Re: [PATCH v2 01/26] iommu/fsl: Sprinkle some __init* annotations

[Emil Medve <Emilian.Medve-eDlz3WWmN0ll57MIdRCFDg@public.gmane.org>]

Hello Varun,


On 02/09/2015 08:26 PM, Sethi Varun-B16395 wrote:
> Hi Emil,
> 
> 
>> -----Original Message-----
>> From: Emil Medve [mailto:Emilian.Medve-eDlz3WWmN0ll57MIdRCFDg@public.gmane.org]
>> Sent: Tuesday, February 10, 2015 3:17 AM
>> To: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org; joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org; jroedel-l3A5Bk7waGM@public.gmane.org;
>> Sethi Varun-B16395
>> Subject: Re: [PATCH v2 01/26] iommu/fsl: Sprinkle some __init* annotations
>>
>> Hello Joerg,
>>
>>
>> On 01/28/2015 08:34 AM, Emil Medve wrote:
>>> Signed-off-by: Emil Medve <Emilian.Medve-eDlz3WWmN0ll57MIdRCFDg@public.gmane.org>
>>> ---
>>>  drivers/iommu/fsl_pamu.c        | 12 ++++++------
>>>  drivers/iommu/fsl_pamu_domain.c |  2 +-
>>>  2 files changed, 7 insertions(+), 7 deletions(-)
>>
>> Please don't apply this patch as it's wrong. It's based on
>> https://git.kernel.org/cgit/linux/kernel/git/joro/iommu.git/commit/?h=ppc/
>> pamu&id=0f1fb99b62ce226f8d818852f812c5d79071ce58
>> which is wrong as well and its causing semi-random crashes upon more
>> extensive testing. I will follow-up with details shortly
> 
> Are you seeing  a crash with
> https://git.kernel.org/cgit/linux/kernel/git/joro/iommu.git/commit/?h=ppc/pamu&id=0f1fb99b62ce226f8d818852f812c5d79071ce58
> ? At, what point do you see crashes?

platform_driver.device_driver gets added to a (platform) bus klist of
drivers. (There are also a handful of other pointers that get set to
fsl_of_pamu_driver) Once fsl_of_pamu_driver gets released that klist
becomes "corrupted" and, depending on how said memory gets re-used,
traversing it for any reason will end up into a crash

Anyway, I identified easier ways to produce kernel crashes related to
the PAMU driver via sysfs (with or without my __init* annotation
patches). For example a "unbind, bind" sequence will cause a crash with
the driver as is in v3.19

BTW, why is the PAMU an "early" driver?

I'll send out some patches to properly fix all these __init* annotations


Cheers,