Re: [PATCH 2/2] mm: fix race between shift_arg_pages and rmap_walk

[Linus Torvalds]

On Mon, 3 May 2010, Rik van Riel wrote:
> 
> migrate.c requires rmap to be able to find all ptes mapping a page at
> all times, otherwise the migration entry can be instantiated, but it
> can't be removed if the second rmap_walk fails to find the page.

Please correct me if I'm wrong, but this patch looks like pure and utter 
garbage.

It looks like it makes execve() do a totally insane "create and then 
immediately destroy temporary vma and anon_vma chain" for a case that is 
unlikely to ever matter. 

In fact, for a case that isn't even normally _enabled_, namely migration.

Why would we want to slow down execve() for that?

		Linus
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