Heads up - crash/panic on -current when unloading mqueue module

[Paul Goyette <paul%vps1.whooppee.com@localhost>]

Recently I added a module dependency, so compat_netbsd32 will autoload 
mqueue module.

Well, it seems that something during a pkgsrc build-from-source will
trigger this.  A little bit later, when the module auto-unload thread
tries to unload mqueue, I got a panic, with backtrace

	pool_destroy + 0xb1
	pool_cache_destroy + 0xd
	mqueue_sysfini + 0x44
	mqueue_modcmd + 0x28
	module_do_unload + 0x74
	module_thread + 0xf8

This is on a amd64 system, with kernel and modules built from sources
dated 2015-10-13 at 11:29:08 UTC.

I'm going to dig a little bit deeper soon, to see what is broken.  In
the meantime, if anyone uses a run-time loaded mqueue module, rather
than one built-in to your kernel, I recommend that you manually load
the module at start-up rather than letting it auto-{,un}load.

(GENERIC kernels include all relevant modules as built-in, so this will
not apply.)


+------------------+--------------------------+-------------------------+
| Paul Goyette     | PGP Key fingerprint:     | E-mail addresses:       |
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