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[RFC PATCH 0/2] arm64: memory-hotplug: Add Memory Hotplug support

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  [RFC PATCH 0/2] arm64: memory-hotplug: Add Memory Hotplug support Scott Branden <scott.branden@broadcom.com> - 2016-12-02 01:30 +0100
    [RFC PATCH 2/2] arm64: defconfig: enable MEMORY_HOTPLUG config options Scott Branden <scott.branden@broadcom.com> - 2016-12-02 01:30 +0100
    [RFC PATCH 1/2] arm64: memory-hotplug: Add MEMORY_HOTPLUG, MEMORY_HOTREMOVE, MEMORY_PROBE Scott Branden <scott.branden@broadcom.com> - 2016-12-02 01:30 +0100
    Re: [RFC PATCH 0/2] arm64: memory-hotplug: Add Memory Hotplug support Xishi Qiu <qiuxishi@huawei.com> - 2016-12-02 03:00 +0100
      Re: [RFC PATCH 0/2] arm64: memory-hotplug: Add Memory Hotplug support Scott Branden <scott.branden@broadcom.com> - 2016-12-02 03:40 +0100
        Re: [RFC PATCH 0/2] arm64: memory-hotplug: Add Memory Hotplug support Xishi Qiu <qiuxishi@huawei.com> - 2016-12-02 04:20 +0100
          Re: [RFC PATCH 0/2] arm64: memory-hotplug: Add Memory Hotplug support Scott Branden <scott.branden@broadcom.com> - 2016-12-07 09:50 +0100
            Re: [RFC PATCH 0/2] arm64: memory-hotplug: Add Memory Hotplug support Xishi Qiu <qiuxishi@huawei.com> - 2016-12-07 12:30 +0100
    Re: [RFC PATCH 0/2] arm64: memory-hotplug: Add Memory Hotplug support Maciej Bielski <m.bielski@virtualopensystems.com> - 2016-12-02 10:20 +0100
      Re: [RFC PATCH 0/2] arm64: memory-hotplug: Add Memory Hotplug support Will Deacon <will.deacon@arm.com> - 2016-12-02 11:50 +0100
        Re: [RFC PATCH 0/2] arm64: memory-hotplug: Add Memory Hotplug support Maciej Bielski <m.bielski@virtualopensystems.com> - 2016-12-02 12:00 +0100
          Re: [RFC PATCH 0/2] arm64: memory-hotplug: Add Memory Hotplug support Scott Branden <scott.branden@broadcom.com> - 2016-12-02 18:50 +0100

#1534583 — [RFC PATCH 0/2] arm64: memory-hotplug: Add Memory Hotplug support

This patchset is sent for comment to add memory hotplug support for ARM64
based platforms.  It follows hotplug code added for other architectures
in the linux kernel.

I tried testing the memory hotplug feature following documentation from
Documentation/memory-hotplug.txt.  I don't think it is working as expected
- see below:

To add memory to the system I did the following:
echo 0x400000000 > /sys/devices/system/memory/probe

The memory is displayed as system ram:
cat /proc/iomem:
74000000-77ffffff : System RAM
  74080000-748dffff : Kernel code
  74950000-749d2fff : Kernel data
400000000-43fffffff : System RAM

But does not seem to be added to the kernel memory.
/proc/meminfo did not change.

What else needs to be done so the memory is added to the kernel memory
pool for normal allocation?

Scott Branden (2):
  arm64: memory-hotplug: Add MEMORY_HOTPLUG, MEMORY_HOTREMOVE,
    MEMORY_PROBE
  arm64: defconfig: enable MEMORY_HOTPLUG config options

 arch/arm64/Kconfig           | 10 ++++++++++
 arch/arm64/configs/defconfig |  3 +++
 arch/arm64/mm/init.c         | 42 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 55 insertions(+)

-- 
2.5.0

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#1534586 — [RFC PATCH 2/2] arm64: defconfig: enable MEMORY_HOTPLUG config options

Enable memory hotplug config options to add/remove memory.

