mm: define __init_reserved_page_zone function

Sometimes page structs must be unconditionally initialized as reserved,
regardless of DEFERRED_STRUCT_PAGE_INIT.

Define a function, __init_reserved_page_zone, containing code that already
did all of the work in init_reserved_page, and make it available for use.

Link: https://lkml.kernel.org/r/20250228182928.2645936-13-fvdl@google.com
Signed-off-by: Frank van der Linden <fvdl@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roman Gushchin (Cruise) <roman.gushchin@linux.dev>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 23 insertions, 15 deletions

diff --git a/mm/mm_init.c b/mm/mm_init.c
index 56f4a8cfb764..419b7db220d2 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -650,6 +650,28 @@ static inline void fixup_hashdist(void)
 static inline void fixup_hashdist(void) {}
 #endif /* CONFIG_NUMA */
 
+/*
+ * Initialize a reserved page unconditionally, finding its zone first.
+ */
+void __meminit __init_reserved_page_zone(unsigned long pfn, int nid)
+{
+	pg_data_t *pgdat;
+	int zid;
+
+	pgdat = NODE_DATA(nid);
+
+	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+		struct zone *zone = &pgdat->node_zones[zid];
+
+		if (zone_spans_pfn(zone, pfn))
+			break;
+	}
+	__init_single_page(pfn_to_page(pfn), pfn, zid, nid);
+
+	if (pageblock_aligned(pfn))
+		set_pageblock_migratetype(pfn_to_page(pfn), MIGRATE_MOVABLE);
+}
+
 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
 static inline void pgdat_set_deferred_range(pg_data_t *pgdat)
 {
@@ -708,24 +730,10 @@ defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
 
 static void __meminit init_reserved_page(unsigned long pfn, int nid)
 {
-	pg_data_t *pgdat;
-	int zid;
-
 	if (early_page_initialised(pfn, nid))
 		return;
 
-	pgdat = NODE_DATA(nid);
-
-	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
-		struct zone *zone = &pgdat->node_zones[zid];
-
-		if (zone_spans_pfn(zone, pfn))
-			break;
-	}
-	__init_single_page(pfn_to_page(pfn), pfn, zid, nid);
-
-	if (pageblock_aligned(pfn))
-		set_pageblock_migratetype(pfn_to_page(pfn), MIGRATE_MOVABLE);
+	__init_reserved_page_zone(pfn, nid);
 }
 #else
 static inline void pgdat_set_deferred_range(pg_data_t *pgdat) {}