Re: New reliability technique

[Jesper Juhl]

On 2/25/06, Avi Kivity <avi@xxxxxxxxxx> wrote:
> 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.
>

Ohh, ok, then it makes sense as a debug thing.

Let's see an implementation then.

--
Jesper Juhl <jesper.juhl@xxxxxxxxx>
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