Who takes care of memory synchronization in case of multi core or multi processor system?

Question

In multi-processor system it is possible that 2 core's trying to modify same memory, then who takes care of it? - MMU/OS?
And, in single processor but multi-core system who takes care of it? - CPU itself or MMU/OS?

Answer 1

In both the cases, OS responsibility to share the memory between the processes running in them, this will be achieved by allocating different memory for each, will be handled in MMU(Virtual address space). If the memory is shred between two threads, then it's the responsibility of the programmer synchronize