Signed-off-by: Scott Branden <scott.branden@broadcom.com>
---
 arch/arm64/configs/defconfig | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
index dab2cb0..e801b37 100644
--- a/arch/arm64/configs/defconfig
+++ b/arch/arm64/configs/defconfig
@@ -73,6 +73,9 @@ CONFIG_PCIE_ARMADA_8K=y
 CONFIG_ARM64_VA_BITS_48=y
 CONFIG_SCHED_MC=y
 CONFIG_PREEMPT=y
+CONFIG_MEMORY_HOTPLUG=y
+CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y
+CONFIG_MEMORY_HOTREMOVE=y
 CONFIG_KSM=y
 CONFIG_TRANSPARENT_HUGEPAGE=y
 CONFIG_CMA=y
-- 
2.5.0

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#1534588 — [RFC PATCH 1/2] arm64: memory-hotplug: Add MEMORY_HOTPLUG, MEMORY_HOTREMOVE, MEMORY_PROBE

Add memory-hotplug support for ARM64 platform.

This requires addition of
ARCH_ENABLE_MEMORY_HOTPLUG and ARCH_ENABLE_MEMORY_HOTREMOVE config options.

MEMORY_PROBE config option is added to support
/sys/devices/system/memory/probe functionality.

In addition architecture specific arch_add_memory and
arch_remove memory management functions are added.

Signed-off-by: Scott Branden <scott.branden@broadcom.com>
---
 arch/arm64/Kconfig   | 10 ++++++++++
 arch/arm64/mm/init.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 969ef88..2482fdd 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -576,6 +576,12 @@ config HOTPLUG_CPU
 	  Say Y here to experiment with turning CPUs off and on.  CPUs
 	  can be controlled through /sys/devices/system/cpu.
 
+config ARCH_ENABLE_MEMORY_HOTPLUG
+	def_bool y
+
+config ARCH_ENABLE_MEMORY_HOTREMOVE
+	def_bool y
+
 # Common NUMA Features
 config NUMA
 	bool "Numa Memory Allocation and Scheduler Support"
@@ -646,6 +652,10 @@ config ARCH_HAS_CACHE_LINE_SIZE
 
 source "mm/Kconfig"
 
+config ARCH_MEMORY_PROBE
+	def_bool y
+	depends on MEMORY_HOTPLUG
+
 config SECCOMP
 	bool "Enable seccomp to safely compute untrusted bytecode"
 	---help---
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 212c4d1..687d087 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -536,3 +536,45 @@ static int __init register_mem_limit_dumper(void)
 	return 0;
 }
 __initcall(register_mem_limit_dumper);
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
+{
+	pg_data_t *pgdat;
+	struct zone *zone;
+	unsigned long start_pfn = start >> PAGE_SHIFT;
+	unsigned long nr_pages = size >> PAGE_SHIFT;
+	int ret;
+
+	pgdat = NODE_DATA(nid);
+
+	zone = pgdat->node_zones +
+		zone_for_memory(nid, start, size, ZONE_NORMAL, for_device);
+	ret = __add_pages(nid, zone, start_pfn, nr_pages);
+
+	if (ret)
+		pr_warn("%s: Problem encountered in __add_pages() ret=%d\n",
+			__func__, ret);
+
+	return ret;
+}
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+int arch_remove_memory(u64 start, u64 size)
+{
+	unsigned long start_pfn = start >> PAGE_SHIFT;
+	unsigned long nr_pages = size >> PAGE_SHIFT;
+	struct zone *zone;
+	int ret;
+
+	zone = page_zone(pfn_to_page(start_pfn));
+	ret = __remove_pages(zone, start_pfn, nr_pages);
+	if (ret)
+		pr_warn("%s: Problem encountered in __remove_pages() ret=%d\n",
+			__func__, ret);
+
+	return ret;
+}
+#endif
+#endif
+
-- 
2.5.0

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#1534615

On 2016/12/2 8:19, Scott Branden wrote:

> This patchset is sent for comment to add memory hotplug support for ARM64
> based platforms.  It follows hotplug code added for other architectures
> in the linux kernel.
> 
> I tried testing the memory hotplug feature following documentation from
> Documentation/memory-hotplug.txt.  I don't think it is working as expected
> - see below:
> 
> To add memory to the system I did the following:
> echo 0x400000000 > /sys/devices/system/memory/probe
> 
> The memory is displayed as system ram:
> cat /proc/iomem:
> 74000000-77ffffff : System RAM
>   74080000-748dffff : Kernel code
>   74950000-749d2fff : Kernel data
> 400000000-43fffffff : System RAM
> 
> But does not seem to be added to the kernel memory.
> /proc/meminfo did not change.
> 
> What else needs to be done so the memory is added to the kernel memory
> pool for normal allocation?
> 

Hi Scott,

Do you mean it still don't support hod-add after apply this patchset?

