On Wednesday 23 January 2008 17:22, Shaohua Li wrote:
> Anonymous page might have fs-private metadata, the page is truncated. As
> the page hasn't mapping, page migration refuse to migrate the page. It
> appears the page is only freed in page reclaim and if zone watermark is
> low, the page is never freed, as a result migration always fail. I
> thought we could free the metadata so such page can be freed in
> migration and make migration more reliable?

Anonymous pages should not have fs-private metadata.

Orphaned pages I guess you mean? They should not be accessable via
the pagecache or the page tables, so how do they keep tangling up
migration? Where/how is migration finding these pages?!


>
> Thanks,
> Shaohua
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 6a207e8..6bc38f7 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -633,6 +633,17 @@ static int unmap_and_move(new_page_t get_new_page,
> unsigned long private, goto unlock;
>               wait_on_page_writeback(page);
>       }
> +
> +     /*
> +      * See truncate_complete_page(). Anonymous page might have
> +      * fs-private metadata, the page is truncated. Such page can't be
> +      * migrated. Try to free metadata, so the page can be freed.
> +      */
> +     if (!page->mapping && !PageAnon(page) && PagePrivate(page)) {
> +             try_to_release_page(page, GFP_KERNEL);
> +             goto unlock;
> +     }
> +
>       /*
>        * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
>        * we cannot notice that anon_vma is freed while we migrates a page.
>
>
> --
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Reply via email to