On 12/13/2014 01:25 AM, Tejun Heo wrote: > On Fri, Dec 12, 2014 at 06:19:53PM +0800, Lai Jiangshan wrote: >> Yasuaki Ishimatsu hit a bug when the numa mapping between CPU and node >> is changed. And the previous path fixup wq_numa_possible_cpumask. >> (See more information form the changelog of that patch) >> >> After wq_numa_possible_cpumask was updated, the new pool->node will be >> correct, but the existing pools (and workers) are still running, some of >> them are running with the wrong pool->node, or even worse, with pool->node >> which is quitted node, they create_worker() on wrong pool->node. >> These create_worker() may create workers on wrong node or failed without >> any progress (when with pool->node which is quitted node). >> >> So we need to update the pool->node when the numa mapping is changed. >> >> We simply re-calc the pool->node when the numa mapping changed. It reuses >> the code from get_unbound_pool() for unbound pool. > > I don't get this patch. If a node is gone, all its cpus would be gone > and the pool should be discarded. If a new node comes online with > different mappings, new sets of pools should serve them instead of > recycling the old ones. Wouldn't it make a lot more sense to make > sure we don't reuse the pools w/ old mappings for new pwqs? >
The pwqs of the old node's cpumask do be discarded. But the pools of the old node's cpumask maybe recycle. For example, a new workqueue's affinity is set to the old node's cpumask before the pool is dead. Any old pool can long live. > Thanks. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