Thanks,
Xishi Qiu

> Scott Branden (2):
>   arm64: memory-hotplug: Add MEMORY_HOTPLUG, MEMORY_HOTREMOVE,
>     MEMORY_PROBE
>   arm64: defconfig: enable MEMORY_HOTPLUG config options
> 
>  arch/arm64/Kconfig           | 10 ++++++++++
>  arch/arm64/configs/defconfig |  3 +++
>  arch/arm64/mm/init.c         | 42 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 55 insertions(+)
> 

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#1534623

Hi Xishi,

Thanks for the reply - please see comments below.

On 16-12-01 05:49 PM, Xishi Qiu wrote:
> On 2016/12/2 8:19, Scott Branden wrote:
>
>> This patchset is sent for comment to add memory hotplug support for ARM64
>> based platforms.  It follows hotplug code added for other architectures
>> in the linux kernel.
>>
>> I tried testing the memory hotplug feature following documentation from
>> Documentation/memory-hotplug.txt.  I don't think it is working as expected
>> - see below:
>>
>> To add memory to the system I did the following:
>> echo 0x400000000 > /sys/devices/system/memory/probe
>>
>> The memory is displayed as system ram:
>> cat /proc/iomem:
>> 74000000-77ffffff : System RAM
>>   74080000-748dffff : Kernel code
>>   74950000-749d2fff : Kernel data
>> 400000000-43fffffff : System RAM
>>
>> But does not seem to be added to the kernel memory.
>> /proc/meminfo did not change.
>>
>> What else needs to be done so the memory is added to the kernel memory
>> pool for normal allocation?
>>
>
> Hi Scott,
>
> Do you mean it still don't support hod-add after apply this patchset?

After applying the patch it appears to partially support hot-add. 
Please let me know if you think it is working as expected?

The memory probe functions in that the memory is registered with the 
system and shows up in /proc/iomem.  But, the memory is not available in 
/proc/meminfo.  Do you think something else needs to be adjusted for 
ARM64 to hotadd the memory

I just found another clue:
under /sys/devices/system/memory I only see one memory entry (before or 
after I try to hotadd additional memory).

/sys/devices/system/memory # ls
auto_online_blocks  memory0            uevent
block_size_bytes    probe

In arch/arm64/include/asm/sparsemem.h if I change SECTION_SIZE_BITS from 
30 to 28 and recompile I get the following:
/sys/devices/system/memory # ls
auto_online_blocks  memory7            uevent
block_size_bytes    probe


In arch/arm64/include/asm/sparsemem.h if I change SECTION_SIZE_BITS from 
30 to 27 and recompile I get the following:
/sys/devices/system/memory # ls
auto_online_blocks  memory14            uevent
block_size_bytes    probe

If looks to me like something is not working properly in the ARM64 
implementation.  I should expect to see multiple memoryX entries under 
/sys/devices/system/memory?



>
> Thanks,
> Xishi Qiu
>
>> Scott Branden (2):
>>   arm64: memory-hotplug: Add MEMORY_HOTPLUG, MEMORY_HOTREMOVE,
>>     MEMORY_PROBE
>>   arm64: defconfig: enable MEMORY_HOTPLUG config options
>>
>>  arch/arm64/Kconfig           | 10 ++++++++++
>>  arch/arm64/configs/defconfig |  3 +++
>>  arch/arm64/mm/init.c         | 42 ++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 55 insertions(+)
>>
>
>
>

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#1534645

On 2016/12/2 10:38, Scott Branden wrote:

