Re: New reliability technique

[Avi Kivity]

Jesper Juhl wrote:

> On 2/25/06, Jesper Juhl <jesper.juhl@xxxxxxxxx> wrote:
>  
>
> > On 2/25/06, Victor Porton <porton@xxxxxxxxxxx> 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.

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