On Mon, Dec 26, 2005 at 21:33:25 -0800, Rajaram Suryanarayanan wrote:
> I was able to change the state of the parent process by including the following line in my init_module()
>
> current->parent->state = TASK_UNINTERRUPTIBLE;
>
> When I inserted this module with "insmod process-1.ko", the bash shell hung.
> I understand that this is because the bash was actually in TASK_INTERRUPTIBLE state waiting for SIGCHLD signal, but I changed it to TASK_UNINTERRUPTIBLE state so that even when SIGCHLD is given by insmod on its completion, the parent bash process was not receiving the signal. So it hung. I was not able to kill and remove the bash process at all, even by "kill -9". Because I guess it never responded to signals.
>
> But I do not understand one thing. I wrote another module to change the state of that bash shell ( pid = 4256 ) again to TASK_INTERRUPTIBLE.
>
> for_each_process(task)
> {
> if (task->pid==4256)
> {
> printk(KERN_INFO "Found the idiot process 4256\nGoing to repair it");
> printk(KERN_INFO "Process state before repair :%d \n",task->state);
> task->state = TASK_INTERRUPTIBLE;
> printk(KERN_INFO "Process state after repair :%d \n",task->state);
> }
> }
>
> Then I tried to kill the process using "kill -9 4256". But still it was not receiving kill signal .
>
> Could you please explain this ?
No, I can't. But that state transition (between interruptible and
uninterruptible) is not supported. So it might be that the scheduler never
actually notices.
--
Jan 'Bulb' Hudec <bulb@xxxxxx>
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