> Hi Xishi,
> 
> Thanks for the reply - please see comments below.
> 
> On 16-12-01 05:49 PM, Xishi Qiu wrote:
>> On 2016/12/2 8:19, Scott Branden wrote:
>>
>>> This patchset is sent for comment to add memory hotplug support for ARM64
>>> based platforms.  It follows hotplug code added for other architectures
>>> in the linux kernel.
>>>
>>> I tried testing the memory hotplug feature following documentation from
>>> Documentation/memory-hotplug.txt.  I don't think it is working as expected
>>> - see below:
>>>
>>> To add memory to the system I did the following:
>>> echo 0x400000000 > /sys/devices/system/memory/probe
>>>
>>> The memory is displayed as system ram:
>>> cat /proc/iomem:
>>> 74000000-77ffffff : System RAM
>>>   74080000-748dffff : Kernel code
>>>   74950000-749d2fff : Kernel data
>>> 400000000-43fffffff : System RAM
>>>
>>> But does not seem to be added to the kernel memory.
>>> /proc/meminfo did not change.
>>>
>>> What else needs to be done so the memory is added to the kernel memory
>>> pool for normal allocation?
>>>
>>
>> Hi Scott,
>>
>> Do you mean it still don't support hod-add after apply this patchset?
> 
> After applying the patch it appears to partially support hot-add. Please let me know if you think it is working as expected?
> 
> The memory probe functions in that the memory is registered with the system and shows up in /proc/iomem.  But, the memory is not available in /proc/meminfo.  Do you think something else needs to be adjusted for ARM64 to hotadd the memory
> 
> I just found another clue:
> under /sys/devices/system/memory I only see one memory entry (before or after I try to hotadd additional memory).
> 
> /sys/devices/system/memory # ls
> auto_online_blocks  memory0            uevent
> block_size_bytes    probe
> 
> In arch/arm64/include/asm/sparsemem.h if I change SECTION_SIZE_BITS from 30 to 28 and recompile I get the following:
> /sys/devices/system/memory # ls
> auto_online_blocks  memory7            uevent
> block_size_bytes    probe
> 
> 
> In arch/arm64/include/asm/sparsemem.h if I change SECTION_SIZE_BITS from 30 to 27 and recompile I get the following:
> /sys/devices/system/memory # ls
> auto_online_blocks  memory14            uevent
> block_size_bytes    probe
> 
> If looks to me like something is not working properly in the ARM64 implementation.  I should expect to see multiple memoryX entries under /sys/devices/system/memory?
> 

Hi Scott,

1. Do you enable the following configs?
CONFIG_SPARSEMEM
MEMORY_HOTPLUG
CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE

2. I find you missed create mapping in arch_add_memory(), and x86 has it.

3. We will add memblock first, so pfn_valid() maybe always return true(in the
following function), and this will lead __add_section() failed. Please check
it.

int pfn_valid(unsigned long pfn)
{
	return (pfn & PFN_MASK) == pfn && memblock_is_memory(pfn << PAGE_SHIFT);
}

add_memory
  add_memory_resource
    memblock_add_node
      arch_add_memory
        __add_pages
          __add_section
            pfn_valid

Thanks,
Xishi Qiu

> 
> 
>>
>> Thanks,
>> Xishi Qiu
>>
>>> Scott Branden (2):
>>>   arm64: memory-hotplug: Add MEMORY_HOTPLUG, MEMORY_HOTREMOVE,
>>>     MEMORY_PROBE
>>>   arm64: defconfig: enable MEMORY_HOTPLUG config options
>>>
>>>  arch/arm64/Kconfig           | 10 ++++++++++
>>>  arch/arm64/configs/defconfig |  3 +++
>>>  arch/arm64/mm/init.c         | 42 ++++++++++++++++++++++++++++++++++++++++++
>>>  3 files changed, 55 insertions(+)
>>>
>>
>>
>>
> 
> .
> 

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#1537611

Hi Xishi,

I followed you suggestions and found pfn_valid is always true.  Answers 
to your questions inline.

I could keep debugging this but hope Marcin sends out some code - I'm 
quite willing to test and help clean up the patchset.

