(2012/12/24 21:09), Tang Chen wrote:
> From: Wen Congyang <we...@cn.fujitsu.com>
> 
> We call hotadd_new_pgdat() to allocate memory to store node_data. So we
> should free it when removing a node.
> 
> Signed-off-by: Wen Congyang <we...@cn.fujitsu.com>

I'm sorry but is it safe to remove pgdat ? All zone cache and zonelists are
properly cleared/rebuilded in synchronous way ? and No threads are visinting
zone in vmscan.c ?

Thanks,
-Kame

> ---
>   mm/memory_hotplug.c |   20 +++++++++++++++++++-
>   1 files changed, 19 insertions(+), 1 deletions(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index f8a1d2f..447fa24 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1680,9 +1680,12 @@ static int check_cpu_on_node(void *data)
>   /* offline the node if all memory sections of this node are removed */
>   static void try_offline_node(int nid)
>   {
> +     pg_data_t *pgdat = NODE_DATA(nid);
>       unsigned long start_pfn = NODE_DATA(nid)->node_start_pfn;
> -     unsigned long end_pfn = start_pfn + NODE_DATA(nid)->node_spanned_pages;
> +     unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
>       unsigned long pfn;
> +     struct page *pgdat_page = virt_to_page(pgdat);
> +     int i;
>   
>       for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
>               unsigned long section_nr = pfn_to_section_nr(pfn);
> @@ -1709,6 +1712,21 @@ static void try_offline_node(int nid)
>        */
>       node_set_offline(nid);
>       unregister_one_node(nid);
> +
> +     if (!PageSlab(pgdat_page) && !PageCompound(pgdat_page))
> +             /* node data is allocated from boot memory */
> +             return;
> +
> +     /* free waittable in each zone */
> +     for (i = 0; i < MAX_NR_ZONES; i++) {
> +             struct zone *zone = pgdat->node_zones + i;
> +
> +             if (zone->wait_table)
> +                     vfree(zone->wait_table);
> +     }
> +
> +     arch_refresh_nodedata(nid, NULL);
> +     arch_free_nodedata(pgdat);
>   }
>   
>   int __ref remove_memory(int nid, u64 start, u64 size)
> 


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