Date: Wed, 17 Nov 2004 13:29:48 -0800
From: Dave Olien <dmo@osdl.org>
To: ccantwel@uci.edu
Cc: linux-kernel@vger.kernel.org
Subject: Re: DAC960 and latest kernels
Message-ID: <20041117212948.GA2154@osdl.org>
References: <20041117192018.GA25403@zee.ps.uci.edu>
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I'll look into this.  I'll see if I can reproduce any of these
problems locally and get back to you.

Dave

On Wed, Nov 17, 2004 at 11:20:18AM -0800, ccantwel@uci.edu wrote:
> It seems that I have found a very serious bug relating to the DAC960
> driver, it is present in 2.4.27 and 2.6.8.1 but I haven't tried any
> development kernels newer than that.  This message is meant to inform
> the people who may be able to figure out what the problem is and
> repair the bug.  If anyone wants to respond to me or has further
> information on this problem, please cc me directly, as I am not a
> member of this mailing list.
> 
> There is a bug in latest released kernels for both 2.4 and 2.6
> trees that seems to relate to the DAC960 driver.  I have tried
> 2.4.27 and 2.6.8.1 and both have the following problem.  After
> replacing and testing every piece of hardware I've determined
> the problem is in the kernel and not the machine.  Also, going
> back to kernel 2.4.17 makes everything work perfectly.
> 
> When copying a large number of files over the network using nc
> and tar and also stress testing on the receiving side with
> frequent du commands where the data is being written to (not
> required for the problem but it seems to make it more likely
> to happen) the machine randomly hangs.  Sometimes it crashes
> completely with an Unable to handle kernel paging request at
> virtual address, with various processes, and sometimes it just
> completely halts and responds to nothing even though it seems
> to sort of be running (answers on sockets but transfers no data,
> no more communication of any kind on other open sockets, entering
> a login name and enter on the console also hangs before the
> password prompt.
> 
> Upon rebooting the filesystem that was being written to is corrupt.
> When this file system is XFS I can still inspect it.  If it is
> reiser the machine will often hang trying to run fsck.reiserfs.
> 
> In addition, after enough network tar copying I can stop the process,
> and even if it has not hung the machine often the filesystem has
> become corrupt.  Since this happens with both xfs and reiser and
> there are paging problems too I believe it has to relate to the
> dac960 driver itself.
> 
> I've also tried swapping DAC960 cards, and that doesn't matter,
> they both work perfectly in 2.4.17 and the problems occur in
> both cases in 2.4.27 and 2.6.8.1.  I'm planning to try some
> more kernels in between to narrow down when the problem was
> introduced but I'm not a kernel developer and that is about the
> most I will be able to do.
> 
> I think the DAC960 driver isn't used very often and also without this
> specific type of stress testing it is hard to realize the problem is
> occuring before the filesystem is irreperably corrupt weeks down the
> road, which is why this problem may have not been found yet.  Without
> stress testing using tar the machine can go for weeks and act like it
> is fine.
> 
> Again, if anyone has any information, please cc me when you reply as
> I am not a member of this list.
> 
> Thank you
> -
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