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

KAMEZAWA Hiroyuki
2006-11-30T12:18:41Z

On Thu, 30 Nov 2006 03:25:21 -0800
"Paul Menage" <menage@google.com> wrote:

> On 11/30/06, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> >
> > > How does kswapd do this safely?
> > >
> > kswapd doesn't touches page->mapping after page_mapcount() goes down to 0.
>
> OK, so we could do the same, and just assume that pages with a
> page_mapcount() of 0 are either about to be freed or can be picked up
> on a later migration sweep. Is it common for a page to have a 0
> page_mapcount() for a long period of time without being freed or
> remapped?
>
see shrink_page_list().

unmap -> (write to swap) -> freed. depends on how long write-back needs.

-Kame