On 08/10/2017 10:26 AM, Bart Van Assche wrote:
> On Thu, 2017-08-10 at 20:32 +1000, Michael Ellerman wrote:
>> "Martin K. Petersen" <martin.peter...@oracle.com> writes:
>>>> One of the two scsi-mq functions that requeue a request unprepares a
>>>> request before requeueing (scsi_io_completion()) but the other
>>>> function not (__scsi_queue_insert()). Make sure that a request is
>>>> unprepared before requeuing it.
>>> Applied to 4.13/scsi-fixes. Thanks much!
>> This seems to be preventing my Power8 box, which uses IPR, from booting.
>> Bisect said so:
>> # first bad commit: [270065e92c317845d69095ec8e3d18616b5b39d5] scsi: 
>> scsi-mq: Always unprepare before requeuing a request
>> And if I revert that on top of next-20170809 my system boots again.
>> The symptom is that it just gets "stuck" during boot and never gets to
>> mounting root, full log below, the end is:
>>   .
>>   ready
>>   ready
>>   sd 0:2:4:0: [sde] 554287104 512-byte logical blocks: (284 GB/264 GiB)
>>   sd 0:2:4:0: [sde] 4096-byte physical blocks
>>   sd 0:2:5:0: [sdf] 272646144 512-byte logical blocks: (140 GB/130 GiB)
>>   sd 0:2:5:0: [sdf] 4096-byte physical blocks
>>   sd 0:2:4:0: [sde] Write Protect is off
>>   sd 0:2:4:0: [sde] Mode Sense: 0b 00 00 08
>>   sd 0:2:5:0: [sdf] Write Protect is off
>>   sd 0:2:5:0: [sdf] Mode Sense: 0b 00 00 08
>> And it just sits there for at least hours.
>> I compared a good and bad boot log and there appears to be essentially
>> no difference. Certainly nothing that looks suspicous.
> Hello Michael,
> Thanks for having reported this early. Is there any chance that you can
> reproduce this state, press SysRq-w on the console and collect the task
> overview that is reported on the console (see also Documentation/admin-guide/
> sysrq.rst)? If this is not possible or if that task overview does not report
> any blocked tasks, can you add scsi_mod.scsi_logging_level=-1 to the kernel
> command line (either through /etc/default/grub or in /boot/grub2/grub.cfg
> when using GRUB), reboot the system, capture the console output and report
> that output as a reply to this e-mail?

I'm building a kernel to try to reproduce this on a machine with ipr.


Brian King
Power Linux I/O
IBM Linux Technology Center

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