Hi,

With might_sleep reports several calls from invalid contexts during 
early boot:

First some calls due to irq off, preempt off: This are the first stages 
of start_kernel, irqs are not yet enabled.
Then calls with only preemption off: The kernel runs on the future idle 
thread, and these threads have preempt_count==1.

Attached is a patch that fixes the latter bug: ignore the preemption 
counter for the idle threads. I haven't figured out how to identify the 
calls before the first local_irq_enable().

--
    Manfred