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    SubjectRe: [PATCH -v5][RFC]: mutex: implement adaptive spinning
    On Wed, 7 Jan 2009 21:33:31 -0500 (EST)
    Steven Rostedt <rostedt@goodmis.org> wrote:

    >
    > On Wed, 7 Jan 2009, Linus Torvalds wrote:
    > > > Should that be:
    > > >
    > > > #if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_MEMORY_HOTPLUG)
    > >
    > > Well, probably CONFIG_MEMORY_HOTREMOVE, no? And I'd actually suggest that
    > > unplugging should have a stop-machine if it doesn't already, just because
    > > it's such a special case - like module removal.
    >
    > I do not think stop-machine will help, unless that spinning is protected
    > by preempt-disable. If the task gets preempted after grabbing the owner
    > thread_info, and then stop-machine runs, the memory disappears, the task
    > is scheduled back, accesses the owner thread_info and then page-fault.
    >
    How about recording "cpu" into mutex at locking explicitly ?
    too bad ?

    -Kame



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