mm/page_alloc: integrate classzone_idx and high_zoneidx

classzone_idx is just different name for high_zoneidx now.  So, integrate
them and add some comment to struct alloc_context in order to reduce
future confusion about the meaning of this variable.

The accessor, ac_classzone_idx() is also removed since it isn't needed
after integration.

In addition to integration, this patch also renames high_zoneidx to
highest_zoneidx since it represents more precise meaning.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Ye Xiaolong <xiaolong.ye@intel.com>
Link: http://lkml.kernel.org/r/1587095923-7515-3-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 33 insertions, 24 deletions

diff --git a/include/linux/compaction.h b/include/linux/compaction.h
index 4b898cdbdf05..3ed2f22b588a 100644
--- a/include/linux/compaction.h
+++ b/include/linux/compaction.h
@@ -97,7 +97,7 @@ extern enum compact_result try_to_compact_pages(gfp_t gfp_mask,
 		struct page **page);
 extern void reset_isolation_suitable(pg_data_t *pgdat);
 extern enum compact_result compaction_suitable(struct zone *zone, int order,
-		unsigned int alloc_flags, int classzone_idx);
+		unsigned int alloc_flags, int highest_zoneidx);
 
 extern void defer_compaction(struct zone *zone, int order);
 extern bool compaction_deferred(struct zone *zone, int order);
@@ -182,7 +182,7 @@ bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
 
 extern int kcompactd_run(int nid);
 extern void kcompactd_stop(int nid);
-extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx);
+extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx);
 
 #else
 static inline void reset_isolation_suitable(pg_data_t *pgdat)
@@ -190,7 +190,7 @@ static inline void reset_isolation_suitable(pg_data_t *pgdat)
 }
 
 static inline enum compact_result compaction_suitable(struct zone *zone, int order,
-					int alloc_flags, int classzone_idx)
+					int alloc_flags, int highest_zoneidx)
 {
 	return COMPACT_SKIPPED;
 }
@@ -232,7 +232,8 @@ static inline void kcompactd_stop(int nid)
 {
 }
 
-static inline void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx)
+static inline void wakeup_kcompactd(pg_data_t *pgdat,
+				int order, int highest_zoneidx)
 {
 }
 
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 0c575c3d7feb..cd8bd5f90552 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -699,13 +699,13 @@ typedef struct pglist_data {
 	struct task_struct *kswapd;	/* Protected by
 					   mem_hotplug_begin/end() */
 	int kswapd_order;
-	enum zone_type kswapd_classzone_idx;
+	enum zone_type kswapd_highest_zoneidx;
 
 	int kswapd_failures;		/* Number of 'reclaimed == 0' runs */
 
 #ifdef CONFIG_COMPACTION
 	int kcompactd_max_order;
-	enum zone_type kcompactd_classzone_idx;
+	enum zone_type kcompactd_highest_zoneidx;
 	wait_queue_head_t kcompactd_wait;
 	struct task_struct *kcompactd;
 #endif
@@ -783,15 +783,15 @@ static inline bool pgdat_is_empty(pg_data_t *pgdat)
 
 void build_all_zonelists(pg_data_t *pgdat);
 void wakeup_kswapd(struct zone *zone, gfp_t gfp_mask, int order,
-		   enum zone_type classzone_idx);
+		   enum zone_type highest_zoneidx);
 bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
-			 int classzone_idx, unsigned int alloc_flags,
+			 int highest_zoneidx, unsigned int alloc_flags,
 			 long free_pages);
 bool zone_watermark_ok(struct zone *z, unsigned int order,
-		unsigned long mark, int classzone_idx,
+		unsigned long mark, int highest_zoneidx,
 		unsigned int alloc_flags);
 bool zone_watermark_ok_safe(struct zone *z, unsigned int order,
-		unsigned long mark, int classzone_idx);
+		unsigned long mark, int highest_zoneidx);
 enum memmap_context {
 	MEMMAP_EARLY,
 	MEMMAP_HOTPLUG,
diff --git a/include/trace/events/compaction.h b/include/trace/events/compaction.h
index e5bf6ee4e814..54e5bf081171 100644
--- a/include/trace/events/compaction.h
+++ b/include/trace/events/compaction.h
@@ -314,40 +314,44 @@ TRACE_EVENT(mm_compaction_kcompactd_sleep,
 
