On macOS 11.6 (Intel), zfs dataset couldn't mount and will hang the host

[michael-yuji]

System information

Type	Version/Name
Distribution Name	macOS
Distribution Version	11.6
Architecture	Intel
zfs-macOS Version	2.1.0-1
zfs-kmod Version	2.1.0-1

Describe the problem you're observing

I noticed that after I upgrade to 11.6 and reboot my machine (the first boot just after upgrading is fine), the OS start to hang and become unresponsive.

After some investigation, it seems ZFS mount to be the problem since the system boots and can be use normally (without zfs) after I modify /usr/local/zfs/libexec/launchd.d/zpool-import-all.sh and basically make it exit immediately.

After further more investigations, I noticed that I can zpool import -N zroot just fine as well as zfs send, however when I run zfs mount $dataset the command will exit however the dataset will not mount properly, further more, the system starts to hang and the OS basically becomes unusable.

Describe how to reproduce the problem

Upgrade your macOS to 11.6, and reboot a few times.
Try to mount a dataset

Include any warning/errors/backtraces from the system logs

[michael-yuji]

additional information: The issue also exists for v2. This led me to believe it must be some changes on the macOS side.
more additional information and suspicion: zfs mount itself works just fine. I have basically very little to no knowledge in macOS vfs stack but it led me to think it's something vfs lookup related bug(?)

[lundman]

If you can run the manual "zfs mount $dataset" command, and the run sudo spindump at some point, we can see what it is doing.

[michael-yuji]

thx. unfortunately a few days after the event my entire macbook is dead and won't boot anymore, so I have no way now to reproduce the issue. (or it could mean hardware issue on my mac causing this bug, i have no idea)