Subject: Re: Kernel error

From: Stephen Hemminger <[email-masked]>
Date: Mon, 17 Apr 2006 09:12:56 -0700

On Sun, 16 Apr 2006 01:43:08 -0500
"Saurabh Jain" <[email-masked]> wrote:

> Hi Guys,
> 
> I am getting the following kernel error while doing some experiments.
> Any idea where things are going wrong. To me it looks like there is an
> error while copying data from user space to kernel space. The
> application which i am running is iperf. However i also have netem
> module for emulating some wide area network characteristics like
> delay. I am using delay of 100ms.
> 
> ##################Error Message#############################
> Unable to handle kernel NULL pointer dereference at virtual address 00000004
>  printing eip:
> c02fee3c
> *pde = 7ded4067
> Oops: 0002 [#5]
> Modules linked in: setparam(U) sch_netem(U) nfs(U) lockd(U) autofs4(U)
> sunrpc(U)CPU:    0
> EIP:    0060:[<c02fee3c>]    Not tainted VLI
> EFLAGS: 00010286   (2.6.12-1.1390_FC4-emulab-1)
> EIP is at tcp_transmit_skb+0x3ef/0x8de
> eax: 00000000   ebx: f71a1a40   ecx: ed64f960   edx: ed64ff60
> esi: 00000000   edi: f2f98500   ebp: ed71b780   esp: f47bddd4
> ds: 007b   es: 007b   ss: 0068
> Process iperf (pid: 2443, threadinfo=f47bc000 task=f71a1a40)
> Stack: f2f9854c c02d1019 ed71b7b8 f2f98500 ed15cc80 00000282 ed71b780 00000100
>        c02ce99f f71a1a40 f2f98500 f71a1a40 00000000 f2f98500 f2f9854c c02f53ad
>        00000000 ed335db8 f2f98500 f2f98500 f47bdeb8 00000000 00000000 002ce99f
> Call Trace:
>  [<c02d1019>] skb_copy_datagram_iovec+0x180/0x1f8
>  [<c02ce99f>] alloc_skb+0x31/0xc1
>  [<c02f53ad>] tcp_recvmsg+0x2b1/0x74e
>  [<c02fd83f>] tcp_rcv_established+0x5d2/0x77a
>  [<c02ce2e0>] sock_common_recvmsg+0x41/0x57
>  [<c02cb052>] sock_aio_read+0xf9/0x12b
>  [<c014fccb>] do_sync_read+0x9e/0xec
>  [<c01291ae>] autoremove_wake_function+0x0/0x37
>  [<c014fe23>] vfs_read+0x10a/0x10e
>  [<c0150064>] sys_read+0x41/0x6a
>  [<c0102d29>] syscall_call+0x7/0xb
> Code: a1 04 07 39 c0 e8 c0 e5 e3 ff 89 c2 85 c0 74 2d 83 87 08 04 00 00 01 8b 8
> #############################################################

Please provide full info: kernel version and configuration as well
as hardware information (lspci).
Since it looks like a Fedora Core kernel, you may have to ask the fedora
list.