 DECLARE_EVENT_CLASS(kcompactd_wake_template,
 
-	TP_PROTO(int nid, int order, enum zone_type classzone_idx),
+	TP_PROTO(int nid, int order, enum zone_type highest_zoneidx),
 
-	TP_ARGS(nid, order, classzone_idx),
+	TP_ARGS(nid, order, highest_zoneidx),
 
 	TP_STRUCT__entry(
 		__field(int, nid)
 		__field(int, order)
-		__field(enum zone_type, classzone_idx)
+		__field(enum zone_type, highest_zoneidx)
 	),
 
 	TP_fast_assign(
 		__entry->nid = nid;
 		__entry->order = order;
-		__entry->classzone_idx = classzone_idx;
+		__entry->highest_zoneidx = highest_zoneidx;
 	),
 
+	/*
+	 * classzone_idx is previous name of the highest_zoneidx.
+	 * Reason not to change it is the ABI requirement of the tracepoint.
+	 */
 	TP_printk("nid=%d order=%d classzone_idx=%-8s",
 		__entry->nid,
 		__entry->order,
-		__print_symbolic(__entry->classzone_idx, ZONE_TYPE))
+		__print_symbolic(__entry->highest_zoneidx, ZONE_TYPE))
 );
 
 DEFINE_EVENT(kcompactd_wake_template, mm_compaction_wakeup_kcompactd,
 
-	TP_PROTO(int nid, int order, enum zone_type classzone_idx),
+	TP_PROTO(int nid, int order, enum zone_type highest_zoneidx),
 
-	TP_ARGS(nid, order, classzone_idx)
+	TP_ARGS(nid, order, highest_zoneidx)
 );
 
 DEFINE_EVENT(kcompactd_wake_template, mm_compaction_kcompactd_wake,
 
-	TP_PROTO(int nid, int order, enum zone_type classzone_idx),
+	TP_PROTO(int nid, int order, enum zone_type highest_zoneidx),
 
-	TP_ARGS(nid, order, classzone_idx)
+	TP_ARGS(nid, order, highest_zoneidx)
 );
 #endif
 
diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
index 74bb594ccb25..2070df64958e 100644
--- a/include/trace/events/vmscan.h
+++ b/include/trace/events/vmscan.h
@@ -265,7 +265,7 @@ TRACE_EVENT(mm_shrink_slab_end,
 );
 
 TRACE_EVENT(mm_vmscan_lru_isolate,
-	TP_PROTO(int classzone_idx,
+	TP_PROTO(int highest_zoneidx,
 		int order,
 		unsigned long nr_requested,
 		unsigned long nr_scanned,
@@ -274,10 +274,10 @@ TRACE_EVENT(mm_vmscan_lru_isolate,
 		isolate_mode_t isolate_mode,
 		int lru),
 
-	TP_ARGS(classzone_idx, order, nr_requested, nr_scanned, nr_skipped, nr_taken, isolate_mode, lru),
+	TP_ARGS(highest_zoneidx, order, nr_requested, nr_scanned, nr_skipped, nr_taken, isolate_mode, lru),
 
 	TP_STRUCT__entry(
-		__field(int, classzone_idx)
+		__field(int, highest_zoneidx)
 		__field(int, order)
 		__field(unsigned long, nr_requested)
 		__field(unsigned long, nr_scanned)
@@ -288,7 +288,7 @@ TRACE_EVENT(mm_vmscan_lru_isolate,
 	),
 
 	TP_fast_assign(
-		__entry->classzone_idx = classzone_idx;
+		__entry->highest_zoneidx = highest_zoneidx;
 		__entry->order = order;
 		__entry->nr_requested = nr_requested;
 		__entry->nr_scanned = nr_scanned;
@@ -298,9 +298,13 @@ TRACE_EVENT(mm_vmscan_lru_isolate,
 		__entry->lru = lru;
 	),
 
+	/*
+	 * classzone is previous name of the highest_zoneidx.
+	 * Reason not to change it is the ABI requirement of the tracepoint.
+	 */
 	TP_printk("isolate_mode=%d classzone=%d order=%d nr_requested=%lu nr_scanned=%lu nr_skipped=%lu nr_taken=%lu lru=%s",
 		__entry->isolate_mode,
-		__entry->classzone_idx,
+		__entry->highest_zoneidx,
 		__entry->order,
 		__entry->nr_requested,
 		__entry->nr_scanned,