Function write_llc_bitmaps 

pub fn write_llc_bitmaps(skel: &mut BpfSkel<'_>, plan: &LlcPlan) -> Result<()>

Phase 2 (post-load): write the per-LLC membership bitmaps.

One bitmap per LLC domain. On failure the affected domain’s bitmap is left empty, so the selector finds no idle candidate there and falls through to the global placement path.