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    SubjectRe: x86_64: potential critical issue with quicklists and page table pages
    On Fri, 21 Sep 2007, Linus Torvalds wrote:

    > Yeah, and the whole thing seems totally bogus. It totally depends on
    > mmu_gather doing everything right (which very much includes the dependency
    > on mmu gathering disabling preempt).

    The quicklists have been existing for a long time in this relationship
    and were actually developed initially (by Dave Miller I believe) to work
    this way. The generic TLB flushing thing may have developed in parallel on
    other platforms that did not use quicklists.

    > For exmaple, if we were to go back to the original small tlb_gather with a
    > simple quicklist on the stack, rather than the per-cpu datastructure, the
    > quicklists would immediately break horribly - simply because they are
    > incorrectly now depending on the internal semantics of that tlb-gather.

    Hmmmm.. Right the integration of the approaches that have now diverged on
    various platforms could be better.

    > As it is, the quicklists try to be something separate, but by virtue of
    > being separate, they will always be buggy.

    I guess we need to re-join what was separated by developments on different
    platforms.

    > The only way to fix it would be to integrate the quicklist stuff *with*
    > the mmu_gather stuff, so that these kinds of implementation issues are
    > explicitly shown in the relationship, instead of havign two "independent"
    > pieces of code where one piece very subtly depends on the exact
    > implementation of the other.

    Right. But will that not mean that quicklists would have to be used on all
    platforms in a generic way?
    -
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