Re: THP, rmap and page_referenced_one()

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

> On 03/08/2011 06:32 AM, Andrea Arcangeli wrote:
> 
> > Subject: thp: fix page_referenced to modify mapcount/vm_flags only if page is found
> >
> > From: Andrea Arcangeli<aarcange@redhat.com>
> >
> > When vmscan.c calls page_referenced, if an anon page was created before a
> > process forked, rmap will search for it in both of the processes, even though
> > one of them might have since broken COW. If the child process mlocks the vma
> > where the COWed page belongs to, page_referenced() running on the page mapped
> > by the parent would lead to *vm_flags getting VM_LOCKED set erroneously (leading
> > to the references on the parent page being ignored and evicting the parent page
> > too early).
> 
> > Signed-off-by: Andrea Arcangeli<aarcange@redhat.com>
> > Reported-by: Michel Lespinasse<walken@google.com>
> 
> Reviewed-by: Rik van Riel<riel@redhat.com>

Thank you, Andrea.
	Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>




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