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>

1 files changed, 31 insertions, 29 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5b8d0966d429..5ef1eff330a2 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2593,7 +2593,7 @@ static bool unreserve_highatomic_pageblock(const struct alloc_context *ac,
 	int order;
 	bool ret;
 
-	for_each_zone_zonelist_nodemask(zone, z, zonelist, ac->high_zoneidx,
+	for_each_zone_zonelist_nodemask(zone, z, zonelist, ac->highest_zoneidx,
 								ac->nodemask) {
 		/*
 		 * Preserve at least one pageblock unless memory pressure
@@ -3462,7 +3462,7 @@ ALLOW_ERROR_INJECTION(should_fail_alloc_page, TRUE);
  * to check in the allocation paths if no pages are free.
  */
 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)
 {
 	long min = mark;
@@ -3507,7 +3507,7 @@ bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
 	 * are not met, then a high-order request also cannot go ahead
 	 * even if a suitable page happened to be free.
 	 */
-	if (free_pages <= min + z->lowmem_reserve[classzone_idx])
+	if (free_pages <= min + z->lowmem_reserve[highest_zoneidx])
 		return false;
 
 	/* If this is an order-0 request then the watermark is fine */
@@ -3540,14 +3540,15 @@ bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
 }
 
 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)
 {
-	return __zone_watermark_ok(z, order, mark, classzone_idx, alloc_flags,
+	return __zone_watermark_ok(z, order, mark, highest_zoneidx, alloc_flags,
 					zone_page_state(z, NR_FREE_PAGES));
 }
 
 static inline bool zone_watermark_fast(struct zone *z, unsigned int order,
-		unsigned long mark, int classzone_idx, unsigned int alloc_flags)
+				unsigned long mark, int highest_zoneidx,
+				unsigned int alloc_flags)
 {
 	long free_pages = zone_page_state(z, NR_FREE_PAGES);
 	long cma_pages = 0;
@@ -3565,22 +3566,23 @@ static inline bool zone_watermark_fast(struct zone *z, unsigned int order,
 	 * the caller is !atomic then it'll uselessly search the free
 	 * list. That corner case is then slower but it is harmless.
 	 */
-	if (!order && (free_pages - cma_pages) > mark + z->lowmem_reserve[classzone_idx])
+	if (!order && (free_pages - cma_pages) >
+				mark + z->lowmem_reserve[highest_zoneidx])
 		return true;
 
-	return __zone_watermark_ok(z, order, mark, classzone_idx, alloc_flags,
+	return __zone_watermark_ok(z, order, mark, highest_zoneidx, alloc_flags,
 					free_pages);
 }
 
 bool zone_watermark_ok_safe(struct zone *z, unsigned int order,
-			unsigned long mark, int classzone_idx)
+			unsigned long mark, int highest_zoneidx)
 {
 	long free_pages = zone_page_state(z, NR_FREE_PAGES);
 
 	if (z->percpu_drift_mark && free_pages < z->percpu_drift_mark)
 		free_pages = zone_page_state_snapshot(z, NR_FREE_PAGES);
 
-	return __zone_watermark_ok(z, order, mark, classzone_idx, 0,
+	return __zone_watermark_ok(z, order, mark, highest_zoneidx, 0,
 								free_pages);
 }
 
@@ -3657,8 +3659,8 @@ retry:
 	 */
 	no_fallback = alloc_flags & ALLOC_NOFRAGMENT;
 	z = ac->preferred_zoneref;
-	for_next_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx,
-								ac->nodemask) {
+	for_next_zone_zonelist_nodemask(zone, z, ac->zonelist,
+					ac->highest_zoneidx, ac->nodemask) {
 		struct page *page;
 		unsigned long mark;
 
@@ -3713,7 +3715,7 @@ retry:
 
 		mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK);
 		if (!zone_watermark_fast(zone, order, mark,
-				       ac_classzone_idx(ac), alloc_flags)) {
+				       ac->highest_zoneidx, alloc_flags)) {
 			int ret;
 
