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Date:   Fri, 7 Dec 2018 09:11:16 -0800
From:   Matthew Wilcox <willy@infradead.org>
To:     Robin Murphy <robin.murphy@arm.com>
Cc:     Souptick Joarder <jrdr.linux@gmail.com>, akpm@linux-foundation.org,
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Subject: Re: [PATCH v3 1/9] mm: Introduce new vm_insert_range API
Message-ID: <20181207171116.GA29923@bombadil.infradead.org>
References: <20181206183945.GA20932@jordon-HP-15-Notebook-PC>
 <53bbc095-c9f5-5d6a-6e50-6e060d17eb68@arm.com>
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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;