Date: Mon, 10 Jan 2022 17:11:16 -0500 From: Shawn Webb <shawn.webb@hardenedbsd.org> To: freebsd-hackers@freebsd.org Subject: Debugging a (potentially?) ZFS-related panic, and discussion about large patchsets Message-ID: <20220110221116.gustgfgfge6pb5fe@mutt-hbsd>
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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,
--=20
Shawn Webb
Cofounder / Security Engineer
HardenedBSD
https://git.hardenedbsd.org/hardenedbsd/pubkeys/-/raw/master/Shawn_Webb/03A=
4CBEBB82EA5A67D9F3853FF2E67A277F8E1FA.pub.asc
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