Function format_optional_limit 

pub fn format_optional_limit(v: Option<u64>, ladder: ScaleLadder) -> String

Render an Option<u64> cgroup limit as either max (no limit / kernel emitted the literal max token) or the auto-scaled value. Used for memory.max, memory.high, pids.max. Mirrors the kernel’s own display: cat memory.max prints max when no cap is set, a u64 byte count otherwise.