An exactly-solvable model of the non-relativistic harmonic oscillator with a position-dependent effective mass is constructed. The model behaves itself as a semi-infinite quantum well of the non-rectangular profile. Such a form of the profile looks like a step-harmonic potential as a consequence of the certain analytical dependence of the effective mass from the position and semiconfinement parameter a. Wavefunctions of the oscillator model are expressed through the Bessel polynomials. The energy spectrum is discrete, non-equidistant, and finite as a consequence of its dependence from parameter a, too. At the limit, when the parameter a goes to infinity, both wavefunctions, and the energy spectrum of the model under construction correctly reduce to corresponding results of the usual non-relativistic harmonic oscillator with a constant effective mass. We also present a new limit relation that reduces Bessel polynomials directly to Hermite polynomials and prove its correctness by using the mathematical induction technique.