Questions about Shared Memory bank conflict in CUDA

2 contains 1. true + true

1 also contains an exception: broadcasting. If not only 2 but all threads access same bank, it is broadcasted to all items of warp.

1 is true because shared memory serializes access to same bank if its not intended to broadcast.

2 is true because shared memory serves multiple warps concurrently.

There is also another thing from CUDA documentation:

Devices of compute capability 2.0 and higher have the additional ability to multicast shared memory accesses, meaning that multiple accesses to the same location by any number of threads within a warp are served simultaneously.