Messages in this thread | | | Date | Tue, 25 May 2004 19:26:21 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [PATCH] ppc64: Fix possible race with set_pte on a present PTE |
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On Wed, 26 May 2004, Andrea Arcangeli wrote: > > after various searching on the x86 docs I found: > > Whenever a page-directory or page-table entry is changed (including when > the present flag is set to zero), the operating-system must immediately > invalidate the corresponding entry in the TLB so that it can be updated > the next time the entry is referenced. > > according to the above we'd need to flush the tlb even in > do_anonymous_page on x86, or am I reading it wrong?
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".
Anytime the P flag was clear _before_, we don't need to invalidate, because non-present entries are not cached in the TLB.
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