In JLS, §17.4.5. Happens-before Order, it says that
A program is correctly synchronized if and only if all sequentially consistent executions are free of data races.
According to discussion in Does a correctly synchronized program still allow data race?(Part I),we get following conclusion:
A program can be correctly synchronized and have data races.
The combination of two conclusions means that it must exists such an example:
All sequentially consistent executions of a program are data race free, but the normal executions (executions other than sequentially consistent executions) of such a program contain data race.
After heavy consideration, I still can not find such a code sample. So how about you?