Description of Problem:
Kernel panic during disk write.
  Supermicro
370DLE motherboard, 2x1GHZ Pentium III processors, 1 GB memory.
As far as I can tell, it's writing to disk drive /dev/hdc at the
time of the kernel panic, because after the panic all access to that
drive hangs, and the load goes up by one each time you try to access it,
with another hung process. (/dev/hdc is an IBM 40 GB disk drive,
model IC35L040AVER07-0). There is an identical /dev/hdd, and a 20 GB
/dev/hda.  We run them all with UltraDMA mode 2.
/dev/hdc:
 multcount    = 16 (on)
 I/O support  =  3 (32-bit w/sync)
 unmaskirq    =  0 (off)
 using_dma    =  1 (on)
 keepsettings =  0 (off)
 nowerr       =  0 (off)
 readonly     =  0 (off)
 readahead    =  8 (on)
 geometry     = 5005/255/63, sectors = 80418240, start = 0


Version-Release number of selected component (if applicable):
kernel-smp-2.4.18-4.i686.rpm
(as downloaded from redhat update site).

How Reproducible:
Have seen this problem about eight times in the past two months
on four machines with identical configuration and near-continuous 
disk access.

Steps to Reproduce:
1. Load kernel on the system
2. Let users pound with near-continuous disk access, randomly reading and
writing for a couple of months
3. During a disk read, you will see the kernel panic

Actual Results:
The machine stays up after the message but access to the disk 
is impossible and has to be cleared by reboot.
Full dump appears below:
Unable to handle kernel NULL pointer dereference at virtual address 00000008
 printing eip:
c016a0e9
*pde = 00000000
Oops: 0000
nfs lockd sunrpc autofs e1000 ipchains ide-cd cdrom usb-ohci usbcore
CPU:    1
EIP:    0010:[<c016a0e9>]    Tainted: P
EFLAGS: 00010202
 
EIP is at ext2_new_block [kernel] 0x589 (2.4.18-4smp)
eax: 00000000   ebx: 00001000   ecx: 0000000c   edx: ea5b9ba0
esi: 00000000   edi: f28a0000   ebp: 00002b2f   esp: f28a1d3c
ds: 0018   es: 0018   ss: 0018
Process AC++Dump_4.6.2 (pid: 1511, stackpage=f28a1000)
Stack: ea5b9ba0 00001000 00000000 00000000 c01e41df c5491c80 ef2473e0 f28a1d8c
       ef2473e0 f6ce3800 f897a792 00000001 eb94dd80 eb94dd80 f6d8c400 f6d8bc60
       f7ce1000 f6ce3800 00000063 ef2473e0 f6db7720 0000012b 1219c8a5 00000cdd
Call Trace: [<c01e41df>] nf_hook_slow [kernel] 0x10f
[<f897a792>] e1000_clean_rx_irq [e1000] 0x2b2
[<c016c793>] ext2_alloc_block [kernel] 0x73
[<c016c9c0>] ext2_alloc_branch [kernel] 0x30
[<c016c922>] ext2_get_branch [kernel] 0x52
[<c016cdb6>] ext2_get_block [kernel] 0x256
[<c0144c0f>] __block_prepare_write [kernel] 0x12f
[<c0144186>] balance_dirty [kernel] 0x6
[<c0144ee1>] __block_commit_write [kernel] 0xb1
[<c01455a2>] block_prepare_write [kernel] 0x22
[<c016cb60>] ext2_get_block [kernel] 0x0
[<c013285d>] generic_file_write [kernel] 0x4fd
[<c016cb60>] ext2_get_block [kernel] 0x0
[<c0127233>] sys_rt_sigaction [kernel] 0x93
[<c0141bf6>] sys_write [kernel] 0x96
[<c014190f>] sys_lseek [kernel] 0xbf
[<c0108c6b>] system_call [kernel] 0x33
 
 
Code: ff 50 08 83 c4 10 48 75 6a 8b 47 1c 85 c0 79 13 6a 3e 68 c0



Expected Results:


Additional Information: