[PATCH] compaction: fix build error in CMA && !COMPACTION

[PATCH] compaction: fix build error in CMA && !COMPACTION

[Minchan Kim]

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@suse.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 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
+
 #if defined CONFIG_COMPACTION || defined CONFIG_CMA
 
 #define CREATE_TRACE_POINTS
@@ -303,10 +318,9 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
 	if (blockpfn == end_pfn)
 		update_pageblock_skip(cc, valid_page, total_isolated, false);
 
-	count_vm_events(COMPACTFREE_SCANNED, nr_scanned);
+	count_compact_events(COMPACTFREE_SCANNED, nr_scanned);
 	if (total_isolated)
-		count_vm_events(COMPACTISOLATED, total_isolated);
-
+		count_compact_events(COMPACTISOLATED, total_isolated);
 	return total_isolated;
 }
 
@@ -613,9 +627,9 @@ next_pageblock:
 
 	trace_mm_compaction_isolate_migratepages(nr_scanned, nr_isolated);
 
-	count_vm_events(COMPACTMIGRATE_SCANNED, nr_scanned);
+	count_compact_events(COMPACTMIGRATE_SCANNED, nr_scanned);
 	if (nr_isolated)
-		count_vm_events(COMPACTISOLATED, nr_isolated);
+		count_compact_events(COMPACTISOLATED, nr_isolated);
 
 	return low_pfn;
 }
@@ -1110,7 +1124,7 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
 	if (!order || !may_enter_fs || !may_perform_io)
 		return rc;
 
-	count_vm_event(COMPACTSTALL);
+	count_compact_event(COMPACTSTALL);
 
 #ifdef CONFIG_CMA
 	if (allocflags_to_migratetype(gfp_mask) == MIGRATE_MOVABLE)
-- 
1.7.9.5

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Re: [PATCH] compaction: fix build error in CMA && !COMPACTION

[Mel Gorman]

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@suse.de>
> Cc: Marek Szyprowski <m.szyprowski@samsung.com>
> Signed-off-by: Minchan Kim <minchan@kernel.org>
> ---
>  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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Re: [PATCH] compaction: fix build error in CMA && !COMPACTION

[Minchan Kim]

On Thu, Dec 20, 2012 at 10:47:07AM +0000, Mel Gorman wrote:
> 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@suse.de>
> > Cc: Marek Szyprowski <m.szyprowski@samsung.com>
> > Signed-off-by: Minchan Kim <minchan@kernel.org>
> > ---
> >  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.

Indeed.

> 
> 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

If I noticed it, I should named it as count_vm_compact_events for the consistency.

> 
> count_compact_events(COMPACTFREE_SCANNED, foo++);
> 
> There happens to be no examples where we depend on such side-effects but

Agreed.

> I've taken a TODO item to fix it up in the New Year.

Andrew picked up the patch with your fix. Please correct it for New Year's
present. :)

Thanks, Mel.

> 
> -- 
> Mel Gorman
> SUSE Labs
> 
> --
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-- 
Kind regards,
Minchan Kim

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