Unable to mount a USB disk on Raspberry Pi 4

Question

I'm trying to mount a USB disk on a Raspberry Pi running Ubuntu 19.10 (arm64 kernel 5.3.0-1007-raspi2) and I'm getting the following errors (it seems to switch between the two):

tom@cl0:/tmp$ sudo mount /dev/sda mnt
mount: /tmp/mnt: mount(2) system call failed: Structure needs cleaning.
tom@cl0:/tmp$ sudo mount /dev/sda mnt
mount: /tmp/mnt: wrong fs type, bad option, bad superblock on /dev/sda, 
missing codepage or helper program, or other error.

blkid returns:

/dev/sda: LABEL="Skynet" UUID="85e8dbfd-7f8f-4bcd-ad69-bf593504854f" TYPE="ext3"

The disk contains a single filesystem (no partitions), which is unusual, but shouldn't be an issue.

Mounting on another linux host (Debian Testing, kernel 5.2.0-3-amd64)

Does anyone have any idea what's going on here?

Answer 1

After some more testing (with another disk) it managed to mount once (by literally just running the mount command until it worked). This pretty clearly says that this isn't an issue with the disk, but something related to USB.

Upon researching a little more, I found that this is a bug: https://bugs.launchpad.net/ubuntu/+source/linux-raspi2/+bug/1848790

Specifically, the bug is only present when booted with more than 3072mb of RAM. So a quick (but unfortunate) workaround is to add the following line to /boot/firmware/usercfg.txt: total_mem=3072