Transferring cache line ownership between processors in a shared memory multi-processor computer system. A request for ownership of a cache line is sent from a requesting processor to a memory unit. The memory unit receives the request and determines which one of a plurality of processors other than the requesting processor has ownership of the requested cache line. The memory sends an ownership recall to that processor. In response to the ownership recall, the other processor sends the requested cache line to the requesting processor, which may send a response to the memory unit to confirm receipt of the requested cache line. The other processor may optionally send a response to the memory unit to confirm that the other processor has sent the requested cache line to the requesting processor. A copy of the data for the requested cache line may, under some circumstances, also be sent to the memory unit by the other processor as part of the response.