linux-kernel - Re: [PATCH 2/2] s390/mm: use ipte range to invalidate multiple page table entries

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Date:	Wed, 06 Jul 2016 14:42:16 +0800
From:	"Hillf Danton" <hillf.zj@...baba-inc.com>
To:	"'Martin Schwidefsky'" <schwidefsky@...ibm.com>
Cc:	"'linux-kernel'" <linux-kernel@...r.kernel.org>,
	<linux-mm@...ck.org>
Subject: Re: [PATCH 2/2] s390/mm: use ipte range to invalidate multiple page table entries

> > >
> > > +void ptep_invalidate_range(struct mm_struct *mm, unsigned long start,
> > > +			   unsigned long end, pte_t *ptep)
> > > +{
> > > +	unsigned long nr;
> > > +
> > > +	if (!MACHINE_HAS_IPTE_RANGE || mm_has_pgste(mm))
> > > +		return;
> > > +	preempt_disable();
> > > +	nr = (end - start) >> PAGE_SHIFT;
> > > +	/* If the flush is likely to be local skip the ipte range */
> > > +	if (nr && !cpumask_equal(mm_cpumask(mm),
> > > +				 cpumask_of(smp_processor_id())))
> >
> > s/smp/raw_smp/ to avoid adding schedule entry with page table
> > lock held?
> 
> There can not be a schedule entry with either the page table lock held
> or the preempt_disable() a few lines above.
> 
Yes, Sir.

> > > +		__ptep_ipte_range(start, nr - 1, ptep);
> > > +	preempt_enable();

Then would you please, Sir, take a look at another case where
preempt is enabled?

> > > +}
> > > +EXPORT_SYMBOL(ptep_invalidate_range);
> > > +
> >

thanks
Hillf