blk-mq: fix q->mq_usage_counter access race
CPU hotplug handling for blk-mq (blk_mq_queue_reinit) accesses q->mq_usage_counter while freezing all request queues in all_q_list. On the other hand, q->mq_usage_counter is deinitialized in blk_mq_free_queue() before deleting the queue from all_q_list. So if CPU hotplug event occurs in the window, percpu_ref_kill() is called with q->mq_usage_counter which has already been marked dead, and it triggers warning. Fix it by deleting the queue from all_q_list earlier than destroying q->mq_usage_counter. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Reviewed-by: Ming Lei <tom.leiming@gmail.com> Cc: Ming Lei <tom.leiming@gmail.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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Родитель
a723bab3d7
Коммит
0e62636820
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@ -2067,15 +2067,16 @@ void blk_mq_free_queue(struct request_queue *q)
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{
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{
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struct blk_mq_tag_set *set = q->tag_set;
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struct blk_mq_tag_set *set = q->tag_set;
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mutex_lock(&all_q_mutex);
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list_del_init(&q->all_q_node);
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mutex_unlock(&all_q_mutex);
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blk_mq_del_queue_tag_set(q);
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blk_mq_del_queue_tag_set(q);
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blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
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blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
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blk_mq_free_hw_queues(q, set);
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blk_mq_free_hw_queues(q, set);
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percpu_ref_exit(&q->mq_usage_counter);
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percpu_ref_exit(&q->mq_usage_counter);
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mutex_lock(&all_q_mutex);
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list_del_init(&q->all_q_node);
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mutex_unlock(&all_q_mutex);
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}
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}
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/* Basically redo blk_mq_init_queue with queue frozen */
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/* Basically redo blk_mq_init_queue with queue frozen */
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