Debugging a (potentially?) ZFS-related panic, and discussion about large patchsets

Hey all,

So I'm getting an interesting ZFS-related kernel panic. I've uploaded
the core.txt at [0]. I suspect it's related to FreeBSD commit
681ce946f33e75c590e97c53076e86dff1fe8f4a (zfs: merge
openzfs/zfs@f291fa658 (master) into main).

I'm able to reproduce it on a single system with some level of
determinism: I'm building the security appliance firmware at ${DAYJOB}
in a bhyve VM that's backed by a zvol. The host is a Dell Precision
7540 laptop with a single NVMe drive in it. The VM is configured with
a single zvol, booting with UEFI.

Looking at the commit email sent to dev-commits-src-all@, I see this:
146 files changed, 4933 insertions(+), 1572 deletions(-)

Strangely, when I run `git show
681ce946f33e75c590e97c53076e86dff1fe8f4a`, I only see a small subset
of those changes.

As a downstream consumer of 14-CURRENT, how am I supposed to even
start debugging such a large patchset in any manner that respects my
time?

It seems to me that breaking up commits into smaller, bite-size chunks
would make life easier for those experiencing bugs, especially ones
that result in kernel panics.

ZFS in and of itself is a beast, and I've yet to study any of its
code, so when there's a commit that large, even thinking about
debugging it is a daunting task.

Needless to say, I'm going to need some hand holding here for
debugging this. Anyone have any idea what's going on?

I guess this email is to serve three purposes:

1. Report that a bug was introduced recently.
2. Ask for help in squashing the bug. I'm more than happy to test any
   patches.
3. Start a dialogue on making life just a little easier for
   downstreams.

[0]: https://hardenedbsd.org/~shawn/2022-01-10_zfs_core-r01.txt

Thanks,

-- 
Shawn Webb
Cofounder / Security Engineer
HardenedBSD

https://git.hardenedbsd.org/hardenedbsd/pubkeys/-/raw/master/Shawn_Webb/03A4CBEBB82EA5A67D9F3853FF2E67A277F8E1FA.pub.asc