Re: race with page_referenced_one->ptep_test_and_clear_young and pagetable setup/pulldown

Rik van Riel
2007-10-05T19:57:08Z

On Fri, 05 Oct 2007 12:40:05 -0700
Jeremy Fitzhardinge <jeremy@goop.org> wrote:

> Well, isn't the correct fix to make Xen take all the pagetable locks
> while pinning/unpinning? Adding exception handling to
> test_and_clear_bit would solve this particular race, but are there
> others (either now or potentially)? Seems fragile.

You're right, holding the pagetable lock(s) across pinning/unpinning
operations would avoid the problem too.

While we do not care about the accessed bit, there are similar operations
going on with the dirty bit - which is a lot more important :)

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