A processing unit includes a store-in lower level cache having reservation logic that determines presence or absence of a reservation and a processor core including a store-through upper level cache, an instruction execution unit, a load unit that, responsive to a hit in the upper level cache on a load-reserve operation generated through execution of a load-reserve instruction by the instruction execution unit, temporarily buffers a load target address of the load-reserve operation, and a flag indicating that the load-reserve operation bound to a value in the upper level cache. If a storage-modifying operation is received that conflicts with the load target address of the load-reserve operation, the processor core sets the flag to a particular state, and, responsive to execution of a store-conditional instruction, transmits an associated store-conditional operation to the lower level cache with a fail indication if the flag is set to the particular state.