Hi, Apologies for posting another trivial query. After reading about ISRs and sleeping, I have cleared my doubts on why ISRs cannot sleep, but I still cannot understand why a normal kernel thread cannot sleep once it has disable preemption. Assuming that the kernel thread does NOT hold any locks, nor any per-cpu data, why stops it from sleeping after a call to preempt_disable()? TIA, LL - To unsubscribe from this list: send the line "unsubscribe linux-newbie" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.linux-learn.org/faqs