On 16-12-01 07:11 PM, Xishi Qiu wrote:
> On 2016/12/2 10:38, Scott Branden wrote:
>
>> Hi Xishi,
>>
>> Thanks for the reply - please see comments below.
>>
>> On 16-12-01 05:49 PM, Xishi Qiu wrote:
>>> On 2016/12/2 8:19, Scott Branden wrote:
>>>
>>>> This patchset is sent for comment to add memory hotplug support for ARM64
>>>> based platforms.  It follows hotplug code added for other architectures
>>>> in the linux kernel.
>>>>
>>>> I tried testing the memory hotplug feature following documentation from
>>>> Documentation/memory-hotplug.txt.  I don't think it is working as expected
>>>> - see below:
>>>>
>>>> To add memory to the system I did the following:
>>>> echo 0x400000000 > /sys/devices/system/memory/probe
>>>>
>>>> The memory is displayed as system ram:
>>>> cat /proc/iomem:
>>>> 74000000-77ffffff : System RAM
>>>>   74080000-748dffff : Kernel code
>>>>   74950000-749d2fff : Kernel data
>>>> 400000000-43fffffff : System RAM
>>>>
>>>> But does not seem to be added to the kernel memory.
>>>> /proc/meminfo did not change.
>>>>
>>>> What else needs to be done so the memory is added to the kernel memory
>>>> pool for normal allocation?
>>>>
>>>
>>> Hi Scott,
>>>
>>> Do you mean it still don't support hod-add after apply this patchset?
>>
>> After applying the patch it appears to partially support hot-add. Please let me know if you think it is working as expected?
>>
>> The memory probe functions in that the memory is registered with the system and shows up in /proc/iomem.  But, the memory is not available in /proc/meminfo.  Do you think something else needs to be adjusted for ARM64 to hotadd the memory
>>
>> I just found another clue:
>> under /sys/devices/system/memory I only see one memory entry (before or after I try to hotadd additional memory).
>>
>> /sys/devices/system/memory # ls
>> auto_online_blocks  memory0            uevent
>> block_size_bytes    probe
>>
>> In arch/arm64/include/asm/sparsemem.h if I change SECTION_SIZE_BITS from 30 to 28 and recompile I get the following:
>> /sys/devices/system/memory # ls
>> auto_online_blocks  memory7            uevent
>> block_size_bytes    probe
>>
>>
>> In arch/arm64/include/asm/sparsemem.h if I change SECTION_SIZE_BITS from 30 to 27 and recompile I get the following:
>> /sys/devices/system/memory # ls
>> auto_online_blocks  memory14            uevent
>> block_size_bytes    probe
>>
>> If looks to me like something is not working properly in the ARM64 implementation.  I should expect to see multiple memoryX entries under /sys/devices/system/memory?
>>
>
> Hi Scott,
>
> 1. Do you enable the following configs?
> CONFIG_SPARSEMEM
> MEMORY_HOTPLUG
> CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
Yes, these configs are enabled
>
> 2. I find you missed create mapping in arch_add_memory(), and x86 has it.
Could you please explain this further?  The patch I submitted hass 
arch_add_memory identical to the ia64 implementation.
>
> 3. We will add memblock first, so pfn_valid() maybe always return true(in the
> following function), and this will lead __add_section() failed. Please check
> it.
You are correct - pfn_valid always returns true.  The function is in 
arch/arm64/mm/init.c and different than the one you indicated below:

#ifdef CONFIG_HAVE_ARCH_PFN_VALID
int pfn_valid(unsigned long pfn)
{
	return memblock_is_map_memory(pfn << PAGE_SHIFT);
}
EXPORT_SYMBOL(pfn_valid);
#endif

>
> int pfn_valid(unsigned long pfn)
> {
> 	return (pfn & PFN_MASK) == pfn && memblock_is_memory(pfn << PAGE_SHIFT);
> }
>
> add_memory
>   add_memory_resource
>     memblock_add_node
>       arch_add_memory
>         __add_pages
>           __add_section
>             pfn_valid
>
> Thanks,
> Xishi Qiu
>
>>
>>
>>>
>>> Thanks,
>>> Xishi Qiu
>>>
>>>> Scott Branden (2):
>>>>   arm64: memory-hotplug: Add MEMORY_HOTPLUG, MEMORY_HOTREMOVE,
>>>>     MEMORY_PROBE
>>>>   arm64: defconfig: enable MEMORY_HOTPLUG config options
>>>>
>>>>  arch/arm64/Kconfig           | 10 ++++++++++
>>>>  arch/arm64/configs/defconfig |  3 +++
>>>>  arch/arm64/mm/init.c         | 42 ++++++++++++++++++++++++++++++++++++++++++
>>>>  3 files changed, 55 insertions(+)
>>>>
>>>
>>>
>>>
>>
>> .
>>
>
>
>

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#1537693

On 2016/12/7 16:43, Scott Branden wrote:

