On Sat, May 20, 2017 at 17:30 +0200, Sebastien Marie wrote:
> Hi,
> 
> Yesterday, I upgraded my amd64 gateway (pppoe + vlans) with a recent
> -current in order to test a bit codel queue.
> 
> OpenBSD 6.1-current (GENERIC.MP) #67: Thu May 18 18:28:26 MDT 2017
>     [email protected]:/usr/src/sys/arch/amd64/compile/GENERIC.MP
> 
> 
> This first panic occured while running (panic after 1 day):
> 
> [handwritten ddb output: I stripped out pointer addresses]
> 
> panic: kernel diagnostic assertion "ifq_is_serialized(ifq)" failed: file 
> "/usr/src/sys/net/ifq.c" line 394
> Stopped at    db_enter+0x9:   leave
>       TID     PID     UID     PRFLAGS PFLAGS  CPU     COMMAND
>     *208580   11878   0       0x14000 0x200   0       softnet
>       62492   51658   0       0x14000 0x200   1       systq
> db_enter(...) at db_enter+0x9
> panic(...) at panic+0x102
> __assert(...) at __assert+0x35
> ifq_mfreeml(...) at ifq_mfreeml+0x6c
> fq_codel_deq_begin(x,x,x,x,7,x) at fq_codel_deq_begin+0x1d9
> ifq_deq_begin(x,7,x,0,x,x) at ifq_deq_begin+0x45
> ifq_dequeue(x,x,x,0,x,x) at ifq_dequeue+0x1c
> sppp_dequeue(x,x,c,x,x,x) at sppp_dequeue+0x6f
> pppoe_start(x,285,x,x,7,x) at pppoe_start+0xbf
> if_qstart_compat(x,x,c,5,x,20) at if_qstart_compat+0x3f
> sppp_cp_send(x,8021,1,e,6,x) at sppp_cp_send+0x202
> sppp_ipcp_scr(x,x,1,x,x,x) at sppp_ipcp_scr+0x97
> sppp_phase_network(x,f0,x,5,0,x) at sppp_phase_network+0xad
> sppp_pap_input(x,x,0,x,0,x) at sppp_pap_input+0x33f
> endtrace frame: 0xffff8000131a6dc0, count: 0
> 
> I kept the photography of the screen if pointer addresses are in
> interest (`x' inside the trace).
> 
> 
> 
> # ifconfig pppoe0
> pppoe0: flags=208851<UP,POINTOPOINT,RUNNING,SIMPLEX,MULTICAST,AUTOCONF6> mtu 
> 1492
>         index 17 priority 0 llprio 3
>         dev: vlan10 state: session
>         sid: 0x3fad PADI retries: 1 PADR retries: 0 time: 01:34:11
>         sppp: phase network authproto pap authname "XXX"
>         groups: pppoe internet egress
>         status: active
>         inet6 fe80::cabe:19ff:fee2:2ced%pppoe0 ->  prefixlen 64 scopeid 0x11
>         inet 109.190.33.218 --> 178.32.37.4 netmask 0xffffffff
> 
> # ifconfig vlan10
> vlan10: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> rdomain 10 mtu 1500
>         lladdr c8:be:19:e2:2c:ed
>         index 7 priority 0 llprio 3
>         vlan: 10 parent interface: re0
>         vnetid: 10
>         parent: re0
>         groups: vlan adsl
>         status: active
>         inet 192.168.10.1 netmask 0xffffff00 broadcast 192.168.10.255
>         inet 192.168.1.10 netmask 0xffffff00 broadcast 192.168.1.255
> 
> # ifconfig re0
> re0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1504
>         lladdr c8:be:19:e2:2c:ed
>         index 1 priority 0 llprio 3
>         media: Ethernet autoselect (1000baseT full-duplex)
>         status: active
> 
> 
> From my pf configuration, I had removed queue with bandwidth and
> replaced them with:
> 
> queue fq on pppoe0 flows 1024 default
> queue fq on re0    flows 1024 default
> 
> Thanks.
> -- 
> Sebastien Marie

Hi, you've managed to find and open a big can of worms :-)
The reason for the panic is that fq-codel relies on features
provided by the new queueing interface and it would be counter-
productive to shove in a compatibility layer.  The new queueing
interface is used when an interface defines if_qstart callback
instead of an old if_start.  The good news is that the compat
shim that we have if_qstart_compat can be made to call into
ifq_serialize or do something similar since under KERNEL_LOCK
your ifq is serialized by definition.

Regarding your configuration, I'd advise you to use hfsc (the
default queueing) on pppoe0.  Set it to your *uplink* bandwidth:

  queue pppoe0-rootq on pppoe0 bandwidth 2M max 2M default

And use the flow queue only on the underlying interface.

Since this is what I've been advising folks to use, I didn't
manage to find this bug beforehands.  Apologies for that.

I'll try to come up with the diff to do ifq_serialize for
if_qstart_compat.

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