 00 05 40 05 7c c0 2b 80 4c 03 00 
> EIP: [<c0193144>] page_address+0x14/0xe0 SS:ESP 0069:df40feb4
> CR2: 0000000000000000
> ---[ end trace 19ddaabd0d19ad12 ]---
> Kernel panic - not syncing: Fatal exception in interrupt
> Pid: 0, comm: swapper Tainted: G      D     2.6.38.3-linode32 #1
> Call Trace:
>  [<c063cfbf>] ? panic+0x57/0x13e
>  [<c010bec6>] ? oops_end+0x96/0xa0
>  [<c011e362>] ? no_context+0xc2/0x190
>  [<c011e58f>] ? bad_area_nosemaphore+0xf/0x20
>  [<c011e943>] ? do_page_fault+0x223/0x3e0
>  [<c0184325>] ? __alloc_pages_nodemask+0xf5/0x670
>  [<c011e720>] ? do_page_fault+0x0/0x3e0
>  [<c063fea6>] ? error_code+0x5a/0x60
>  [<c011e720>] ? do_page_fault+0x0/0x3e0
>  [<c0193144>] ? page_address+0x14/0xe0
>  [<c049e742>] ? xennet_alloc_rx_buffers+0x1c2/0x300
>  [<c049fcff>] ? xennet_poll+0x4df/0xc20
>  [<c04fc43a>] ? net_rx_action+0x9a/0x130
>  [<c01380ec>] ? __do_softirq+0x7c/0x130
>  [<c0138070>] ? __do_softirq+0x0/0x130
>  <IRQ>  [<c0137fe5>] ? irq_exit+0x65/0x70
>  [<c043a03d>] ? xen_evtchn_do_upcall+0x1d/0x30
>  [<c0109487>] ? xen_do_upcall+0x7/0xc
>  [<c01013a7>] ? hypercall_page+0x3a7/0x1010
>  [<c0105b8f>] ? xen_safe_halt+0xf/0x20
>  [<c010f66f>] ? default_idle+0x2f/0x60
>  [<c0107ed2>] ? cpu_idle+0x42/0x70
>  [<c07ca8ac>] ? start_kernel+0x2da/0x2df
>  [<c07ca410>] ? unknown_bootoption+0x0/0x190
>  [<c07cdaa5>] ? xen_start_kernel+0x530/0x538
> 
> 
> --
> View this message in context: 
> http://xen.1045712.n5.nabble.com/2-6-38-x86-64-domU-null-pointer-in-xennet-alloc-rx-buffers-tp4298573p4419471.html
> Sent from the Xen - Dev mailing list archive at Nabble.com.
> 
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