Re: [PATCH 4.4 02/96] s390/runtime instrumention: fix possible memory corruption

[Greg Kroah-Hartman]

On Tue, Dec 05, 2017 at 05:02:32PM +0000, Ben Hutchings wrote:
> On Tue, 2017-11-28 at 11:22 +0100, Greg Kroah-Hartman wrote:
> > 4.4-stable review patch.  If anyone has any objections, please let me know.
> > 
> > ------------------
> > 
> > From: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
> > 
> > commit d6e646ad7cfa7034d280459b2b2546288f247144 upstream.
> [...]
> > --- a/arch/s390/kernel/runtime_instr.c
> > +++ b/arch/s390/kernel/runtime_instr.c
> > @@ -47,11 +47,13 @@ void exit_thread_runtime_instr(void)
> >  {
> >  	struct task_struct *task = current;
> >  
> > +	preempt_disable();
> >  	if (!task->thread.ri_cb)
> >  		return;
> 
> This return path now leaves preemption disabled.  This seems to have
> been fixed upstream by commit 8d9047f8b967 "s390/runtime
> instrumentation: simplify task exit handling".

"simplify" doesn't seem to imply "fixes a bug" :)

Heiko, should I also queue this patch up?

thanks Ben for the review.

greg k-h