I got this just before I went away on a trip.
Nov 20 13:46:47 localhost kernel: buffer layer error at fs/buffer.c:399
Nov 20 13:46:47 localhost kernel: Pass this trace through ksymoops for reporting
Nov 20 13:46:47 localhost kernel: Call Trace: [<c0139526>] [<c013a447>] [<c013a9e6>] [<c013aa17>] [<c012d554>] [<c013b45c>] [<c0160050>] [<c0127e42>] [<c0160050>] [<c011133b>] [<c0128226>] [<c0137f32>] [<c017a3e3>] [<c0137ff8>] [<c0108a0f>]
ksymoops 2.4.4 on i686 2.5.47. Options used
-V (default)
-k /proc/ksyms (default)
-l /proc/modules (default)
-o /lib/modules/2.5.47/ (default)
-m /boot/System.map-2.5.47 (default)
Warning: You did not tell me where to find symbol information. I will
assume that the log matches the kernel and modules that are running
right now and I'll use the default options above for symbol resolution.
If the current kernel and/or modules do not match the log, you can get
more accurate output by telling me the kernel version and where to find
map, modules, ksyms etc. ksymoops -h explains the options.
No modules in ksyms, skipping objects
Warning (read_lsmod): no symbols in lsmod, is /proc/modules a valid lsmod file?
Nov 20 13:46:47 localhost kernel: Call Trace: [<c0139526>] [<c013a447>] [<c013a9e6>] [<c013aa17>] [<c012d554>] [<c013b45c>] [<c0160050>] [<c0127e42>] [<c0160050>] [<c011133b>] [<c0128226>] [<c0137f32>] [<c017a3e3>] [<c0137ff8>] [<c0108a0f>]
Warning (Oops_read): Code line not seen, dumping what data is available
Trace; c0139526 <__find_get_block_slow+a6/e0>
Trace; c013a447 <unmap_underlying_metadata+17/50>
Trace; c013a9e6 <__block_prepare_write+166/420>
Trace; c013aa17 <__block_prepare_write+197/420>
Trace; c012d554 <buffered_rmqueue+c4/d0>
Trace; c013b45c <block_prepare_write+1c/40>
Trace; c0160050 <ext2_get_block+0/390>
Trace; c0127e42 <generic_file_write_nolock+5e2/960>
Trace; c0160050 <ext2_get_block+0/390>
Trace; c011133b <do_page_fault+11b/41f>
Trace; c0128226 <generic_file_write+46/60>
Trace; c0137f32 <vfs_write+b2/110>
Trace; c017a3e3 <copy_to_user+33/40>
Trace; c0137ff8 <sys_write+28/40>
Trace; c0108a0f <syscall_call+7/b>
3 warnings issued. Results may not be reliable.
Hope this helps, or even better is fixed already.