rhashtable_insert_rehash() requires RCU locks to be held in order
to access ht->tbl and traverse to the last table.
Fixes: ccd57b1bd324 ("rhashtable: Add immediate rehash during insertion") Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>