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Date:      Fri, 2 Dec 2005 08:54:18 -0500
From:      John Baldwin <jhb@freebsd.org>
To:        freebsd-hackers@freebsd.org
Cc:        Yuri Khotyaintsev <yuri@irfu.se>, freebsd-stable@freebsd.org
Subject:   Re: Fatal trap 12: page fault while in kernel mode
Message-ID:  <200512020854.20959.jhb@freebsd.org>
In-Reply-To: <200512021100.03167.yuri@irfu.se>
References:  <200512021100.03167.yuri@irfu.se>

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On Friday 02 December 2005 05:00 am, Yuri Khotyaintsev wrote:
> I have the following panic occurring several times a week. The machine is
> an NFS server, and it usually panics early in the morning, when first
> people try to access it. After reboot it may work OK for 1-2 days, and th=
en
> panics again. I have tried changing memory and replacing disk which was
> exported via NFS, but nothing helped :(
>
> Any suggestion on how to fix this panic will be very much appreciated !

This panic (in propagate_priority) is usually caused when a thread goes to=
=20
sleep while holding a mutex (which is forbidden).  If you enable INVARIANTS=
=20
and/or WITNESS you should get a better panic, and with WITNESS you will eve=
n=20
be warned when a thread goes to sleep while holding a mutex.  However, thes=
e=20
options do introduce considerable execution overhead, and sometimes that=20
overhead changes the timing enough to hide the race. :(

=2D-=20
John Baldwin <jhb@FreeBSD.org> =A0<>< =A0http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve" =A0=3D =A0http://www.FreeBSD.org



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