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

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Date:	Tue, 03 Nov 2015 08:13:57 -0800 (PST)
From:	Yasuaki Ishimatsu <yasu.isimatu@...il.com>
To:	Changsheng Liu <liuchangsheng@...pur.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

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.

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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