On Thu, Dec 20, 2012 at 02:25:30PM +0900, Minchan Kim wrote:
> isolate_freepages_block and isolate_migratepages_range is used for CMA
> as well as compaction so it breaks build for CONFIG_CMA &&
> !CONFIG_COMPACTION.
>
> This patch fixes it.
>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
> ---
> mm/compaction.c | 26 ++++++++++++++++++++------
> 1 file changed, 20 insertions(+), 6 deletions(-)
>
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 5ad7f4f..70f4443 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -17,6 +17,21 @@
> #include <linux/balloon_compaction.h>
> #include "internal.h"
>
> +#ifdef CONFIG_COMPACTION
> +static inline void count_compact_event(enum vm_event_item item)
> +{
> + count_vm_event(item);
> +}
> +
> +static inline void count_compact_events(enum vm_event_item item, long delta)
> +{
> + count_vm_events(item, delta);
> +}
> +#else
> +#define count_compact_event(item)
> +#define count_compact_events(item, delta)
> +#endif
> +
That should be
do {} while (0)
otherwise a block like this
if (foo)
count_compact_event(COMPACTFREE_SCANNED)
bar;
will get parsed as
if (foo)
bar;
which is wrong.
Now that I look at the do {} while (0) thing it is also strictly speaking
wrong for count_vm_numa_events() too because it would do the wrong thing for
count_compact_events(COMPACTFREE_SCANNED, foo++);
There happens to be no examples where we depend on such side-effects but
I've taken a TODO item to fix it up in the New Year.
--
Mel Gorman
SUSE Labs
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