Re: [PATCH stable-3.0] ptrace: don't clear GROUP_STOP_SIGMASK on double-stop

[Greg KH <greg@kroah.com>]

On Mon, Sep 26, 2011 at 07:06:32PM +0200, Oleg Nesterov wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=740121
> 
> 1. Luke Macken triggered WARN_ON(!(group_stop & GROUP_STOP_SIGMASK))
>    in do_signal_stop().
> 
>    This is because do_signal_stop() clears GROUP_STOP_SIGMASK part
>    unconditionally but doesn't update it if task_is_stopped().
> 
> 2. Looking at this problem I noticed that WARN_ON_ONCE(!ptrace) is
>    not right, a stopped-but-resumed tracee can clone the untraced
>    thread in the SIGNAL_STOP_STOPPED group, the new thread can start
>    another group-stop.
> 
>    Remove this warning, we need more fixes to make it true.
> 
> Reported-by: Luke Macken <lmacken@redhat.com>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>

I still don't understand, did this fix ever get into Linus's tree?  If
so, what is the git commit id.

If not, why not?  I can't apply it to the 3.0-stable tree unless it is
there, or there is a very good reason why it isn't.

thanks,

greg k-h