Grids are not properly nested.

[FR13ndSDP]

I'm trying to implement an embedded boundary algorithm and in my code I got this error "WARNING: Grids are not properly nested. Consider using amr.blocking_factor = 4 4 4
amrex::Abort::2::Grids must be properly nested for EB or GPU !!!" only when my refinement level is larger than 3, so I'm wondering what this stands for?

Code from where abort happens:

#if defined(AMREX_USE_EB) || defined(AMREX_USE_GPU)
#  if defined(AMREX_USE_EB) && !defined(AMREX_USE_GPU)
                if (EB2::TopIndexSpaceIfPresent())
#  endif
                {
                    IntVect new_blocking_factor = AmrLevel::ProperBlockingFactor
                        (m_amrlevel, boxGrow, boxType, desc, SComp);
                    amrex::Print() << "WARNING: Grids are not properly nested. Consider using amr.blocking_factor = "
                                   << AMREX_D_TERM(new_blocking_factor[0],
                                         << " " << new_blocking_factor[1],
                                         << " " << new_blocking_factor[2])
                                   << "\n";
                    amrex::Abort("Grids must be properly nested for EB or GPU");
                }
#endif

[WeiqunZhang]

"Grids are not properly nested" means the gap between level lev/lev-1 boundary and lev-1/lev-2 boundary is not wide enough. To fill ghost cells on Level lev, we would need data from Level lev-2.