Is it okay to buy and use other people's patented utility model products for production and operation purposes without the permission of the patentee?

1. If the patentee sells it by himself or with the permission of others, it is already in exhaustion. You can buy again without his permission.

2. If it is not sold by the patentee himself or licensed by others, you buy and use it without knowing it:

Anyone who uses, promises to sell or sells an infringing patented product for the purpose of production and operation without knowing that it was manufactured and sold without the permission of the patentee shall not be liable for compensation if he can prove the legal source of the product.

But this kind of behavior is still infringement.