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    SubjectRe: [PATCH] robust futex thread exit race

    * Thomas Gleixner <tglx@linutronix.de> wrote:

    >
    > On Sun, 30 Sep 2007, Ingo Molnar wrote:
    > > * Martin Schwidefsky <schwidefsky@de.ibm.com> wrote:
    > >
    > > > Hi Ingo,
    > > > I finally found the bug that causes tst-robust8 from the glibc to fail
    > > > on s390x. Turned out to be a common code problem with the processing of
    > > > the robust futex list. The patch below fixes the bug for me.
    > >
    > > good catch! A quick preliminary review of your patch indicates it's fine
    > > - and it might be v2.6.23 material.
    > >
    > > Acked-by: Ingo Molnar <mingo@elte.hu>
    >
    > Acked-by: Thomas Gleixner <tglx@linutronix.de>
    >
    > > > Calling handle_futex_death in exit_robust_list for the different
    > > > robust mutexes of a thread basically frees the mutex. Another thread
    > > > might grab the lock immediately which updates the next pointer of the
    > > > mutex. fetch_robust_entry over the next pointer might therefore branch
    > > > into the robust mutex list of a different thread. This can cause two
    > > > problems: 1) some mutexes held by the dead thread are not getting
    > > > freed and 2) some mutexs held by a different thread are freed. The
    > > > next point need to be read before calling handle_futex_death.
    > >
    > > nasty race... Ulrich, Thomas, do you concur?
    >
    > Yes. Where do they sell those brown paperbags again ?

    i've still got plenty of them stacked up, can pass over a few. (i'm
    getting them cheap from the manufacturer - large quantity discount)

    Ingo
    -
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