BUG: scheduling while atomic

"Scheduling while atomic" means that a thread has called schedule() during an operation which is supposed to be atomic (ie uninterrupted).

printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",  prev->comm, prev->pid, preempt_count());

ex.

spin_lock_irqsave(&sysLock, flags);

msleep(100);

spin_lock_irqsave -> preempt_disable -> inc_preempt_count [current_thread_info()->preempt_count = 1 ]

msleep -> schedule -> preempt_disable -> inc_preempt_count [current_thread_info()->preempt_count = 2 ]

msleep -> schedule -> schedule_debug -> in_atomic_preempt_off

[ in_atomic_preempt_off checks if (preempt_count != 1) then printk "BUG: scheduling while atomic" ]