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Subject: Re: kernel BUG at drivers/scsi/scsi_lib.c:1096!
To: Michael Ellerman <mpe@ellerman.id.au>, Ming Lei <ming.lei@canonical.com>
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Cc: Christoph Hellwig <hch@infradead.org>, Mark Salter <msalter@redhat.com>,
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From: Laurent Dufour <ldufour@linux.vnet.ibm.com>
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On 20/11/2015 13:10, Michael Ellerman wrote:
> On Thu, 2015-11-19 at 00:23 -0800, Christoph Hellwig wrote:
> 
>> It's pretty much guaranteed a block layer bug, most likely in the
>> merge bios to request infrastucture where we don't obey the merging
>> limits properly.
>>
>> Does either of you have a known good and first known bad kernel?
> 
> Not me, I've only hit it one or two times. All I can say is I have hit it in
> 4.4-rc1.
> 
> Laurent, can you narrow it down at all?

It seems that the panic is triggered by the commit bdced438acd8 ("block:
setup bi_phys_segments after splitting") which has been pulled by the
merge d9734e0d1ccf ("Merge branch 'for-4.4/core' of
git://git.kernel.dk/linux-block").

My system is panicing promptly when running a kernel built at
d9734e0d1ccf, while reverting the commit bdced438acd8, it can run hours
without panicing.

This being said, I can't explain what's going wrong.

May Ming shed some light here ?

Cheers