Per discussion here is the panic I hit yesterday and again today, I will also add hw info. This occurred when having multiple rsync's pounding the fileystem (ext4 on a USB 1TB disk) after about an hour. Will also test brad's kernel to see if it gets any better. 


Jun 30 23:46:12 frylock kernel: [114450.175420] BUG: unable to handle kernel NULL pointer dereference at 00
00000c
Jun 30 23:46:12 frylock kernel: [114450.175425] IP: [<c01d9f13>] do_writepages+0x13/0x40
Jun 30 23:46:12 frylock kernel: [114450.175431] *pdpt = 000000000088f001 *pde = 0000000000000000 
Jun 30 23:46:12 frylock kernel: [114450.175434] Oops: 0000 [#1] SMP 
Jun 30 23:46:12 frylock kernel: [114450.175437] last sysfs file: /sys/devices/pci0000:00/0000:00:1a.7/usb1/
1-5/1-5:1.0/host0/target0:0:0/0:0:0:0/block/sde/sde1/stat
Jun 30 23:46:12 frylock kernel: [114450.175439] Modules linked in: raid0 binfmt_misc ppdev nfsd exportfs nf
s lockd nfs_acl auth_rpcgss sunrpc xt_TCPMSS xt_limit xt_tcpudp nf_nat_irc nf_nat_ftp snd_hda_codec_intelhd
mi ipt_LOG ipt_MASQUERADE snd_hda_codec_realtek xt_DSCP ipt_REJECT nf_conntrack_irc nf_conntrack_ftp snd_hd
a_intel xt_state iptable_nat snd_hda_codec nf_nat snd_hwdep nf_conntrack_ipv4 nf_conntrack snd_pcm_oss snd_
mixer_oss nf_defrag_ipv4 snd_pcm fbcon tileblit snd_seq_dummy iptable_mangle font snd_seq_oss iptable_filte
r bitblit ip_tables snd_seq_midi softcursor snd_rawmidi x_tables snd_seq_midi_event snd_seq vga16fb vgastat
e snd_timer snd_seq_device snd i915 drm_kms_helper soundcore snd_page_alloc drm i2c_algo_bit video intel_ag
p agpgart output lp parport hid_belkin usbhid hid usb_storage r8169 mii ahci e1000e
Jun 30 23:46:12 frylock kernel: [114450.175485] 
Jun 30 23:46:12 frylock kernel: [114450.175487] Pid: 4448, comm: flush-9:0 Not tainted (2.6.32-22-generic-p
ae #36-Ubuntu) Product Name To Be Filled By O.E.M.
Jun 30 23:46:12 frylock kernel: [114450.175489] EIP: 0060:[<c01d9f13>] EFLAGS: 00010206 CPU: 0
Jun 30 23:46:12 frylock kernel: [114450.175492] EIP is at do_writepages+0x13/0x40
Jun 30 23:46:12 frylock kernel: [114450.175493] EAX: d3d31d98 EBX: d3d31d08 ECX: 00000000 EDX: e034bf10
Jun 30 23:46:12 frylock kernel: [114450.175495] ESI: 00000007 EDI: f69f90e0 EBP: e034be90 ESP: e034be90
Jun 30 23:46:12 frylock kernel: [114450.175497]  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
Jun 30 23:46:12 frylock kernel: [114450.175499] Process flush-9:0 (pid: 4448, ti=e034a000 task=f6a4b340 tas
k.ti=e034a000)
Jun 30 23:46:12 frylock kernel: [114450.175500] Stack:
Jun 30 23:46:12 frylock kernel: [114450.175502]  e034beb0 c022f895 d3d31d98 00000000 e034bf10 d3d31d08 0000
0000 f69f90e0
Jun 30 23:46:12 frylock kernel: [114450.175506] <0> e034bef8 c0230399 e034bee0 01b372c7 f69f9108 00000000 0
0000000 e034bf10
Jun 30 23:46:12 frylock kernel: [114450.175511] <0> f69f90f8 f69f9100 00000000 f69f90e0 dfedc7b0 d78ba8f0 e
ed5cc00 e034bf68
Jun 30 23:46:12 frylock kernel: [114450.175517] Call Trace:
Jun 30 23:46:12 frylock kernel: [114450.175521]  [<c022f895>] ? writeback_single_inode+0xd5/0x380
Jun 30 23:46:12 frylock kernel: [114450.175524]  [<c0230399>] ? writeback_inodes_wb+0x389/0x530
Jun 30 23:46:12 frylock kernel: [114450.175527]  [<c0230637>] ? wb_writeback+0xf7/0x1a0
Jun 30 23:46:12 frylock kernel: [114450.175529]  [<c02308fe>] ? wb_do_writeback+0x15e/0x170
Jun 30 23:46:12 frylock kernel: [114450.175532]  [<c023094b>] ? bdi_writeback_task+0x3b/0xb0
Jun 30 23:46:12 frylock kernel: [114450.175535]  [<c01e91d0>] ? bdi_start_fn+0x0/0xc0
Jun 30 23:46:12 frylock kernel: [114450.175538]  [<c01e922d>] ? bdi_start_fn+0x5d/0xc0
Jun 30 23:46:12 frylock kernel: [114450.175540]  [<c01e91d0>] ? bdi_start_fn+0x0/0xc0
Jun 30 23:46:12 frylock kernel: [114450.175543]  [<c016f914>] ? kthread+0x74/0x80
Jun 30 23:46:12 frylock kernel: [114450.175545]  [<c016f8a0>] ? kthread+0x0/0x80
Jun 30 23:46:12 frylock kernel: [114450.175548]  [<c010a4e7>] ? kernel_thread_helper+0x7/0x10
Jun 30 23:46:12 frylock kernel: [114450.175550] Code: 70 8c 1d c0 89 04 24 e8 7c fc ff ff 89 c1 83 c4 04 89
 c8 5b 5d c3 66 90 55 89 e5 0f 1f 44 00 00 31 c9 83 7a 10 00 7e 0e 8b 48 38 <8b> 49 0c 85 c9 74 0e ff d1 89
 c1 89 c8 5d c3 8d b6 00 00 00 00 
Jun 30 23:46:12 frylock kernel: [114450.175578] EIP: [<c01d9f13>] do_writepages+0x13/0x40 SS:ESP 0068:e034b
e90
Jun 30 23:46:12 frylock kernel: [114450.175582] CR2: 000000000000000c
Jun 30 23:46:12 frylock kernel: [114450.175584] ---[ end trace bfc5584c11e2bb89 ]---