> Yah, some printk sprinkling might be a good start. But debugging in that > atomic context is always nasty. ;-\ Some very light printk sprinkling (one message in queue_task_work() in atomic context, one each in kill_me_now() and kill_me_maybe() to check when task_work actually called them. Cases 1 & 2 (user & normal copyin) now work just fine (hundreds of iterations). Case 3 (my futex test) just hangs with only two characters making it to the serial port "[ " Deeply strange. -Tony