Dear All, Today on my ARM Board one problem hit. pthread_mutex_lock.c:62: __pthread_mutex_lock: Assertion `mutex->__data.__owner == 0' failed. This happen in pthread_mutex_lock.c. May you pls let me know in which all cases it can happen. int __pthread_mutex_lock (mutex) pthread_mutex_t *mutex; { assert (sizeof (mutex->__size) >= sizeof (mutex->__data)); unsigned int type = PTHREAD_MUTEX_TYPE (mutex); if (__builtin_expect (type & ~PTHREAD_MUTEX_KIND_MASK_NP, 0)) return __pthread_mutex_lock_full (mutex); pid_t id = THREAD_GETMEM (THREAD_SELF, tid); if (__builtin_expect (type, PTHREAD_MUTEX_TIMED_NP) == PTHREAD_MUTEX_TIMED_NP) { simple: /* Normal mutex. */ LLL_MUTEX_LOCK (mutex); assert (mutex->__data.__owner == 0);<-------------------------------------------------Here. } else if (__builtin_expect (type == PTHREAD_MUTEX_RECURSIVE_NP, 1)) ...... Thanks