Hello, I got the following stack trace when booting a 3.19.4 kernel (with grsecurity enabled, but this should not be related here), possible at the moment when the xhci driver was initially processing the USB devices: kernel BUG at lib/list_debug.c:39 Workqueue;: usb_hub_wq hub_event __list_add queue_command xhci_queue_slot_control xhci_alloc_dev usb_alloc_dev hub_event process_one_work The complete screenshot with all information can be found at http://picpaste.com/pics/IMG_20150805_072836-LAhi91tT.1439187381.jpg The system is a Lenovo T450s docked within a Lenovo Ultra Dock docking station. Attached are two external USB3 hubs (no devices attached there). USB devices attached during boot were a keyboard and a mouse, both attached to the docking unit. The error was not yet reproducible. The error seems to indicate that the xhci->cmd_list got modified while the list_add operation was taking place. I already checked the xhci code and apart from some shutdown handling didn't find any place, were the list was modified without taking the xhci->lock. Any idea, what might be the concurrent user causing this problem? Thanks for any input, Torsten -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
