I'm testing some functionality to monitor processes and I need to emulate long core dump with determined "delay" (for example I need to make a process to "dump core" for 30 seconds). I'm noticed that process that dumping a core is in uninterruptible sleep, so it can't be killed with SIGKILL, but when I'm trying to emulate this behavior using pipe commands that receives coredump I can easily kill such process. So is there some way to make process to get into uninterruptible sleep (with such status in ps) and make it ignore the SIGKILL?
To put a process in an interruptible sleep mode you will have to go into kernel code.
Using the functionality of wake_up_interruptible and spin locks you will be able to achieve this state.