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Date: Tue, 5 Dec 2017 18:08:47 +0100
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Ben Hutchings <ben.hutchings@codethink.co.uk>
Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>
Subject: Re: [PATCH 4.4 02/96] s390/runtime instrumention: fix possible
 memory corruption
Message-ID: <20171205170847.GA22747@kroah.com>
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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@de.ibm.com>
> > 
> > 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