Panic with recent -CURRENT kernel in EC2

[Bradley T. Hughes]

(Cross-posting to -net, but I'm not subscribed there... yet)

I was wondering if anyone else has experienced this panic when dhclient tries to get an IP address after booting a recent 12.0-CURRENT kernel? Using the 12.0-CURRENT AMI from early November works, but with the latest snapshot or when using a kernel built from source I get this:

ixv0: <Intel(R) PRO/10GbE Virtual Function Network Driver> mem 0xf3000000-0xf3003fff,0xf3004000-0xf3007fff at device 3.0 on pci0
ixv0: using 2048 tx descriptors and 2048 rx descriptors
ixv0: msix_init qsets capped at 1
ixv0: pxm cpus: 2 queue msgs: 2 admincnt: 1
ixv0: using 1 rx queues 1 tx queues 
ixv0: Using MSIX interrupts with 2 vectors
ixv0: allocated for 1 queues
ixv0: allocated for 1 rx queues
taskqgroup_attach_cpu: setaffinity failed: 22
taskqgroup_attach_cpu: setaffinity failed: 22
ixv0: Ethernet address: 0a:ad:68:70:ea:78
ixv0: netmap queues/slots: TX 1/2048, RX 1/2048
...
panic: Assertion if_getdrvflags(ifp) == i failed at /usr/src/sys/net/iflib.c:2199
cpuid = 3
time = 1515673176
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe008a8ee600
vpanic() at vpanic+0x19c/frame 0xfffffe008a8ee680
kassert_panic() at kassert_panic+0x126/frame 0xfffffe008a8ee6f0
iflib_init_locked() at iflib_init_locked+0x75f/frame 0xfffffe008a8ee750
iflib_if_ioctl() at iflib_if_ioctl+0x744/frame 0xfffffe008a8ee7b0
ifioctl() at ifioctl+0x1903/frame 0xfffffe008a8ee850
kern_ioctl() at kern_ioctl+0x2c4/frame 0xfffffe008a8ee8b0
sys_ioctl() at sys_ioctl+0x15c/frame 0xfffffe008a8ee980
amd64_syscall() at amd64_syscall+0x79b/frame 0xfffffe008a8eeab0
Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe008a8eeab0
--- syscall (54, FreeBSD ELF64, sys_ioctl), rip = 0x80100a4fa, rsp = 0x7fffffffe408, rbp = 0x7fffffffe460 ---

Thanks in advance :)

--
Bradley T. Hughes
bhughes at freebsd.org