At 11/26/2012 10:27 PM, Jianguo Wu Wrote:
> On 2012/11/1 17:44, Wen Congyang wrote:
>> This patch introduces a new function try_offline_node() to
>> remove sysfs file of node when all memory sections of this
>> node are removed. If some memory sections of this node are
>> not removed, this function does nothing.
>>
>> CC: David Rientjes <rientjes@xxxxxxxxxx>
>> CC: Jiang Liu <liuj97@xxxxxxxxx>
>> CC: Len Brown <len.brown@xxxxxxxxx>
>> CC: Christoph Lameter <cl@xxxxxxxxx>
>> Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
>> CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>> CC: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
>> CC: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
>> Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
>> ---
>> drivers/acpi/acpi_memhotplug.c | 8 +++++-
>> include/linux/memory_hotplug.h | 2 +-
>> mm/memory_hotplug.c | 58 ++++++++++++++++++++++++++++++++++++++++--
>> 3 files changed, 64 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
>> index 24c807f..0780f99 100644
>> --- a/drivers/acpi/acpi_memhotplug.c
>> +++ b/drivers/acpi/acpi_memhotplug.c
>> @@ -310,7 +310,9 @@ static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
>> {
>> int result;
>> struct acpi_memory_info *info, *n;
>> + int node;
>>
>> + node = acpi_get_node(mem_device->device->handle);
>>
>> /*
>> * Ask the VM to offline this memory range.
>> @@ -318,7 +320,11 @@ static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
>> */
>> list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
>> if (info->enabled) {
>> - result = remove_memory(info->start_addr, info->length);
>> + if (node < 0)
>> + node = memory_add_physaddr_to_nid(
>> + info->start_addr);
>> + result = remove_memory(node, info->start_addr,
>> + info->length);
>> if (result)
>> return result;
>> }
>> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
>> index d4c4402..7b4cfe6 100644
>> --- a/include/linux/memory_hotplug.h
>> +++ b/include/linux/memory_hotplug.h
>> @@ -231,7 +231,7 @@ extern int arch_add_memory(int nid, u64 start, u64 size);
>> extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
>> extern int offline_memory_block(struct memory_block *mem);
>> extern bool is_memblock_offlined(struct memory_block *mem);
>> -extern int remove_memory(u64 start, u64 size);
>> +extern int remove_memory(int node, u64 start, u64 size);
>> extern int sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
>> int nr_pages);
>> extern void sparse_remove_one_section(struct zone *zone, struct mem_section *ms);
>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>> index 7bcced0..d965da3 100644
>> --- a/mm/memory_hotplug.c
>> +++ b/mm/memory_hotplug.c
>> @@ -29,6 +29,7 @@
>> #include <linux/suspend.h>
>> #include <linux/mm_inline.h>
>> #include <linux/firmware-map.h>
>> +#include <linux/stop_machine.h>
>>
>> #include <asm/tlbflush.h>
>>
>> @@ -1299,7 +1300,58 @@ static int is_memblock_offlined_cb(struct memory_block *mem, void *arg)
>> return ret;
>> }
>>
>> -int __ref remove_memory(u64 start, u64 size)
>> +static int check_cpu_on_node(void *data)
>> +{
>> + struct pglist_data *pgdat = data;
>> + int cpu;
>> +
>> + for_each_present_cpu(cpu) {
>> + if (cpu_to_node(cpu) == pgdat->node_id)
>> + /*
>> + * the cpu on this node isn't removed, and we can't
>> + * offline this node.
>> + */
>> + return -EBUSY;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +/* offline the node if all memory sections of this node are removed */
>> +static void try_offline_node(int 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 pfn;
>> +
>> + for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
>> + unsigned long section_nr = pfn_to_section_nr(pfn);
>> +
>> + if (!present_section_nr(section_nr))
>> + continue;
>> +
>> + if (pfn_to_nid(pfn) != nid)
>> + continue;
>> +
>> + /*
>> + * some memory sections of this node are not removed, and we
>> + * can't offline node now.
>> + */
>> + return;
>> + }
>> +
>> + if (stop_machine(check_cpu_on_node, NODE_DATA(nid), NULL))
>> + return;
>
> how about:
> if (nr_cpus_node(nid))
If all cpus on the node is offlined, but not removed, nr_cpus_node(nid) will
return 0. In this case, we still can't offline the node.
Another purpose to use stop_machine() is to prevent cpu hotplug. We can't lock
cpuhotplug here.
Thanks
Wen Congyang
> return;
>> +
>> + /*
>> + * all memory/cpu of this node are removed, we can offline this
>> + * node now.
>> + */
>> + node_set_offline(nid);
>> + unregister_one_node(nid);
>> +}
>> +
>> +int __ref remove_memory(int nid, u64 start, u64 size)
>> {
>> unsigned long start_pfn, end_pfn;
>> int ret = 0;
>> @@ -1346,6 +1398,8 @@ repeat:
>>
>> arch_remove_memory(start, size);
>>
>> + try_offline_node(nid);
>> +
>> unlock_memory_hotplug();
>>
>> return 0;
>> @@ -1355,7 +1409,7 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
>> {
>> return -EINVAL;
>> }
>> -int remove_memory(u64 start, u64 size)
>> +int remove_memory(int nid, u64 start, u64 size)
>> {
>> return -EINVAL;
>> }
>>
>
>
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