Re: [RFC][PATCH 0/1] Node-based reclaim/migration

Christoph Lameter
2006-11-30T18:39:33Z

On Thu, 30 Nov 2006, Paul Menage wrote:

> It sounds as though if we come across a page with page_mapcount() = 0
> while gathering pages for migration, it's probably in the process of
> being swapped out and so is best not to muck around with anyway?

F.e. A page cache page may have mapcount == 0. Mapcount 0 only means that
the page is not mapped into any processes memory via a page table. It may
be used for purposes that do not require mapping into a processes memory.

If the reference count is zero (page freed) then page migration will
discard the page and consider the migration a success.