* Preeti Murthy <preeti.lkml@xxxxxxxxx> [2013-11-13 16:22:37]: > Hi Srikar, > > update_group_power() is called only during load balancing during > update_sg_lb_stats(). > Load balancing begins at the base domain of the CPU,rq(cpu)->sd. This is > checked for > NULL. So how can update_group_power() be called in a scenario where the > base domain > of the CPU is not initialized? I say 'initialized' since you check for NULL > on rq(cpu)->sd. > update_group_power() also gets called from init_sched_groups_power(). And if you see the oops message, we know that the oops happens from that path. In build_sched_domains(), we do cpu_attach_domain() what updates rq->sd after the call to init_sched_groups_power(). So by the time init_sched_groups_power() is called rq->sd is not yet initialized. We only hit oops case, when the sd->flags has SD_OVERLAP set. > In the changelog, you say 'updated'. Are you saying that it has a stale > value? I said, "before the sched_domain for a cpu is updated", so its not yet updated or has stale value. As I said earlier in this mail, the initialization happens after we do a update_group_power(). > Please do elaborate on how you observed this. > Does this clarify? -- Thanks and Regards Srikar Dronamraju -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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