mm/page_alloc: move set_page_refcounted() to callers of post_alloc_hook()

In preparation for allocating frozen pages, stop initialising the page
refcount in post_alloc_hook().

Link: https://lkml.kernel.org/r/20241125210149.2976098-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: Matthew Wilcox (Oracle)

mm/compaction.c

@@ -83,6 +83,7 @@ static inline bool is_via_compact_memory(int order) { return false; }
 static struct page *mark_allocated_noprof(struct page *page, unsigned int order, gfp_t gfp_flags)
 {
 	post_alloc_hook(page, order, __GFP_MOVABLE);
+	set_page_refcounted(page);
 	return page;
 }
 #define mark_allocated(...)	alloc_hooks(mark_allocated_noprof(__VA_ARGS__))
@@ -1868,6 +1869,7 @@ static struct folio *compaction_alloc_noprof(struct folio *src, unsigned long da
 	dst = (struct folio *)freepage;
 
 	post_alloc_hook(&dst->page, order, __GFP_MOVABLE);
+	set_page_refcounted(&dst->page);
 	if (order)
 		prep_compound_page(&dst->page, order);
 	cc->nr_freepages -= 1 << order;

mm/internal.h

@@ -735,8 +735,7 @@ static inline void prep_compound_tail(struct page *head, int tail_idx)
 
 extern void prep_compound_page(struct page *page, unsigned int order);
 
-extern void post_alloc_hook(struct page *page, unsigned int order,
-					gfp_t gfp_flags);
+void post_alloc_hook(struct page *page, unsigned int order, gfp_t gfp_flags);
 extern bool free_pages_prepare(struct page *page, unsigned int order);
 
 extern int user_min_free_kbytes;

mm/page_alloc.c

@@ -1508,7 +1508,6 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
 	int i;
 
 	set_page_private(page, 0);
-	set_page_refcounted(page);
 
 	arch_alloc_page(page, order);
 	debug_pagealloc_map_pages(page, 1 << order);
@@ -1564,6 +1563,7 @@ static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags
 							unsigned int alloc_flags)
 {
 	post_alloc_hook(page, order, gfp_flags);
+	set_page_refcounted(page);
 
 	if (order && (gfp_flags & __GFP_COMP))
 		prep_compound_page(page, order);
@@ -6360,6 +6360,7 @@ static void split_free_pages(struct list_head *list)
 			int i;
 
 			post_alloc_hook(page, order, __GFP_MOVABLE);
+			set_page_refcounted(page);
 			if (!order)
 				continue;