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SubjectRe: [PATCH 09/22] HWPOISON: Handle hardware poisoned pages in try_to_unmap
On Mon, 15 Jun 2009 23:26:12 +0800
Wu Fengguang <fengguang.wu@intel.com> wrote:

> On Mon, Jun 15, 2009 at 09:09:03PM +0800, Minchan Kim wrote:
> > On Mon, Jun 15, 2009 at 11:45 AM, Wu Fengguang<fengguang.wu@intel.com> wrote:
> > > From: Andi Kleen <ak@linux.intel.com>
> > >
> > > When a page has the poison bit set replace the PTE with a poison entry.
> > > This causes the right error handling to be done later when a process runs
> > > into it.
> > >
> > > Also add a new flag to not do that (needed for the memory-failure handler
> > > later)
> > >
> > > Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
> > > Signed-off-by: Andi Kleen <ak@linux.intel.com>
> > >
> > > ---
> > >  include/linux/rmap.h |    1 +
> > >  mm/rmap.c            |    9 ++++++++-
> > >  2 files changed, 9 insertions(+), 1 deletion(-)
> > >
> > > --- sound-2.6.orig/mm/rmap.c
> > > +++ sound-2.6/mm/rmap.c
> > > @@ -958,7 +958,14 @@ static int try_to_unmap_one(struct page
> > >        /* Update high watermark before we lower rss */
> > >        update_hiwater_rss(mm);
> > >
> > > -       if (PageAnon(page)) {
> > > +       if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
> > > +               if (PageAnon(page))
> > > +                       dec_mm_counter(mm, anon_rss);
> > > +               else if (!is_migration_entry(pte_to_swp_entry(*pte)))
> >
> > Isn't it straightforward to use !is_hwpoison_entry ?
>
> Good catch! It looks like a redundant check: the
> page_check_address() at the beginning of the function guarantees that
> !is_migration_entry() or !is_migration_entry() tests will all be TRUE.
> So let's do this?
It seems you expand my sight :)

I don't know migration well.
How page_check_address guarantee it's not migration entry ?

In addtion, If the page is poison while we are going to migration((PAGE_MIGRATION && migration) == TRUE), we should decrease file_rss ?

>
> -               else if (!is_migration_entry(pte_to_swp_entry(*pte)))
> +               else
>
>
> Thanks,
> Fengguang


--
Kinds Regards
Minchan Kim
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