Messages in this thread | | | Date | Mon, 24 May 2004 21:39:05 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [PATCH] ppc64: Fix possible race with set_pte on a present PTE |
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On Tue, 25 May 2004, Andrea Arcangeli wrote:
> On Mon, May 24, 2004 at 09:00:02PM -0700, Linus Torvalds wrote: > > > > > > On Tue, 25 May 2004, Andrea Arcangeli wrote: > > > > > > The below patch should fix it, the only problem is that it can screwup > > > some arch that might use page-faults to keep track of the accessed bit, > > > > Indeed. At least alpha does this - that's where this code came from. SO > > this will cause infinite page faults on alpha and any other "accessed bit > > in software" architectures. > > as you say the alpha has no accessed bit at all in hardware, so > it cannot generate page faults.
It _does_ generate page faults.
We do the accessed bit by clearing the "user readable" thing (or something. I forget the exact details, and I'm too lazy to check it out). And a page won't be _really_ readable until it has been marked young.
If you don't mark it young, you'll get infinite page faults.
That's how we do the accessed bit.
> "accessed bit in software" is fine with my fix.
NO IT IS NOT.
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