[PATCH] [RFC] mm/mm_init.c: simplify logic of deferred_[init|free]_pages

[Wei Yang <richard.weiyang@xxxxxxxxx>]

Function deferred_[init|free]_pages are only used in
deferred_init_maxorder(), which makes sure the range to init/free is
within MAX_ORDER_NR_PAGES size.

With this knowledge, we can simplify these two functions. Since

  * only the first pfn could be IS_MAX_ORDER_ALIGNED()

Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
CC: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
CC: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
CC: David Hildenbrand <david@xxxxxxxxxx>

---
But my question is why we just test pfn_valid for the
IS_MAX_ORDER_ALIGNED pfn? I thought we should test pfn_valid for each
pfn until the first one in MAX_ORDER pages. Do I miss something?
---
 mm/mm_init.c | 43 ++++++++++++++-----------------------------
 1 file changed, 14 insertions(+), 29 deletions(-)

diff --git a/mm/mm_init.c b/mm/mm_init.c
index bbaf3a2c1cfd..6a4adf9e7d9a 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -1970,21 +1970,10 @@ static inline bool __init deferred_pfn_valid(unsigned long pfn)
 static void __init deferred_free_pages(unsigned long pfn,
 				       unsigned long end_pfn)
 {
-	unsigned long nr_free = 0;
-
-	for (; pfn < end_pfn; pfn++) {
-		if (!deferred_pfn_valid(pfn)) {
-			deferred_free_range(pfn - nr_free, nr_free);
-			nr_free = 0;
-		} else if (IS_MAX_ORDER_ALIGNED(pfn)) {
-			deferred_free_range(pfn - nr_free, nr_free);
-			nr_free = 1;
-		} else {
-			nr_free++;
-		}
-	}
-	/* Free the last block of pages to allocator */
-	deferred_free_range(pfn - nr_free, nr_free);
+	if (!deferred_pfn_valid(pfn))
+		pfn++;
+
+	deferred_free_range(pfn, end_pfn - pfn);
 }
 
 /*
@@ -1992,27 +1981,23 @@ static void __init deferred_free_pages(unsigned long pfn,
  * by performing it only once every MAX_ORDER_NR_PAGES.
  * Return number of pages initialized.
  */
-static unsigned long  __init deferred_init_pages(struct zone *zone,
-						 unsigned long pfn,
-						 unsigned long end_pfn)
+static unsigned long __init deferred_init_pages(struct zone *zone,
+						unsigned long pfn,
+						unsigned long end_pfn)
 {
 	int nid = zone_to_nid(zone);
 	unsigned long nr_pages = 0;
 	int zid = zone_idx(zone);
 	struct page *page = NULL;
 
-	for (; pfn < end_pfn; pfn++) {
-		if (!deferred_pfn_valid(pfn)) {
-			page = NULL;
-			continue;
-		} else if (!page || IS_MAX_ORDER_ALIGNED(pfn)) {
-			page = pfn_to_page(pfn);
-		} else {
-			page++;
-		}
+	if (!deferred_pfn_valid(pfn))
+		pfn++;
+
+	page = pfn_to_page(pfn);
+	nr_pages = end_pfn - pfn;
+
+	for (; pfn < end_pfn; pfn++, page++)
 		__init_single_page(page, pfn, zid, nid);
-		nr_pages++;
-	}
 	return nr_pages;
 }
 
-- 
2.34.1