Re: [PATCH] arch_ptrace_stop

[Oleg Nesterov <oleg@tv-sign.ru>]

On 12/13, Matthew Wilcox wrote:
>
> On Thu, Dec 13, 2007 at 08:29:26PM +0300, Oleg Nesterov wrote:
> > How is it possible that SIGKILL is blocked?
> 
> I *think* it's possible that kernel threads may block SIGKILL.
> And I think init (pid 1) gets SIGKILL blocked.

Yes. But this shouldn't matter because we can't ptrace them. /sbin/init
doesn't block SIGKILL, but it can't be ptraced either.

Also, SIGKILL is blocked only if kthread was created by kernel_thread() and
then it does daemonize(). kthread_create()'ed kthreads don't block SIGKILL
but ignore it. The latter behaviour is more correct, but we can't do the same
for kernel_thread() threads.

Oleg.