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SubjectRe: [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is patching the handler
On Thu, Sep 03, 2015 at 12:41:47PM +0200, Thomas Gleixner wrote:
> On Thu, 3 Sep 2015, Borislav Petkov wrote:
> > On Wed, Sep 02, 2015 at 11:11:55AM +0200, Thomas Gleixner wrote:
> > > static void __init_or_module add_nops(void *insns, unsigned int len)
> > > {
> > > + unsigned long flags;
> > > +
> > > + local_irq_save(flags);
> > > while (len > 0) {
> >
> > I guess you want to optimize the len==0 case to not disable interrupts
> > needlessly:
> >
> > if (!len)
> > return;
> >
> > local_irq_save(flags);
> > while (len > 0)
> > ...
>
> Nah. I rather put the local_irq_save into optimize_nops(). All other
> callers of add_nops() are operating on a buffer and use text_poke
> after that. Aside of that optimize_nops() is missing a sync_core().
>
> Updated patch below.

The V2 patch has got to 900 iterations without hitting the problem.
As that is a lot more than without the patch, you can add:

Tested-by: Richard W.M. Jones <rjones@redhat.com>

I will leave it going overnight just in case.

Thanks,

Rich.

--
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