Subject: Re: Regression in kernel 4.12-rc1 for Powerpc 32 - bisected to commit
 3448890c32c3
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: LKML <linux-kernel@vger.kernel.org>,
        Thorsten Leemhuis <regressions@leemhuis.info>
References: <69187aa4-611f-b08a-8d14-b8fa47b4c464@lwfinger.net>
 <1588557c-2706-0c0e-3387-4ae65d0b5790@lwfinger.net>
 <20170621212257.GN10672@ZenIV.linux.org.uk>
 <5f4b9fa4-262a-31b1-32ba-a2f6e789b3d6@lwfinger.net>
 <20170621213415.GO10672@ZenIV.linux.org.uk>
 <655d304e-e455-6e0c-56e1-f127653ea13c@lwfinger.net>
 <20170622141203.GP10672@ZenIV.linux.org.uk>
From: Larry Finger <Larry.Finger@lwfinger.net>
Message-ID: <7bbd4c87-e8ff-5f83-8c4c-e205872083bf@lwfinger.net>
Date: Thu, 22 Jun 2017 09:19:58 -0500
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On 06/22/2017 09:12 AM, Al Viro wrote:
> On Wed, Jun 21, 2017 at 04:49:46PM -0500, Larry Finger wrote:
>> On 06/21/2017 04:34 PM, Al Viro wrote:
>>> On Wed, Jun 21, 2017 at 04:31:40PM -0500, Larry Finger wrote:
>>>> On 06/21/2017 04:22 PM, Al Viro wrote:
>>>>> How about the .config that works on parent of that commit?
>>>>
>>>> Attached.
>>>
>>> OK... am I right assuming straight jessie/powerpc userland?
>>>
>>
>> Actually Mint 12 with noting fancy. The machine mainly exists to test the
>> wireless drivers work on big-endian hardware.
>>
>> 'cat /etc/issue' reports "Debian GNU/Linux 7".
> 
> Ugh...  MintPPC appears to be dead.  On KVM with Debian userland (either
> jessie or wheezy - no difference in result) booting the commit in
> question with your .config oopses as soon as pata_macio is initialized,
> due to the bug in "treewide: Move dma_ops from struct dev_archdata into
> struct device", and after cherry-picking your own fix for that (commit
> 46f401c4297a "powerpc/pmac: Fix crash in dma-mapping.h with NULL dma_ops")
> the result boots just fine.
> 
> Again, that happens both for Debian 8 and Debian 7 userlands, so unless
> Mint had been doing something very odd there, I would question the accuracy
> of your bisect...

Any chance that real hardware differs from KVM emulation? All I know at this 
point is that commit f2ed8beb with 46f401c4 backported boots OK and commit 
3448890c with the same backport fails.

I will try loading jessie and see what happens.

Thanks for investigating.

Larry