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Date: Mon, 24 Dec 2007 21:04:29 +0100
From: Kris Kennaway <kris@FreeBSD.org>
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To: Scot Hetzel <swhetzel@gmail.com>
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Cc: bzeeb+freebsd+lor@zabbadoz.net, freebsd-current@freebsd.org
Subject: Re: lock order reversal: devel/dbus causes a lock order reversal
 when	it is started.
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Scot Hetzel wrote:
> I'm getting the following lock order reversal when the rc.d/dbus
> script is started:
> 
> lock order reversal:
>  1st 0xffffff000b0ae500 kqueue (kqueue) @ kern/kern_event.c:1397
>  2nd 0xffffffff80e3cac0 sleep mtxpool (sleep mtxpool) @ kern/sys_generic.c:1255
> KDB: stack backtrace:
> db_trace_self_wrapper() at db_trace_self_wrapper+0x2a
> witness_checkorder() at witness_checkorder+0x655
> _mtx_lock_flags() at _mtx_lock_flags+0x75
> selrecord() at selrecord+0x86
> kqueue_poll() at kqueue_poll+0xa5
> poll() at poll+0x343
> syscall() at syscall+0x1ca
> Xfast_syscall() at Xfast_syscall+0xab
> --- syscall (209, FreeBSD ELF64, poll), rip = 0x800822b0c, rsp =
> 0x7fffffffe658, rbp = 0 ---
> 
> FreeBSD hp010.hetzel.org 8.0-CURRENT FreeBSD 8.0-CURRENT #0: Wed Dec
> 19 11:27:48 CST 2007
> root@hp010.hetzel.org:/usr/src/8x/sys-orig/amd64/compile/DV8135NR
> amd64
> 
> # ident /sys/kern/{kern_event.c,sys_generic.c}
> /sys/kern/kern_event.c:
>      $FreeBSD: src/sys/kern/kern_event.c,v 1.114 2007/12/16 06:21:19 jeff Exp $
> 
> /sys/kern/sys_generic.c:
>      $FreeBSD: src/sys/kern/sys_generic.c,v 1.160 2007/12/16 06:21:19 jeff Exp $
> 
> Scot

This was reported a couple of days previously.  Jeff says he will work 
on it.

Kris