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    SubjectRe: [BUG] futex_unlock_pi() hurts my brain and may cause application deadlock
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    On Thu, 2007-05-31 at 16:24 +0200, Ingo Molnar wrote:
    > * john stultz <johnstul@us.ibm.com> wrote:
    >
    > > So we've been seeing PI mutex deadlocks with a few of our
    > > applications using the -rt kernel. After narrowing things down, we
    > > were finding that the applications were indirectly calling
    > > futex_unlock_pi(), which on occasion would return -EFAULT, which is
    > > promptly ignored by glibc. This would cause the application to
    > > continue on as if it has unlocked the mutex, until it tried to
    > > reacquire it and deadlock.
    >
    > > --- a/kernel/futex.c
    > > +++ b/kernel/futex.c
    > > @@ -2011,6 +2011,7 @@ pi_faulted:
    > > attempt);
    > > if (ret)
    > > goto out_unlock;
    > > + uval = 0;
    > > goto retry_locked;
    >
    > this looks good to me. Oleg has posted a few more fixes as well - have
    > you tried those too?

    Do you have a URL or subject line for the discussion?
    I'll take a look and give them a whirl.

    thanks
    -john

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