This is where the problem lies. T2 will not be able to lock the mutex for A, because T1 is holding it. T1 will not be able to lock the mutex for B, because T1T2 is holding it. More importantly, neither T1 nor T2 will be able to release the mutex that the other needs, since they are both blocking trying to acquire the mutex the other has.
What needs to be fixed?
In the Deadlocks section, in the 4th paragraph --
This is where the problem lies. T2 will not be able to lock the mutex for A, because T1 is holding it. T1 will not be able to lock the mutex for B, because
T1T2 is holding it. More importantly, neither T1 nor T2 will be able to release the mutex that the other needs, since they are both blocking trying to acquire the mutex the other has.