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


On Mon, 24 May 2004, Benjamin Herrenschmidt wrote:
>
> Typically, you can have a thread faulting on a page. It goes through hash_page,
> doesn't find the entry, and gets to do_page_fault(). However, just before it
> takes the mm sem, another thread actually mmap's that page in. Thus we end up
> in handle_pte_fault() with a present PTE which has a valid mapping already.

Ok, with you so far. But I don't see how you get to set_pte() that way,
since handle_pte_fault() will re-test the pte_present() bit, and never
even try to set_pte() if one already exists. Hmm?

Linus
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