[PATCH] x86: numa: mm: kill double initialization for NODE_DATA

[PATCH] x86: numa: mm: kill double initialization for NODE_DATA

[Lin Feng]

We initialize node_id, node_start_pfn and node_spanned_pages for NODE_DATA in
initmem_init() while the later two members are kept unused and will be
recaculated soon in paging_init(), so remove the useless assignments.

PS. For clarifying calling chains are showed as follows:
setup_arch()
  ...
  initmem_init()
    x86_numa_init()
      numa_init()
        numa_register_memblks()
          setup_node_data()
            NODE_DATA(nid)->node_id = nid;
            NODE_DATA(nid)->node_start_pfn = start >> PAGE_SHIFT;
            NODE_DATA(nid)->node_spanned_pages = (end - start) >> PAGE_SHIFT;
  ...
  x86_init.paging.pagetable_init()
  paging_init()
    ...
    sparse_init()
      sparse_early_usemaps_alloc_node()
        sparse_early_usemaps_alloc_pgdat_section()
          ___alloc_bootmem_node_nopanic()
            __alloc_memory_core_early(pgdat->node_id,...)
    ...
    zone_sizes_init()
      free_area_init_nodes()
        free_area_init_node()
          pgdat->node_id = nid;
          pgdat->node_start_pfn = node_start_pfn;
          calculate_node_totalpages();
            pgdat->node_spanned_pages = totalpages;


Signed-off-by: Lin Feng <linfeng@cn.fujitsu.com>
---
 arch/x86/mm/numa.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index 72fe01e..efdd08f 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -230,8 +230,6 @@ static void __init setup_node_data(int nid, u64 start, u64 end)
 	node_data[nid] = nd;
 	memset(NODE_DATA(nid), 0, sizeof(pg_data_t));
 	NODE_DATA(nid)->node_id = nid;
-	NODE_DATA(nid)->node_start_pfn = start >> PAGE_SHIFT;
-	NODE_DATA(nid)->node_spanned_pages = (end - start) >> PAGE_SHIFT;
 
 	node_set_online(nid);
 }
-- 
1.7.1

Re: [PATCH] x86: numa: mm: kill double initialization for NODE_DATA

[Lin Feng]

Hi Wanpeng,

On 04/02/2013 06:57 PM, Wanpeng Li wrote:
>> >PS. For clarifying calling chains are showed as follows:
>> >setup_arch()
>> >  ...
>> >  initmem_init()
>> >    x86_numa_init()
>> >      numa_init()
>> >        numa_register_memblks()
>> >          setup_node_data()
>> >            NODE_DATA(nid)->node_id = nid;
>> >            NODE_DATA(nid)->node_start_pfn = start >> PAGE_SHIFT;
>> >            NODE_DATA(nid)->node_spanned_pages = (end - start) >> PAGE_SHIFT;
>> >  ...
>> >  x86_init.paging.pagetable_init()
>> >  paging_init()
>> >    ...
>> >    sparse_init()
>> >      sparse_early_usemaps_alloc_node()
>> >        sparse_early_usemaps_alloc_pgdat_section()
>> >          ___alloc_bootmem_node_nopanic()
>> >            __alloc_memory_core_early(pgdat->node_id,...)
>> >    ...
>> >    zone_sizes_init()
>> >      free_area_init_nodes()
>> >        free_area_init_node()
>> >          pgdat->node_id = nid;
>> >          pgdat->node_start_pfn = node_start_pfn;
>> >          calculate_node_totalpages();
>> >            pgdat->node_spanned_pages = totalpages;
>> >
> You miss the nodes which could become online at some point, but not
> online currently. 

Sorry, I'm not quite understanding what you said.

I keep node_set_online(nid) there. In boot phase if a node is online now it wil be 
reinitialized later by zone_sizes_init() else if a node is hotpluged after system is
up it will also be initialized by hotadd_new_pgdat() which falls into calling 
free_area_init_node().

Besides this I'm not sure there are any other dependency besides what you worry about,
while I tested this on a x86_64 numa system with hot-add nodes and the meminfo statics
looks right before and after hot-add memory.

thanks for your patient,
linfeng