I found below call trace today morning in dmesg output on one of my test computer:
============================================= [ INFO: possible recursive locking detected ] 2.6.21.4-2.1 #1 --------------------------------------------- usb-storage/1806 is trying to acquire lock: (&(us->dev_mutex)){--..}, at: [<c05f28a2>] mutex_lock+0x1c/0x1f but task is already holding lock: (&(us->dev_mutex)){--..}, at: [<c05f28a2>] mutex_lock+0x1c/0x1f other info that might help us debug this: 1 lock held by usb-storage/1806: #0: (&(us->dev_mutex)){--..}, at: [<c05f28a2>] mutex_lock+0x1c/0x1f stack backtrace: [<c04064d4>] show_trace_log_lvl+0x1a/0x2f [<c0406a7f>] show_trace+0x12/0x14 [<c0406afa>] dump_stack+0x16/0x18 [<c043fb88>] __lock_acquire+0x116/0xb4b [<c044097e>] lock_acquire+0x56/0x6f [<c05f2721>] __mutex_lock_slowpath+0xe5/0x24a [<c05f28a2>] mutex_lock+0x1c/0x1f [<f89981d3>] storage_pre_reset+0xe/0x10 [usb_storage] [<c0552e3d>] usb_reset_composite_device+0x9c/0x124 [<f8996888>] usb_stor_port_reset+0x34/0x57 [usb_storage] [<f899778e>] usb_stor_invoke_transport+0x255/0x293 [usb_storage] [<f89967b9>] usb_stor_transparent_scsi_command+0x8/0xa [usb_storage] [<f899833e>] usb_stor_control_thread+0x136/0x1b7 [usb_storage] [<c0435edf>] kthread+0xb3/0xdc [<c0406177>] kernel_thread_helper+0x7/0x10 ======================= usb 1-1.2: reset high speed USB device using ehci_hcd and address 5 kloczek -- ----------------------------------------------------------- *Ludzie nie mają problemów, tylko sobie sami je stwarzają* ----------------------------------------------------------- Tomasz Kłoczko, sys adm @zie.pg.gda.pl|*e-mail: [EMAIL PROTECTED]