Re: [Xenomai-help] mlockall error after calling mlockall()

[Jan Kiszka <jan.kiszka@domain.hid>]

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Charlton, John wrote:
> I have a xenomai application that runs without problems with xenomai-2.4.6.1/linux-2.6.27.7. When run under xenomai-2.5.1/linux-2.6.32.7 it fails with the warning: Xenomai: process memory not locked (missing mlockall?).  I verified that mlockall() is being called before any xenomai calls are made as follows with out error:
> 

I'm afraid that warning is misleading.

>   // lock process in memory for xenomai
>   int err = mlockall(MCL_CURRENT | MCL_FUTURE);
>   if (err)
>   {
>     fprintf(stderr, "TimerInit: mlockall failed to lock process into memory: %d\n", err);
>     exit(1);
>   }
>   fprintf(stdout, "TimerInit: Locked process memory\n");
> 
> The relevant message in dmesg output is:
> Xenomai: watchdog triggered -- signaling runaway thread 'timerloop-2166'

That is the actual error message, likely pointing to an application bug.
Try to attach gdb to your application, it will catch the signal and
allow to dump a stack trace that should give some hint what loops
endlessly here.

> 
> This occurs when creating a native xenomai task (created by CanFestival library) with the following code with no errors:
> 
> void StartTimerLoop(TimerCallback_t _init_callback)
> {
>   int ret = 0;
>   stop_timer = 0;
>   init_callback = _init_callback;
> 
>   char taskname[32];
>   snprintf(taskname, sizeof(taskname), "timerloop-%d", getpid());
> 
>   printf("Starting timerloop task %s\n", taskname);
>   /* create timerloop_task */
>   ret = rt_task_create(&timerloop_task, taskname, 0, 50, T_JOINABLE);
>   if (ret) {
>     printf("Failed to create timerloop_task, code %d\n",errno);
>     return;
>   }
> 
>   /* start timerloop_task */
>   ret = rt_task_start(&timerloop_task,&timerloop_task_proc,NULL);
>   if (ret) {
>     printf("Failed to start timerloop_task, code %u\n",errno);
>     goto error;
>   }
> 
>   return;
> 
> error:
>   cleanup_all();
> }
> 
> Debug output is displayed from the timerloop_task indicating that the task starts, but the mlockall warning is displayed before those outputs and the application already begins to shut down.

Way more interesting is how timerloop_task_proc looks like. Can you post
a complete test case? Besides that this would allow us to help you with
the runaway timerloop, I would like to understand why this wrong warning
is dumped in user space.

Jan


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