Re: race with page_referenced_one->ptep_test_and_clear_young andpagetable setup/pulldown

[Jeremy Fitzhardinge]

Rik van Riel wrote:
> Either of these two would work.  Another alternative could be to
> let test_and_clear_pte_flags have an exception table entry, where
> we jump right to the next instruction if the instruction clearing
> the flag fails.
>
> That is the essentially variant you need for Xen, except the fast
> path is still exactly the same it is as when running on native
> hardware.
>   

Hm, that wouldn't end up clearing the bit.  You'd need a Xen-specific
exception handler to do that, which would turn the whole thing into
Xen-specific code, and you're back at adding a pv-op.

    J

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