mm/page_alloc: make zone_pcp_update() static

Since commit b92ca18e ("mm/page_alloc: disassociate the pcp->high from
pcp->batch"), zone_pcp_update() is only used in mm/page_alloc.c.  Move
zone_pcp_update() up to avoid forward declaration and then make it static.
No functional change intended.

Link: https://lkml.kernel.org/r/20220916072257.9639-3-linmiaohe@huawei.comSigned-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/internal.h

@@ -367,7 +367,6 @@ extern int user_min_free_kbytes;
 extern void free_unref_page(struct page *page, unsigned int order);
 extern void free_unref_page_list(struct list_head *list);
 
-extern void zone_pcp_update(struct zone *zone, int cpu_online);
 extern void zone_pcp_reset(struct zone *zone);
 extern void zone_pcp_disable(struct zone *zone);
 extern void zone_pcp_enable(struct zone *zone);

mm/page_alloc.c

@@ -7242,6 +7242,17 @@ void __meminit setup_zone_pageset(struct zone *zone)
 	zone_set_pageset_high_and_batch(zone, 0);
 }
 
+/*
+ * The zone indicated has a new number of managed_pages; batch sizes and percpu
+ * page high values need to be recalculated.
+ */
+static void zone_pcp_update(struct zone *zone, int cpu_online)
+{
+	mutex_lock(&pcp_batch_high_lock);
+	zone_set_pageset_high_and_batch(zone, cpu_online);
+	mutex_unlock(&pcp_batch_high_lock);
+}
+
 /*
  * Allocate per cpu pagesets and initialize them.
  * Before this call only boot pagesets were available.
@@ -9473,17 +9484,6 @@ void free_contig_range(unsigned long pfn, unsigned long nr_pages)
 }
 EXPORT_SYMBOL(free_contig_range);
 
-/*
- * The zone indicated has a new number of managed_pages; batch sizes and percpu
- * page high values need to be recalculated.
- */
-void zone_pcp_update(struct zone *zone, int cpu_online)
-{
-	mutex_lock(&pcp_batch_high_lock);
-	zone_set_pageset_high_and_batch(zone, cpu_online);
-	mutex_unlock(&pcp_batch_high_lock);
-}
-
 /*
  * Effectively disable pcplists for the zone by setting the high limit to 0
  * and draining all cpus. A concurrent page freeing on another CPU that's about