I think the problem is easy to reproduce. On a Lustre file system that doesn't have nodemap configured, which is the majority case I think, do the following:

1. mount -t ldiskfs $MGT $MNT
2. llog_reader $MNT/CONFIGS/nodemap
   llog_reader will quit with following error:

 llog_reader: Error allocating -16 bytes for recs_buf: Cannot allocate memory (12)
 llog_reader: Could not pack buffer.: Cannot allocate memory (12)

Apparently, the llog of nodemap is never initialized so all the values are gabage.

Header size : 3987452397
Time : Fri Jan 2 20:30:12 1970
Number of records: 4294967295
Target uuid :

I think in this case, llog_reader should just quit with proper message printed.