What does it mean when zdb -R x:xxx:xxx:g crashes?

[Zaphod Beeblebrox]

I have retried this on a brand new pool with a brand new filesystem
containing one file.  zdb -R x:xxx:xxx:g <--- ie: retrieve the gang block
header crashes.  It also crashes with -A -AA and -AAA (which are supposed
to prevent assertions from stopping the debugger).

Help?

On Mon, Nov 24, 2014 at 2:40 PM, Zaphod Beeblebrox <zbeeble at gmail.com>
wrote:

> So... another barrier in figuring out my zfs problem is that zdb crashes
> when asked to print the gang block header:
>
> [1:97:397]root at virtual:/vr1/tmp/diag> zdb -AAA -R vr2
> 0:94048dc9000:24000:g
> Found vdev type: raidz
> Assertion failed: (zio->io_error == 0 || (zio->io_flags &
> ZIO_FLAG_CANFAIL)), file
> /usr/src/cddl/lib/libzpool/../../../sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zio.c,
> line 3297.
> Abort trap (core dumped)
>
> Now... this trace looks odd to me: there are no bookmarks in the
> filesystem... neither are there snapshots for this specific filesystem.
>
> (gdb) bt
> #0  0x0000000801cb26ca in thr_kill () from /lib/libc.so.7
> #1  0x0000000801d87149 in abort () from /lib/libc.so.7
> #2  0x0000000801920e21 in zio_init () from /lib/libzpool.so.2
> #3  0x0000000801927e0e in zbookmark_is_before () from /lib/libzpool.so.2
> #4  0x0000000801922df7 in zio_execute () from /lib/libzpool.so.2
> #5  0x0000000801927f11 in zbookmark_is_before () from /lib/libzpool.so.2
> #6  0x0000000801922df7 in zio_execute () from /lib/libzpool.so.2
> #7  0x0000000801927f11 in zbookmark_is_before () from /lib/libzpool.so.2
> #8  0x0000000801922df7 in zio_execute () from /lib/libzpool.so.2
> #9  0x0000000801927f11 in zbookmark_is_before () from /lib/libzpool.so.2
> #10 0x0000000801922df7 in zio_execute () from /lib/libzpool.so.2
> #11 0x0000000801927f11 in zbookmark_is_before () from /lib/libzpool.so.2
> #12 0x0000000801922df7 in zio_execute () from /lib/libzpool.so.2
> #13 0x000000080191b8d9 in taskq_create () from /lib/libzpool.so.2
> #14 0x0000000800e814f5 in pthread_create () from /lib/libthr.so.3
> #15 0x00007ffff6fb9000 in ?? ()
> Cannot access memory at address 0x7ffff71b9000
>
> Help?
>