Searches for both resonant and nonresonant Higgs boson pair production are performed in the hh\u2192bb\u3c4\u3c4, \u3b3\u3b3WW 17 final states using 20.3 fb-1 of pp collision data at a center-of-mass energy of 8 TeV recorded with the ATLAS detector at the Large Hadron Collider. No evidence of their production is observed and 95% confidence-level upper limits on the production cross sections are set. These results are then combined with the published results of the hh\u2192\u3b3\u3b3bb, bbbb analyses. An upper limit of 0.69 (0.47) pb on the nonresonant hh production is observed (expected), corresponding to 70 (48) times the SM gg\u2192hh cross section. For production via narrow resonances, cross-section limits of hh production from a heavy H...