linux-kernel - Re: [PATCH V5] mm: memory hot-add: memory can not be added to movable zone defaultly

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Message-ID: <5639710F.7040103@inspur.com>
Date:	Wed, 4 Nov 2015 10:44:31 +0800
From:	Changsheng Liu <liuchangsheng@...pur.com>
To:	Yasuaki Ishimatsu <yasu.isimatu@...il.com>
CC:	<akpm@...ux-foundation.org>, <isimatu.yasuaki@...fujitsu.com>,
	<vbabka@...e.cz>, <linux-mm@...ck.org>,
	<linux-kernel@...r.kernel.org>, <wunan@...pur.com>,
	<yanxiaofeng@...pur.com>, <fandd@...pur.com>,
	"Changsheng Liu" <liuchangcheng@...pur.com>
Subject: Re: [PATCH V5] mm: memory hot-add: memory can not be added to movable
 zone defaultly



On 11/4 2015 0:13, Yasuaki Ishimatsu wrote:
> Hi Changsheng,
>
> According to the following thread, Tang has no objection to change kernel
> behavior since udev cannot online memory as movable.
>
> https://lkml.org/lkml/2015/10/21/159
>
> So how about reposting the v5 patch?
> I have a comment about the patch. Please see below.
      Thanks，I will update the patch and repost it
> On Tue, 15 Sep 2015 03:49:58 -0400
> Changsheng Liu <liuchangsheng@...pur.com> wrote:
>
>> From: Changsheng Liu <liuchangcheng@...pur.com>
>>
>> .After the user config CONFIG_MOVABLE_NODE and movable_node kernel option,
>> When the memory is hot added, should_add_memory_movable() return 0
>> because all zones including movable zone are empty,
>> so the memory that was hot added will be added  to the normal zone
>> and the normal zone will be created firstly.
>> But we want the whole node to be added to movable zone defaultly.
>>
>> So we change should_add_memory_movable(): if the user config
>> CONFIG_MOVABLE_NODE and movable_node kernel option
>> it will always return 1 and all zones is empty at the same time,
>> so that the movable zone will be created firstly
>> and then the whole node will be added to movable zone defaultly.
>> If we want the node to be added to normal zone,
>> we can do it as follows:
>> "echo online_kernel > /sys/devices/system/memory/memoryXXX/state"
>>
>> Signed-off-by: Xiaofeng Yan <yanxiaofeng@...pur.com>
>> Signed-off-by: Changsheng Liu <liuchangcheng@...pur.com>
>> Tested-by: Dongdong Fan <fandd@...pur.com>
>> ---
>>   mm/memory_hotplug.c |    8 ++++++++
>>   1 files changed, 8 insertions(+), 0 deletions(-)
>>
>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>> index 26fbba7..d39dbb0 100644
>> --- a/mm/memory_hotplug.c
>> +++ b/mm/memory_hotplug.c
>> @@ -1190,6 +1190,9 @@ static int check_hotplug_memory_range(u64 start, u64 size)
>>   /*
>>    * If movable zone has already been setup, newly added memory should be check.
>>    * If its address is higher than movable zone, it should be added as movable.
>> + * And if system boots up with movable_node and config CONFIG_MOVABLE_NOD and
>> + * added memory does not overlap the zone before MOVABLE_ZONE,
>> + * the memory is added as movable
>>    * Without this check, movable zone may overlap with other zone.
>>    */
>>   static int should_add_memory_movable(int nid, u64 start, u64 size)
>> @@ -1197,6 +1200,11 @@ static int should_add_memory_movable(int nid, u64 start, u64 size)
>>   	unsigned long start_pfn = start >> PAGE_SHIFT;
>>   	pg_data_t *pgdat = NODE_DATA(nid);
>>   	struct zone *movable_zone = pgdat->node_zones + ZONE_MOVABLE;
>> +	struct zone *pre_zone = pgdat->node_zones + (ZONE_MOVABLE - 1);
>> +
>> +	if (movable_node_is_enabled()
>> +	&& zone_end_pfn(pre_zone) <= start_pfn)
>> +		return 1;
> 	if (movable_node_is_enabled() && (zone_end_pfn(pre_zone) <= start_pfn))
>
> Thanks,
> Yasuaki Ishimatsu
>
>>   
>>   	if (zone_is_empty(movable_zone))
>>   		return 0;
>> -- 
>> 1.7.1
>>
> .
>

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