Re: [RFC PATCH v2 2/13] memory-hotplug : add physical memory hotplug code to acpi_memory_device_remove

Wen Congyang
2012-07-03T07:44:58Z

At 07/03/2012 03:40 PM, Yasuaki Ishimatsu Wrote:
> Hi Wen,
>
> 2012/07/03 15:21, Wen Congyang wrote:
>> At 07/03/2012 01:54 PM, Yasuaki Ishimatsu Wrote:
>>> acpi_memory_device_remove() has been prepared to remove physical memory.
>>> But, the function only frees acpi_memory_device currentlry.
>>>
>>> The patch adds following functions into acpi_memory_device_remove():
>>> - offline memory
>>> - remove physical memory (only return -EBUSY)
>>> - free acpi_memory_device
>>>
>>> CC: David Rientjes <rientjes@google.com>
>>> CC: Jiang Liu <liuj97@gmail.com>
>>> CC: Len Brown <len.brown@intel.com>
>>> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>>> CC: Paul Mackerras <paulus@samba.org>
>>> CC: Christoph Lameter <cl@linux.com>
>>> Cc: Minchan Kim <minchan.kim@gmail.com>
>>> CC: Andrew Morton <akpm@linux-foundation.org>
>>> CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
>>> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>>>
>>> ---
>>> drivers/acpi/acpi_memhotplug.c | 26 +++++++++++++++++++++++++-
>>> drivers/base/memory.c | 38 ++++++++++++++++++++++++++++++++++++++
>>> include/linux/memory.h | 5 +++++
>>> include/linux/memory_hotplug.h | 1 +
>>> mm/memory_hotplug.c | 8 ++++++++
>>> 5 files changed, 77 insertions(+), 1 deletion(-)
>>>
>>> Index: linux-3.5-rc4/drivers/acpi/acpi_memhotplug.c
>>> ===================================================================
>>> --- linux-3.5-rc4.orig/drivers/acpi/acpi_memhotplug.c 2012-07-03 14:21:49.458374960 +0900
>>> +++ linux-3.5-rc4/drivers/acpi/acpi_memhotplug.c 2012-07-03 14:21:58.329264059 +0900
>>> @@ -29,6 +29,7 @@
>>> #include <linux/module.h>
>>> #include <linux/init.h>
>>> #include <linux/types.h>
>>> +#include <linux/memory.h>
>>> #include <linux/memory_hotplug.h>
>>> #include <linux/slab.h>
>>> #include <acpi/acpi_drivers.h>
>>> @@ -452,12 +453,35 @@ static int acpi_memory_device_add(struct
>>> static int acpi_memory_device_remove(struct acpi_device *device, int type)
>>> {
>>> struct acpi_memory_device *mem_device = NULL;
>>> -
>>> + struct acpi_memory_info *info, *tmp;
>>> + int result;
>>> + int node;
>>>
>>> if (!device || !acpi_driver_data(device))
>>> return -EINVAL;
>>>
>>> mem_device = acpi_driver_data(device);
>>> +
>>> + node = acpi_get_node(mem_device->device->handle);
>>> +
>>> + list_for_each_entry_safe(info, tmp, &mem_device->res_list, list) {
>>> + if (!info->enabled)
>>> + continue;
>>> +
>>> + if (!is_memblk_offline(info->start_addr, info->length)) {
>>> + result = offline_memory(info->start_addr, info->length);
>>> + if (result)
>>> + return result;
>>> + }
>>> +
>>> + result = remove_memory(node, info->start_addr, info->length);
>>> + if (result)
>>> + return result;
>>> +
>>> + list_del(&info->list);
>>> + kfree(info);
>>> + }
>>> +
>>> kfree(mem_device);
>>
>> The caller does not care the return value, and after this function returns, the
>> memory device will be unbound from this driver, so we should free all memory
>> allocated for driver data.
>
> We can ignore return value of remove_memory() because I think that it should
> return 0. But we cannot ignore return value of offline_memory() because
> kernel panic will occurs if kernel removes online memory. How do we deal with
> online memory?

Yes, We can not remove online memory, so just free the memory if offline_memory()
or remove_memory() fails.

