Process permanently stuck on D state [closed]

Answer 1

This is the dreaded un-interruptible (TASK_UNINTERRUPTIBLE) state of a process. This is the state where the process doesn't react to signals until what it started to wait for, gets done. Unfortunately it is a necessary evil. See here and here What is an uninterruptable process?.

My answer is to reboot the system.
Do rebooting cause any issues ?
Hard to tell, it may it may not. The process which is in the D state may have to do some crucial updates which it wont if you reboot.
If you really cant afford to reboot, try to find the disk on which the process is waiting and see if the disk is working fine by opening, closing, reading/writing into it

Answer 2

No - you cannot kill them, period. kill -9 does not work either. And it is not kernel bug, it is by design. All signals are blocked until those processes leave the D state. They either leave the D state or the system gets rebooted. No, rebooting does not have any problem with these guys.

The usual culprits for this kind of problem are removable media devices like a cdrom. The device may be defective or somebody found a way to do something stupid.