 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
@@ -3746,7 +3748,7 @@ retry:
 			default:
 				/* did we reclaim enough */
 				if (zone_watermark_ok(zone, order, mark,
-						ac_classzone_idx(ac), alloc_flags))
+					ac->highest_zoneidx, alloc_flags))
 					goto try_this_zone;
 
 				continue;
@@ -3905,7 +3907,7 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
 	if (gfp_mask & __GFP_RETRY_MAYFAIL)
 		goto out;
 	/* The OOM killer does not needlessly kill tasks for lowmem */
-	if (ac->high_zoneidx < ZONE_NORMAL)
+	if (ac->highest_zoneidx < ZONE_NORMAL)
 		goto out;
 	if (pm_suspended_storage())
 		goto out;
@@ -4108,10 +4110,10 @@ should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_fla
 	 * Let's give them a good hope and keep retrying while the order-0
 	 * watermarks are OK.
 	 */
-	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx,
-					ac->nodemask) {
+	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
+				ac->highest_zoneidx, ac->nodemask) {
 		if (zone_watermark_ok(zone, 0, min_wmark_pages(zone),
-					ac_classzone_idx(ac), alloc_flags))
+					ac->highest_zoneidx, alloc_flags))
 			return true;
 	}
 	return false;
@@ -4235,12 +4237,12 @@ static void wake_all_kswapds(unsigned int order, gfp_t gfp_mask,
 	struct zoneref *z;
 	struct zone *zone;
 	pg_data_t *last_pgdat = NULL;
-	enum zone_type high_zoneidx = ac->high_zoneidx;
+	enum zone_type highest_zoneidx = ac->highest_zoneidx;
 
-	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, high_zoneidx,
+	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, highest_zoneidx,
 					ac->nodemask) {
 		if (last_pgdat != zone->zone_pgdat)
-			wakeup_kswapd(zone, gfp_mask, order, high_zoneidx);
+			wakeup_kswapd(zone, gfp_mask, order, highest_zoneidx);
 		last_pgdat = zone->zone_pgdat;
 	}
 }
@@ -4375,8 +4377,8 @@ should_reclaim_retry(gfp_t gfp_mask, unsigned order,
 	 * request even if all reclaimable pages are considered then we are
 	 * screwed and have to go OOM.
 	 */
-	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx,
-					ac->nodemask) {
+	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
+				ac->highest_zoneidx, ac->nodemask) {
 		unsigned long available;
 		unsigned long reclaimable;
 		unsigned long min_wmark = min_wmark_pages(zone);
@@ -4390,7 +4392,7 @@ should_reclaim_retry(gfp_t gfp_mask, unsigned order,
 		 * reclaimable pages?
 		 */
 		wmark = __zone_watermark_ok(zone, order, min_wmark,
-				ac_classzone_idx(ac), alloc_flags, available);
+				ac->highest_zoneidx, alloc_flags, available);
 		trace_reclaim_retry_zone(z, order, reclaimable,
 				available, min_wmark, *no_progress_loops, wmark);
 		if (wmark) {
@@ -4509,7 +4511,7 @@ retry_cpuset:
 	 * could end up iterating over non-eligible zones endlessly.
 	 */
 	ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
-					ac->high_zoneidx, ac->nodemask);
+					ac->highest_zoneidx, ac->nodemask);
 	if (!ac->preferred_zoneref->zone)
 		goto nopage;
 
@@ -4596,7 +4598,7 @@ retry:
 	if (!(alloc_flags & ALLOC_CPUSET) || reserve_flags) {
 		ac->nodemask = NULL;
 		ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
-					ac->high_zoneidx, ac->nodemask);
+					ac->highest_zoneidx, ac->nodemask);
 	}
 
 	/* Attempt with potentially adjusted zonelist and alloc_flags */
@@ -4730,7 +4732,7 @@ static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
 		struct alloc_context *ac, gfp_t *alloc_mask,
 		unsigned int *alloc_flags)
 {
-	ac->high_zoneidx = gfp_zone(gfp_mask);
+	ac->highest_zoneidx = gfp_zone(gfp_mask);
 	ac->zonelist = node_zonelist(preferred_nid, gfp_mask);
 	ac->nodemask = nodemask;
 	ac->migratetype = gfpflags_to_migratetype(gfp_mask);
@@ -4769,7 +4771,7 @@ static inline void finalise_ac(gfp_t gfp_mask, struct alloc_context *ac)
 	 * may get reset for allocations that ignore memory policies.
 	 */
 	ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
-					ac->high_zoneidx, ac->nodemask);
+					ac->highest_zoneidx, ac->nodemask);
 }
 
 /*
@@ -6867,7 +6869,7 @@ static void __init free_area_init_node(int nid)
 	unsigned long end_pfn = 0;
 
 	/* pg_data_t should be reset to zero when it's allocated */
-	WARN_ON(pgdat->nr_zones || pgdat->kswapd_classzone_idx);
+	WARN_ON(pgdat->nr_zones || pgdat->kswapd_highest_zoneidx);
 
 	get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);