* If the cpu isn't present, the cpu is mapped to first hctx.
         */
        for_each_possible_cpu(i) {
-               hctx_idx = q->mq_map[i];
+               hctx_idx = set->mq_map[i];
                /* unmapped hw queue can be remapped after CPU topo changed */
                if (!set->tags[hctx_idx] &&
                    !__blk_mq_alloc_rq_map(set, hctx_idx)) {
                         * case, remap the current ctx to hctx[0] which
                         * is guaranteed to always have tags allocated
                         */
-                       q->mq_map[i] = 0;
+                       set->mq_map[i] = 0;
                }
 
                ctx = per_cpu_ptr(q->queue_ctx, i);
 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
                                     struct request_queue *q)
 {
-       q->tag_set = set;
-
        mutex_lock(&set->tag_list_lock);
 
        /*
                kobject_put(&hctx->kobj);
        }
 
-       q->mq_map = NULL;
-
        kfree(q->queue_hw_ctx);
 
        /*
                int node;
                struct blk_mq_hw_ctx *hctx;
 
-               node = blk_mq_hw_queue_to_node(q->mq_map, i);
+               node = blk_mq_hw_queue_to_node(set->mq_map, i);
                /*
                 * If the hw queue has been mapped to another numa node,
                 * we need to realloc the hctx. If allocation fails, fallback
        if (!q->queue_hw_ctx)
                goto err_percpu;
 
-       q->mq_map = set->mq_map;
-
        blk_mq_realloc_hw_ctxs(set, q);
        if (!q->nr_hw_queues)
                goto err_hctxs;
        blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
 
        q->nr_queues = nr_cpu_ids;
+       q->tag_set = set;
 
        q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
 
 
 static inline struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q,
                int cpu)
 {
-       return q->queue_hw_ctx[q->mq_map[cpu]];
+       struct blk_mq_tag_set *set = q->tag_set;
+
+       return q->queue_hw_ctx[set->mq_map[cpu]];
 }
 
 /*