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References: <20181206183945.GA20932@jordon-HP-15-Notebook-PC>
 <53bbc095-c9f5-5d6a-6e50-6e060d17eb68@arm.com> <20181207171116.GA29923@bombadil.infradead.org>
In-Reply-To: <20181207171116.GA29923@bombadil.infradead.org>
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
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To: Matthew Wilcox <willy@infradead.org>
Cc: robin.murphy@arm.com, Andrew Morton <akpm@linux-foundation.org>, Michal Hocko <mhocko@suse.com>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, vbabka@suse.cz, Rik van Riel <riel@surriel.com>, Stephen Rothwell <sfr@canb.auug.org.au>, rppt@linux.vnet.ibm.com, Peter Zijlstra <peterz@infradead.org>, Russell King - ARM Linux <linux@armlinux.org.uk>, iamjoonsoo.kim@lge.com, treding@nvidia.com, Kees Cook <keescook@chromium.org>, Marek Szyprowski <m.szyprowski@samsung.com>, stefanr@s5r6.in-berlin.de, hjc@rock-chips.com, Heiko Stuebner <heiko@sntech.de>, airlied@linux.ie, oleksandr_andrushchenko@epam.com, joro@8bytes.org, pawel@osciak.com, Kyungmin Park <kyungmin.park@samsung.com>, mchehab@kernel.org, Boris Ostrovsky <boris.ostrovsky@oracle.com>, Juergen Gross <jgross@suse.com>, linux-kernel@vger.kernel.org, Linux-MM <linux-mm@kvack.org>, linux-arm-kernel@lists.infradead.org, linux1394-devel@lists.sourceforge.net, dri-devel@lists.freedesktop.org, linux-rockchip@lists.infradead.org, xen-devel@lists.xen.org, iommu@lists.linux-foundation.org, linux-media@vger.kernel.org

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.