Re: [PATCH v2] nommu: add page_align to mmap

[Bob Liu <lliubbo@gmail.com>]

Hi, Greg

On Fri, Jun 10, 2011 at 11:51 AM, Greg Ungerer <gerg@snapgear.com> wrote:
> Hi Bob,
>
> On 09/06/11 20:30, Bob Liu wrote:
>>
>> On Wed, Jun 8, 2011 at 6:19 PM, Greg Ungerer<gerg@snapgear.com>  wrote:
>>>>>>>
>>>>>>> When booting on a ColdFire (m68knommu) target the init process (or
>>>>>>> there abouts at least) fails. Last console messages are:
>>>>>>>
>>>>>>> ...
>>>>>>> VFS: Mounted root (romfs filesystem) readonly on device 31:0.
>>>>>>> Freeing unused kernel memory: 52k freed (0x401aa000 - 0x401b6000)
>>>>>>> Unable to mmap process text, errno 22
>>>>>>>
>>>>>>
>>>>>> Oh, bad news. I will try to reproduce it on my board.
>>>>>> If you are free please enable debug in nommu.c and then we can see
>>>>>> what
>>>>>> caused the problem.
>>>>>
>>>>> Yep, with debug on:
>>>>>
>>>>> ­...
>>>>> VFS: Mounted root (romfs filesystem) readonly on device 31:0.
>>>>> Freeing unused kernel memory: 52k freed (0x4018c000 - 0x40198000)
>>>>> ==>  Ã¡do_mmap_pgoff(,0,6780,5,1002,0)
>>>>> <== do_mmap_pgoff() = -22
>>>>> Unable to mmap process text, errno 22
>>>>>
>>>>
>>>> Since I can't reproduce this problem, could you please attach the
>>>> whole dmesg log with nommu debug on or
>>>> you can step into to see why errno 22 is returned, is it returned by
>>>> do_mmap_private()?
>>>
>>> There was no other debug messages with debug turned on in nommu.c.
>>> (I can give you the boot msgs before this if you want, but there
>>> was no nommu.c debug in it).
>>>
>>> But I did trace it into do_mmap_pgoff() to see what was failing.
>>> It fails based on the return value from:
>>>
>>> addr = file->f_op->get_unmapped_area(file, addr, len,
>>>                                           ¡pgoff, flags);
>>>
>>
>> Thanks for this information.
>> But it's a callback function. I still can't know what's the problem maybe.
>> Would you do me a favor to do more trace to see where it callback to,
>> fs or some driver etc..?
>
> Its calling to romfs_get_unmapped_area() [fs/romfs/mmap-nommu.c]. It is
> being called with:
>
>  romfs_get_unmapped_area(addr=0,len=7000,pgoff=0,flags=1002)
>
> This is failing the first size check because isize comes back
> as 0x6ca8, and this is smaller then len (0x7000). Thus returning
> -EINVAL.
>

I look into file fs/romfs/mmap-nommu.c based on your trace.
In my opinion, romfs_get_unmapped_area() in mmap-nommu.c is buggy.
Would you please try below commit.
Thanks a lot.