diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index dd8ad2a..a0db1fe 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1077,14 +1077,31 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 	}
 }
 
+static void scsi_dump_req(struct request *req)
+{
+	struct bio_vec bvec;
+	struct bio *bio;
+	struct bvec_iter iter;
+	int i = 0;
+
+	__rq_for_each_bio(bio, req) {
+		printk("%d-%p\n", i, bio);
+		bio_for_each_segment(bvec, bio, iter) {
+			printk("\t %p %u %u\n", bvec.bv_page,
+					bvec.bv_offset, bvec.bv_len);
+		}
+	}
+}
+
 static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb)
 {
-	int count;
+	int count, pre_count = req->nr_phys_segments;
+	int alloc_cnt = queue_max_segments(req->q);
 
 	/*
 	 * If sg table allocation fails, requeue request later.
 	 */
-	if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments,
+	if (unlikely(scsi_alloc_sgtable(sdb, alloc_cnt,
 					req->mq_ctx != NULL)))
 		return BLKPREP_DEFER;
 
@@ -1093,6 +1110,11 @@ static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb)
 	 * each segment.
 	 */
 	count = blk_rq_map_sg(req->q, req, sdb->table.sgl);
+
+	if (count > sdb->table.nents) {
+		printk("%s prev vs. now: %d-%d\n", __func__, pre_count, count);
+		scsi_dump_req(req);
+	}
 	BUG_ON(count > sdb->table.nents);
 	sdb->table.nents = count;
 	sdb->length = blk_rq_bytes(req);