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    Subject[PATCH 3.14 68/70] futex: Drop refcount if requeue_pi() acquired the rtmutex
    Date
    3.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Thomas Gleixner <tglx@linutronix.de>

    commit fb75a4282d0d9a3c7c44d940582c2d226cf3acfb upstream.

    If the proxy lock in the requeue loop acquires the rtmutex for a
    waiter then it acquired also refcount on the pi_state related to the
    futex, but the waiter side does not drop the reference count.

    Add the missing free_pi_state() call.

    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Darren Hart <darren@dvhart.com>
    Cc: Davidlohr Bueso <dave@stgolabs.net>
    Cc: Bhuvanesh_Surachari@mentor.com
    Cc: Andy Lowe <Andy_Lowe@mentor.com>
    Link: http://lkml.kernel.org/r/20151219200607.178132067@linutronix.de
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    kernel/futex.c | 5 +++++
    1 file changed, 5 insertions(+)

    --- a/kernel/futex.c
    +++ b/kernel/futex.c
    @@ -2648,6 +2648,11 @@ static int futex_wait_requeue_pi(u32 __u
    if (q.pi_state && (q.pi_state->owner != current)) {
    spin_lock(q.lock_ptr);
    ret = fixup_pi_state_owner(uaddr2, &q, current);
    + /*
    + * Drop the reference to the pi state which
    + * the requeue_pi() code acquired for us.
    + */
    + free_pi_state(q.pi_state);
    spin_unlock(q.lock_ptr);
    }
    } else {

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