------------[ cut here ]------------
WARNING: at /build/buildd/linux-2.6.28/drivers/usb/serial/usb-serial.c:326 serial_write_room+0x81/0x90()
Modules linked in: usb_storage option binfmt_misc radeon drm ppdev bridge stp bnep video output input_polldev ipt_REJECT ipt_LOG xt_limit xt_tcpudp xt_state ipt_addrtype ip6table_filter ip6_tables nf_nat_irc nf_conntrack_irc nf_nat_ftp nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_conntrack_ftp nf_conntrack iptable_filter ip_tables x_tables lp parport snd_emu10k1_synth snd_emux_synth snd_seq_virmidi snd_seq_midi_emul snd_emu10k1 snd_hda_intel snd_ac97_codec snd_pcm_oss snd_mixer_oss ac97_bus snd_util_mem snd_pcm snd_hwdep snd_seq_dummy snd_seq_oss snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq snd_timer snd_seq_device snd snd_page_alloc psmouse emu10k1_gp soundcore shpchp gameport i2c_piix4 serio_raw pcspkr btusb joydev sha256_generic aes_x86_64 aes_generic cbc hid_logitech ff_memless usbhid ohci1394 ieee1394 floppy dm_crypt atl1e fbcon tileblit font bitblit softcursor
Pid: 17382, comm: metropolis_3.12 Tainted: G        W  2.6.28-11-generic #42-Ubuntu
Call Trace:
 <IRQ>  [<ffffffff802509bf>] warn_on_slowpath+0x5f/0x90
 [<ffffffff8052e4c2>] ? usb_hcd_submit_urb+0x82/0x1b0
 [<ffffffff8052ea4d>] ? usb_submit_urb+0xdd/0x260
 [<ffffffffa0478684>] ? option_write+0x114/0x220 [option]
 [<ffffffff80550361>] serial_write_room+0x81/0x90
 [<ffffffff80492a28>] tty_write_room+0x18/0x20
 [<ffffffff8048fef1>] opost+0x21/0x290
 [<ffffffff80490198>] echo_char+0x38/0x80
 [<ffffffff80491e2c>] n_tty_receive_char+0x13c/0x7a0
 [<ffffffff80492704>] n_tty_receive_buf+0x274/0x490
 [<ffffffff802424b2>] ? enqueue_entity+0x122/0x2b0
 [<ffffffff8069e569>] ? _spin_lock+0x9/0x10
 [<ffffffff8022f669>] ? default_spin_lock_flags+0x9/0x10
 [<ffffffff80494515>] ? tty_ldisc_try+0x45/0x60
 [<ffffffff804951f8>] flush_to_ldisc+0x128/0x1f0
 [<ffffffff80495334>] tty_flip_buffer_push+0x74/0x80
 [<ffffffffa04790c2>] option_indat_callback+0xf2/0x168 [option]
 [<ffffffff8052d14f>] usb_hcd_giveback_urb+0x5f/0xe0
 [<ffffffff80542e84>] ehci_urb_done+0xd4/0xf0
 [<ffffffff805444b5>] qh_completions+0xb5/0x4d0
 [<ffffffff8054496e>] scan_async+0x9e/0x1d0
 [<ffffffff8054531b>] ehci_work+0x4b/0xc0
 [<ffffffff80545e85>] ehci_irq+0x1f5/0x210
 [<ffffffff8025bf20>] ? run_timer_softirq+0x220/0x260
 [<ffffffff8052cb6a>] usb_hcd_irq+0x4a/0xa0
 [<ffffffff8029f055>] handle_IRQ_event+0x45/0x80
 [<ffffffff802a0e7a>] handle_fasteoi_irq+0x8a/0x100
 [<ffffffff80213d8c>] ? call_softirq+0x1c/0x30
 [<ffffffff802152c0>] do_IRQ+0xc0/0x110
 [<ffffffff80212bf3>] ret_from_intr+0x0/0x29
 <EOI> <4>---[ end trace 2dc55e2921be02f0 ]---