Hi

noticed OOM on big amount of data

Apr 28 23:17:04 d02l kernel: Tasks state (memory values in pages):
Apr 28 23:17:04 d02l kernel: [ pid ] uid tgid total_vm rss pgtables_bytes swapents oom_score_adj name
...
Apr 28 23:17:05 d02l kernel: [ 378468] 0 378468 28402621 27067014 227512320 1300054 0 virtnbdbackup
...
Apr 28 23:17:05 d02l kernel: Out of memory: Killed process 378468 (virtnbdbackup) total-vm:113610484kB, anon-rss:108264172kB, file-rss:3884kB, shmem-rss:0kB, UID:0 pgtables:222180kB oom_score_adj:0

It was a VM with 150+ Gb of data to backup

Can you reproduce it in your environment ?
Have --verbose log (another run, hit Ctrl-C at ~10+ Gb VSZ) if needed