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    SubjectRe: [PATCH tip/core/urgent] rcu: protect fork-time cgroup access
    On Mon, Mar 29, 2010 at 11:42:55PM +0200, Peter Zijlstra wrote:
    > On Mon, 2010-03-29 at 14:34 -0700, Paul E. McKenney wrote:
    > > And it appears that my patch is at best insufficient:
    > >
    > >
    > > Left to myself, I would wrap copy_process() with rcu_read_lock(),
    > > but I would rather hear your thoughts before doing too much more
    > > semi-random hacking. ;-)
    > Well, I don't think you can get away with that, copy_process() wants to
    > sleep on quite a few places ;-) Also, locks should be taken at the
    > smallest possible scope, unless we want to go back to BKL style
    > locking :-)

    No argument here! ;-)

    > As to that freezer splat, you'd have to chase down the cgroup folks, I'm
    > fully ignorant on that.

    K, adding them to CC. The two splats are:

    Some additional RCU protection is required, or perhaps some suppression
    of false positives. Thoughts?

    > For the set_task_rq() one, I'm afraid someone (which again I'm afraid
    > will be me) will have to look into how the task_group muck ties into the
    > cgroup muck as I think the original authors of that ran off :/


    Thanx, Paul

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