Comment 26 for bug 1296660

Also seeing the issue here (on occasion) w/ 3.13.0-37-generic:

fb: conflicting fb hw usage nouveaufb vs VESA VGA - removing generic driver
Console: switching to colour dummy device 80x25
BUG: unable to handle kernel NULL pointer dereference at 0000000000000138
IP: [<ffffffff8145d382>] con_set_unimap+0x32/0x290
....
Call Trace:
[<ffffffff8131226d>] ? apparmor_capable+0x1d/0x130
[<ffffffff81457223>] vt_ioctl+0xe83/0x11c0
[<ffffffff8144ad3d>] tty_ioctl+0x26d/0xbb0
[<ffffffff811d03a0>] do_vfs_ioctl+0x2e0/0x4c0
[<ffffffff811d0601>] SyS_ioctl+0x81/0xa0
[<ffffffff8172f82d>] system_call_fastpath+0x1a/0x1f