Radio-loud narrow-line Seyfert 1 galaxies (RL-NLS1) are characterized by relatively small widths of emission lines, hence their virial black hole mass estimates are typically smaller (and Eddington ratios correspondingly higher) than those of broad line Type 1 active galactic nuclei. However independent black hole mass estimation methods, such as those based on the accretion disk spectrum modeling, suggest that RL-NLS1 black hole masses are significantly larger than those estimated by virial methods, and that masses for both narrow and broad line Type 1 sources lie in the same range. In this paper we provide new black hole mass estimates for 25 RL-NLS1 sources (using the disk modeling method) and argue that a plausible way to solve the black hole mass discrepancy is to assume that the accretion disk in RL-NLS1 has a radiatively efficiency $\eta \sim 1$\%, significantly lower than previously assumed.