Subject: Re: kernel BUG at drivers/scsi/scsi_lib.c:1096!
To: Michael Ellerman <mpe@ellerman.id.au>, Ming Lei <ming.lei@canonical.com>
References: <1447838334.1564.2.camel@ellerman.id.au>
 <1447855399.3974.24.camel@redhat.com>
 <1447894964.15206.0.camel@ellerman.id.au>
 <20151119082325.GA11419@infradead.org>
 <1448021448.14769.7.camel@ellerman.id.au>
Cc: Christoph Hellwig <hch@infradead.org>, Mark Salter <msalter@redhat.com>,
        "James E. J. Bottomley" <JBottomley@odin.com>,
        brking <brking@us.ibm.com>, linux-scsi@vger.kernel.org,
        linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-block@vger.kernel.org
From: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Message-ID: <565055C6.5040801@linux.vnet.ibm.com>
Date: Sat, 21 Nov 2015 12:30:14 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101
 Thunderbird/38.3.0
MIME-Version: 1.0
In-Reply-To: <1448021448.14769.7.camel@ellerman.id.au>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1205
Lines: 35

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


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/