From:   Michal Hocko <mhocko@kernel.org>
To:     Andrew Morton <akpm@linux-foundation.org>,
        David Hildenbrand <david@redhat.com>,
        Alexey Makhalov <amakhalov@vmware.com>
Cc:     LKML <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
        Dennis Zhou <dennis@kernel.org>,
        Eric Dumazet <eric.dumazet@gmail.com>,
        Oscar Salvador <osalvador@suse.de>, Tejun Heo <tj@kernel.org>,
        Christoph Lameter <cl@linux.com>,
        Nico Pache <npache@redhat.com>, Michal Hocko <mhocko@suse.com>
Subject: [PATCH v2 3/4] mm, memory_hotplug: drop arch_free_nodedata
Date:   Tue, 14 Dec 2021 11:07:31 +0100
Message-Id: <20211214100732.26335-4-mhocko@kernel.org>
In-Reply-To: <20211214100732.26335-1-mhocko@kernel.org>
References: <YbHfBgPQMkjtuHYF@dhcp22.suse.cz>
 <20211214100732.26335-1-mhocko@kernel.org>
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From: Michal Hocko <mhocko@suse.com>

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.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 arch/ia64/mm/discontig.c       |  5 -----
 include/linux/memory_hotplug.h |  3 ---
 mm/memory_hotplug.c            | 10 ----------
 3 files changed, 18 deletions(-)

diff --git a/arch/ia64/mm/discontig.c b/arch/ia64/mm/discontig.c
index b4c46925792f..f177390fdee1 100644
--- a/arch/ia64/mm/discontig.c
+++ b/arch/ia64/mm/discontig.c
@@ -615,11 +615,6 @@ pg_data_t *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;
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index cdd66bfdf855..60f09d3ebb3d 100644
--- a/include/linux/memory_hotplug.h
+++ b/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
 /*
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 9009a7b2a170..2daa88ce8c80 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1216,16 +1216,6 @@ 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
-- 
2.30.2