Re: [PATCH V4] mm: memory hot-add: memory can not be added to movable zone defaultly

[Changsheng Liu]

On 9/1/2015 23:37, Yasuaki Ishimatsu wrote:
> On Mon, 31 Aug 2015 01:58:40 -0400
> Changsheng Liu <liuchangsheng@xxxxxxxxxx> wrote:
>
> > From: Changsheng Liu <liuchangcheng@xxxxxxxxxx>
> >
> > 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"
> >
> > If the memory is added to movable zone defaultly,
> > the user can offline it and add it to other zone again.
> > But if the memory is added to normal zone defaultly,
> > the user will not offline the memory used by kernel.
> >
> > Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > Reviewed-by: Yasuaki Ishimatsu <yasu.isimatu@xxxxxxxxx>
> > Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
> > Reviewed-by: Xiaofeng Yan <yanxiaofeng@xxxxxxxxxx>
> > Signed-off-by: Changsheng Liu <liuchangcheng@xxxxxxxxxx>
> > Tested-by: Dongdong Fan <fandd@xxxxxxxxxx>
> > ---
> >   mm/memory_hotplug.c |    5 +++++
> >   1 files changed, 5 insertions(+), 0 deletions(-)
> >
> > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> > index 26fbba7..d1149ff 100644
> > --- a/mm/memory_hotplug.c
> > +++ b/mm/memory_hotplug.c
> > @@ -1197,6 +1197,11 @@ 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 *normal_zone = pgdat->node_zones + ZONE_NORMAL;
> > +
> > +	if (movable_node_is_enabled()
> > +	&& (zone_end_pfn(normal_zone) <= start_pfn))
> > +		return 1;
> If system boots up without movable_node, kernel behavior is changed by the patch.
> And you syould consider other zone.
>
> How about it. The patch is no build and test.
    Thanks for your suggestion. We will test the patch on our platform
> ---
>   mm/memory_hotplug.c |   36 ++++++++++++++++++++++++++++++++----
>   1 files changed, 32 insertions(+), 4 deletions(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 6da82bc..321595d 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1198,6 +1198,8 @@ 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_zone and added memory does not overlap
> + * other zone except for 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)
> @@ -1205,14 +1207,40 @@ 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 *zone;
> +	enum zone_type zt = ZONE_MOVABLE - 1;
> +
> +	/*
> +	 * If memory is added after ZONE_MOVALBE, the memory is managed as
> +	 * movable.
> +	 */
> +	if (!zone_is_empty(movable_zone) &&
> +	    (movable_zone->zone_start_pfn <= start_pfn))
> +		return 1;
>   
> -	if (zone_is_empty(movable_zone))
> +	if (!movable_node_is_enabled())
>   		return 0;
>   
> -	if (movable_zone->zone_start_pfn <= start_pfn)
> -		return 1;
> +	/*
> +	 * Find enabled zone and check the added memory.
> +	 * If the memory is added after the enabled zone, the memory is
> +	 * managed as movable.
> +	 *
> +	 * If all zones are empty, the memory is also managed as movable.
> +	 */
> +	for (; zt >= ZONE_DMA; zt--) {
> +		zone = pgdat->node_zones + zt;
>   
> -	return 0;
> +		if (zone_is_empty(zone))
> +			continue;
> +
> +		if (zone_end_pfn(zone) <= start_pfn)
> +			return 1;
> +		else
> +			return 0;
> +	}
> +
> +	return 1;
>   }
>   
>   int zone_for_memory(int nid, u64 start, u64 size, int zone_default)

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/