Marcelo Tosatti wrote:
On Tue, Mar 31, 2009 at 03:00:02AM +0300, Izik Eidus wrote:
When using mmu notifiers, we are allowed to remove the page count
reference tooken by get_user_pages to a specific page that is mapped
inside the shadow page tables.
This is needed so we can balance the pagecount against mapcount
checking.
(Right now kvm increase the pagecount and does not increase the
mapcount when mapping page into shadow page table entry,
so when comparing pagecount against mapcount, you have no
reliable result.)
IMO ifdef'ing CONFIG_MMU_NOTIFIERS here (and keeping the ref if unset)
instead of in the backward compat code gives less room for headaches.
That was the first version of this patch, Avi preferred not to do it...
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