[$] The trouble with SMC-R

Among the many features merged for the 4.11kernel was the "shared memory communications over RDMA" (SMC-R)protocol from IBM. SMC-R is ahigh-speed data-center communications protocol that is claimed to be muchmore efficient than basic TCP sockets. As it turns out, though, the merging of this code was a surprise - and an unpleasantone at that - to a relevant segment of the kernel development community.This issue and the difficulties in resolving it are an indicator of how theincreasingly fast-paced kernel development community can go off track.