kernel crashes because crypto unloading?

[dieter roelants <dieter.NetBSD%pandora.be@localhost>]

Hi all, and I think Paul in particular ;)

After updating my kernel to current -current yesterday, I had 3 crashes
while compiling userland. I have no info about the first crash, but ran
my system with serial console afterwards, so I have cores and
backtraces of the next 2. Anyway, they seemed kinda random to me, so
today I built the same kernel config with DEBUG and DIAGNOSTIC enabled.

Now the kernel cleanly panics (instead of uvm faults) with the message
"pool_destroy: pool busy: still out: 2" a few seconds after starting X
(reproducable). The backtrace looks like this:

breakpoint() at breakpoint+0x5
vpanic() at vpanic+0x136
printf_nolog() at printf_nolog
pool_destroy() at pool_destroy+0x363
crypto_detach() at crypto_detach+0x10
config_detach() at config_detach+0xda
config_cfdata_detach() at config_cfdata_detach+0xd9
crypto_modcmd() at crypto_modcmd+0x55
module_do_unload() at module_do_unload+0x7c
module_thread() at module_thread+0xfc

Looking at yesterdays' kernel messages; I noticed that they contain
"crypto0: detached" about 12 seconds after starting X (which I can tell
from the (radeon)drm messages), which is probably odd because it never
attached in the first place (or at least there's no trace of it in the
logging).

The workaround I'm using so far successfully, is to modload crypto
manually before starting X.

Anyway, I'll send a PR for this soonish, unless a fix is committed
earlier. :)

kind reagrds
dieter