Re: [PATCH -v2] rmap: make anon_vma_prepare link in all the anon_vmasof a mergeable VMA

[Rik van Riel]

On 04/12/2010 10:40 AM, Peter Zijlstra wrote:

> So the reason page->mapping isn't cleared in page_remove_rmap() isn't
> detailed beyond a (possible) race with page_add_anon_rmap() (which I
> guess would be reclaim trying to unmap the page and a fault re-instating
> it).
>
> This also complicates the whole page_lock_anon_vma() thing, so it would
> be nice to be able to remove this race and clear page->mapping in
> page_remove_rmap().

For anonymous pages, I don't see where the race comes from.

Both do_swap_page and the reclaim code hold the page lock
across the entire operation, so they are already excluding
each other.

Hugh, do you remember what the race between page_remove_rmap
and page_add_anon_rmap is/was all about?

I don't see a race in the current code...
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