[PATCH 3/3] mm/mm_init.c: not always search next deferred_init_pfn from very beginning

[Wei Yang <richard.weiyang@gmail.com>]

In function deferred_init_memmap(), we call
deferred_init_mem_pfn_range_in_zone() to get the next deferred_init_pfn.
But we always search it from the very beginning.

Since we save the index in i, we can leverage this to search from i next
time.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
---
 include/linux/memblock.h | 19 -------------------
 mm/mm_init.c             | 21 ++++++++++++---------
 2 files changed, 12 insertions(+), 28 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 6cf18dc2b4d0..45cac33334c8 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -299,25 +299,6 @@ void __next_mem_pfn_range(int *idx, int nid, unsigned long *out_start_pfn,
 void __next_mem_pfn_range_in_zone(u64 *idx, struct zone *zone,
 				  unsigned long *out_spfn,
 				  unsigned long *out_epfn);
-/**
- * for_each_free_mem_pfn_range_in_zone - iterate through zone specific free
- * memblock areas
- * @i: u64 used as loop variable
- * @zone: zone in which all of the memory blocks reside
- * @p_start: ptr to phys_addr_t for start address of the range, can be %NULL
- * @p_end: ptr to phys_addr_t for end address of the range, can be %NULL
- *
- * Walks over free (memory && !reserved) areas of memblock in a specific
- * zone. Available once memblock and an empty zone is initialized. The main
- * assumption is that the zone start, end, and pgdat have been associated.
- * This way we can use the zone to determine NUMA node, and if a given part
- * of the memblock is valid for the zone.
- */
-#define for_each_free_mem_pfn_range_in_zone(i, zone, p_start, p_end)	\
-	for (i = 0,							\
-	     __next_mem_pfn_range_in_zone(&i, zone, p_start, p_end);	\
-	     i != U64_MAX;					\
-	     __next_mem_pfn_range_in_zone(&i, zone, p_start, p_end))
 
 /**
  * for_each_free_mem_pfn_range_in_zone_from - iterate through zone specific
diff --git a/mm/mm_init.c b/mm/mm_init.c
index d05a4c38310f..ec17bf93f946 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -2023,18 +2023,21 @@ static unsigned long  __init deferred_init_pages(struct zone *zone,
  * return false indicating there are no valid ranges left.
  */
 static bool __init
-deferred_init_mem_pfn_range_in_zone(u64 *i, struct zone *zone,
+deferred_init_mem_pfn_range_in_zone_from(u64 *i, struct zone *zone,
 				    unsigned long *spfn, unsigned long *epfn,
 				    unsigned long first_init_pfn)
 {
-	u64 j;
+	u64 j = *i;
+
+	if (j == 0)
+		__next_mem_pfn_range_in_zone(&j, zone, spfn, epfn);
 
 	/*
 	 * Start out by walking through the ranges in this zone that have
 	 * already been initialized. We don't need to do anything with them
 	 * so we just need to flush them out of the system.
 	 */
-	for_each_free_mem_pfn_range_in_zone(j, zone, spfn, epfn) {
+	for_each_free_mem_pfn_range_in_zone_from(j, zone, spfn, epfn) {
 		if (*epfn <= first_init_pfn)
 			continue;
 		if (*spfn < first_init_pfn)
@@ -2106,9 +2109,9 @@ deferred_init_memmap_chunk(unsigned long start_pfn, unsigned long end_pfn,
 {
 	unsigned long spfn, epfn;
 	struct zone *zone = arg;
-	u64 i;
+	u64 i = 0;
 
-	deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn, start_pfn);
+	deferred_init_mem_pfn_range_in_zone_from(&i, zone, &spfn, &epfn, start_pfn);
 
 	/*
 	 * Initialize and free pages in MAX_PAGE_ORDER sized increments so that
@@ -2137,7 +2140,7 @@ static int __init deferred_init_memmap(void *data)
 	unsigned long start = jiffies;
 	struct zone *zone;
 	int max_threads;
-	u64 i;
+	u64 i = 0;
 
 	/* Bind memory initialisation thread to a local node if possible */
 	if (!cpumask_empty(cpumask))
@@ -2168,7 +2171,7 @@ static int __init deferred_init_memmap(void *data)
 
 	max_threads = deferred_page_init_max_threads(cpumask);
 
-	while (deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn, first_init_pfn)) {
+	while (deferred_init_mem_pfn_range_in_zone_from(&i, zone, &spfn, &epfn, first_init_pfn)) {
 		first_init_pfn = ALIGN(epfn, PAGES_PER_SECTION);
 		struct padata_mt_job job = {
 			.thread_fn   = deferred_init_memmap_chunk,
@@ -2212,7 +2215,7 @@ bool __init deferred_grow_zone(struct zone *zone, unsigned int order)
 	unsigned long first_deferred_pfn = pgdat->first_deferred_pfn;
 	unsigned long spfn, epfn, flags;
 	unsigned long nr_pages = 0;
-	u64 i;
+	u64 i = 0;
 
 	/* Only the last zone may have deferred pages */
 	if (zone_end_pfn(zone) != pgdat_end_pfn(pgdat))
@@ -2230,7 +2233,7 @@ bool __init deferred_grow_zone(struct zone *zone, unsigned int order)
 	}
 
 	/* If the zone is empty somebody else may have cleared out the zone */
-	if (!deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
+	if (!deferred_init_mem_pfn_range_in_zone_from(&i, zone, &spfn, &epfn,
 						 first_deferred_pfn)) {
 		pgdat->first_deferred_pfn = ULONG_MAX;
 		pgdat_resize_unlock(pgdat, &flags);
-- 
2.34.1