Re: panic: assertion failed in iflib_txq_drain()

> On 18. Apr 2026, at 19:14, David Wolfskill <david@catwhisker.org> wrote:
> 
> On Sat, Apr 18, 2026 at 03:53:33PM +0200, Michael Tuexen wrote:
>> ...
>>> So... one of the machines on which I track head got this, as well -- my
>>> (mostly-)headless build machine.  (2 laptops, updated in sync with the
>>> build machine, did not panic.  One of those also uses a wired NIC.)
>> Do the network drivers of the machines not being affected use iflib?
> 
> Apparently not -- they are em(4), iwm(4), & iwn(4), while the panicking
> machine uses igb(4).
> 
>> I do see the problem also on one of my machines and local testing shows that
>> https://cgit.FreeBSD.org/src/commit/?id=3fade68cfdf95ee0b517b5d69b270bd8da633404 <https://cgit.freebsd.org/src/commit/?id=3fade68cfdf95ee0b517b5d69b270bd8da633404>
>> is the problem. At least reverting it locally resolves the problem.
>> Can you confirm this?
> 
> I can, and do:  after reverting main-n285140-3fade68cfdf9 & rebuilding,
> I am able to ssh in without issue; the machine reports:
> 
> freebeast(16.0-C)[2] uname -aUK
> FreeBSD freebeast.catwhisker.org 16.0-CURRENT FreeBSD 16.0-CURRENT #549 main-n285180-23a84efeb191: Sat Apr 18 17:01:25 UTC 2026     root@freebeast.catwhisker.org:/common/S3/obj/usr/src/amd64.amd64/sys/GENERIC amd64 1600015 1600015
> 
> Thanks!
You could also disable TSO. I will put up a review for a fix soon.

Best regards
Michael
> 
> Peace,
> david
> -- 
> David H. Wolfskill                              david@catwhisker.org
> 
> See https://www.catwhisker.org/~david/publickey.gpg for my public key.