Kernel panic in zfs code; 12-STABLE

[Eugene Grosbein]

19.07.2019 3:13, Karl Denninger wrote:

> FreeBSD 12.0-STABLE #2 r349024M: Thu Jun 13 18:01:16 CDT 2019    
> karl at NewFS.denninger.net:/usr/obj/usr/src/amd64.amd64/sys/KSD-SMP
> 
> Note -- no patches of any sort in the ZFS code; I am NOT running any of
> my former patch set.
> 
> NewFS.denninger.net dumped core - see /var/crash/vmcore.8
> 
> Thu Jul 18 15:02:54 CDT 2019
> 
> FreeBSD NewFS.denninger.net 12.0-STABLE FreeBSD 12.0-STABLE #2 r349024M:
> Thu Jun 13 18:01:16 CDT 2019    
> karl at NewFS.denninger.net:/usr/obj/usr/src/amd64.amd64/sys/KSD-SMP  amd64
> 
> panic: double fault

[skip]

> #283 0xffffffff82748d91 in zio_vdev_io_done (zio=0xfffff8000b8b8000)
>     at /usr/src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zio.c:3376
> #284 0xffffffff82744eac in zio_execute (zio=0xfffff8000b8b8000)
>     at /usr/src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zio.c:1786
> #285 0xffffffff80c3b7f4 in taskqueue_run_locked (queue=0xfffff801a8b35100)
>     at /usr/src/sys/kern/subr_taskqueue.c:467
> #286 0xffffffff80c3cb28 in taskqueue_thread_loop (arg=<value optimized out>)
>     at /usr/src/sys/kern/subr_taskqueue.c:773
> #287 0xffffffff80b9ab23 in fork_exit (
>     callout=0xffffffff80c3ca90 <taskqueue_thread_loop>,
>     arg=0xfffff801a0577520, frame=0xfffffe009d4edc00)
>     at /usr/src/sys/kern/kern_fork.c:1063
> #288 0xffffffff810b367e in fork_trampoline ()
>     at /usr/src/sys/amd64/amd64/exception.S:996
> #289 0x0000000000000000 in ?? ()
> Current language:  auto; currently minimal
> (kgdb)

You have "double fault" and completely insane number of stack frames in the trace.
This is obviously infinite recursion resulting in kernel stack overflow and panic.