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Message-ID: <55DC4DC3.30509@suse.cz>
Date: Tue, 25 Aug 2015 13:13:07 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Changsheng Liu <liuchangsheng@...pur.com>,
Yasuaki Ishimatsu <yasu.isimatu@...il.com>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: isimatu.yasuaki@...fujitsu.com, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, yanxiaofeng@...pur.com,
Changsheng Liu <liuchangcheng@...pur.com>
Subject: Re: [PATCH] Memory hot added,The memory can not been added to movable
zone
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.
> 在 2015/8/25 3:15, Yasuaki Ishimatsu 写道:
So you agree to drop the patch from -mm?
>> Hi
>> On Thu, 20 Aug 2015 14:15:13 +0800
>> Changsheng Liu <liuchangsheng@...pur.com> wrote:
>>
>>> Hi Andrew Morton:
>>> First, thanks very much for your review, I will update codes according
>>> to your suggestio
>>>
>>> 在 2015/8/20 7:50, Andrew Morton 写道:
>>>> On Wed, 19 Aug 2015 04:18:26 -0400 Changsheng Liu <liuchangsheng@...pur.com> wrote:
>>>>
>>>>> From: Changsheng Liu <liuchangcheng@...pur.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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