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Date:      Mon, 26 Mar 2001 17:56:11 -0800 (PST)
From:      John Baldwin <jhb@FreeBSD.org>
To:        John Baldwin <jhb@FreeBSD.org>
Cc:        obrien@FreeBSD.org, alpha@FreeBSD.org, Andrew Gallatin <gallatin@cs.duke.edu>
Subject:   Re: dump(8)
Message-ID:  <XFMail.010326175611.jhb@FreeBSD.org>
In-Reply-To: <XFMail.010326172439.jhb@FreeBSD.org>

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On 27-Mar-01 John Baldwin wrote:
> 
> On 27-Mar-01 Andrew Gallatin wrote:
>> 
>> David O'Brien writes:
>>  > This broken dump(8) situation *must* get fixed.  It is time to back out
>>  > commits.  Does anyone have any idea what commit(s) broke dump?
>> 
>> Nope.
>> 
>> Its almost certainly related to the linuxthreads problem I was talking
>> about last week where a userland app dies on an instruction fault
>> with a PC somwhere in witness_exit().
>> 
>> I haven't been able to figure it out yet..
> 
> Try turning preemption off (i.e. remove it from the kernel config).  On the
> x86
> side we've seen that non-preemption safe code can blow up in very bad ways.
>:(

Well, I turned preemption off and the only difference it made was in the value
spammed into vp->v_op:

vp->v_op = 0x79e4f100df39ba4e

It's not even an obvious value such as a string, but looks like pure garbage. :(

Hmm, in ddb it seems that the rest of the vnode is fine, so it's just the vnode
op table pointer that is hosed.

-- 

John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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