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Date:      Thu, 6 Aug 2009 08:34:38 -0500 (CDT)
From:      Larry Rosenman <ler@lerctr.org>
To:        Robert Watson <rwatson@FreeBSD.org>
Cc:        jeff@FreeBSD.org, "Bjoern A. Zeeb" <bz@FreeBSD.org>, freebsd-current@freebsd.org, kib@FreeBSD.org, Navdeep Parhar <np@FreeBSD.org>, Navdeep Parhar <nparhar@gmail.com>, lstewart@FreeBSD.org
Subject:   Re: reproducible panic in netisr
Message-ID:  <alpine.BSF.2.00.0908060834120.21318@thebighonker.lerctr.org>
In-Reply-To: <alpine.BSF.2.00.0908060011490.59996@fledge.watson.org>
References:  <20090804225806.GA54680@hub.freebsd.org> <20090805054115.O93661@maildrop.int.zabbadoz.net> <20090805063417.GA10969@doormat.home> <alpine.BSF.2.00.0908060011490.59996@fledge.watson.org>

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On Thu, 6 Aug 2009, Robert Watson wrote:

> On Tue, 4 Aug 2009, Navdeep Parhar wrote:
>
>>>> This occurs on today's HEAD + some unrelated patches.  That makes it 
>>>> 8.0BETA2+ code.  I haven't tried older builds.
>>> 
>>> We have finally been able to reproduce this ourselves yesterday and
>> 
>> Well, it happens every single time on all of my amd64 machines. After I'd 
>> already sent my email I noticed that the netisr mutex has an odd address 
>> (pun intended :-))
>> 
>> m=0xffffffff8144d867
>
> Heh, indeed.  We just spotted the same result here.  In this case it's 
> causing a panic because it leads to a non-atomic read due to mtx_lock 
> spanning a cache line boundary, followed shortly by a panic because it's not 
> a valid thread pointer when it's dereferenced, as we get a fractional 
> pointer.
[snip]

Do we have an ETA for a testable patch?


-- 
Larry Rosenman                     http://www.lerctr.org/~ler
Phone: +1 512-248-2683                 E-Mail: ler@lerctr.org
US Mail: 430 Valona Loop, Round Rock, TX 78681-3893



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