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Sat, 18 Apr 2026 15:52:19 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface List-Id: Discussions about the use of FreeBSD-current List-Archive: https://lists.freebsd.org/archives/freebsd-current List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-current@FreeBSD.org MIME-Version: 1.0 X-ThreadId: APgOGAU08yF- Date: Sat, 18 Apr 2026 15:51:58 -0400 From: "Drew Gallatin" To: tuexen Cc: current@freebsd.org, "Ricardo Branco" , freebsd-current@freebsd.org Message-Id: In-Reply-To: References: <9d640ae4-7133-4d4f-917f-d715ab71ee7b@suse.de> <3b60c3e6-f53f-4084-a435-fe5371c56e58@app.fastmail.com> Subject: Re: panic: assertion failed in iflib_txq_drain() Content-Type: multipart/alternative; boundary=754d0919e6487d801aec91f7696bfe04c053baca --754d0919e6487d801aec91f7696bfe04c053baca Content-Type: text/plain Content-Transfer-Encoding: 7bit That is indeed the proper fix. I just reviewed & tested it. Thank you so much! Until it lands, another workaround is to use the new, cheaper, faster, simpler iflib transmit routine by setting the tunable dev.$NIC.$UNIT.iflib.simple_tx=1 Eg, dev.bnxt.0.iflib.simple_tx=1 In loader.conf I plan to deprecate the current complex transmit routine (mp_ring) in favor of the simple mechanism, and I confess that I sometimes don't test "straightforward" changes like this on mp_ring. I'll try to get better about that. Drew On Sat, Apr 18, 2026, at 3:12 PM, Michael Tuexen wrote: > > On 18. Apr 2026, at 21:09, Drew Gallatin wrote: > > > > Sorry, looking into this now. I did not test this change with the mp_ring path.. i don't see how fixing the counters could cause this panic. Looking at it now.. > Hi Drew, > > I think https://reviews.freebsd.org/D56509 fixes it. > > Best regards > Michael > > > > Drew > > > > On Sat, Apr 18, 2026, at 1:38 PM, Michael Tuexen wrote: > >> > >> > >> > On 18. Apr 2026, at 19:14, David Wolfskill 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 > >> >> 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. > >> > >> > >> > > > > --754d0919e6487d801aec91f7696bfe04c053baca Content-Type: text/html Content-Transfer-Encoding: quoted-printable

That is indeed the proper fix.   I just reviewed & test= ed it.  Thank you so much!

Until it lands,= another workaround is to use the new, cheaper, faster, simpler iflib tr= ansmit routine by setting the tunable

dev.$NIC.= $UNIT.iflib.simple_tx=3D1

Eg, dev.bnxt.0.i= flib.simple_tx=3D1

In loader.conf
I plan to deprecate the current complex transmit routine (mp= _ring) in favor of the simple mechanism, and I confess that I sometimes = don't test "straightforward" changes like this on mp_ring.  I'll tr= y to get better about that.

Drew

=
On Sat, Apr 18, 2026, at 3:12 PM, Michael Tuexen wrote:
=
> On 18. Apr 2026= , at 21:09, Drew Gallatin <ga= llatin@freebsd.org> wrote:
> 
> So= rry, looking into this now.  I did not test this change with the mp= _ring path.. i don't see how fixing the counters could cause this panic.=    Looking at it now..
Hi Drew,

=

Best = regards
Michael
> 
> Drew
=
> 
> On Sat, Apr 18, 2026, at 1:38 PM, Michael= Tuexen wrote:
>> 
>> 
>> > On 18. Apr 2026, at 19:14, David Wolfskill <david@catwhisker.org> wrote:<= div>>> > 
>> > On Sat, Apr 18, 2026 at = 03:53:33PM +0200, Michael Tuexen wrote:
>> >> ...<= /div>
>> >>> So... one of the machines on which I tra= ck head got this, as well -- my
>> >>> (mostly-= )headless build machine.  (2 laptops, updated in sync with the
>> >>> build machine, did not panic.  One of t= hose also uses a wired NIC.)
>> >> Do the network = drivers of the machines not being affected use iflib?
>>= > 
>> > Apparently not -- they are em(4), iw= m(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 t= hat
>> >= > is the problem. At least reverting it locally resolves the problem.=
>> >> Can you confirm this?
>> &g= t; 
>> > I can, and do:  after reverting ma= in-n285140-3fade68cfdf9 & rebuilding,
>> > I am a= ble 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 mai= n-n285180-23a84efeb191: Sat Apr 18 17:01:25 UTC 2026   &n= bsp; root@freebeas= t.catwhisker.org:/common/S3/obj/usr/src/amd64.amd64/sys/GENERIC amd6= 4 1600015 1600015
>> > 
>> > = Thanks!
>> You could also disable TSO. I will put up a r= eview for a fix soon.
>> 
>> Best r= egards
>> Michael
>> > 
>> > Peace,
>> > david
>> = > -- 
>> > David H. Wolfskill  &nbs= p;           &nbs= p;           &nbs= p;   david@catwhi= sker.org
>> > 
>> > See&n= bsp;https://= www.catwhisker.org/~david/publickey.gpg for my public key.
>> 
>> 
>> 
<= div>> 



=
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