> Hi Xishi,
> 
> I followed you suggestions and found pfn_valid is always true.  Answers to your questions inline.
> 
> I could keep debugging this but hope Marcin sends out some code - I'm quite willing to test and help clean up the patchset.
> 
> On 16-12-01 07:11 PM, Xishi Qiu wrote:
>> On 2016/12/2 10:38, Scott Branden wrote:
>>
>>> Hi Xishi,
>>>
>>> Thanks for the reply - please see comments below.
>>>
>>> On 16-12-01 05:49 PM, Xishi Qiu wrote:
>>>> On 2016/12/2 8:19, Scott Branden wrote:
>>>>
>>>>> This patchset is sent for comment to add memory hotplug support for ARM64
>>>>> based platforms.  It follows hotplug code added for other architectures
>>>>> in the linux kernel.
>>>>>
>>>>> I tried testing the memory hotplug feature following documentation from
>>>>> Documentation/memory-hotplug.txt.  I don't think it is working as expected
>>>>> - see below:
>>>>>
>>>>> To add memory to the system I did the following:
>>>>> echo 0x400000000 > /sys/devices/system/memory/probe
>>>>>
>>>>> The memory is displayed as system ram:
>>>>> cat /proc/iomem:
>>>>> 74000000-77ffffff : System RAM
>>>>>   74080000-748dffff : Kernel code
>>>>>   74950000-749d2fff : Kernel data
>>>>> 400000000-43fffffff : System RAM
>>>>>
>>>>> But does not seem to be added to the kernel memory.
>>>>> /proc/meminfo did not change.
>>>>>
>>>>> What else needs to be done so the memory is added to the kernel memory
>>>>> pool for normal allocation?
>>>>>
>>>>
>>>> Hi Scott,
>>>>
>>>> Do you mean it still don't support hod-add after apply this patchset?
>>>
>>> After applying the patch it appears to partially support hot-add. Please let me know if you think it is working as expected?
>>>
>>> The memory probe functions in that the memory is registered with the system and shows up in /proc/iomem.  But, the memory is not available in /proc/meminfo.  Do you think something else needs to be adjusted for ARM64 to hotadd the memory
>>>
>>> I just found another clue:
>>> under /sys/devices/system/memory I only see one memory entry (before or after I try to hotadd additional memory).
>>>
>>> /sys/devices/system/memory # ls
>>> auto_online_blocks  memory0            uevent
>>> block_size_bytes    probe
>>>
>>> In arch/arm64/include/asm/sparsemem.h if I change SECTION_SIZE_BITS from 30 to 28 and recompile I get the following:
>>> /sys/devices/system/memory # ls
>>> auto_online_blocks  memory7            uevent
>>> block_size_bytes    probe
>>>
>>>
>>> In arch/arm64/include/asm/sparsemem.h if I change SECTION_SIZE_BITS from 30 to 27 and recompile I get the following:
>>> /sys/devices/system/memory # ls
>>> auto_online_blocks  memory14            uevent
>>> block_size_bytes    probe
>>>
>>> If looks to me like something is not working properly in the ARM64 implementation.  I should expect to see multiple memoryX entries under /sys/devices/system/memory?
>>>
>>
>> Hi Scott,
>>
>> 1. Do you enable the following configs?
>> CONFIG_SPARSEMEM
>> MEMORY_HOTPLUG
>> CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
> Yes, these configs are enabled
>>
>> 2. I find you missed create mapping in arch_add_memory(), and x86 has it.
> Could you please explain this further?  The patch I submitted hass arch_add_memory identical to the ia64 implementation.

Hi Scott,

I think we should create page table first for the new hotadd memory.
e.g. create_mapping_late(start, __phys_to_virt(start), size, PAGE_KERNEL);

I don't know why ia64 don't have this step.
CC Tony

>>
>> 3. We will add memblock first, so pfn_valid() maybe always return true(in the
>> following function), and this will lead __add_section() failed. Please check
>> it.
> You are correct - pfn_valid always returns true.  The function is in arch/arm64/mm/init.c and different than the one you indicated below:
> 

> #ifdef CONFIG_HAVE_ARCH_PFN_VALID
> int pfn_valid(unsigned long pfn)
> {
>     return memblock_is_map_memory(pfn << PAGE_SHIFT);
> }
> EXPORT_SYMBOL(pfn_valid);
> #endif
> 
>>
>> int pfn_valid(unsigned long pfn)
>> {
>>     return (pfn & PFN_MASK) == pfn && memblock_is_memory(pfn << PAGE_SHIFT);
>> }
>>
>> add_memory
>>   add_memory_resource
>>     memblock_add_node
>>       arch_add_memory
>>         __add_pages
>>           __add_section
>>             pfn_valid
>>
>> Thanks,
>> Xishi Qiu
>>
>>>
>>>
>>>>
>>>> Thanks,
>>>> Xishi Qiu
>>>>
>>>>> Scott Branden (2):
>>>>>   arm64: memory-hotplug: Add MEMORY_HOTPLUG, MEMORY_HOTREMOVE,
>>>>>     MEMORY_PROBE
>>>>>   arm64: defconfig: enable MEMORY_HOTPLUG config options
>>>>>
>>>>>  arch/arm64/Kconfig           | 10 ++++++++++
>>>>>  arch/arm64/configs/defconfig |  3 +++
>>>>>  arch/arm64/mm/init.c         | 42 ++++++++++++++++++++++++++++++++++++++++++
>>>>>  3 files changed, 55 insertions(+)
>>>>>
>>>>
>>>>
>>>>
>>>
>>> .
>>>
>>
>>
>>
> 
> .
> 

