mm/mm_init.c: move nr_initialised reset down a bit

We don't need to count nr_initialised in two cases:

* for low zones that are always populated
* after first_deferred_pfn is detected

Let's move the nr_initialised reset down a bit to reduce some comparison
of prev_end_pfn and end_pfn.

Signed-off-by: Wei Yang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mike Rapoport (IBM) <[email protected]>

Author: RichardWeiYang

mm/mm_init.c

@@ -676,6 +676,14 @@ 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;
+
+	if (NODE_DATA(nid)->first_deferred_pfn != ULONG_MAX)
+		return true;
+
 	/*
 	 * prev_end_pfn static that contains the end of previous zone
 	 * No need to protect because called very early in boot before smp_init.
@@ -685,12 +693,6 @@ 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;
 	/*
 	 * We start only with one section of pages, more pages are added as
 	 * needed until the rest of deferred pages are initialized.