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

[Linus Torvalds]

On Sun, 11 Apr 2010, Rik van Riel wrote:
> 
> Looking around the code some more, zap_pte_range()
> calls page_remove_rmap(), which leaves the
> page->mapping in place and has this comment:

See my earlier email about this exact issue. It's well-known that there 
are stale page->mapping pointers. The "page_mapped()" check _should_ have 
meant that in that case we never follow them, though.

> I wonder if we can clear page->mapping here, if
> list_is_singular(anon_vma->head).  That way we
> will not leave stale pointers behind.

What does that help? What if list _isn't_ singular?

		Linus
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