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#1534761

Hello,

Recently we have announced our effort on that:
https://lkml.org/lkml/2016/11/17/49

For now we have a working solution for hotplug and we are performing
code cleanup to push the patches soon.

BR,

On 02/12/2016 01:19, Scott Branden wrote:
> This patchset is sent for comment to add memory hotplug support for ARM64
> based platforms.  It follows hotplug code added for other architectures
> in the linux kernel.
> 
> I tried testing the memory hotplug feature following documentation from
> Documentation/memory-hotplug.txt.  I don't think it is working as expected
> - see below:
> 
> To add memory to the system I did the following:
> echo 0x400000000 > /sys/devices/system/memory/probe
> 
> The memory is displayed as system ram:
> cat /proc/iomem:
> 74000000-77ffffff : System RAM
>   74080000-748dffff : Kernel code
>   74950000-749d2fff : Kernel data
> 400000000-43fffffff : System RAM
> 
> But does not seem to be added to the kernel memory.
> /proc/meminfo did not change.
> 
> What else needs to be done so the memory is added to the kernel memory
> pool for normal allocation?
> 
> Scott Branden (2):
>   arm64: memory-hotplug: Add MEMORY_HOTPLUG, MEMORY_HOTREMOVE,
>     MEMORY_PROBE
>   arm64: defconfig: enable MEMORY_HOTPLUG config options
> 
>  arch/arm64/Kconfig           | 10 ++++++++++
>  arch/arm64/configs/defconfig |  3 +++
>  arch/arm64/mm/init.c         | 42 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 55 insertions(+)
> 

-- 
Maciej Bielski

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#1534835

On Fri, Dec 02, 2016 at 10:13:43AM +0100, Maciej Bielski wrote:
> Recently we have announced our effort on that:
> https://lkml.org/lkml/2016/11/17/49
> 
> For now we have a working solution for hotplug and we are performing
> code cleanup to push the patches soon.

Are these intended to replace or extend Scott's patches? If the former,
please work with Scott's stuff as a base rather than posting a competing
series.

Will

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#1534839

On 02/12/2016 11:49, Will Deacon wrote:
> On Fri, Dec 02, 2016 at 10:13:43AM +0100, Maciej Bielski wrote:
>> Recently we have announced our effort on that:
>> https://lkml.org/lkml/2016/11/17/49
>>
>> For now we have a working solution for hotplug and we are performing
>> code cleanup to push the patches soon.
> Are these intended to replace or extend Scott's patches? If the former,
> please work with Scott's stuff as a base rather than posting a competing
> series.
In the piece of code provided by Scott I have seen similar steps to what
is done by us but our work went further since we have the mapping
created and everything is working via the sysfs interface. I am now
having closer look and comparing them.
>
> Will

-- 
Maciej Bielski

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#1535102

Hi Maciej,

On 16-12-02 02:55 AM, Maciej Bielski wrote:
>
>
> On 02/12/2016 11:49, Will Deacon wrote:
>> On Fri, Dec 02, 2016 at 10:13:43AM +0100, Maciej Bielski wrote:
>>> Recently we have announced our effort on that:
>>> https://lkml.org/lkml/2016/11/17/49
>>>
>>> For now we have a working solution for hotplug and we are performing
>>> code cleanup to push the patches soon.
>> Are these intended to replace or extend Scott's patches? If the former,
>> please work with Scott's stuff as a base rather than posting a competing
>> series.
> In the piece of code provided by Scott I have seen similar steps to what
> is done by us but our work went further since we have the mapping
> created and everything is working via the sysfs interface. I am now
> having closer look and comparing them.

I would love to see the missing section mapping step and any other 
additions to test out.  Please send additions as soon as you have a chance.

Regards,
  Scott

>>
>> Will
>

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