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    SubjectRe: [PATCH 1/3] mmu_notifier: Add mmu_notifier_invalidate_range()
    On Thu, 24 Jul 2014 16:35:39 +0200
    Joerg Roedel <joro@8bytes.org> wrote:

    > From: Joerg Roedel <jroedel@suse.de>
    >
    > This notifier closes an important gap with the current
    > invalidate_range_start()/end() notifiers. The _start() part
    > is called when all pages are still mapped while the _end()
    > notifier is called when all pages are potentially unmapped
    > and already freed.
    >
    > This does not allow to manage external (non-CPU) hardware
    > TLBs with MMU-notifiers because there is no way to prevent
    > that hardware will establish new TLB entries between the
    > calls of these two functions. But this is a requirement to
    > the subsytem that implements these existing notifiers.
    >
    > To allow managing external TLBs the MMU-notifiers need to
    > catch the moment when pages are unmapped but not yet freed.
    > This new notifier catches that moment and notifies the
    > interested subsytem when pages that were unmapped are about
    > to be freed. The new notifier will only be called between
    > invalidate_range_start()/end().

    So if we were actually sharing page tables, we should be able to make
    start/end no-ops and just use this new callback, assuming we didn't
    need to do any other serialization or debug stuff, right?

    Seems like a good addition, and saves us a bunch of trouble...

    Thanks,
    --
    Jesse Barnes, Intel Open Source Technology Center


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