Messages in this thread | | | Subject | Re: [PATCH][RFC][0/4] InfiniBand userspace verbs implementation | From | Roland Dreier <> | Date | Mon, 11 Apr 2005 17:21:04 -0700 |
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Roland> Yes, because the kernel may go through and unmap pages Roland> from userspace while trying to swap. Since we have the Roland> page locked in the kernel, the physical page won't go Roland> anywhere, but userspace might end up with a different page Roland> mapped at the same virtual address.
Andrew> That shouldn't happen. If get_user_pages() has elevated Andrew> the refcount on a page then the following can happen:
...
Andrew> IOW: while the page has an elevated refcount from Andrew> get_user_pages(), that physical page is 100% pinned. Andrew> Once you've done the set_page_dirty+put_page(), the page Andrew> is again under control of the VM.
Hmm... I've never tested it first hand but Libor assures me there is a something like what I said. Libor, did I get the explanation right?
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