Limited partners are just that. Limited to the extent of their investment in the partnership, i.e. what they paid for their stock. The GP is liable for losses in the partnership, not the LP's. Below is an excerpt from Wikipedia defining a limited partnership.
Limited liability
Like shareholders in a corporation, LPs have limited liability, meaning they are only liable on debts incurred by the firm to the extent of their registered investment and have no management authority. The GPs pay the LPs a return on their investment (similar to a dividend), the nature and extent of which is usually defined in the partnership agreement. General Partners thus carry more liability, and in cases of financial loss, the GPs will be liable.