On Wed, Nov 08, 2017 at 01:07:10PM +0100, Arnd Bergmann wrote:
> The new balloon_page_push/balloon_page_pop helpers got added
> inside of an #ifdef, causing a build failure when CONFIG_BALLOON_COMPACTION
> is disabled:
>
> drivers/virtio/virtio_balloon.c: In function 'fill_balloon':
> drivers/virtio/virtio_balloon.c:164:3: error: implicit declaration of
> function 'balloon_page_push'
>
> This adds another empty stub function for the case that
> CONFIG_BALLOON_COMPACTION is disabled.
>
> Fixes: f09517b35de8 ("virtio_balloon: fix deadlock on OOM")
> Signed-off-by: Arnd Bergmann <a...@arndb.de>
> ---
> I couldn't easily figure out whether the new functions were indeed
> intended to be only used when BALLOON_COMPACTION is enabled, or
> whether they should always be there. In case I picked the wrong
> one of the two, the answer would obviously be to move the
> definitions outside of the #ifdef, or into a different file.
Hmm no, I think we actually need these to work.
I'll fix it up, thanks for the report.
> ---
> include/linux/balloon_compaction.h | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/include/linux/balloon_compaction.h
> b/include/linux/balloon_compaction.h
> index 36734ff07213..730b962fd572 100644
> --- a/include/linux/balloon_compaction.h
> +++ b/include/linux/balloon_compaction.h
> @@ -223,6 +223,15 @@ static inline int balloon_page_migrate(struct page
> *newpage,
> return 0;
> }
>
> +static inline void balloon_page_push(struct list_head *pages, struct page
> *page)
> +{
> +}
> +
> +static inline struct page *balloon_page_pop(struct list_head *pages)
> +{
> + return NULL;
> +}
> +
> static inline gfp_t balloon_mapping_gfp_mask(void)
> {
> return GFP_HIGHUSER;
> --
> 2.9.0
