I was trying to open a 7.2TB encrypted ext4 partition on my Raspberry Pi (1G memory, 8G swap, using cryptsetup 2.0.2) but got:

Mar 27 00:26:25 Pi3BP kernel: Out of memory: Kill process 738 (cryptsetup) score 93 or sacrifice child
Mar 27 00:26:25 Pi3BP kernel: Killed process 738 (cryptsetup) total-vm:1056100kB, anon-rss:888844kB, file-rss:5704kB, shmem-rss:0kB
Mar 27 00:26:25 Pi3BP kernel: oom_reaper: reaped process 738 (cryptsetup), now anon-rss:888940kB, file-rss:5692kB, shmem-rss:0kB

The partition was created via

cryptsetup --cipher aes-xts-plain64 --key-size 256 --hash sha256 luksFormat --type luks2 /dev/sdb1

Having no idea why cryptsetup open was consuming such a large amount of memory, I spent hours googling the issue but got no clue at the end. But since most of the successful examples I found were quite old and apparently they were using LUKS1, I tried re-formatting the partition with --type luks1 and this time it just got mounted on Raspberry Pi without any error.

May I know:

1. Are there any workarounds to this issue?
2. What factors influence the memory usage?

This is pretty much the first time for me to try out disk encryption and I am still absolutely a n00b. It would be greatly appreciated if you could provide me some suggestions. Thanks!