Re: [PATCH 3/3] mm,migration: Remove straggling migration PTEswhen page tables are being moved after the VMA has already moved

[Andrea Arcangeli]

On Wed, Apr 28, 2010 at 03:05:43AM +0200, Andrea Arcangeli wrote:
> 1) adjusting page->index atomically with the pte updates inside pt
>    lock (while it moves from one pte to another)

actually no need of this at all! of course the dst vma will have
vma->vm_pgoff adjusted instead... never mind. So I don't see a problem
there.

I think this is very special of how exec.c abuses move_page_tables by
passing vma as src and dst, when it obviously cannot be indexed in two
anon-vmas because there's a single vma and a single vma->anon_vma, and
src and dst obviously cannot have two different vm_pgoff again because
there's a single vma and there can't be two different vma->vm_pgoff.

So I'm very hopeful do_mremap is already fully safe...
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