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Date:      Thu, 06 Mar 2003 13:01:43 -0500 (EST)
From:      John Baldwin <jhb@FreeBSD.org>
To:        John Baldwin <jhb@FreeBSD.org>
Cc:        cvs-all@FreeBSD.org, cvs-src@FreeBSD.org, src-committers@FreeBSD.org
Subject:   RE: cvs commit: src/sys/kern subr_witness.c
Message-ID:  <XFMail.20030306130143.jhb@FreeBSD.org>
In-Reply-To: <200303061725.h26HP66f033827@repoman.freebsd.org>

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On 06-Mar-2003 John Baldwin wrote:
> jhb         2003/03/06 09:25:06 PST
> 
>   FreeBSD src repository
> 
>   Modified files:
>     sys/kern             subr_witness.c 
>   Log:
>   Oops, fix the double faults people were seeing with the recent changes to
>   witness.  Sleepable locks such as sx locks always come before all mutexes
>   including Giant.  However, the static lock order list placed Giant before
>   the proctree and allproc sx locks.  This resulted in witness creating a
>   cycle in its lock order "tree" (real trees don't have cycles) leading to
>   infinite recursion and eventually a double fault.  To fix, put Giant after
>   sx locks in the lock order list.
>   
>   Revision  Changes    Path
>   1.141     +1 -1      src/sys/kern/subr_witness.c

Should have added:

Thanks to jlemon for a full backtrace with some helpful symbols.

-- 

John Baldwin <jhb@FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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