[PATCH 2/2] mm/mm_init.c: count nr_initialised only for last zone

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

Since we always populate low zones, it is not necessary to count
nr_initialised for them. Let's move the last zone check ahead to skip
the nr_initialised reset.

Assume low zones counts for 4G, this change may reduce 1M times
comparison of prev_end_pfn and end_pfn.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
---
 mm/mm_init.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/mm/mm_init.c b/mm/mm_init.c
index 2dfb87841fdb..4cc627b4ebfe 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -676,6 +676,11 @@ defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
 
 	if (early_page_ext_enabled())
 		return false;
+
+	/* Always populate low zones for address-constrained allocations */
+	if (end_pfn < pgdat_end_pfn(NODE_DATA(nid)))
+		return false;
+
 	/*
 	 * prev_end_pfn static that contains the end of previous zone
 	 * No need to protect because called very early in boot before smp_init.
@@ -685,10 +690,6 @@ defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
 		nr_initialised = 0;
 	}
 
-	/* Always populate low zones for address-constrained allocations */
-	if (end_pfn < pgdat_end_pfn(NODE_DATA(nid)))
-		return false;
-
 	if (NODE_DATA(nid)->first_deferred_pfn != ULONG_MAX)
 		return true;
 	/*
-- 
2.34.1