mm, compaction: some tracepoints should be defined only when CONFIG_COMPACTION is set

Only mm_compaction_isolate_{free, migrate}pages may be used when
CONFIG_COMPACTION is not set. All others are used only when
CONFIG_COMPACTION is set.

After this change, if CONFIG_COMPACTION is not set, the tracepoints that
only work when CONFIG_COMPACTION is set will not be exposed to userspace.
Without this change, they will always be exposed in debugfs whether
CONFIG_COMPACTION is set or not. This is an improvement.

Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Yafang Shao <[e-mail]>
Reviewed-by: Andrew Morton <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Mel Gorman <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/trace/events/compaction.h

···
 	TP_ARGS(start_pfn, end_pfn, nr_scanned, nr_taken)
 );
 
+#ifdef CONFIG_COMPACTION
 TRACE_EVENT(mm_compaction_migratepages,
 
 	TP_PROTO(unsigned long nr_all,
···
 		__entry->sync ? "sync" : "async")
 );
 
-#ifdef CONFIG_COMPACTION
 TRACE_EVENT(mm_compaction_end,
 	TP_PROTO(unsigned long zone_start, unsigned long migrate_pfn,
 		unsigned long free_pfn, unsigned long zone_end, bool sync,
···
 		__entry->sync ? "sync" : "async",
 		__print_symbolic(__entry->status, COMPACTION_STATUS))
 );
-#endif
 
 TRACE_EVENT(mm_compaction_try_to_compact_pages,
 
···
 		__entry->prio)
 );
 
-#ifdef CONFIG_COMPACTION
 DECLARE_EVENT_CLASS(mm_compaction_suitable_template,
 
 	TP_PROTO(struct zone *zone,
···
 
 	TP_ARGS(zone, order)
 );
-#endif
 
 TRACE_EVENT(mm_compaction_kcompactd_sleep,
 
···
 
 	TP_ARGS(nid, order, classzone_idx)
 );
+#endif
 
 #endif /* _TRACE_COMPACTION_H */