Kernel panic - not syncing: Segfault with no mm

EIP: 0073:[<083e3e31>] CPU: 0 Not tainted ESP: 007b:b7f63fb8 EFLAGS: 00000292
    Not tainted
EAX: 00000000 EBX: 0000531e ECX: 00000013 EDX: 0000531e
ESI: 0000531a EDI: 00000000 EBP: 00000000 DS: 007b ES: 007b
085ef948:  [<08090890>] notifier_call_chain+0x2a/0x40
085ef964:  [<08081de7>] panic+0x70/0x102
085ef97c:  [<0806615d>] segv+0x23b/0x29c
085ef984:  [<0807db2c>] __activate_task+0x27/0x3f
085ef99c:  [<0807dc70>] activate_task+0x77/0xb4
085ef9c0:  [<0807dd7f>] try_to_wake_up+0x90/0xa5
085efa40:  [<08065eac>] segv_handler+0x0/0x76
085efa48:  [<08065f1b>] segv_handler+0x6f/0x76
085efa58:  [<083e3e31>] kill+0x11/0x20
085efa68:  [<08078aee>] sig_handler_common_skas+0x92/0xe1
085efa88:  [<08075063>] sig_handler+0x37/0x6c
085efaa0:  [<0807716d>] hard_handler+0x19/0x20
085efaac:  [<083e3bd8>] __restore+0x0/0x8
085efaec:  [<0829eb74>] cfq_dispatch_insert+0x1e/0x71
085efda0:  [<0829ecc3>] __cfq_dispatch_requests+0x72/0x200
085efdb8:  [<0829ec26>] cfq_select_queue+0x5f/0x8a
085efdcc:  [<0829efa7>] cfq_dispatch_requests+0x70/0x9a
085efdec:  [<0829448e>] elv_next_request+0x45/0x156
085efdf8:  [<08079fc4>] arch_switch_to_skas+0x17/0x4a
085efe0c:  [<0806ee17>] do_ubd_request+0x2c/0xbe
085efe20:  [<08063585>] _switch_to+0x4d/0xd6
085efe58:  [<08421ed2>] schedule+0x2f0/0x579
085efe68:  [<08297523>] blk_start_queueing+0x26/0x2a
085efe70:  [<082a0183>] cfq_kick_queue+0x29/0x3d
085efe80:  [<08094480>] run_workqueue+0xad/0x1b1
085efea8:  [<082a015a>] cfq_kick_queue+0x0/0x3d
085efeb8:  [<080754a4>] set_signals+0x1f/0x2c
085efed0:  [<08094737>] worker_thread+0x1b3/0x1db
085efee4:  [<08421ed2>] schedule+0x2f0/0x579
085eff14:  [<0807e5fc>] default_wake_function+0x0/0x12
085eff34:  [<0807e5fc>] default_wake_function+0x0/0x12
085eff54:  [<08094584>] worker_thread+0x0/0x1db
085eff5c:  [<0809793f>] kthread+0xcb/0xcf
085eff94:  [<08074868>] run_kernel_thread+0x61/0x65
085effb4:  [<08074835>] run_kernel_thread+0x2e/0x65
085effd0:  [<08066f4a>] new_thread_handler+0x87/0xda
085effd4:  [<08097874>] kthread+0x0/0xcf

2.6.20-linode28