atmel-mci causes kernel panic when CONFIG_DEBUG_VM is set

[ludovic.desroches@atmel.com (Ludovic Desroches)]

On 5/19/2011 10:04 AM, Barry Song wrote:
> 2011/5/19 Ludovic Desroches<ludovic.desroches@atmel.com>:
>> Hello,
>>
>> There is a bug with the atmel-mci driver when the debug feature
>> CONFIG_DEBUG_VM is set.
>>
>> Into the atmci_read_data_pio function we use flush_dcache_page (do we really
>> need it?) which call the page_mapping function where we can find
>> VM_BUG_ON(PageSlab(Page)). Then a kernel panic happens.
>>
>> I don't understand the purpose of the VM_BUG_ON(PageSlab(Page)) (the page
>> comes from a scatter list). How could I correct this problem?
> linux/include/linux/mmdebug.h:
>
> #ifdef CONFIG_DEBUG_VM
> #define VM_BUG_ON(cond) BUG_ON(cond)
> #else
> #define VM_BUG_ON(cond) do { (void)(cond); } while (0)
> #endif
>
> it is something like "assert" in kernel.

Thanks for your answer but I know that. My question is more focused on 
why there is this check.

Is flushing a page taken from a slab forbidden ? Is it risky ? Is it no 
sense ?


Regards,

Ludovic