bin/164526: kill(1) can not kill process despite on -KILL

[Jilles Tjoelker]

The following reply was made to PR bin/164526; it has been noted by GNATS.

From: Jilles Tjoelker <jilles at stack.nl>
To: bug-followup at FreeBSD.org, kes-kes at yandex.ru
Cc:  
Subject: Re: bin/164526: kill(1) can not kill process despite on -KILL
Date: Sat, 28 Jan 2012 19:24:07 +0100

 > [stuck process cannot be killed, system hangs when reboot is
 > attempted]
 
 A signal cannot forcibly kill a process that is stuck in the kernel.
 Allowing this would put the integrity of the kernel data structures at
 risk and likely cause hangs, data corruption or panics later on.
 
 If a process is stuck in the kernel for a long time, this can be things
 like broken hardware, a non-responsive NFS server or a bug.
 
 A state 'T' (stopped) probably means the process is multi-threaded and
 is trying to suspend but one or more threads will not cooperate
 (non-interruptible sleep or running in the kernel).
 
 Useful commands to obtain more information (supposing pid is 45471):
 
 ps Hl45471
 procstat -k 45471
 
 Of course, this does not help if you already rebooted.
 
 -- 
 Jilles Tjoelker