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

[Changsheng Liu]

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.
     ThanksïI will update the patch and repost it
> On Tue, 15 Sep 2015 03:49:58 -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"
> >
> > Signed-off-by: Xiaofeng Yan <yanxiaofeng@xxxxxxxxxx>
> > Signed-off-by: Changsheng Liu <liuchangcheng@xxxxxxxxxx>
> > Tested-by: Dongdong Fan <fandd@xxxxxxxxxx>
> > ---
> >   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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