diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index 8ba1e97..5328f3c 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -10,6 +10,8 @@
 #include <linux/hrtimer.h>
 #include <linux/lightnvm.h>
 
+#define MAX_SG	128
+
 struct nullb_cmd {
 	struct list_head list;
 	struct llist_node ll_list;
@@ -19,6 +21,7 @@ struct nullb_cmd {
 	unsigned int tag;
 	struct nullb_queue *nq;
 	struct hrtimer timer;
+	struct scatterlist sg[MAX_SG];
 };
 
 struct nullb_queue {
@@ -351,6 +354,23 @@ static void null_request_fn(struct request_queue *q)
 	}
 }
 
+static int handle_sg(struct nullb_cmd *cmd)
+{
+	int num, i;
+	struct request *rq = cmd->rq;
+
+	num = blk_rq_map_sg(rq->q, rq, cmd->sg);
+	trace_printk("%s dump sg for %p(%d)\n", __func__, rq, rq->tag);
+	for (i = 0; i < num; i++) {
+		struct scatterlist *sg = &cmd->sg[i];
+		trace_printk("\t %4d: %u %u %llu\n",
+			     i, sg->offset, sg->length,
+			     (unsigned long long)sg->dma_address);
+	}
+
+	return 0;
+}
+
 static int null_queue_rq(struct blk_mq_hw_ctx *hctx,
 			 const struct blk_mq_queue_data *bd)
 {
@@ -365,6 +385,8 @@ static int null_queue_rq(struct blk_mq_hw_ctx *hctx,
 
 	blk_mq_start_request(bd->rq);
 
+	handle_sg(cmd);
+
 	null_handle_cmd(cmd);
 	return BLK_MQ_RQ_QUEUE_OK;
 }
@@ -707,6 +729,8 @@ static int null_add_dev(void)
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, nullb->q);
 	queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, nullb->q);
 
+	blk_queue_virt_boundary(nullb->q, (1UL << 12) - 1);
+	blk_queue_max_segments(nullb->q, MAX_SG);
 
 	mutex_lock(&lock);
 	list_add_tail(&nullb->list, &nullb_list);