On Wed, 16 Sep 2015, Zhu Jefferry wrote:
> The application is a multi-thread program, to use the pairs of mutex_lock and
> mutex_unlock to protect the shared data structure. The type of this mutex
> is PTHREAD_MUTEX_PI_RECURSIVE_NP. After running long time, to say several
> days,
> the mutex_lock data structure in user space looks like corrupt.
>
> thread 0 can do mutex_lock/unlock
> __lock = this thread | FUTEX_WAITERS
> __owner = 0, should be this thread
The kernel does not know about __owner.
> __counter keep increasing, although there is no recursive mutex_lock call.
>
> thread 1 will be stuck
>
> The primary debugging shows the content of __lock is wrong in first. After a
> call of
> Mutex_unlock, the value of __lock should not be this thread self. But we
> observed
> The value of __lock is still self after unlock. So, other threads will be
> stuck,
How did you observe that?
> This thread could lock due to recursive type and __counter keep increasing,
> although mutex_unlock return fails, due to the wrong value of __owner,
> but the application did not check the return value. So the thread 0 looks
> like fine. But thread 1 will be stuck forever.
Oh well. So thread 0 looks all fine, despite not checking return
values.
Thanks,
tglx
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