>
>>>
>>> return 0;
>>> Index: linux-3.5-rc4/include/linux/memory_hotplug.h
>>> ===================================================================
>>> --- linux-3.5-rc4.orig/include/linux/memory_hotplug.h 2012-07-03 14:21:49.471374796 +0900
>>> +++ linux-3.5-rc4/include/linux/memory_hotplug.h 2012-07-03 14:21:58.330264047 +0900
>>> @@ -233,6 +233,7 @@ static inline int is_mem_section_removab
>>> extern int mem_online_node(int nid);
>>> extern int add_memory(int nid, u64 start, u64 size);
>>> extern int arch_add_memory(int nid, u64 start, u64 size);
>>> +extern int remove_memory(int nid, u64 start, u64 size);
>>> extern int offline_memory(u64 start, u64 size);
>>> extern int sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
>>> int nr_pages);
>>> Index: linux-3.5-rc4/mm/memory_hotplug.c
>>> ===================================================================
>>> --- linux-3.5-rc4.orig/mm/memory_hotplug.c 2012-07-03 14:21:49.466374860 +0900
>>> +++ linux-3.5-rc4/mm/memory_hotplug.c 2012-07-03 14:21:58.332264022 +0900
>>> @@ -659,6 +659,14 @@ out:
>>> }
>>> EXPORT_SYMBOL_GPL(add_memory);
>>>
>>> +int remove_memory(int nid, u64 start, u64 size)
>>> +{
>>> + return -EBUSY;
>>> +
>>> +}
>>> +EXPORT_SYMBOL_GPL(remove_memory);
>>> +
>>> +
>>> #ifdef CONFIG_MEMORY_HOTREMOVE
>>> /*
>>> * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy
>>> Index: linux-3.5-rc4/drivers/base/memory.c
>>> ===================================================================
>>> --- linux-3.5-rc4.orig/drivers/base/memory.c 2012-07-03 14:21:49.459374948 +0900
>>> +++ linux-3.5-rc4/drivers/base/memory.c 2012-07-03 14:21:58.335263984 +0900
>>> @@ -70,6 +70,44 @@ void unregister_memory_isolate_notifier(
>>> }
>>> EXPORT_SYMBOL(unregister_memory_isolate_notifier);
>>>
>>> +bool is_memblk_offline(unsigned long start, unsigned long size)
>>> +{
>>> + struct memory_block *mem = NULL;
>>> + struct mem_section *section;
>>> + unsigned long start_pfn, end_pfn;
>>> + unsigned long pfn, section_nr;
>>> +
>>> + start_pfn = PFN_DOWN(start);
>>> + end_pfn = start_pfn + PFN_DOWN(start);
>>> +
>>> + for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
>>> + section_nr = pfn_to_section_nr(pfn);
>>> + if (!present_section_nr(section_nr));
>>> + continue;
>>> +
>>> + section = __nr_to_section(section_nr);
>>> + /* same memblock? */
>>> + if (mem)
>>> + if((section_nr >= mem->start_section_nr) &&
>>> + (section_nr <= mem->end_section_nr))
>>> + continue;
>>> +
>>> + mem = find_memory_block_hinted(section, mem);
>>
>> The second parameter should be NULL. Otherwise, the mem->dev.kobj will
>> be put twice:
>> 1. we put it when mem->state is MEM_OFFLINE
>> 2. we put it in find_memory_block_hinted().
>
> Ah, O.K.
> How about it?

This version looks fine to me.

Thanks
Wen Congyang

>
> +bool is_memblk_offline(unsigned long start, unsigned long size)
> +{
> + struct memory_block *mem = NULL;
> + struct mem_section *section;
> + unsigned long start_pfn, end_pfn;
> + unsigned long pfn, section_nr;
> +
> + start_pfn = PFN_DOWN(start);
> + end_pfn = start_pfn + PFN_DOWN(start);
> +
> + for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
> + section_nr = pfn_to_section_nr(pfn);
> + if (!present_section_nr(section_nr));
> + continue;
> +
> + section = __nr_to_section(section_nr);
> + /* same memblock? */
> + if (mem)
> + if((section_nr >= mem->start_section_nr) &&
> + (section_nr <= mem->end_section_nr))
> + continue;
> +
> + mem = find_memory_block_hinted(section, mem);
> + if (!mem)
> + continue;
> + if (mem->state == MEM_OFFLINE)
> + continue;
> +
> + kobject_put(&mem->dev.kobj);
> + return false;
> + }
> +
> + if (mem)
> + kobject_put(&mem->dev.kobj);
> +
> + return true;
> +}
> +EXPORT_SYMBOL(is_memblk_offline);
>
> Thanks,
> Yasuaki Ishimatsu
>
>>
>> Thanks
>> Wen Congyang
>>
>>> + if (!mem)
>>> + continue;
>>> + if (mem->state == MEM_OFFLINE) {
>>> + kobject_put(&mem->dev.kobj);
>>> + continue;
>>> + }
>>> +
>>> + kobject_put(&mem->dev.kobj);
>>> + return false;
>>> + }
>>> +
>>> + return true;
>>> +}
>>> +EXPORT_SYMBOL(is_memblk_offline);
>>> +
>>> /*
>>> * register_memory - Setup a sysfs device for a memory block
>>> */
>>> Index: linux-3.5-rc4/include/linux/memory.h
>>> ===================================================================
>>> --- linux-3.5-rc4.orig/include/linux/memory.h 2012-07-03 14:21:45.998418215 +0900
>>> +++ linux-3.5-rc4/include/linux/memory.h 2012-07-03 14:21:58.340263922 +0900
>>> @@ -106,6 +106,10 @@ static inline int memory_isolate_notify(
>>> {
>>> return 0;
>>> }
>>> +static inline bool is_memblk_offline(unsigned long start, unsigned long size)
>>> +{
>>> + return false;
>>> +}
>>> #else
>>> extern int register_memory_notifier(struct notifier_block *nb);
>>> extern void unregister_memory_notifier(struct notifier_block *nb);
>>> @@ -120,6 +124,7 @@ extern int memory_isolate_notify(unsigne
>>> extern struct memory_block *find_memory_block_hinted(struct mem_section *,
>>> struct memory_block *);
>>> extern struct memory_block *find_memory_block(struct mem_section *);
>>> +extern bool is_memblk_offline(unsigned long start, unsigned long size);
>>> #define CONFIG_MEM_BLOCK_SIZE (PAGES_PER_SECTION<<PAGE_SHIFT)
>>> enum mem_add_context { BOOT, HOTPLUG };
>>> #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
>>>
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>>
>
>
>
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