mm, memory_hotplug: drop arch_free_nodedata

Prior to "mm: handle uninitialized numa nodes gracefully" memory hotplug
used to allocate pgdat when memory has been added to a node
(hotadd_init_pgdat) arch_free_nodedata has been only used in the failure
path because once the pgdat is exported (to be visible by NODA_DATA(nid))
it cannot really be freed because there is no synchronization available
for that.

pgdat is allocated for each possible nodes now so the memory hotplug
doesn't need to do the ever use arch_free_nodedata so drop it.

This patch doesn't introduce any functional change.

Link: https://lkml.kernel.org/r/20220127085305.20890-4-mhocko@kernel.orgSigned-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Rafael Aquini <raquini@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Alexey Makhalov <amakhalov@vmware.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/ia64/mm/discontig.c

@@ -615,11 +615,6 @@ pg_data_t * __init arch_alloc_nodedata(int nid)
 	return memblock_alloc(size, SMP_CACHE_BYTES);
 }
 
-void arch_free_nodedata(pg_data_t *pgdat)
-{
-	kfree(pgdat);
-}
-
 void arch_refresh_nodedata(int update_node, pg_data_t *update_pgdat)
 {
 	pgdat_list[update_node] = update_pgdat;

include/linux/memory_hotplug.h

@@ -24,17 +24,14 @@ struct vmem_altmap;
  * node_data[nid] = kzalloc() works well. But it depends on the architecture.
  *
  * In general, generic_alloc_nodedata() is used.
- * Now, arch_free_nodedata() is just defined for error path of node_hot_add.
  *
  */
 extern pg_data_t *arch_alloc_nodedata(int nid);
-extern void arch_free_nodedata(pg_data_t *pgdat);
 extern void arch_refresh_nodedata(int nid, pg_data_t *pgdat);
 
 #else /* CONFIG_HAVE_ARCH_NODEDATA_EXTENSION */
 
 #define arch_alloc_nodedata(nid)	generic_alloc_nodedata(nid)
-#define arch_free_nodedata(pgdat)	generic_free_nodedata(pgdat)
 
 #ifdef CONFIG_NUMA
 /*

mm/memory_hotplug.c

@@ -1217,16 +1217,6 @@ static pg_data_t __ref *hotadd_init_pgdat(int nid)
 	return pgdat;
 }
 
-static void rollback_node_hotadd(int nid)
-{
-	pg_data_t *pgdat = NODE_DATA(nid);
-
-	arch_refresh_nodedata(nid, NULL);
-	free_percpu(pgdat->per_cpu_nodestats);
-	arch_free_nodedata(pgdat);
-}
-
-
 /*
  * __try_online_node - online a node if offlined
  * @nid: the node ID