Re: New reliability technique

[Avi Kivity <avi@argo.co.il>]

Jesper Juhl wrote:

>On 2/25/06, Jesper Juhl <jesper.juhl@gmail.com> wrote:
>  
>
>>On 2/25/06, Victor Porton <porton@ex-code.com> wrote:
>>    
>>
>>>A minute ago I invented a new reliability enhancing technique.
>>>
>>>In idle cycles (or periodically in expense of some performance) Linux can
>>>calculate MD5 or CRC sums of _unused_ (free) memory areas and compare these
>>>sums with previously calculated sums.
>>>
>>>Additionally it can be done for allocated memory, if it will be write
>>>protected before the first actual write. Moreover, all memory may be made
>>>write-protected if it is not written e.g. more than a second. (When it
>>>is written kernel would unlock it and allow to write, by a techniqie like
>>>to how swap works.) If write-protected memory appears to be modified by
>>>a check sum, this likewise indicates a bug.
>>>
>>>If a sum is inequal, it would notice a bug in kernel or in hardware.
>>>
>>>I suggest to add "Check free memory control sums" in config.
>>>
>>>      
>>>
>>Implement it then and send a patch.
>>
>>    
>>
>
>But, doesn't slab poisoning and the like already cover this ground somewhat?
>
>  
>
No, they don't. They cover only a very small percentage of memory.

On the other hand, ECC memory and caches do this in hardware.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.