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From:   Souptick Joarder <jrdr.linux@gmail.com>
Date:   Sat, 8 Dec 2018 00:58:26 +0530
Message-ID: <CAFqt6zYCWOK-uS85GqCzcgT=+YKn1nBrRPq+M9y6eJjmXEKH+g@mail.gmail.com>
Subject: Re: [PATCH v3 1/9] mm: Introduce new vm_insert_range API
To:     Matthew Wilcox <willy@infradead.org>
Cc:     robin.murphy@arm.com, Andrew Morton <akpm@linux-foundation.org>,
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On Fri, Dec 7, 2018 at 10:41 PM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Fri, Dec 07, 2018 at 03:34:56PM +0000, Robin Murphy wrote:
> > > +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
> > > +                   struct page **pages, unsigned long page_count)
> > > +{
> > > +   unsigned long uaddr = addr;
> > > +   int ret = 0, i;
> >
> > Some of the sites being replaced were effectively ensuring that vma and
> > pages were mutually compatible as an initial condition - would it be worth
> > adding something here for robustness, e.g.:
> >
> > +     if (page_count != vma_pages(vma))
> > +             return -ENXIO;
>
> I think we want to allow this to be used to populate part of a VMA.
> So perhaps:
>
>         if (page_count > vma_pages(vma))
>                 return -ENXIO;

Ok, This can be added.

I think Patch [2/9] is the only leftover place where this
check could be removed.