Re: [patch] Real-Time Preemption, -RT-2.6.10-rc3-mm1-V0.7.34-01

Re: [patch] Real-Time Preemption, -RT-2.6.10-rc3-mm1-V0.7.34-01

[Kevin Hilman]

Using V0.7.34-01, I'm seeing the 'lock held at task exit time' bug. 
It's coming from a kernel module which in its init function creates a
thread.  The thread does a daemonize() and then goes to sleep waiting
on a semaphore which will be up'ed elsewhere.  In other words:

init_module()
 - sema_init(&sem, 0)
 - kernel_thread(thread_func, 0, 0);

thread_func()
 - daemonize()
 - down(&sem)

The BUG() (see below for log) seems to be triggered when insmod exits.  

BUG: insmod/2115, lock held at task exit time!
 [c883225c] {&tinfo[i].sem}
.. held by:            insmod: 2115 [c7b6f340,   0]
... acquired at:  threads_init+0x8e/0x170 [rt_kthreads]
hm, PI interest held at exit time? Task:
          insmod: 2115 [c7b6f340,   0]-------------------------
| waiter struct c4c1bf74:
| w->task:
          insmod: 2123 [c7e68680,   0]
| lock:
 [c883225c] {&tinfo[i].sem}
.. held by:            insmod: 2115 [c7b6f340,   0]
... acquired at:  threads_init+0x8e/0x170 [rt_kthreads]
| blocked at:  thread_func+0x3d/0xb0 [rt_kthreads]
-------------------------


--
Kevin Hilman
http://hilman.org/kevin/