linux-kernel - Re: Regression in 4.11 - PowerPC crashes on boot, bisected to commit 5657933dbb6e

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Message-ID: <d97db35e-e535-8d3f-d73b-095c45f7c927@lwfinger.net>
Date:   Thu, 2 Mar 2017 06:40:40 -0600
From:   Larry Finger <Larry.Finger@...inger.net>
To:     Bart Van Assche <Bart.VanAssche@...disk.com>,
        "regressions@...mhuis.info" <regressions@...mhuis.info>,
        "benh@...nel.crashing.org" <benh@...nel.crashing.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Regression in 4.11 - PowerPC crashes on boot, bisected to commit
 5657933dbb6e

On 03/01/2017 11:22 PM, Bart Van Assche wrote:
> On Thu, 2017-03-02 at 16:14 +1100, Benjamin Herrenschmidt wrote:
>> On Wed, 2017-03-01 at 21:26 -0600, Larry Finger wrote:
>>> My Powerbook G4 Aluminum generates a fatal splat early in the boot process, just
>>> after identifying the driver for the disk. Unfortunately, it turns off almost
>>> immediately, thus I cannot report the message. After this bug has been
>>> triggered, the system clock has been reset to Dec. 31, 1969. I assume this is a
>>> side effect of an uncontrolled DMA operation.
>>>
>>> This problem has been bisected to commit 5657933dbb6e ("treewide: Move dma_ops
>>> from struct dev_archdata into struct device").
>>
>> Side effect of a crash during boot... the PMU gets upset when we crash while
>> there's a request in flight, that's probably what is happening.
>>
>> As to why that commit is broken, I don't have time to look into it right  now,
>> maybe next week of nobody beats me to it.
>
> Hello Ben,
>
> Thanks. I will try to reproduce what has been reported with qemu-ppc on Friday to
> double check that it's really commit 5657933dbb6e that is causing this. I reread it
> but couldn't find any reason why it works on x86-64 but not on powerpc. BTW, the
> following patch is needed on at least s390 but probably also on powerpc to restore
> InfiniBand support: http://marc.info/?l=linux-rdma&m=148823342415501&w=2. This is
> why I asked for the kernel config.

I am very confident of the bisection. A kernel built from commit 5299709, which 
is just before 5657933, boots correctly.

As you have probably seen, my configuration does not include InfiniBand support.

Larry