diff --git a/drivers/crypto/hisilicon/sgl.c b/drivers/crypto/hisilicon/sgl.c
index 3bff6394acaf..cf1629c367b3 100644
--- a/drivers/crypto/hisilicon/sgl.c
+++ b/drivers/crypto/hisilicon/sgl.c
@@ -66,6 +66,11 @@ struct hisi_acc_sgl_pool *hisi_acc_create_sgl_pool(struct device *dev,
 
 	sgl_size = sizeof(struct acc_hw_sge) * sge_nr +
 		   sizeof(struct hisi_acc_hw_sgl);
+
+	/*
+	 * the pool may allocate a block of memory of size PAGE_SIZE * 2^(MAX_ORDER - 1),
+	 * block size may exceed 2^31 on ia64, so the max of block size is 2^31
+	 */
 	block_size = 1 << (PAGE_SHIFT + MAX_ORDER <= 32 ?
 			   PAGE_SHIFT + MAX_ORDER - 1 : 31);
 	sgl_num_per_block = block_size / sgl_size;