Re: [PATCH] Memory hot added,The memory can not been added to movable zone

[Changsheng Liu <liuchangsheng@inspur.com>]

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a?? 2015/8/25 19:13, Vlastimil Babka a??e??:
> On 08/25/2015 12:25 PM, Changsheng Liu wrote:
>> Thanks very much for your review, I can move the memory from normal zone
>> to movable zone succesfully.
>> And thank you for let me understand the memory mechanism better.
>> a?? 2015/8/25 3:15, Yasuaki Ishimatsu a??e??:
>
> So you agree to drop the patch from -mm?
     The patch using movable_node_is_enabled() will provide a more 
direct approach to add the hot-added memory to movable zone If we want 
to remove the whole node.
>>> Hi
>>> On Thu, 20 Aug 2015 14:15:13 +0800
>>> Changsheng Liu <liuchangsheng@inspur.com> wrote:
>>>
>>>> Hi Andrew Morton:
>>>> First, thanks very much for your review, I will update codes according
>>>> to  your suggestio
>>>>
>>>> a?? 2015/8/20 7:50, Andrew Morton a??e??:
>>>>> On Wed, 19 Aug 2015 04:18:26 -0400 Changsheng Liu 
>>>>> <liuchangsheng@inspur.com> wrote:
>>>>>
>>>>>> From: Changsheng Liu <liuchangcheng@inspur.com>
>>>>>>
>>>>>> When memory hot added, the function should_add_memory_movable
>>>>>> always return 0,because the movable zone is empty,
>>>>>> so the memory that hot added will add to normal zone even if
>>>>>> we want to remove the memory.
>>>>>> So we change the function should_add_memory_movable,if the user
>>>>>> config CONFIG_MOVABLE_NODE it will return 1 when
>>>>>> movable zone is empty
>>>>> I cleaned this up a bit:
>>>>>
>>>>> : Subject: mm: memory hot-add: memory can not been added to 
>>>>> movable zone
>>>>> :
>>>>> : When memory is hot added, should_add_memory_movable() always 
>>>>> returns 0
>>>>> : because the movable zone is empty, so the memory that was hot 
>>>>> added will
>>>>> : add to the normal zone even if we want to remove the memory.
>>>>> :
>>>>> : So we change should_add_memory_movable(): if the user config
>>>>> : CONFIG_MOVABLE_NODE it will return 1 when the movable zone is 
>>>>> empty.
>>>>>
>>>>> But I don't understand the "even if we want to remove the memory".
>>>>> This is hot-add, not hot-remove.  What do you mean here?
>>>>        After the system startup, we hot added one memory. After 
>>>> some time
>>>> we wanted to hot remove the memroy that was hot added,
>>>>        but we could not offline some memory blocks successfully 
>>>> because
>>>> the memory was added to normal zone defaultly and the value of the 
>>>> file
>>>>        named removable under some memory blocks is 0.
>>> For this, we prepared online_movable. When memory is onlined by 
>>> online_movable,
>>> the memory move from ZONE_NORMAL to ZONE_MOVABLE.
>>>
>>> Ex.
>>> # echo online_movable > /sys/devices/system/memory/memoryXXX/state
>>>
>>> Thanks,
>>> Yasuaki Ishimatsu
>>>
>>>>        we checked the value of the file under some memory blocks as 
>>>> follows:
>>>>        "cat /sys/devices/system/memory/ memory***/removable"
>>>>        When memory being hot added we let the memory be added to 
>>>> movable
>>>> zone,
>>>>        so we will be able to hot remove the memory that have been 
>>>> hot added
>>>>>> --- a/mm/memory_hotplug.c
>>>>>> +++ b/mm/memory_hotplug.c
>>>>>> @@ -1198,9 +1198,13 @@ static int should_add_memory_movable(int 
>>>>>> nid, u64 start, u64 size)
>>>>>>         pg_data_t *pgdat = NODE_DATA(nid);
>>>>>>         struct zone *movable_zone = pgdat->node_zones + 
>>>>>> ZONE_MOVABLE;
>>>>>>
>>>>>> -    if (zone_is_empty(movable_zone))
>>>>>> +    if (zone_is_empty(movable_zone)) {
>>>>>> +    #ifdef CONFIG_MOVABLE_NODE
>>>>>> +        return 1;
>>>>>> +    #else
>>>>>>             return 0;
>>>>>> -
>>>>>> +    #endif
>>>>>> +    }
>>>>>>         if (movable_zone->zone_start_pfn <= start_pfn)
>>>>>>             return 1;
>>>>> Cleaner:
>>>>>
>>>>> --- 
>>>>> a/mm/memory_hotplug.c~memory-hot-addedthe-memory-can-not-been-added-to-movable-zone-fix
>>>>> +++ a/mm/memory_hotplug.c
>>>>> @@ -1181,13 +1181,9 @@ static int should_add_memory_movable(int
>>>>>         pg_data_t *pgdat = NODE_DATA(nid);
>>>>>         struct zone *movable_zone = pgdat->node_zones + ZONE_MOVABLE;
>>>>>
>>>>> -    if (zone_is_empty(movable_zone)) {
>>>>> -    #ifdef CONFIG_MOVABLE_NODE
>>>>> -        return 1;
>>>>> -    #else
>>>>> -        return 0;
>>>>> -    #endif
>>>>> -    }
>>>>> +    if (zone_is_empty(movable_zone))
>>>>> +        return IS_ENABLED(CONFIG_MOVABLE_NODE);
>>>>> +
>>>>>         if (movable_zone->zone_start_pfn <= start_pfn)
>>>>>             return 1;
>>>>>
>>>>> _
>>>>>
>>>>> .
>>>>>
>>> .
>>>
>>
>
> .
>


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