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Date: Wed, 4 Aug 2004 15:54:37 +0200
From: Simon Barner <barner@in.tum.de>
To: Roberto Nunnari <roberto.nunnari@supsi.ch>
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cc: freebsd-questions@freebsd.org
Subject: Re: strange kernel messages..
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Roberto Nunnari wrote:
> Hello.
>=20
> Please send replies also to my mailbox, as I'm not on this list.
>=20
> Can anybody tell me what are these messages about? Are them
> just informational or do I have to worry?
>=20
> Aug  2 18:23:59 web kernel: lock order reversal
> Aug  2 18:23:59 web kernel: 1st 0xc07066e0 UMA lock (UMA lock) @=20
> /usr/src/sys/vm/uma_core.c:1200
> Aug  2 18:23:59 web kernel: 2nd 0xc0c31100 system map (system map) @=20
> /usr/src/sys/vm/vm_map.c:2210
> Aug  2 19:12:21 web kernel: lock order reversal
> Aug  2 19:12:21 web kernel: 1st 0xc8c1c39c vm object (vm object) @=20
> /usr/src/sys/vm/swap_pager.c:1323
> Aug  2 19:12:21 web kernel: 2nd 0xc0705b80 swap_pager swhash (swap_pager=
=20
> swhash) @ /usr/src/sys/vm/swap_pager.c:1838
> Aug  2 19:12:21 web kernel: 3rd 0xc6853108 vm object (vm object) @=20
> /usr/src/sys/vm/uma_core.c:873

This is a so-called lock order reversal (LOR). To learn more about LORs
in general and specifically about the one you are seeing, please see
here:

http://sources.zabbadoz.net/freebsd/lor.html --> # 007

Simon


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