Comment 75 for bug 1906476

As many people here, I upgraded my encrypted ZFS Ubuntu system to 21.10, unaware of the issues with ZFS,

I only used 5.13.0-19 for a day, and began to notice odd things, like: incapacity to suspend to RAM, freezes, some process were impossible to kill.
I updated my kernel to 5.13.0-20 and then 5.13.0-21, but I still have issues with my ZFS encrypted filesystem. It seems the kernel update does not fix everything.

Even now it is unable to suspend (it says some process refuse to suspend), which is really annoying for a laptop. Moreoever, automatically scheduled "updatedb" and "apt update" get stuck.
Even system shutdown often takes a long time, to the point I have to force it with power button. Many times it seems to get stuck waiting for AppArmor.
In addition I keep getting errors with stack traces in dmesg, I put an example in attachment.

Now I am wondering what I should do to repair it ? I considered trying to downgrade my kernel to 5.11.0-37 which was my version before upgrading to 21.10, but it was automatically removed, and it does not seem very easy to put it back. I am wondering if it is worth the hassle.

Besides, the ZFS version was also upgraded in the process, and it is not clear to me whether I could keep the new version with the old kernel, or not. It seems to have evolved from 0.8.4-1ubuntu11.3 to 2.0.2-1ubuntu5.1, and then 2.0.2-1ubuntu5.2, and 2.0.6-1ubuntu2 (though oddly I cannot find any trace of this last version being installed in apt logs).
I am wondering if rolling back to 0.8.4 can do any good ?

My whole system is based on ZFS, if I have to reinstall it all, it will take me days to put everything back. Is there a real corruption on the filesystem, which would be interpreted as such by an older ZFS version, or is it just new 2.0.x versions that are disturbed by it ?
Would there be a way to fix the corruption ? Deleting some files or changing meta-data ?

[EDIT] Also, I have a ZFS snapshot of the / and /var datasets (but not /home), from before the update to 21.10, I am wondering if it could help to rollback back to them or if the corruption is so bad that it could affect snapshots too ? The issue may arise if some corrupted files where not modified by the upgrade, in which case they would not have been copied and both the snapshot and the current tree would reference the same corrupted file. Anyway, I have no backup of the /boot, so I am not very sure it would work just restoring snapshots from a USB live system or if I would have to rollback the kernel to 5.11.0-37 and ZFS to 0.8.4 before that, so that everything seem identical to the system.

Any help would be greatly appreciated !
Thank you.