Re: [PATCH] parisc: fix LMMIO mismatch between PAT length and MASK register

[John David Anglin <dave.anglin@bell.net>]

On 7/10/2013 4:19 PM, Alex Ivanov wrote:
> Sorry for not CC'ing to the list.
>
> 10.07.2013, 03:35, "John David Anglin" <dave.anglin@bell.net>:
>
>>   On 9-Jul-13, at 4:59 PM, John David Anglin wrote:
>>>    On 7/9/2013 3:45 PM, Alex Ivanov wrote:
>>>>    The panic on SMP kernel changed to another one:
>>>>    http://pastebin.com/SfUfd0Un
>>>    This is just a guess but I don't think page is valid
>>>    if the pfn is not valid.  You might try this untested change.
>>>
>>>    flush_cache_mm might have same problem (i.e., we may need to
>>>    check whether the pfn for the pte is valid).
>>   This version compiles and boots on rp3440.
>>
>>   Dave
>>   --
>>   John David Anglin dave.anglin@bell.net
> Dave,
>
> Thank you so much! Your guess looks to be right. After applying of your
> patch there was no more KP and X just worked.
I have been studying this issue a bit more.  It looks to me as if it 
would be better to call
vm_normal_page to get the page.  It returns NULL when we a have special 
mapping that
doesn't want to be associated with a struct page.  See comment in 
mm/memory.c.

I'll send a patch when I get a chance to test this approach.

Dave

-- 
John David Anglin    dave.anglin@bell.net