[RFC] early_fault handler

[Dave Hansen]

On 11/13/2013 05:47 AM, Matthew Wilcox wrote:
> Looking to minimise the changes to the VM, here's a small piece of
> the puzzle.
> 
> Instead of adding a new special case at the start of handle_mm_fault,
> introduce a new vm_op, the ->early_fault method.  Convert both hugetlb
> and the XIP hpage code to use it.  Patch compile-tested only.
> 
> (Mostly the patch is so big because I have to change the calling
> convention of either hugetlb or hpage_xip.  I chose the latter for
> obvious reasons).

That looks pretty sane, although hugetlbfs is _bad_ company to be in. :)

I'm glad you also managed to nuke this gem:

> -		vmf.pgoff = (((address & PAGE_MASK) - vma->vm_start) >> PAGE_SHIFT)
> -															+ vma->vm_pgoff;