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    SubjectRe: mmu_notifier: Move mmu_notifier_release up to get rid of the invalidat_all() callback
    On Thu, Jan 31, 2008 at 02:21:58PM -0800, Christoph Lameter wrote:
    > Is this okay for KVM too?

    ->release isn't implemented at all in KVM, only the list_del generates

    I think current code could be already safe through the mm_count pin,
    becasue KVM relies on the fact anybody pinning through mm_count like
    KVM does, is forbidden to call unregister and it's forced to wait the
    auto-disarming when mm_users hits zero, but I feel like something's
    still wrong if I think that I'm not using call_rcu to free the
    notifier (OTOH we agreed the list had to be frozen and w/o readers
    (modulo _release) before _release is called, so if this initial
    assumption is ok it seems I may be safe w/o call_rcu?).

    But it's really tricky path. Anyway this is the last of my worries
    right now, it works perfectly fine with a single user obviously, and
    the moment KVM threads runs remotely through GRU/XPMEM isn't happening
    too soon ;) so let's concentrate on the rest first. I can say
    hlist_del_init doesn't seem to provide any benefit given nobody could
    possibly decide to call register or unregister after _release run.

     \ /
      Last update: 2008-02-01 01:23    [W:0.020 / U:2.212 seconds]
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