  Relativistic collisionless shocks are associated with efficient particle
acceleration when propagating into weakly magnetized homogeneous media; as the
magnetization increases, particle acceleration becomes suppressed. We
demonstrate that this changes when the upstream carries kinetic-scale
inhomogeneities, as is often the case in astrophysical environments. We use
fully-kinetic simulations to study relativistic perpendicular shocks in
magnetized pair plasmas interacting with upstream density perturbations. For
amplitudes of $\delta \rho/\rho \gtrsim 0.5$, the upstream fluctuations are
found to corrugate the shock front and generate large-scale turbulent shear
motions in the downstream, which in turn are capable of accelerating particles.
This can revive relativistic magnetized shocks as viable energization sites in
astrophysical systems, such as jets and accretion disks. The generation of
large-scale magnetic structures also has important implications for
polarization signals from blazars.
