Removing USB card reader causes boot failure.

[ShadYoung]

Hi gang,

So... odd problem. I have a defective USB card reader that I want to remove from my system, but when I unplug it and restart the computer the computer will not boot. I need to shut down and plug it back into the exact same port it was in. The problem is, even plugged in the computer will fail to boot about 50% of the time and I am forced to <ctrl><alt><del> from a hung Kubuntu splash screen. Leaving it hanging for a few minutes results in the computer going into "maintenance mode" prior to it even really starting much, and the mode does not work. The other 50% it boots normally.

After much exploring with limited success, the only thing I can find out is the kernel seems to consider the card reader a dependency... why I do not know. The boot logs do not show me much.

Kubuntu 22.04.1 upgraded from 21.10. Problem preexisted in 21.10.
MSI X470 GP Mobo with 8 USB ports, Ryzen 2600x
Genesys USB 5 slot XDXC card reader
LVM on Samsung 970 NVME. <<--- might LVM be the culprit?

Any ideas?
TIA

[claydoh]

When rebooting, try hitting your esc key to toggle between the splash and tty output, which may reveal more specific info.
Is the hang happening before or after you reach the login screen?

Check your /etc/fstab to see if there is any oddball entry in there for a USB device.
Also look at your Removable Storage options in System Settings and try 'forgetting' all your entries from there, and perhaps disabling automounting to test if this may be a cause.

I don't think LVM could be the issue, unless a USB device was associated with this maybe?

[ShadYoung]

I think I just found a major security bug. I decided to let it ride out from its errors. 4 modules are failing to load, this occurs immediately after LVM does a volume check. It then sits there until it times out after about a minute and drops into "emergency mode". Trying the recommended commands failed, so I typed "exit" out of habit and suddenly dropped into root. No password required. I then did some tests and sure enough... I got full root access. Security=zero. WTF

So, I need to figure out why this USB device not being present causes these modules to fail, which causes a boot failure. Then how to fix it. Would dpkg be able to reconfigure the modules if I were to unplug it from the running system? Would trying to manually prevent the modules from attempting to load solve the boot issue?

[claydoh]

4 modules are failing to load

Umm.....which ones

suddenly dropped into root. No password required

'emergency'. or recovery mode is a root shell, usually without networking. Quite normal, and no less secure than any situation with someone having physical access to the hardware -- it can't decrypt a drive without the passphrase, for example. And anyone physically there can boot a computer to recovery mode, with identical access.

Would dpkg be able to reconfigure the modules

dpkg involves software package installation (deb file) installation, I don't think this is relevant in itself.

this occurs immediately after LVM does a volume check

This may a clue. Is it doing a check every boot? I am not sure that this is normal or not. But I lack any experience with this myself. Maybe a problem with the file system?

[ShadYoung]

So, you were indeed correct in it turned out to be a wayward fstab entry for a 4tb Toshiba HDD formatted with NTFS. After blowing away the root partition (had to use windows to get rid of the LVM) and reinstalling, I finally got some usable information when the problem re-occurred. It complained about failing to mount SDD2... I commented out the line in the fstab and boom... problem went away. Boots and shuts down 10 times faster. I had originally added the fstab entry as it seemed not to want to automount back in 21.10. But, it seems to be OK automounting now. So the next question is, will this also solve the problem with the inability to recover from sleep. About to find out now.