Re: [PATCH v2 00/10] evacuate struct page from the block layer, introduce __pfn_t

[Al Viro]

On Fri, May 08, 2015 at 11:26:01AM +0200, Ingo Molnar wrote:
> 
> * Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
> 
> > On Fri, May 08, 2015 at 07:37:59AM +0200, Ingo Molnar wrote:
> > 
> > > So if code does iov_iter_get_pages_alloc() on a user address that 
> > > has a real struct page behind it - and some other code does a 
> > > regular get_user_pages() on it, we'll have two sets of struct page 
> > > descriptors, the 'real' one, and a fake allocated one, right?
> > 
> > Huh?  iov_iter_get_pages() is given an array of pointers to struct 
> > page, which it fills with what it finds.  iov_iter_get_pages_alloc() 
> > *allocates* such an array, fills that with what it finds and gives 
> > the allocated array to caller.
> > 
> > We are not allocating any struct page instances in either of those.
> 
> Ah, stupid me - thanks for the explanation!

	My fault, actually - this "pages array" should've been either
"'pages' array" or "array of pointers to struct page".
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