Re: [PATCH] ppc64: Fix possible race with set_pte on a present PTE

Andrea Arcangeli
2004-05-26T07:06:17Z

On Tue, May 25, 2004 at 07:26:21PM -0700, Linus Torvalds wrote:
> You're reading it wrong.
>
> The "including when the present flag is set to zero" part does not mean
> that the present flag was zero _before_, it means "is being set to zero"
> as in "having been non-zero before that".

"having been non-zero before that" makes a lot more sense indeed, the
wording in the specs wasn't the best IMHO. Interestingly the
ptep_establish at the end of handle_pte_fault would have hidden any
double fault completely, nobody but a tracer would have noticed that,
but it made very little sense that non-present entries can be cached.
It's all clear now thanks.