[Xen-devel] Re: [PATCH v3 1/2] xen: add an "highmem" parameter to alloc_xenballooned_pages

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

On 09/07/2011 09:39 AM, stefano.stabellini@xxxxxxxxxxxxx wrote:
> From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
>
> Add an highmem parameter to alloc_xenballooned_pages, to allow callers to
> request lowmem or highmem pages.
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> ---
>  drivers/xen/balloon.c |   12 ++++++++----
>  drivers/xen/gntdev.c  |    2 +-
>  include/xen/balloon.h |    3 ++-
>  3 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
> index 5dfd8f8..7f7d463 100644
> --- a/drivers/xen/balloon.c
> +++ b/drivers/xen/balloon.c
> @@ -501,20 +501,24 @@ EXPORT_SYMBOL_GPL(balloon_set_new_target);
>   * alloc_xenballooned_pages - get pages that have been ballooned out
>   * @nr_pages: Number of pages to get
>   * @pages: pages returned
> + * @highmem: highmem or lowmem pages
>   * @return 0 on success, error otherwise
>   */
> -int alloc_xenballooned_pages(int nr_pages, struct page** pages)
> +int alloc_xenballooned_pages(int nr_pages, struct page** pages, bool highmem)
>  {
>       int pgno = 0;
>       struct page* page;
>       mutex_lock(&balloon_mutex);
>       while (pgno < nr_pages) {
> -             page = balloon_retrieve(true);
> -             if (page) {
> +             page = balloon_retrieve(highmem);
> +             if (page && PageHighMem(page) == highmem) {
>                       pages[pgno++] = page;
>               } else {
>                       enum bp_state st;
> -                     st = decrease_reservation(nr_pages - pgno, 
> GFP_HIGHUSER);
> +                     if (page)
> +                             balloon_append(page);
> +                     st = decrease_reservation(nr_pages - pgno,
> +                                     highmem ? GFP_HIGHUSER : GFP_USER);
>                       if (st != BP_DONE)
>                               goto out_undo;
>               }
> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
> index f914b26..07a56c2 100644
> --- a/drivers/xen/gntdev.c
> +++ b/drivers/xen/gntdev.c
> @@ -123,7 +123,7 @@ static struct grant_map *gntdev_alloc_map(struct 
> gntdev_priv *priv, int count)
>           NULL == add->pages)
>               goto err;
>  
> -     if (alloc_xenballooned_pages(count, add->pages))
> +     if (alloc_xenballooned_pages(count, add->pages, 0 /* lowmem */))

If the parameter is "bool" you should pass true/false.  But it might be
better to just make it take a GFP_ constant directly.

    J

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