balloon_lock_contig_pfnlist
locked = balloon_lock_contig_pfnlist(fallback_cnt);
locked = balloon_lock_contig_pfnlist(metapgs);
locked = balloon_lock_contig_pfnlist(cnt);
locked = balloon_lock_contig_pfnlist(debit);
locked = balloon_lock_contig_pfnlist(cnt * extlen);