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    SubjectRe: [patch 02/10] emm: notifier logic
    On Sat, 5 Apr 2008, Andrea Arcangeli wrote:

    > > + rcu_assign_pointer(mm->emm_notifier, e);
    > > + mm_unlock(mm);
    >
    > My mm_lock solution makes all rcu serialization an unnecessary
    > overhead so you should remove it like I already did in #v11. If it
    > wasn't the case, then mm_lock wouldn't be a definitive fix for the
    > race.

    There still could be junk in the cache of one cpu. If you just read the
    new pointer but use the earlier content pointed to then you have a
    problem.

    So a memory fence / barrier is needed to guarantee that the contents
    pointed to are fetched after the pointer.



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